E85 SR20 weird misfire wall

[MikeE36]

Hey dudes,

Just had my S13 SR dyno tuned by RS-Enthalpy a few weeks ago and it made 390 rwhp and 300 rwtq @ 22 psi on E85. Now a few weeks later i've started having a weird misfire issue, and now a lean issue. I'm hoping someone can help point me in the right direction as I'm new to SR20s and S-chassis cars. (But love them so far when its running right!)

-S13 redtop SR20DET
-9:1 wiseco pistons, stock rods
-Apexi metal hg
-ARP head studs
-GT2871 .64 A/R
-freddy intake, ISIS exhaust mani
-no bov
-ISIS FMIC
-ISIS Z32 MAF (recently replaced with OEM Z32, more on that in a minute)
-BC springs/ Ti retainers / 272 cams (need degreeing badly, thus the low torque and low power for these cams.)
-Walbro 400 E85 pump
-System 1 SS inline E85 filter
-Five O 1200cc side feeds
-Splitfire coil packs
-NGK BKR7E @ .025" gap
-SARD FPR regulator + gauge
-stock ECU tuned by RS-Enthalpy on the dyno
-new ignition switch
-excessive grounding with huge cable directly to battery, block, intake manifold, and shock tower. All 4 ga or larger.
-timing set at 20* BTDC as per RS-Enthalpy's suggestion for E85 use
-fuel pump relayed directly to battery with 40A relay. A small section of stock wiring that goes through the bulkhead was retained. Not sure if I need to replace this now or what but it's another consideration

I think that is the most relevant stuff for the setup. Please let me know if I missed any important details.

Car ran flawlessly for the past few weeks after getting it tuned. I've probbaly run 6 or 7 tanks of E85 through it and changed the oil once or twice and all looked good. I'm spinning it to 8000 rpm and running 22-23 psi constantly and it feels great and spins hard all through 2nd gear and sometimes a little in 3rd on on-ramps.

Anyways, other day it was pretty hot out (like everyday in Texas) and I was doing a 2nd gear pull, and the car didn't really spin as hard and just took off but still pulled really hard. I thought it was interesting that it didn't spin, and maybe I was just getting great traction because it was hot outside.

Later that day I gave a buddy of mine a ride and it pulled great but didn't spin 2nd again (maybe extra weight in the car and back seat, dunno), then shifted to 3rd and around 7800rpm in 3rd it felt like it hit an early rev limiter, I heard a pop like bumping into the rev limiter, and the power fell flat on its face. I shifted to 4th and it seemed ok boosting in 4th but I got out of the power just because I was a little nervous about it. Did one more high RPM 1st gear rip before going home and it cut out really badly, the same as it did a few minutes earlier at the top of 3rd. Parked it and didn't know what to think.

Now this high RPM misfire wall came back that next day, although only after a couple of back to back pulls giving a friend a ride, and then again last pull in 1st gear it cut out badly, like it was starving for fuel almost. (Felt exactly like fuel slosh with a low fuel tank and losing fuel at the pickup for a second - just no power and falls on its face)

Idle, cruise, and everything else was still fine. Pulled the same 17" hg it did from the beginning with these cams. It can also free rev easily to redline, so I figured the problem was load dependent, meaning MAF or fuel delivery or something.

-Cleaned System 1 filter and found basically nothing in there. It looked perfect.
-Pulled fuel pump and checked the filter sock, and although it was somewhat dark/discolored, I back flowed some water through it and it seemed to flow fine. I will likely replace this and the pump soon just for the hell of it.
-Idle fuel pressure is great. Not sure on boost since gauge is under the hood
-replaced ISIS MAF with OEM Z32 MAF and driveability improved, but misfire wall was still there. 0.8 V key ON engine OFF. 1.4 V at idle
-checked TPS, 0.5 v closed, 4.08 V at WOT. Seemingly smooth voltage increase throughout the range.
-changed plugs to new BKR7E @ .025" gap. Smoother idle and crisper throttle but still had the high RPM issue
-checked compression and around 140-145 across all cylinders still cold. Seems fine.
-Boost leak tested to 20psi and sprayed soapy water on all connections and found zero leaks at all.
-tried to verify 20* timing but with my full fan shroud on I can't see the marks. I will do that later today.

So at this point I'm a bit stuck. I've read that the stock SR20 cars in japan all had ignition relays, and when swapping them to USDM cars, you lose the ignition relay and basically just have the ignition driven straight off the ignition switch. This seems pretty likely to fail on a car from 1989, just like my starter wire did. (I wired up a ford starter relay to use to power the solenoid because after driving and getting the car hot it wouldn't carry enough current to start the car - maybe same issue here?)

I've also read that splitfire coil packs can randomly go out and cause issues, so I am going to put stock coils back on and see if they work. I have turned the boost down to 10psi on the wastegate spring for testing all this so I don't blow things up and it still does the issue at 6k in 1st gear now. (Seemingly has gotten worse since the issue started).

Another thing i've read is a baffle in the fuel tank can break loose, or maybe I am starving the fuel pump baffle area because the Walbro 400 pumps so much fuel and the return line isn't dumping into the baffle or something? Not really sure there either. Another thing to check. If the baffle people are talking about is just the bucket the pump sits in then it seems to still be in the right place. My fuel gauge definitely does not read correctly though (stays at Full or way past for quite a few gallons burnt) which was another thing mentioned in some other thread.

I also recently regrounded the OEM Z32 MAF to a separate ground on the shock tower in an attempt to fix things and it didn't seem to make any difference. The cars idle stays around 1100-1200 and maybe bounces 50-75 rpm but minimally. Driveability and downshift blips are really crisp and great so I think the MAF/airflow side of things is working well. When I got into boost it didn't cut out today, but it ran lean. When stomped at WOT from 2000-2500rpm it immediately went to a WOT map and AFR dropped to around 11.5, but then rose to 13-14 in boost at 4-5-6-7k rpm and was just running lean. Is it possible my Walbro 400 has died or is on it's way out, or that filter sock is actually clogged? It didn't FEEL like a misfire, but I know misfires can also show lean on the wideband, indicating maybe a problem with the splitfire coil packs.


Sorry for the novel, lots of troubleshooting and lots of explaining to do. Any and all insight and suggestions are appreciated. The car runs awesome, just not at high load atm. I'm leaning towards fuel pump, just really surprised it would fail within <10 tanks of E85.

Thanks guys,

Mike

Pics of car in question for fun:

http://i192.photobucket.com/albums/z109/MikeE36/6tag_230614-201012_zps48a01d01.jpg (http://s192.photobucket.com/user/MikeE36/media/6tag_230614-201012_zps48a01d01.jpg.html)
http://i192.photobucket.com/albums/z109/MikeE36/6tag_160714-093547_zps4dde9cf6.jpg (http://s192.photobucket.com/user/MikeE36/media/6tag_160714-093547_zps4dde9cf6.jpg.html)
http://i192.photobucket.com/albums/z109/MikeE36/6tag_090614-104203_zps30954bf8.jpg (http://s192.photobucket.com/user/MikeE36/media/6tag_090614-104203_zps30954bf8.jpg.html)

[ultimateirving]

Some things i have battled with e85 and higher boost.
I saw you have splitfires so that's good, have ou taken the plugs out at all to see if there is any evidence of a problem?
One thing I noticed and you can call me crazy but with the ls2 coilpacks and e85 I was getting hella break up on copper plugs.

I had to switch to the iridium to get any kind of reliable pulls thru the whole rpm range. The day I switched from copper to iridium it was like a switch was flipped and the car pulled to redline with 0 hiccups. I run a similar setup to you except I'm on stock longblock.

[Dboyizmlg]

Sell those splitfire coil packs! They are junk.

Put OEM one on and check that out

[MikeE36]

Sell those splitfire coil packs! They are junk.

Put OEM one on and check that out

So I put the OEM coil harness on and grounded it well. I found out the splitfire ground actually wasn't in the greatest spot as I mounted the little blue box in the car near the ECU, and the bolt it was grounded on was stripped/not fully tight. I went ahead with the OEM coils and grounded them very well to a main spot on my intake manifold, which goes direct to batt.

I also redid some connections at the fuel pump wiring that the PO of the car didn't do all that well, and maybe it was a coincidence or a cooler day and my liquid-filled gauge reading higher but my fuel pressure came up a few psi at idle and seemed solid. On a throttle blip it would easily hit 45psi or so which seems fine. I went ahead and ordered a new Walbro 400 and filter sock anyway to replace tomorrow just to rule it out entirely on load.

The car still seems to stumble when throttle blipped, at least cold for sure. I'm not sure if I have a coolant temp sensor problem, or knock sensor problem, or what else it could really be? I want to get a nissan consult datalogging setup but i'm also trying not to just throw money at it blindly if I don't have to. Worst case scenario if this Walbro 400 is fine, I will use the spare as a lift pump in my M3.

Any more suggestions greatly appreciated. I'm testing several more things tomorrow and replacing pump/filter sock, pulling fan shroud to verify timing with a light, and double checking MAF/MAF wiring and maybe trying a 3rd maf, although voltage seems fine on the output wire at 1.4V at idle.

I miss driving this thing already. Hopefully I figure it out soon and it's solid for awhile.

Mike

[Dboyizmlg]

If it's only happening when it's cold (72C and under), it's normal for it to stumble.

Mine does it all the time when cold, at about 72-73c it's fine and doesn't stumble what so ever.

[MikeE36]

Swapped out to brand new Walbro 400 E85 and new filter sock. Fuel pressure is great, warmed it up and went for a drive and it drove basically flawless until I got on it at WOT and it still cut out at 6k. I really have no idea what to think at this point. I guess I'm going to replace the knock sensor and coolant temp sensor, but my understanding was that the knock sensor isn't active above 4500 rpm anyway, and the coolant temp sensor failing would cause me to run rich all the time, not lean.

Is there anything else I can test? It seems to drive flawlessly until I go WOT. It will rev to 8k no problem at lighter throttle, just not on load.

Mike

[z2roll4life7]

Gap the plugs down to .10 then report back and didn't see if you changed the fuel filter try that as well
FYI i had what you were describing past 17 psi on my 3071r gapped my plugs down to .18 and was fine till 20 now at 24 psi I run .11 gap.

[MikeE36]

Gap the plugs down to .10 then report back and didn't see if you changed the fuel filter try that as well
FYI i had what you were describing past 17 psi on my 3071r gapped my plugs down to .18 and was fine till 20 now at 24 psi I run .11 gap.

It's not spark blowout. It's more of a lean in WOT and complete loss of power at 6k. A spark blowout misfire feels completely different. This is like hitting the brakes.

Also, do you mean .011" gap? That seems extremely low. I have them at .025" gap currently and <50 miles on the plugs. My gapping tool only goes down to .018".

Pulled knock sensor today and the wire seems fine, and the ground shielding on the ECU side of the plug has continuity to ground, so that's good. I was going to replace the knock sensor and coolant temp sensor just for the hell of it today, but I keep reading that the knock sensor turns off around 4800 or 5000 rpm, so that wouldn't really explain an issue above that.

Would a failing coolant temp sensor cause the car to somehow think it is too hot and run lean all the time? I know usually when they fail the car runs rich, didn't know if it could possibly do the opposite or not.


So to recap:

-compression good
-injectors good
-inline fuel filter spotless
-brand new walbro 400 and filter sock, no change (relayed to battery with good voltage)
-Z32 MAF and ISIS Z32 MAF both have issue. Trying another Z32 MAF
-problem happens on both splitfire and stock coil packs
-TPS voltage checks out
-MAF voltage KEY on engine OFF and engine ON both check out (0.8V, 1.4V)
-Fuel pressure is good, around 38 psi at idle. Maybe a little high but certainly not LOW causing a lean condition
-No boost leaks tested to 20psi

Problem occurs only at WOT, and at about 6k RPM on low boost (10psi).
Car can still rev to 8k fine at partial throttle, just at WOT it now hits a wall

Anything else I can test?


Another thing I should mention - the voltage sense wire on my Quest alternator had a loose connection due to a missing plastic piece on the back of the connector, so it was intermittently overvoltaging when testing the other day at idle. I have fixed it and now it holds a solid 14V again, but I dont know if I could have potentially fried anything when it did that for a bit going 14-16-17V, back to 14. I don't really have any idea how long that's been an issue but it is fixed now. (Still have to rev the car to 3k to get it to start charging though)

Thanks guys,

Mike

[Dboyizmlg]

Gap spark plugs down to .20-.22 give that a shot.
Don't buy things you might not need... ECT for example

[z2roll4life7]

.011 is small but it works good if you're running a lot of boost. it sounds like you're either having spark blowout or you are maxing out your maf More pressure doesn't equal more flow. you need to data log what your maf voltage is at wide-open where your having your issues
Side note I use feeler gauges to gap my plug more accurate in my opinion.

[ultimateirving]

.11 is rediculous for his low boost. I was running .028 with the stock coils on 15psi for a long time just fine.
It's hard to say what the wall you're running into is. Can you film or record in cabin while you're driving for some sound/visual


Also I know i had a noticeable improvement using iridium plugs with e85 over the copper ones. Especially on the stock coilpacks

Try it out it's cheap for a set of plugs

[z2roll4life7]

.11 is rediculous for his low boost. I was running .028 with the stock coils on 15psi for a long time just fine.
It's hard to say what the wall you're running into is. Can you film or record in cabin while you're driving for some sound/visual


Also I know i had a noticeable improvement using iridium plugs with e85 over the copper ones. Especially on the stock coilpacks

Try it out it's cheap for a set of plugs

you are correct but its just test to rule out blowout completely
do you have a working consult port OP? some data logs would help alot

[MikeE36]

I put everything back together (knock sensor, coolant temp sensor plug, rewired MAF) and now it won't idle at all. It will rev, go up to 1500 or 2000 for cold start, then when it drops it just sputters and falls through idle. Going to double check MAF sensor output voltage at idle. I unplugged the coolant temp sensor and replugged... but I haven't inspected that part of the harness. Is it possible a break is causing it to do weird things now? It seems really odd that the problem would all of a sudden get much worse and now it is rough and misfires at idle too.

.011" plug gap on anything less than 40psi boost and 1000hp seems retarded. My BMW makes 600whp @ .018". I know I don't need to run .011" on this thing for 300wtq.

Another ignition related question - I've read that these cars with SR swaps into USDM cars don't have ignition relays, and the ignition power is essentially coming directly from the ignition switch. Do most people just run like this? Should I add a relay to batt for ignition power to get better spark? I've read the splitfires actually don't amplify the spark and are more of just a stock replacement.

Thinking again out loud here - since the CAS controls the fuel injector pulses, as well as the ignition firing, as long as it starts, the CAS is functioning right? Can a partially failed/failing CAS cause an intermittent misfire but still run the car?

Any other suggestions are greatly appreciated. Thanks so far guys.

I just got my AC bracket and everything ready to go - my car must know and is trying to sabotage me :facepalm:

Also one last thing, the consult port. I do not have one working yet, but I am considering getting a cable and software to log, since I think that would be by far the easiest way to troubleshoot by seeing exactly what the ECU is seeing. Do you recommend a specific cable? I have heard of PLMS developments, BlazT cables and Nissan DataScan for logging software. Is that the most common program to use?

Mike

[MikeE36]

So I put the splitfire coil packs back on because the OEM ones I have are in really bad shape and I figure they can't be helping. My idle definitely got worse when I went from splitfire to these OEM, so I put splitfire back on.

I also inspected and rewrapped the CAS wiring and it was still doing the sputtering and bad idle thing... on an OEM Z32 MAF I got on CL. I got it to stay alive long enough for my wideband to register and it was showing 14-16.00 (max lean, usually misfire or just super lean), so I thought maybe MAF since fuel pressure is fine.

I decided to throw my ISIS MAF back on and try it, and it initially stumbled and stuttered, so I winged it up to 3200 rpm and it seemed to clear out a bunch of fuel/crap in the exhaust from it misfiring before, then it started idling and running fine. I drove it around the block and other than it catching idle like crap due to the ISIS MAF, it seemed to work again? At WOT at 10 psi it was still showing lean around 13.5 AFR so I didn't run it all the way out. Idle was around 14.5 and seemed fine. I have noticed the ISIS MAF seems to cruise a little leaner too than an OEM Z32 MAF. Not sure why.

I'm going to put another OEM Z32 MAF on now and see if it works better than the ISIS. I'm guessing I killed the other OEM maf from the overvoltaging I was talking about earlier.

Also, I have read threads about drift cars and others breaking the "fuel tank baffle" or some having to remove it for enough fuel pump flow, etc. Does anyone know where this baffle is, or are they just talking about the bucket the pump sits in?

Thanks!

Mike

[ultimateirving]

Mike your symptoms getting worse could point to a failing connection or sensor. And if you wiring harness is oem at all it definitely could be brittle. It seems like you did a full build on this motor, but having a lot of problems. What do the plugs look like now after all this misfiring and bad idling ? I know mine turn black pretty fast.
I have also heard some not so great things about the Isis maf see if you have a known good oem z32 maf you can use

[MikeE36]

Mike your symptoms getting worse could point to a failing connection or sensor. And if you wiring harness is oem at all it definitely could be brittle. It seems like you did a full build on this motor, but having a lot of problems. What do the plugs look like now after all this misfiring and bad idling ? I know mine turn black pretty fast.
I have also heard some not so great things about the Isis maf see if you have a known good oem z32 maf you can use


Put a 3rd known good OEM Z32 MAF on, as well as another set of NGK BKR7E (no one has the iridiums in stock local. I will have to order but im 99% thats not the issue at the moment) @ .022" gap and driveability is perfect again.... but it still has the WOT problem.

I can go WOT from 2000 or 2500 RPM and it immediately barely sputters, then goes to 11.5 AFR and starts pulling great getting going for a split second, then leans out to 13-14 AFR and pulls like crap. I ran it all the way up one pull in 2nd gear at 10 psi and it still hit a random fuel cut wall somewhere around 6000-7000 rpm.

Car drives flawless, just at WOT it goes rich properly, then immediately leans out. After the drive, idle and everything else is fine.

Is it possible my fuel tank vent is clogged or something and is causing my fuel pump to work overtime to keep up with pressure on load? I have heard of people using an S14 fuel tank cap on their S13s for additional venting - does this work?

Going to swap in that new coolant temp sensor, knock sensor, and knock sensor harness for the hell of it since I already bought them.

I am thinking of trying a different FPR too because I am running out of ideas here. Maybe new CAS needed or adding an ignition relay.

Also I noticed today after my short drive, it took a LONG time of cranking to restart and normally restarts are nearly instant. I realize hot restarts on E85 are harder but this seemed a bit excessive.

Any other ideas greatly appreciated. I will get a Go Pro vid today of the issue so maybe you guys can see better. As soon as i go WOT, the AFR goes where it should around 11.5, but RIGHT after that it leans out to 13-14. It's almost like its hitting the WOT map for a split second, then something else is telling it to change maps to part throttle?

Maybe TPS or WOT switch is bad? Does the switch under the pedal do much / is it crucial? I have noticed I have to really push my pedal hard to hit that switch. I'm not sure of the control strat. on the SR20 ecu and if that switch is crucial and needs to be depressed in order to stay on the WOT map properly or not.

Thanks again guys!

Mike

[Dboyizmlg]

Read your original post again.

I noticed you mentioned you have a mis fire, which cylinder is mis firing?

[wawazat8402]

I don't believe the SR has a WOT map. It just uses TPS and MAF to calculate load and goes to that part of the map.

[RalliartRsX]

I feel like this points to a fuel related issue (be it a stuck injector, a loose wire, whatever).

You said the fuel system "checks out", but what exactly have you checked out?? For instance, just because the injector is seeing the correct spec voltage, does not negate the injector itself from physically being at fault.

[Def]

Hey Mike!

I'd honestly say it sounds like an ECU sensor that's throwing things off. Maybe coolant temp sensor? They seem to like to die a lot.

Really, the stock ECU kinda sucks for diagnostics, but if you are running one, I strongly suggest some sort of Consult setup to see sensors. That would rule out a ton of stuff in a few minutes.


Fuel pressure in boost might be an issue too. A black sock means it's probably pretty crudded up - might flow a little bit of water ok, but sucking a ton of E85 through it is bad news. So I'd replace that, plus the filter.


Full datalogging in a standalone makes a modded engine so easy to diagnose. I know it's an expensive solution, but hell, the stock ECU can sometimes be a pain to deal with when you've got a problem.

[MikeE36]

Alright small update tonight and a few more questions / cries for help. I have narrowed down the problem to electrical, and it seems voltage has still been fluctuating around.

I had a problem with the previous Quest alternator not charging until 3100 rpm, and I never had a battery light on the dash with key on, engine off. There was a problem at one time with this alternator overcharging the system, but that was when the connector was not seated properly.

I have since replaced the alternator, after investigating the battery light issue and reading the FSM extensively. I found this picture:

http://i192.photobucket.com/albums/z109/MikeE36/chargingsystem1_zps86e4e585.png (http://s192.photobucket.com/user/MikeE36/media/chargingsystem1_zps86e4e585.png.html)

I have both digital and analog clusters, and the speedo doesn't work in either one so I wanted to run the digital. I have since taken it apart and attempted to fix the speedo by replacing the known capacitor, but I haven't successfully done it yet due to the insanely small working area in there. Anyways, I was testing voltage on the digital harness, which shows I should have voltage across pins 17 and 12 on that harness as shown. Pin 17 is white/red wire that supposedly goes to the alternator, and somehow involves a "bulb check relay" in the wiring. More on that in a minute.

Pin 12 goes to the ignition switch, and is a green wire. It powers the entire cluster, so if you have power to any of the gauges, you have power on this wire just fine. I unplugged the cluster, and turned the key to the ON position, and I had voltage on pin 12 as expected, but I also experienced full 12v battery voltage at pin 17, which I did not expect. From my understanding the white/red wire goes directly from the output of the cluster to the alternator field wire connection, which essentially tells the alternator to charge by putting a small load on that wire through the bulb in the cluster. As soon as the alternator starts charging, it will output voltage at this wire and the voltage from the ignition switch side and alternator side being equal will prevent current flow through the bulb, which turns it off as soon as the car starts. My bulb however, has never lit since I've owned the car. Something is wrong. I have now changed to a new alternator, and have been experiencing voltage related issues with the way the car runs. I have not started the car since installing the new alternator, as I'd like to figure out why I don't have full lights on the dash when I key on in the first place. I want to fix everything to 100% OEM. I have the brake light working from the ebrake, so I would think that means the bulb check relay is working but I am not positive because I am confused by this diagram:

http://i192.photobucket.com/albums/z109/MikeE36/bulbcheckrelay_zps48f33274.png (http://s192.photobucket.com/user/MikeE36/media/bulbcheckrelay_zps48f33274.png.html)

I have noticed that when I key on, I don't have a CEL or any other of the cluster warning lights lighting up when I key on, before I start the engine. Here is a picture of what I get with just key on:

http://i192.photobucket.com/albums/z109/MikeE36/WP_20141124_17_48_14_Pro_zps6d0facf3.jpg (http://s192.photobucket.com/user/MikeE36/media/WP_20141124_17_48_14_Pro_zps6d0facf3.jpg.html)

Now I have looked at wiring diagrams more of the charging system and found this:

http://i192.photobucket.com/albums/z109/MikeE36/chargingsystem2_zps0999f615.png (http://s192.photobucket.com/user/MikeE36/media/chargingsystem2_zps0999f615.png.html)

This shows the W/R wire (small wire on the alternator 2 wire plug) goes and splits somewhere in that harness, goes through 2 different plugs, then re-merges in the other engine harness, goes through the SMJ inside the car, then to the bulb check relay at the top of the diagram, and also the dash plug pin that I tested voltage at previously.

When I unplug the connector at the back of the alternator and then key on, I do not get any voltage at pin 17 of the digital cluster harness, which is the side that goes towards the alternator. This leads me to believe that the voltage source is somewhere on that side of the diagram, and not from a short through the bulb check relay.

I read in a separate thread that the bulb check relay was the blue one in the small fusebox behind the driver's kick panel, so I located it and removed it and tested it and it operates properly with test battery voltages and a push button, so I reinstalled it. I still don't know if it operates in the car though as it could have a bad ground, power, trigger, etc. as installed due to old wiring. This is where I might need some guidance.

Next step I'm thinking is to unplug the alternator plug and then key on and see if I have voltage on the harness at the plug itself, which would mean a short in the wiring somewhere within the harness, possibly where the wire splits into 2 through the 2 different plugs in the diagram above. I will check that in the morning and report back.

If anyone else has any idea as to why I have voltage at pin 17 on my cluster harness with just key on, I'd love to hear about it!

Thanks!

Mike

[MikeE36]

Checked voltages today and realized I was reading the diagram wrong where I thought the W/R wire split into 2 plugs, was actually just auto vs manual.. d'oh.

I verified voltage this morning, key on, green wire on cluster harness has 12.18v, as well as the battery at 12.18v.

The W/R wire at the cluster showed 11.8v with the alternator plugged in. I then unplugged the alternator and still had 11.8v, leading me to believe the voltage at the harness is coming from the bulb check relay or a short somewhere between. I cannot really find much information about the bulb check relay, or how it works with the charging system so if anyone has a good link or explanation of how it's supposed to work, I'd love to hear it. I want all of my dash lights and CEL and everything to work properly when key on, engine off.

I also tested voltage at the plug with it disconnected from the alternator and key on, and I got battery voltage of 12.18v on the large white wire, as expected, and 0v on the W/R wire.... So I have no voltage in that wire at the alternator with key on, which is what I want/expect... I think? But I still have voltage to the dash plug, which doesn't make sense to me.

Any advice or pointing in the right direction is greatly appreciated. My car is a 1989 with an S13 red top swap, and the car was previously auto. The swap was completed by the PO so I'm not too sure how all of it is wired, but I know the fuel pump primes properly and the ECU has power and isn't throwing any codes other than 55. I'd really like to get the battery light situation figured out before I try to drive it again and see if my misfire problem is fixed, as I'm not sure what the true culprit is yet.

Thanks,

Mike

[MikeE36]

Well I fixed it. I traced the W/R wire from behind the dash plug to where it goes. It splits into 2 wires, and 1 wire goes to the alternator, while the other goes to the bulb check relay. The wire going to the alternator was broken, so the ground side of the batt. bulb was never connected, thus no light, and no charging until I revved the car to 3100 rpm and the alternator started auto-charging.

I ran a new wire to the W/R wire on the alt plug, and the wired that up to the junction I mentioned previous where the wire has a factory crimp and splits. Now viola, I have a battery light, and the car is charging perfectly at 14.4 V.

Time to put it back together and see if it'll do a burnout :2f2f:

Mike

[MikeE36]

Well the car starts up and voltage is steady at 14.25v or so at ~700 rpm. It seems to be really lopey and idling really low, which I expected with the 272 cams, but it always idled at like 1100 rpm before for some reason, so I never had the lope really. I just chalked it up to the cams not being degreed in properly and needing cam gears badly.

Now the car still seems to stumble and misfire a bit at idle. It's only pulling ~8-10" hg at idle, whereas it used to pull around 16" hg with these cams at 1100rpm. I will boost leak test again tomorrow to verify that is fine. I readjusted fuel pressure today now that the charging system is fixed and voltage is where it should be. I set it at ~43 psi with the vac reference unplugged. Due to the poor vacuum the engine was pulling from the misfire, idle FP was around 38-40psi, instead of the usual ~35 psi. Idle AFR was 11-12 dead cold, which seems normalish to me. I could never get the coolant temp gauge to rise off dead cold, and my car has always had a few ignition hiccup issues before everything was warmed up so i'm not sure what will happen once it's heated up.

I tested TPS voltage at the ECU pins and it was 0.45v closed, 4.17v WOT, with a smooth input inbetween, and MAF voltage at the ECU is ~0.5v Key on, engine off, and 1.4v at idle. It seems to increase to ~1.8v or more on throttle blips, so I assume it is working at least somewhat based on the idle voltage being mostly correct.

The next thing I plan to do is boost leak test to just rule air leaks out, then test O2 voltages and possibly replace the O2 sensor, as well as check to see any other reasons why I'm getting a solid LED on the ECU when trying to turn the screw to diagnostic mode. I'm not sure if the shop that I took my car to for diagnosis broke my diag. screw or what but I can't get my ECU to blink and give me any codes like I could before, and I know they had it out and shipped it there/back from RS-Enthalpy at one point to get checked out. What can cause the ECU to have the LED stay solid and not give any codes when turning the screw? I have heard this could be a limp mode being forced by something? Can a short in an O2 harness do this? What else could cause this?

Thanks,

Mike

[MikeE36]

Well lots of updates, but my lean issue / hesitation / misfire at WOT and part throttle still exists.

I replaced the entire engine harness and lower trans harness with a Wiring Specialties Pro series harness. I found my old harness had a break on the O2 sensor power wire, so the O2 likely wasn't working.

I also sent the ECU back off to RS-Enthalpy because it had a constant diagnostic LED on, which indicates it had an internal short and was going into limp mode. Martin fixed that back up.

Now to recap on what it's doing, and what' i've checked.

Cold start, car seems to rev up and idle up normally, but might not catch idle or idle all that well until water temp is at least 30-40C. It'll idle in the 13-14 AFR cold now, and 14.5-15.5 warm. When I turn on the headlights, it idles at 16.0 AFR.

Crusing and driving light throttle is initially okay, but the hesitation and misfire / lean condition gets progressively worse as I drive around the block, to the point it's misfiring quite a bit just trying to hold 50mph cruise in 5th gear. Also going WOT, the AFR dips into the 12s, then immediately leans out to 14-15 (yikes.) so I back out of the throttle. It will hold a warm idle pretty well without a bunch of electrical load on it.

Things I've checked:

-Compression good 140psi across
-Leakdown less than 10% on all cyl
-Walbro 400 few months old (when priming system for 5 seconds, it can almost entirely fill a small folgers coffee can... so I think it's flowing fine.)
-Fuel pump relayed externally, stock relay just triggers 40A ext. relay. Previously had the pump grounded through the stock ground wire like a dummy, so the stock redtop 62 ecu apparently tries to vary fuel pump voltage. Not sure if that messed with the health of this walbro or not.
-FueLAB FPR vac line ok and base pressure set @ 44psi
-System1 inline fuel filter is spotless
-Injector screens are spotless, and injectors dont leak when I prime the fuel system
-Baffle in the fuel tank was broken, so I recently removed it. It didnt appear to cut any fuel pump wires or short anything while banging around.
-Mechanical timing is perfect
-Tried a different CAS and reset base ign. timing to +20* BTDC, which is what my tune is set to. My car has always idled around 1000-1100 RPM, so I'm not sure if the timing is set properly there or not. Consult shows TPS closed flag though when setting it, so I assume it's okay?
-TPS 0.44v at idle, 4.17v WOT, smooth in between according to consult
-MAF 1.15v at idle, around 2v ish cruising. 2 different Z32 mafs tested, both read around the same.
-New knock sensor
-Coolant temp sensor appears to be reporting correctly on the consult. Fully warm is 70C and stays there.
-Boost leak tested to 20psi awhile back with zero leaks, but I'll double check.
-Both wheel well harnesses have been inspected, and moved. My drivers side one was damaged and I repaired it.
-Car charges at 14.6v cold, 14.2-14.3v warm. Quest alternator
-Splitfire coil packs, not much mileage on them. When I was chasing this issue weeks ago, I swapped to OEM coils and the problem got worse, so I'm not sure what to think there.
-NGK BKR7E @ .025" gap (just changed yesterday. Old ones were white / lean)
-New ignition switch
-I noticed I was showing 0v on the O2 voltage on my consult, but RS-enthalpy told me this is normal and I won't see voltage there on my consult. I thought it was an issue and ordered an 87 300zx turbo O2 sensor to replace mine, and repinned it and plugged it in. It is a skinny type sensor also like my old redtop one, but the thread diameter is smaller, so I had to use a small screw-in adapter piece in my turbine elbow and now I don't think the sensor sticks out far enough into the exhaust stream - need to get a new turbine elbow.

Also, I have an ISIS screamer pipe elbow, and the divider didnt' fit in my GT2871, so I have a big exhaust leak all the time there. (Getting a new elbow, tired of it.) I didn't think this could affect WOT though, as I was told the O2 isn't used at WOT.

So the only thing I haven't replaced is the ignitor chip at this point. I would assume I should clean my MAF also, but I have only had this car running for around 8 tanks of E85 now. I can't imagine it got dirty in a few short months and minimal miles of driving.


I've read lots of threads about hesistation in SRs, but its always something stupid and simple like boost leaks, or bad fuel pump, etc. I am not really sure on this one! I'm going to run a line in the car to watch fuel pressure while driving and see if it starts dropping on load. Another thought I had was the stock fuel pump relay was turning off the pump / ext. relay intermittently, but I'm not sure how feasible that is.

Also, where is the fuel tank vent line? Is there something else that fails in the fuel system that would cause these issues? I saw a metal line that comes out near the fuel sender bulkhead, but I'm not sure where it goes inside the tank, and where the rubber end of it coming out of the tank goes.

Going to see if I can unplug the O2 today and see if that makes it richer, as well as swap ignitors with someone else, and try to monitor fuel pressure while driving.

Any ideas are greatly appreciated!

Mike

[Tom N]

You sure those five-o 1200cc side feeds aren't the problem?