Flicktitty

Here is the issue:

It's an odd misfire issue and i can't seem to get a hold of it started last fall (October/November) On the way home from a cruise night the Air temp was approximately 45F And i noticed at cruising speeds the car had a slight misfire (AFR's were in the 16+) but when at idle it was fine and when i was accelerating off stop lights it seemed fine. I Assumed it was do to the cold weather and when i had the car tuned it was roughly 100F and very humid, I parked the car for the season and thought I’ll see how it is once spring comes around.

So this spring i decided to take the car out for a spin and see if it was infact a cold weather thing. I went got the car and put gas in it and in 55degree F weather the car seemed fine. took it back out a the next day and it was 65F and the misfire was back. I noticed again at idle/acceleration it was fine but just straight cruising the AFR's would go way lean (16.0+) and it would misfire. Then once i got back into it a little the AFR's would drop into the 12-13 range and the misfire would clear up. I went home pulled the fuel pump to make sure there wasn't a bad line in the tank, or the sock was junk. those checked out fine, i put a new piece of fuel line in tank and put the car back together, car reacted the same exact way. I checked the fuel pressure with the car sitting in the garage at a few different RPM increments and the fuel pressure held steady, I thought maybe it's only when there is a load on the car, so I ran the gauge to the wiper area and took the car for a drive and the fuel pressure held steady in the low 40's and began to climb when I got into boost. I got the car home and got my infrared temp gun and tried to get the temps off each exhaust runner (Cast manifold so had a hard time) I noticed 1-5 (3 and 4 were slightly warmer) all were about the same 350F while the 6th one was closer to 290-30 That could be a coincidence or being further from the turbo/etc it didn't have the radiant heat as much. But thought it was worth a shot. I decided to pull the spark plugs



The plugs to me do not look very good especially for only having 800 or so miles on them. They look like they are burning uneven. Also the rubber boots on the coil packs 2/4/5/6 all seem to be slightly damp/dirty with a smell of fuel (Not much of a smell or wetness but worth mentioning) Also i then checked the oil cap which has a slight gassy scent (again not very bad but there was a scent) Could be do to the fact the car runs rich on start up for a while and it idled a lot. I checked the piston tops and I noticed a slight glossy/wet finish on top of the number 2 and 6 piston. But not a lot. I went ahead and put new plugs in the car (NGK 3330's) gapped them down to .28 Noticed no difference. (Was previously running .32 gap) I went ahead and swapped the number 3 and 4 coilpacks with 5 and 6. and noticed no difference and the temp on cyl 6 was still down compared to the other two. After taking the car back out and noticing no change I came home and let the car cool down for a few hours. I then tested the voltage for the map sensor and that checked out will within specs given by AEM. Not sure how i can test the map sensor with positive pressure going through it however.

I checked the resistance of the AEM IAT sensor and that was a good portion off from where AEM states it should be. so i went to the part store and picked up a "GM Style" IAT sensor and tested it and it was much closer to the specs AEM stated it should be at, installed it on the car and it ran decent for a little bit but still had a misfire. I then let the car cool down a little bit and tried a spare wideband 02 sensor I had (Bosch LSU 4.2?) and the issue remained if not got worse. So I put the aem sensor back in the car. Not sure what else it could be. It almost seems that the car runs fine until it gets above 165-175 Degree water temps. (have a TRD Thermostat) So i'm leaning on maybe the coolant temp sensor isn't reading correctly and thats why the car's AFR's fluctuate? Thoughts? Or could it be a faulty crank or cam positioning sensor? Or maybe even a failing ignitor? I Talked to my tuner and he has assured me it is infact NOT a tuning issue, but he is willing to look at the tune on the car to prove it.

Here is a current mod list:
2JZ-GTE Aristo (Never Rebuilt)
AEM EMS V2 (Sound Performance Tune)
AEM 3.5 Bar Map sensor / AEM IAT Sensor (1.5 years old 1500 miles)
FIC 750CC Injectors/Rail (3.5 years old, 2400 miles)
New fuel lines and fuel filter (3.5 years old, 2400 miles)
Deatschwerks DW300 Fuel pump (2 years old, 1800 miles)
Low Mile coilpacks i got last year, rumored to be about 25k miles, 3 years old
New Coilpack connectors and pig tails (8 months old, 500 miles)
STOCK ignitor
USDM Camshafts. All other sensors are still stock on the car from the aristo.

Car runs 91/93 octane and 14.5 PSI

Thanks for your time and any help or opinion you have on the issue.

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

Flicktitty

So no one has an idea?

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

RaNMaN

To begin with I know that your tuner is worried about his reputation but I would never rule out any part until you can do so without a doubt. Changing out sensors will affect the tune but it should not have that much of an affect on it.

I would bet you that it's the 20 year old ignition parts meaning coil packs and maybe igniter. It doesn't really seem to make much of a difference whether or not the parts were taken care of or lightly used or not, I have seen a lot of misfires issues lately popping up and it's probably mostly due to age.

To fix my cars misfire (that we found when I was already on the dyno with Darin), I swapped out to some used LS truck D585 coils. I picked some up on eBay for $180 and wired it up to my Haltech and since mine came from a v8 I have 2 spares.

Your AEM v2 should be able to work with the D585 smart coils as well. It fixed all of my issues, improved power, sound, and spool and can control the spark intensity by changing the dwell settings. I bought new coil springs and the custom laser cut brackets for these coils off of Rick from Mojo Performance. After that I dropped in new NGK 4644 plugs straight outta the box without closing the gap and the car boost up to 18 psi without even a hint of a misfire. These coils need to be used with resistor type plugs, I don't know if NGK 3330's will work or not.

It could also be a clogged fuel injector but you can check for that if it's misfiring at idle by removing fuel injector plugs and listening for it.

I have 6 crappy coils and a good igniter I could send ya to try out if you don't want to go D585 but really the benefits of using them is huge.


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inopsey

what is your compression?

RaNMaN

I looked it up and NGK 3330 have a resistor so you are good there.

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Flicktitty

Thanks, The coilpacks i picked up were from a Friend he bought them from Elmhurst Toyota about 2 years prior to me getting them. I have thought about swapping to an LS based coilpack, but after doing all the new coilpack connectors/pig tails i hate throwing that money away. I have a freind with brand new coils i'm going to throw at it and see if that changes anything.

I talked too two other tuners that are good with AEM's and they said a few things to check.

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

Flicktitty

First thing i'm checking tomorrow morning.

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

JN1AS4

Im having the exact same issue right now, but with a sr20det. My plugs seem to be wearing evenly though. Ive already replaced the fuel pump and the same problem exist. I've almost narrowed mine down to a faulty fuel pressure regulator though. Because if I hold my rpm's around 4k or so, my fuel pressure drops about 10psi or so. And my afr's are around 17.5:1+. And I have those same lean misfires. But my idle/WOT seems to be just fine.

Flicktitty

Worked on the car this weekend, let the car run for a while pulled the plugs, did a compression test, all 6 came back with 155psi. put the car back together ran it for a little while, sprayed some choke/carb cleaner around the injectors and noticed the car ran alot different when i sprayed around a few injectors, so i pulled the intake manifold/fuel rail and injectors. Waiting for new o-rings and injector bungs.

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

jr_ss

My finger is pointing at your ignitor. My buddies Surpa had a similar issue, once warmed up it would start miss firing and breaking up. When it cooled down the car ran and idled great. I'd check the FSM to see if there is a procedure to check if the unit is with in spec, if not replace it.

Injector orings are a good place too look too. Have you noticed loss of vac?

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My SR20VET

Flicktitty

UPDATES:

Tried a known good working ignitor Nothing changed
Tried a ignitor "noise reducer" nothing changed

unplugged front cam position sensor #1 car ran dramatically worse. so that seems to be ok, will test resistance on it still. (rear cam position sensor isn't used with the AEM EMS.

Replaced injector o-rings and bungs after finding out there was a leak when i sprayed choke and carb cleaner around them the car ran different. Once fixed i tried the same test and there was no change in the way the car ran when i sprayed choke and carb cleaner car seemed to run slightly better but only for a little while. Car holds 43-44psi of fuel pressure at idle and climbs when the car comes into boost Fuel pressure doesn't change when the misfire occurs. Tested the new battery that see's 12.8-13.0 Volts when the car is running misfire or not.

car seems to run better when the engine is cool, But once water temps start getting into the 155+ degree range the misfire happens slightly at idle (AFR goes between 15.8 - 17+ AFR) does the same thing on light and partial throttle. But the car seems fine when you go WOT or give it a certain amount of gas, but almost on tip in it goes lean and trying to maintain speed then it goes real lean and misfires. Sometimes when the car is idling and
the AFR's go real high (16-17 Range) the car will die. But it will start back up no problem.

I checked the resistance on the coolant temp sensor and it was a bit "off" but not a whole lot.

Sensor at 140 degrees should see 0.9Volts At 176 degrees should see 0.5Volts at 212 degrees it should see 0.3Volts

At 179-181 degfrees i saw 0.77-0.76 Volts at 183-185 degrees saw 0.72-0.71Volts

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

Flicktitty

Video i made of it today, You can see how on startup the car starts off good (once started) and then it nose dives rich with a strong fuel smell, notice the car runs/idles and revs fine. then once the temps go up the car starts to misfire, as i get to the end of the video you notice when i rev it the last time it actually dies when it goes back to idle.

https://www.youtube.com/watch?v=UXaP6rGZmwc

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

rswails

do you have different fuel maps based on temperature with your setup? Maybe the hot mapping isn't working with your setup.

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Flicktitty

Just the one map that was made for the car, the car was tuned in mid 90 degree weather, it ran fine for a long time in 50-90 degree weather. it was 86 the other day still ran bad.

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo

Mr. Phonso

I have the same issue but it doesn't happen often so it never really bothered me. similar parts that I have are aem v2 and 3.5 map sensor. I doubt any of those have to do with the issue though.

If the car is idling and you hold the window switches up (to create electrical load) does it recreate the same lean condition? Mine certainly does it.. probably related to alternator though.

Flicktitty

Hmmm i don't believe so. I'll check that.

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2JZ-GTE Swapped S13 Coupe - 1994 Supra Turbo