Thoroughly Stumped With My SR!

[jdm>usdm]

I've been struggling for quite some time with this problem now, and seem to be completely out of ideas on what it could be. Here's the deal:

When I give it WOT and boost starts to rise, the engine runs rich to the point where it sounds like I'm hitting 2-step or something. It has no power and completely falls on its face when accelerating. My wideband goes straight to reading 10:1 AFRs under these conditions, and I'm sure it's running way richer than the wideband will even display. It does fine under normal driving though, just when boost starts to approach it's max PSI setting.

My buddy has a spare SR in my shop which he hasn't dropped in his car yet, so I've had the convenience of borrowing things from his swap to test on my car to see if anything changes. Here's what I've done so far:
-Fresh plugs (bkr7e gapped to .024)
-Pressurized the piping and tested for boost leaks (some were found and fixed, but didn't resolve anything)
-Tried different coil packs
-Different ignitor
-Different FPR
-Different MAF (Car was tuned with a blow-through set-up)
-New walbro 255

I've also looked over the wiring harness for any worn/exposed wires and checked over any grounds I could find. I swapped in the new fuel pump because I realized it was running a stock one when I was checking the fuel tank for rust (even though the PO claimed it already had a walbro.lol). The problem has become significantly worse with the new pump. I also moved the MAF to a pull through set-up to see if it would change anything. It ran like it used to as a blow-though with the old fuel pump (which was a little better), still reeeeally rich under WOT, but it ran very lean under normal driving, so I swapped it back to blow-though.

Here's the set-up:

Red Top SR20DET
GT28RS/manual boost controller set at 16PSI
HKS cams
Weisco pistons
ISIS intake manifold
Z32 MAF Blow-through set-up
Nismo 550cc injectors
Tuned with Nistune


If anyone has any idea why it's dumping so much fuel in the cylinders, please let me know! Maybe I'm overlooking something simple. I just need to hear different ideas on what to trouble shoot. Thanks

[[email protected]]

same was going on with mine...harnes was fucked AND i couldnt find any exposed wires..try switching it out..takes about 30min

[jdm>usdm]

same was going on with mine...harnes was fucked AND i couldnt find any exposed wires..try switching it out..takes about 30min


Shit, good idea. My harness has more than a few splices made into it. Hopefully that will do it

[jdm>usdm]

Well, just swapped out the whole upper harness with a new one from wiring specialties. Did nothing :(

Any more suggestions?

[cotbu]

I wanna see your tune? Send me a copy and some logs. [email protected]

[jdm>usdm]

I wanna see your tune? Send me a copy and some logs. [email protected]


I will have to get in touch with the tuner. It was done quite some time ago, hopefully he has some information saved on it. I don't have any kind of cables or software to interface with the ecu myself. But I really appreciate your willingness to help out. I'll be sure to take you up on your offered help if I can get some info on the tune.

It was running great just a few weeks back, though. Is it common for a tune to just be lost or go bad with Nistune?




Moreover, some of the research I've been doing shows that a faulty or out of adjustment TPS can throw things off. I'll give that a test tomorrow and see if I have any luck.

[0wn3r]

Switching your fuel pump made the problem alot worse..?

[s13panic]

Was the fpr you tried a known good working one? Maybe check fuel pressure and see if its within spec.

[s13asher]

my SR had the same issue a few months back - it was always running rich and as soon as boost would come online the engine would flood and blow out the spark plugs.

After a week of scratching my head, getting irritated at constantly having to clean the rear bumper to avoid the Ricer Poop Stain and inspecting various things - i found the issue to be a faulty BOV.

You mentioned that your system is vacuum tight, sweet. Have you verified correct operation of your pressure relief valve as well as the wastegate by actuating the pistons?

-asher

[Jybfan04]

I would test the TPS, it could be going bad which would explain when you hit WOT it doesn't know what voltage to supply to the ecu.

Test the TPS with a voltmeter with it closed and then wot.

[jdm>usdm]

Switching your fuel pump made the problem alot worse..?


Yeah. I'm thinking that the problem actually wanted more fuel than the stock pump was supplying. So with the 255lph pump, the problem is just more evident.



Was the fpr you tried a known good working one? Maybe check fuel pressure and see if its within spec.


It came off of a running swap, so I'm assuming it's good. At the very least, even if it was no good, it seems that I would notice something change for better or worse from running a different regulator. The fact that nothing at all changed leads me to believe that they are both fine.




my SR had the same issue a few months back - it was always running rich and as soon as boost would come online the engine would flood and blow out the spark plugs.

After a week of scratching my head, getting irritated at constantly having to clean the rear bumper to avoid the Ricer Poop Stain and inspecting various things - i found the issue to be a faulty BOV.

You mentioned that your system is vacuum tight, sweet. Have you verified correct operation of your pressure relief valve as well as the wastegate by actuating the pistons?

-asher



Yeah, the BOV flange was actually one of the things leaking boost when I tested for it. But the Valve itself is doing like it should. It's an HKS SSQV, so there's no way to really adjust it (as for as I know). The WG opens and vents fine when it gets to 16psi. Are you recommending that I try to manually open and close it, though?






I would test the TPS, it could be going bad which would explain when you hit WOT it doesn't know what voltage to supply to the ecu.

Test the TPS with a voltmeter with it closed and then wot.



Actually just got done testing it. It was reading around .13V with the throttle closed, so I adjusted it until it read around .5V. When I started it, the idle was hella high, like around 2k rpm. I drove it around to make sure it was completely warmed up, and the idle didn't change. It did make it run better, though! I adjusted it again to where the idle fell around 1k, and now its reading around .2V. It still seems to be running a lot better though with it reading low like that at idle. But I have no idea why! lol

Also, the volts rose smoothly as I opened up the throttle until it reached a max reading of around 3.8V. So I don't think the sensor is faulty or anything.




Since it's running better from messing with the TPS, I'm wondering if my plugs are fouled from how it has been running. Maybe that's the reason why it isn't a full 100% now. I'm going to pull them and have a look after I let my engine cool down.

[jdm>usdm]

Well, plugs don't look that bad at all. Also, problem is back to being really bad again. I thought messing with the TPS did a little something, but it doesn't look like it any more.

Checked the plug and wires coming directly off of the coolant temp sensor as well. Everything look good.

Why must you give me such troubles? :facepalm:

[r33nota240]

i had the same problem with my rb and it ended up being 2 half pluged injectors. does it do it reving also or only under load?

[jdm>usdm]

i had the same problem with my rb and it ended up being 2 half pluged injectors. does it do it reving also or only under load?



Only under load. You mean clogged by half plugged?

[r33nota240]

yeah they wernt flowing the same as the others they had some debre in them like small pieces of ruber from dirty lines and such.

[jdm>usdm]

How would clogged injectors result in anything other than lean conditions?

[cotbu]

Injectors can be stuck open.
You need to set everything back to stock as possible, Timing, Tps, Fuel pressure etc, I don't think you tuner should have tuned you with the tps being set wrong. (actually I know he shouldn't have!)
Have You pulled any codes? If You choose to go back to stockish? I'll help you, but I really hate pissing into the wind and starting from a known to work base is better than throwing guesses at it, if you know what I mean.

And if you have no means of tuning your Nistune yourself, always ask the tuner to give you a copy of the tune on a usb thumb drive, your phone or something.

[4x4le]

.44 is oem closed tps. With that said there are things that can change what the ecu thinks is tps closed voltage. I know one of them is nissan datascan, i havent found a way in nistune but i know there are other ways because i have seen it changed on many ecus that have never been tuned.....