Weird sr20det lean out issue at start up and cruising.

[ryder2101]

Like the title states I'm stumped trying to figure this out. One day I boosted one time to bout 12psi and went to band practice. Later that night I got in my car, fired it up "note it is wibter" revs went to 2k like normal and slowly was dropping 1800,1600,1500, wideband leans out car dies. So I fired it up again, same thing, I have to keep the revs up to keep it running and at same time car will have a hesitation "miss" if you rev in neutral or hold at any rpm. So I left to go home and also noticed while missing and idleing weird vacumm will bounce around anywhere from 8 psi"at the roughest idle/hesitation to 10,15,18 back and forth, seems to bounce around when its running like crap. So I'm cruising at different speeds and gears watching wideband. And while I'm barely touching throttle its 17.8 to 18.0 and flat lines the wideband gauge in lean, where before this happened car would be in the 12-13 area. I noticed one time when tank was almost empty the air fuel corrected to where it ran previously. But that was only once. And when I filled up, it has never done that again. I'm stuck I've checked voltages on tps. Getting .4 shut 4.7 open, change coolant temp sensor, added fuel pump relay. Messed with iacv. Checked timing 15', fixed a exhaust leak. All new Coilpacks, checked plugs they seemed fine. When you go wot the air fuel is still alittle higher than before. But gets a ton better. It's only when on light throttle does it lean out badly and makes car feel like its dragging a piano, and you can feel it jerking with a lean out. And when warm it gets a little better with starting it. Cold starts are really bad it will drop to 300/400 Rpm and bucking then it sometimes will come up or shut off. And vaccum will be way off while its leaning and bucking. Idk why it would do this all the sudden. It was fine , then poof it runs like crap. Plz help. Here's list of whats done to it. Note that car ran good before this happened, but always had slight studder when reved in neutral.


Sr20det blacktop s13
Gt2876r
Fmic
Sard 850cc
Enthalpy ecu
Fpr
Walbro 255
Manual boost controller
Wideband
Boost gauge
Metal head gasket
Megan tubular mani
Aftermarket turbo elbow
3in straight exhaust to Apexi can

I've checked tps .4 to 4.7 "new tps not installed"
Coolant temp sensor
New Coilpacks
Fixed exhaust leak
New walbro 255 "not installed"
Messed with iacv "new iacv. Not installed"
New Ignitor
New pcv valve
Check maf seemed to be working
Check compression
139,141,142,141. While warm, wot, fuel pump fuse pulled

I'm stumped, any help would be awesome, like i said car since I bought it always has a weird stumble at idle, but never did while driving or boosting. I never found out why it did, it was barely noticeable before. Now cold start lean out stumble and leanout cruising at like .5% throttle. If you need any more info just tell me. I really want to no what is going on and how to fix it the right way, like it ran before and fix the stumble/miss at idle, when I purchased it. Thanks a lot fellas, I.searched but couldn't find anything like the situation I'm having

[ryder2101]

Oh and another thing, I found out sometimes when.its. acting.up at idle and when im trying to hold a constant rev, of i stop the rev and barley give it some gas to get back up to say 2krpm, and go off and on with throttle at like 1% then hold. Sometimes its perfect no hesitation and air fuel is 13 or so, then if i release throttle and try again to rev to 2k and hold it leans out and stumbles, then I go off and on throttle at 1% a few times it will be clean and rev perfect. That's why it seems to me to be something with throttle, or fuel delivery, or something. Cause u can make it idle smooth with playing with throttle at 1%.to 2% then hold to move it up to desired rpm. It just dont make sense to me. Harrness is hack job too I believe. But I'm new to these types of cars. Thanks guys

[di-devol]

Hi, I battled the same thing for a year. Motor let go from running lean.
Look into wiring. I've tried everything to figure it out. I'm going as far as getting the whole car re-wired before putting in the 1j.

If you want to see what I tried,thought,re-thought,shit.

lean

[s13 drifta]

I am having a lean issue at part throttle as well. I have tried everything besides getting another fuel pump. I have a walbro fuel pump as well. It did fine with 480cc injectors, but once I change to 740cc injectors I started having the issues. I think the Walbro is having a problem keeping up with the flow of the injectors, so I am going to try a Denso Supra pump and see if it solves my lean issue. It is the only thing I have not changed. I have the Walbro hard wired to get more voltage, but didn't change much.

[inopsey]

i had this issue. the valve cover to intake hose was disconnected at the intake allowing excess air in.

[di-devol]

Originally Posted by inopsey

i had this issue. the valve cover to intake hose was disconnected at the intake allowing excess air in.

I switched to a map senosr with aem, issue persisted. I kinda doubt that's his problem as well.

[4x4le]

Nissan datascan is priceless for issues like this

[ryder2101]

I've changed fuel pump. Fuel pressure regulator, coolant temp, coilpacks, Ignitor, I'm gonna install new tps and iacv cause of the horrible cold start issue as well. I just don't get why all the sudden poof something changed and this issue started. Thx for the replys , anyone else with info is greatly appreciated

[ryder2101]

What your mean by nissan datascan ? Is it something.I can purchase?

[4x4le]

It is a software program. I dont know what it costs now. I think when I bought it a few years ago it was like $15 and I think it is around $25 now.

You also need a consult cable for it. You can get a nice one that costs more than $100 Which will work with better more extensive programs, however you can make your own for cheap or buy some of the cheaper ones and they will work fine for datascan use.

It allows you to view live as well as log all of the oem sensors your ecu is using to make your engine run. You can see if it is throwing codes, what they are, clear them ect.

You can also alter (temporarly) some sensors data in order to diagnose things without actually changing physical parts, lock timing, clear self learn (which there isnt much self learn in these early ecus) or alter base timing. Even can kill cylenders individually.

It is the BEST tool you can have on your side for this problem. Dont just throw parts at it, such a waste of time and money!

[ryder2101]

Put in new tps, check voltage. Getting 0.45/0.46 close so that's fine. Still didn't fix anything. I'm stumped. Only thing left to put on is iacv. It has a small exhaust leak from turbo elbow but very small. I wouldn't think that would cause this issue.

[4x4le]

Originally Posted by ryder2101

Put in new tps, check voltage. Getting 0.45/0.46 close so that's fine.

You would think...... But that isnt always the case. I have seen cars with unmodified ecus that take various tps voltages in order to get the ecu to realize the tps is closed. This is in fact the only thing "self learn" (at least that my observations have proven to reset) is.

I dont know if there is a series of things you can do to clear the self learn or if just leaving the battery unhooked for a while will do it (it may not, I dont know what clears it but I have seen cars with it triggered at voltages not specified by the fsm).

Everyone seems to think that the voltage specified in the fsm is the "end all, set it there and forget it" voltage but that is not the case. If the self learn memory was cleared for whatever reason, however it gets cleared (dunno), and the next time you turn your key on you better hope your tps isnt set wierd or your throttle isnt depressed or you will have a crappy running car.

With data scan, there is a simple button to clear the self learn, and as long as your foot isnt on the throttle and your tps is set close to right, it will take that as your closed throttle voltage even if it isnt per the fsm.



With all that said, it does not seem like what your problem is, however you are diagnosing this aspect of your problem wrong and you cannot quite check it off your list just yet.

[cbcm2435]

did you check your FPR? i would test fuel pressure at idle

[ryder2101]

Got two diffrent adjustable fpr , set at idle to 42-43psi with vac unplugged. And it didn't male a differance. Wish I could figure these issues out. Found a video of my car on YouTube running before i purchased it. Even with them , it had a small miss while holding a solid rev at any rpm. But very faint. I really want to figure this lean issue out. It's does it ay weird times u can play with the gas pedal a few times and it will be lean, then play with it and it will be fine. And that's while driving. Idleing, revving, the whole nine yards

[4x4le]

where at in alabama are you?

[wozrally]

Im having the same issue with lean condition at idle and cruise.

almost identical to your problem.

any update?

[p00t]

This really sounds like a MAF problem. Unplug your maf and see if the problem improves low throttle. You cant rev over 2400 or so, but it will use the O2 when you are driving to get to 14.7.

Unbolt the fuel rail and look at the injectors, make sure the injectors are centered and the end caps are not broken or blocking the nozzle.

Look for leaks in the intake piping.

[p00t]

Also I was under the assumption that this was running right before you boosted to 12psi. And then you posted about it not running correctly in a video by the previous owner....

WitchHunter Performance - Subaru Fuel Injector Modifications

Scroll to the bottom of the page. These are the injectors you have.

[ryder2101]

I live in Birmingham Alabama. Haven't messed with car in a week or so due to my coolant return line cracking and spraying coolant everywhere, but I'm going to pickup new one tommorow and will be pulling whole turbo setup and fixing the line. And also small exhaust leak on the exhaust side of turbo. I'll try the maf test after I get it back together. Like i did say before when I purchased the car it has a very faint miss while free revving, but never was a bad issue. Then i found the video of the car on YouTube. That's when I noticed it was doing it way back then, so issue was never fixed, im gonna figure this out one day forsure. Just really busy with family and work here lately , but I'm going to fix these small issues I find and make a update of how it runs after, exhaust fix, turbo, maf, couplers , and soon on. Thanks for advise guys. I got a small list to handle first and we will see of that helps any.

[silviaNC]

Did you ever figured out the problem? I'm having same problem after a intake manifold gasket change. Make no sense

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[Nissan_Alex]

Check for air leaks.......or the bov is staying open at idle