1991 240sx w/ sr20det redtop conversion - won't idle

[fred_beare]

Hey guys - if any of you have any ideas please let me know. Starting to get really frustrated with this one.

Last fall - car ran fine. Over the winter replaced brake booster, upgraded to 550cc injectors, Enthalpy ECU, and Z32 N62 MAF. Screwed up when I wired in the MAF. Heard the fuel pump kick (as I was being dumb and didn't disconnect the battery.......yeah, I know).

Found some black wires. Replaced those sections, couldn't get it to run.

Switched back to stock ecu (from different car, stock injectors, and stock MAF)Car ran fine for about 1 week.

Inital problem - didn't want to start and was backfiring though exhaust. Don't remember exactly what I did now, but messed w/ timing and cleaned plugs and it seemed to get better.

Now it won't idle. Runs for about 30second and dies. If you rev it and manage to keep it alive, when you get to 4k rpm it runs great. Below 4k it runs like crap and throttle is not responsive at all.

I have checked the ECU self diagnostic and it is coding 5-5 (aka all good). Even still swapped to different CAS, still same problem. I have spark at all 4 cylendars and fuel is ok. Even tried swapping to differnt stock injectors - no improvement.

Cleaned IAV valve (not really dirty).

The only really shakey thing is setting timing. Using an old plug wire between the coil pack and #1 cylendar. it is running rough enough that the timing is basically illegible at low rpm until I can get up near 2k.

Getting ready to buy a new harness and start the wiring from scratch. Any ideas or people who had simmilar issues feedback is appreciated.

Thanks -

[S13240]

Check the spark plugs and regap them.

[jdm s13 tuner]

this happend to me before i have an sr non turbo. have you checked out all the air hoses because last time i forgot to hook up a hose i forgot which one when i made a short ram intake and the car would have trouble starting and if it did it would die out. also check you voltage on ur tps cuz this can cause bogging and eventually dying when motor is cold

[Rookieca18det]

make sure all hoses are connected, intercooler piping etc. You also might want to check you plugs maybe they are flooded, oh and you could start the car without the maf and see if the symptoms change any. Other than that make sure your timing is set correctly and also when you say it runs like crap under 4k do mean its breaking up under 4k? Good luck.

-richard

[Blown240sx]

Are you running the stock SR ECU with stock every thing else or do you still have some of the mods on the car like MAF or something.

[fred_beare]

Thanks for the intial feedback. To answer the responses thus far. Spark plugs have already been exchanged for new and car is back to 100% stock (except for T28 which has always been there)

Maf connected or disconnected makes no difference. Not sure what you mean by breaking up? under 4k the idle is not constant and it wants to die. If you try to give it gas usually instantly kills it. If you continually blip the throttle it will eventually get up to a high enough RPM to run. But as soon as you release the accelerator you are back where the car wants to die.

Haven't checked intercooler plubming yet as the car runs fine at high rpm and high boost. But I got no other leads so I will give it a shot. Thanks for the feedback so far everybody.

[Onizuka]

Sounds like a plumbing leak somewhere. Check the small vac hoses to your fuel pressure regulator, boost controller and throttle body for disconnections or cracks. I really hope you find out the problem soon, nothing worse than having a kick *** motor thats not running well.