Another rb20 problem Misfire/Lean under full boost.

[devil_child]

So, about a week ago out of nowhere I was boosting on the interstate, and when I dropped it down to 4th to pass, I started building boost and then at about 4400 it started to pop, sputter, and buck. Initially I thought it was because I was low on gas at a 1/4 tank, so I pulled off onto an exit and got gas from one of the places I usually do.

Started back up after filling up and it was acting normal again. Drove her the next day to work, and again same problem. So I started tearing into it.

So far:

on startup or first few minutes its fine, but then it starts to hesitate bad after a while liek 10 minutes of driving.

redid Idle speed for 750 and made sure timing was at 15*. Good.

Checked tps and idle switch good but tps is at .48 volts closed throttle???

AFRs are all good until I hit full boost. go from a 14.7-14.9 to a 12 until I hit full boost around 14psi and then it shoots over to lean and misfires.

Changed the fuel filter out and put a new fuel pressure gauge in. Fuel pressure is correct w and w/o vaccum.

Checked for leaks with a boost tester soap water and carb cleaner. Nothing.

replaced O2 sensor. (needed it).

Still need to check coilpack resistance and plugs. I am running a step colder ngk 6s with .028 gap. They are 2 months old.

Ran some seafoam through the fuel and the intake. (once again just maintenance)

tried some octane booster but it didn't help.

no bov leak. Pulling 18 inches at idle. Never pulled more than 18 FYI

Useful info: Internally stock rb20det. garret t3/t4. Rom tune with safc set up locally (no previous problems or recent changes). 450cc injectors. FMIC. Walbro pump 93 octane always, z32 maf.

I'm gonna try a different MAF tomorrow if I have time. Checking plugs and coil resistance too. I also think it could be the 450sbeing clogged. I had them cleaned, but iono plus they are loud. I can hear them from outiside of the car clicking but they have always been like that.

Any other ideas I'm missing? Thankyou in advanced guys.

[DriftX]

I'm having the same exact problems.. I talked to carl about it and he thinks I have a faulty ignitor.. might want to look into that. I should get my z32 in the mail soon, so after i swap them out I'll let you know how it works out.

[DriftingisLame]

Spark will not cause a lean condition.

It sounds to me like your MAF would cause this. I had a leak in my MAF adapter (blowthrough) although it was before the maf, I'd still lean out to the point it would misfire at cruising RPM at any throttle position.

I think its either your MAF or something affecting your MAF, causing it to not work properly. Dont take my word for it, I hate it when I throw out guesses without having strong evidence.

Good luck

[BeyondBiscuits2]

Did you determine your coils were the problem? If so, I hope that Grand National coil conglomeration works out for you. Too bad your radiator decided to die just a day later . You have worst luck than me; but at least you know how to fix your coolant leak... my just keeps on going and going.

[AreszONE]

This just started happening to my RB and I changed the plugs to see if I maybe fouled a plug out but it still does seems to sputter when I hit full boost. Were the coil packs the issue here or was it something else?

[edmonton_skyline]

has anyone figured the problem out yet?... my rb20det runs fine cold.. once it warms up it pops and coughs usually just when boosting.... PLEASE HELP

[leesredgt]

Im still have these same problems with my RB25DET, i would to liek to know what the problem so i can try to apply it to my application.

[flip_pete]

can somebody please help me.. i just a 240 sx and the third day i had it i heard a pop sound.. not that loud thou after that i lost power and my bov isnt working anymore.. the engine ryt now is blowing white smoke at the exhaust the owner checked it out and told me that there was just a leak becuase the smoke wasnt thick.. he told me to tighten all the couplings? and check my vacuum. but everything is tight.. im new to rbs and please can some1 help me

[Romeo_rus]

Any updates? have the same problem!!

[Romeo_rus]

Alright, I read on one of the australian forums that they use electric tape to tape coils and ignitor... so I decided to do the same... taped coils, started the car the same crap... it was time for the ignitor... so I did... started the car - misfired 5th or 6th cylinder!!! started taking the ignitor out (unscrewing 2 bolts) the car stopped misfiring !!! but still misfires under the boost... going to change the ignitor... I hope it will help

[Romeo_rus]

OK... Today I fixed the problem on my car!!! It was a s***ty connector on my CAS... it was plugged in but it bounced like a bi^ch... it caused that problem. So I went to Nissan place in Jacksonville NC and they found a new connector. Now the connector seats properly and my cars runs GREAT!

CHECK UR CAS wiring and connectors!!!