BAH!!! SR bogging at random

[towlie]

Okay so ive been trying to figure this out for several months but cant solve it.

motor is blacktop s13 sr, runs awesome most of the time. minor bolt ons (FMIC, intake, 3" turbo back, etc) and stock boost at .5bar.

every now and then (maybe once every few weeks) it will start to bog and fall flat on its face.

the other day i was cruising on the freeway and after about 35 minutes of normal driving, it started cutting out. revs dropped to about 2300 (5th gear, cruising at 60-65) and would not make power. I was still hitting full boost (.5) and throttle was pretty deep. didnt want to make revs for shit, and my afr's were dead on 12.0 (no fluctuation, like it idle it will bounce around from 13.7 to 14.3 for example). came to idle and it was showing low 13's.. managed to limp to work crusing in low rpm's, ran fine as n/a, until hitting boost. try to do a pull and it would not build revs, just bogging horribly.

the thing that really boggles my mind is after i clocked off work (10 hours later), i fired it up and drove home, ran FINE. boosting normally, afr's were decent (tad lean)

ive noticed it only does this on a warm motor, and after parking it for several hours it will run fine (ie, bogs driving home in the pm, runs fine the next morning)

inspected maf, looks fine, on my next day off ill fully remove it and inspect wiring and everything. checked intercooler piping for cracks/leaks, no ripped couplers, no loose clamps, so im pretty sure its not a boost leak. Evreryone says its probably a boost leak, but if it was why would it come and go? running a sohc maf, z32 fuel filter, walbro 255, stock injectors.

also on occasion with a cold start it will choke at first boost, cut out maybe once or twice, and then take off as normal. ignored this, figured it was just a hiccup due to cold motor.

any ideas? im going to try replacing the FPR with a new OEM (or Nismo) and the cold temp sensor and see what happens. this is stumping me because of how it runs fine for weeks and then it will randomly bog, then run fine the next day.

[streetprototype]

Boostleak ;p towlie

[daftphunk]

I know everybody says it is a boost leak but I'm just going to chime in and my car would have the same problems before. I would be driving and sometimes out of no where the car would bog, and just wouldn't be able to climb past 2.5k rpms. It sure FELT like a boost leak, or felt like my MAFS was going bad. I cleaned my MAFS, tightened everything up, including my down pipe, cat, etc. and I haven't had the problem since.

It seems similar to yours where it would just occur randomly. Sometimes it would fix itself after a couple of miles of driving and easing off the throttle. Sometimes I would just park and come back to it being normal again.

[Coupes_FTW]

im going to say boost leak, check everything THOROUGHLY. Mine would also do this and it was a bad clamp on the hot pipe.

[GuardianLlama]

I have this problem too. Been going insane trying to fix it

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[shifts13]

Have you tried replacing your coolant temp. sensor?

[towlie]

Ill look again at my ic piping couplers, thanks.

And I just had a cts overnited... I'll throw it in and see what happens.. Lately it's been running fine tho

[chetos13]

Check ur turbo manifold bolts got loose from the turbo

[nissanper]

I have noticed a urgent thing and it is that it is coming and going!! well... I had that problem when my head gasket blew, but then it was running on 3-4 cyl all times.
when the engines warm, everything expands so it will be a leak somewhere. most likley i would change exhaust gaskets, but if it wont come over 2,5k rpm... then it might be a different thing... what gasoline are you running? and whats the highest lvl oktan you can get?

[JSL_Zero]

check coils and igniter, especially harness, the problem seems to involve an item exposed to heat causing increased resistance in harness, essentially causing a delay or interference of sorts.

[jlmillionaire]

I have the same problem but my plumbing is rigged,from my turbo inlet pipe i have a coupling that goes on top of a coupling to my hot pipe lol ,and my 90 degree coupling that i bought from ebay was to big i just wanted to get it done ya know. plus the fact of the crappy home depot plumbing clamps im using, dont worry zilvians im going to fix it all but when i play with the cas it gets worse???

[fliprayzin240sx]

Originally Posted by chetos13

Check ur turbo manifold bolts got loose from the turbo

And that fixes a bogging issue how? That has nothing to do with an engine running like crap all of a sudden and then fixing itself.

[ze12o]

Check your spark plugs too. Might be spark blow out if you're fine out of boost

[fliprayzin240sx]

Could also be a bad CAS...I've seen this happen once, replaced the CAS and it fixed the problem.