Stutter and Bogging intermittently - E30 M3

[DS Rook]

Allright folks, I need a little help here. Sorry for the length of this but more info the better usually.
I am having a little trouble with the M3 here that I can't seem to figure out.
Last saturday, i picked the car up from the shop after a valve adjustment, and everything seemed fine. Drove about 20minutes, and the car responded fine, then it stalled in the tim Hortons drive through. Restarted right away, but sounded rough for about 5-10 seconds and then was fine again. drove out of the drive through and about a block down the road, when i shifted into second, it bogged right down, and sputtered. I shifted back to neutral and tried to keep it from stalling and I managed to and it cleared up. Drove the rest of the way home(5 min) no problem. Sunday, no problems. Drove the car from my house on the northshore to Mission raceway, tracked the car on and off for 8 hours, no problems. Drove home and when i got to stop/go traffic under the grandview highway overpass, it bogged down again and tried to stall again. i was able to shift to neutral and blip the throttle a few times to save it, and then drove the rest of the way home with no problems.

Any ideas where to start?
New parts installed within the last 1000k
cap/rotor/wires/coil
coolant sensor
both fuel pumps/fuel filter/air filter
intake boot
Also my car doesn't run AFM runs Miller conversion but its not new.


Thanks Guys/girls

[Al Canuck]

Look for an intermittent vacuum leak. Intake boot not fully seated, etc. Does the CEL flicker when the car is stalling?

Al

[DS Rook]

No cel in e30 M3

[Al Canuck]

Originally Posted by Diamondschwartz rook No cel in e30 M3

, good point! Sorry, end of a long day.

Regardless, check for vacuum leaks.

[DS Rook]

Will do. do you think it could be a bad o2 sensor. I have no idea the age of that thing, but could it even cause this sort of thing? Hmm... K.I.S.S. I am probably getting ahead of myself.

[M635]

Diamond, you have the same problem as me! I can't figure it out! I did replace my O2 sensor, and it didn't change much; (mine hasn't probably been changed when off the lot). I'm actually afraid I do have a vacuum leak... I did check my intake boot and it was fine.

I'm quite bummed that this is happening...

[Dean]

A common intermittent vacuum leak on the S14 is the air hose that supplies idle air. The part number is 13 41 1 309 613 - look it up on realoem.com to see approximately where it attaches. This hose attaches to the Air Accumulator (11 61 1 310 786), on the bottom, front right side, right beside the throttle position switch. The fitting that the hose attaches to is actually part of the Air Accumulator and can't be ordered separately. This fitting frequently works itself loose and can pop out, causing a big vacuum leak.


Dean

[woods]

A big vacuum leak is unlikely to be that intermittent but it's possible. Got a code reader or access to one?

An intermittent electrical connection to any number of sensors is also a possibility. The Throttle position sensor is a common failure on S motors. If it has been stalling at idle - I would also have a look at your ICV - both the electrical connectors and the inside of it to make sure it's working properly.

Is there anything you need to disconnect on an S14 to do the valves? Since it started after the adjustment, I might suspect something that was moved or disassembled when the valves were done.

Cheers.

[DS Rook]

^^^^^^^
TPS is new(somewhat) it was replaced when the miller maf was installed around 5k ago. I removed and cleaned the icv about 2 months ago. Tested it when i did it and it tested properly. Doesn't really stall at idle, its more when i attempt to accelerate with low load. First time I was letting the clutch out and aplying throttle and it just kinda died. second time i was cruising at low rpm in second and went to apply heavier throttle and it chugged, and sputtered like it was going to stall, but i puleed it out of gear and saved it after about 3-4 throttle stabs. Only the crankcase ventilation hose is attached to the valve cover on the s14. I know it goes to the seperater and then to the plenum, but it appears fine. I'll wiggle and spray there when i hunt for some intake leaks though. To be sure.

[DS Rook]

Alright, now I went to aircare the car and it was idleing in the line up and it crapped out. Twice. Car wouldn't start for 3-5 minutes, then started fine. I drove home without testing and it ran fine. SH**. (That was for big brother censor). Think it could be bellhousing sensors? i have all winter to find it now as the car is off the road come the 7th. No intake leaks found.

[woods]

Does it throw any codes?

Not starting at all then suddenly starting... Was there any firing at all when you tried to start it? Did it sound like insufficient fuel or just complete lack of spark? Did it cough and sputter or just suddenly start right up again.

Intermittent cam position sensor? No signal = no spark an no start. Check the contacts. Sh1t - since it's going to be off the road all winter - just go through the engine bay and clean and lube the contacts on everything..... A bad CPS Should throw a fault code.

[Nick]

Have you ruled out any possible issues with the MAF system? Maybe put the barn-door AFM back on and see how she runs.

[DS Rook]

Maf isn't new. Has been on the car for 5k. Never had an issue before though.(i know, doesn't mean anything). As for codes, M3's don't have cel, so no way to check for codes. It sounded like a single stumble when trying to start, sorta like it was going to start, but wouldn't. Was more than just cranking though.

[woods]

Originally Posted by Diamondschwartz rook As for codes, M3's don't have cel, so no way to check for codes. It sounded like a single stumble when trying to start, sorta like it was going to start, but wouldn't. Was more than just cranking though.

Can't you check the codes with an OBD I code reader?

[DS Rook]

AFAIK it can only reset service indicator.