The OFFICIAL bogging, hesitating, no acceleration from idle thread

[dmurray14]

My original thought, which I now assume is way off-base, is that the higher oil pressure at low RPM+large throttle opening was forcing oil into the spark plug wells and causing some misfiring. I guess that's kind of a stretch. When my roomie rode in my car today, he said it felt like a drivetrain problem instead of an engine problem. I doubt that is the case, but an interesting observation nonetheless.

'
Nope, couldn't be the oil....the il leaks out of the top of the valve cover, and would only pool up in the well. Wouldn't get forced in there.


I am 99.99999% sure it's not a drivetrain problem, either...


Dan

[eriebmwfan]

i have the same problem. ppl told me it might be the cat. also, from time to time i have this bad smell in the car coming from the engine bay.

ive done:

new spark plugs
fuel filter
new valve cover gasket
cleaned out ICV
cleaned MAF
checked for vac. leaks (non found)

when its cold, even if its in neutral, if i floor it, the rpm's will goto about 3k, say there until i let off alittle (about 80% throttle) then they'll climb to redline. i think that might be a bad spot in the throttle pos. sensor. idk???

[eriebmwfan]

also at a redlight, its sometime shoots a CEL. checked it and it says oxygen sensor control issue. i just replaced oxygen sensor!!!!. but, i talked to a BMW tech, (fellow co-worker) and he said it wasnt that the oxygen sensor is bad, uts just that the car cant control the air-fuel radio the way it wants too. WTF!!!???

[eriebmwfan]

also, guys.....while the car is idleing, open the oil filler cap and see if it is "huffing" steam or whatnot. mine does this like crazy and its due to blow-by in the #6. i did a compression test and found this out. i need a ring job.(get your mind out of the gutter, lol) guys test this so we can narrow it down. its simple. thx

-Justin

[a32guy]

OK, for some reason tonight I just started to feel like it was the cats. I think mine smell, though I'm not quite sure what bad cats smell like. And I'm just on the verge of failing emissions...

The thing that gets me is that the car will run like a dream when it's started cold - I couldn't believe it, I could dump the clutch at 3k and get some tire spin (usually just get massive bogging) and the car is nice and liner. Sure enough, as it warms up it starts running like shit. This makes me thing it's something temp sensitive...which would certainly be the cat.

Anyway, hopefully the MAF will come tomorrow so I can rule this out. Next up will be the cat, and if that doesn't do anything, I'm spent and she goes to the mechanic...

Dan

I also think its my cats Dan. Its funny, when I drive from Boston to CT in this cold weather the car doesn't bog at all. (Or conciderbly less). But if I'm in traffic, its worst.

My theory is that the heat from sitting there idling is heating up the cats, but when I'm driving on the highway for 2 hrs +, the cold air at 75 mph is cooling the whole exhaust off. I think the cats aren't flowing well when warm, this would explain why our cars run great when cold started.

I'll just have to pull the exhaust off and go for a drive

-Chris

[eriebmwfan]

please let me know how that goes. cuz mine is like super f*cked up. im afraid to drive it far.

[dmurray14]

I also think its my cats Dan. Its funny, when I drive from Boston to CT in this cold weather the car doesn't bog at all. (Or conciderbly less). But if I'm in traffic, its worst.

My theory is that the heat from sitting there idling is heating up the cats, but when I'm driving on the highway for 2 hrs +, the cold air at 75 mph is cooling the whole exhaust off. I think the cats aren't flowing well when warm, this would explain why our cars run great when cold started.

I'll just have to pull the exhaust off and go for a drive

-Chris

Bingo. I think we have a winner.

I also noticed the other day that when it's cold and raining, the car seems to run a LITTLE better - maybe all that water is cooling off the cats. Also possible I'm just making that up.

So anyway, this begs the question - do we replace with regular e36 cats, M3 cats, or do I dare use OBDII cats & headers?

Dan

[eriebmwfan]

i agree, i think it has something to do with the temp of the cats (or at least something that is temp controlled). i have the same issue, after the car warms up alittle, it will hesitate. but if im on the freeway, its raining, or very cold. when i get off, its like a new car. it will pull like i just started it up. then it take alittle bit of city driving to act back up again.

[Spood]

I'll pay more attention to the temp when I drive some more, but honestly, I'm kinda skeptical on this one. Assuming we are having the same problem(s), the car should run crappier at higher RPMs and better off the line if the cats are not flowing well.

[dmurray14]

I'll pay more attention to the temp when I drive some more, but honestly, I'm kinda skeptical on this one. Assuming we are having the same problem(s), the car should run crappier at higher RPMs and better off the line if the cats are not flowing well.

I dunno... if they're clogged, there may not be enough pressure to "break through" until the higher RPMS, which could be our problem. Maybe the higher temps clog them up?

[Spood]

Temperature should not affect how well the cats flow though. The only reason we want the cats to be hot is to light off the catalyst. The 'amount of clogging' isn't gonna change. If it was clogged, it would choke at all RPMs

[eriebmwfan]

i know its really not probible. but who knows!!?? shit, if i need new cats, and thats the prob. im not gonna argue

[Spood]

Well, yeah...if it is the problem, not like I'm gonna argue. I'm just saying it seems like a longshot.

[a32guy]

True, but its worth a shot! Time will tell...

[jackasswhy]

i bog all the time when warm. cold the car flies. on the freeway thats when i feel it most. the car will jump like lets say im at 3000rpm and floor it it will jump to 3500 and back down but accelerate with jumps. if i tap the gas slowly it does not do this

[TboneM3]

I can't say its not that cats but I would keep in mind that there is nothing happening after the cats. Exhaust is just passing through, if they are clogged up or somehow bad it would happen at all rpms. Another way to say it, if you dropped hte muffler and cat mid section and went for a drive, it would probably perform the same (can't say for sure, there's always exceptions). There are even more sensors that haven't been talked about + ones that have:
Trottle position sensor
Camshaft position sensor
Engine temperature sensor
Coolant temperature sensor
another temp sensor but for the intake manifold
Knock (ping) sensor
Crank position sensor

One other thing, I believe bad grounds (electrical) play roles in performance.

[flip213]

this is to everyone with the hesitation problem on theyre 92 or 93 325. ive had the same problem with my car for about 2 years now and i think i have finally solved my hesitation problem which sounds similar to everyone else. for everyone that has brought theyre car in and had it plugged in on the diagnostic and nothing shows up but your car still boggs, get a fuel pressure test because its not an electrical problem. and even after u performed a fuel pressure test and nothing showed up there, try this. when the car is running pinch your return line of the fuel line and take the car for a test run if this solves your problem it is your check valve in your fuel pump. this is problem with mine i just have to get money to change the fuel pump because that is where the check valve is.

[dmurray14]

this is to everyone with the hesitation problem on theyre 92 or 93 325. ive had the same problem with my car for about 2 years now and i think i have finally solved my hesitation problem which sounds similar to everyone else. for everyone that has brought theyre car in and had it plugged in on the diagnostic and nothing shows up but your car still boggs, get a fuel pressure test because its not an electrical problem. and even after u performed a fuel pressure test and nothing showed up there, try this. when the car is running pinch your return line of the fuel line and take the car for a test run if this solves your problem it is your check valve in your fuel pump. this is problem with mine i just have to get money to change the fuel pump because that is where the check valve is.

Hmm....

Where is the fuel return line? Where do you pinch it? Sounds interesting..

[Spood]

this is to everyone with the hesitation problem on theyre 92 or 93 325. ive had the same problem with my car for about 2 years now and i think i have finally solved my hesitation problem which sounds similar to everyone else. for everyone that has brought theyre car in and had it plugged in on the diagnostic and nothing shows up but your car still boggs, get a fuel pressure test because its not an electrical problem. and even after u performed a fuel pressure test and nothing showed up there, try this. when the car is running pinch your return line of the fuel line and take the car for a test run if this solves your problem it is your check valve in your fuel pump. this is problem with mine i just have to get money to change the fuel pump because that is where the check valve is.

So, this doesn't apply to 94+ cars?

[a32guy]

The return line is further back against the firewall right? If so, damn not much room back there but I'll definately try it. Thanks for the tip!

[dmurray14]

Cross the MAF off the list. New one made no difference...

Getting REAL sick of this damn issue...

Chris - do you plan on trying to pinch the return line? I'd do it if I knew how...

Dan

[jackasswhy]

i changed fuel pump and o2 sensor no change. i believe its either the ignition coils or vanos

[dmurray14]

i changed fuel pump and o2 sensor no change. i believe its either the ignition coils or vanos

I've replaced ignition coils and Chris (a32guy) has replaced VANOS.

[dmurray14]

So who's gonna be the guinea pig and take off their cats and go for a ride?

[jackasswhy]

So who's gonna be the guinea pig and take off their cats and go for a ride?

ill try to do it this week at my dads shop never have time to go there . my dad is sick of my car as well the problem being as with this kind of problem you need $$ and time to just try slowly from cheapest to expensive to see what the prob is.