325Ci misses on cold start

Status
Not open for further replies.
A

antonmnster

Joined
Mar 29, 2010
Messages
1,208
Location
Minneapolis
I'm not quite sure where to start with this one.

My 02 325Ci has developed a pretty consistent miss on cold starts. It sounds like it's just one cylinder that doesn't want to fire for between the first 3 to 15 seconds. The miss is only at idle; if I give it a little fuel they all pop.

The car has 149,000 miles on it. I changed the plugs about 10,000 miles ago. Changed the VANOs seals this spring. No CELs. No other problems, just the miss.

I tried a can of SeaFoam in the gas last week when I was down to 1/3 of a tank. All that did was give me a bunch of o2 sensor codes. I cleared those and didn't see anything else.

Any advice? My Toyota-loving co-worker is teasing me when I start my car!
 
I am only guessing here, but it it were mine, I would start with a new fuel filer, and then one bottle of RedLine SL-1 in a full tank of fuel, and run that tank till down to 1/8 before adding any more gas. If the RedLine SL-1 works, then get a 100mL graduated plastic flask from McMaster-Carr and use RedLine SL-1 at the recomended dose with each fill up.
 
Spray some carb cleaner around the intake before starting and while someone starts it for you and see if it stops. It does not give you much time for diagnosis. Someone may have to use a smoke machine while the engine is cold to check for intake gasket leak.
 
Does a misfire show up on a scanner? If so then you can swap coils from cylinder to cylinder and see if the misfire follows.

What plugs did you use? Have you inspected the entire intake duct work between the MAF and the manifold? They're prone to cracking and leaking. This generally shows up as a fuel trim problem though.

Please keep us posted.
 
When I used seafoam 2 months ago I got multiple misfires and my engine sounded horrible. Pulled the plugs, spark plugs were gummed up beyond belief from the seafoam. Check your spark plugs just in case.
 
Originally Posted By: antonmnster
My 02 325Ci has developed a pretty consistent miss on cold starts. It sounds like it's just one cylinder that doesn't want to fire for between the first 3 to 15 seconds. The miss is only at idle; if I give it a little fuel they all pop.

Interesting. My 530i does this too sometimes. It usually happens if I don't drive the car for several days. Mine's been doing it since the car had about 40K miles. I am now at 77K. I also replaced my plugs with OEM ones and have used various fuel system cleaners. None of this has made any difference. No error codes anywhere. But like I said, mine only does it once in a while.
 
Sounds like an injector is faulty from being dirty.
I'd run a tank or two o Chevron Techron, or Gumout REGANE through it. Redline and Amsoil make excellent cleaners, too.

But a miss can be anything! Even a worn spark plug at this point.
 
Originally Posted By: JHZR2
Clean the ICV.

Wouldn't a clogged ICV affect all cylinders rather than just one?

Not sure about OP, but it my case it really does sound/feel like a faulty injector, as mechtech mentioned.
 
Originally Posted By: antonmnster
My 02 325Ci has developed a pretty consistent miss on cold starts. It sounds like it's just one cylinder that doesn't want to fire for between the first 3 to 15 seconds. The miss is only at idle; if I give it a little fuel they all pop.

The car has 149,000 miles on it.

You may be losing the fuel pressure regulator or maybe the fuel pump. Since it only occurs on cold start, the fuel pressure has had many hours to slowly bleed down. Upon cold start, the controller has to enrichen the mixture, so the duty cycle is elevated, the pump has to make up for the dropped pressure overnight AND feed the injectors.

I'd recommend putting a pressure gauge on the fuel rail before shutting her down for the night. Note the reading. Next morning, see if it's dropped.

(BTW: -1 on seafoam. +1 on Redline Si-1 or BG-44K)
 
Last edited:
Originally Posted By: Chris142
I'd look to a weeping head gasket that's fouling a plug with Coolant when it's sitting. I'd put a couple of stop leak pellets in the cooling system to see if that improves it.


That's exactly what my co-worker keeps teasing me about! My 1.5 mile winter commute causes quite a bit of crankcase condensation; the oil cap gets pretty creamy in the winter but clears up once the temps rise. But I really don't see any coolant loss, no smell of coolant in the exhaust on cold starts, and no white vapors (at least when I wouldn't normally see any).

I like a lot of these other suggestions. I have no idea if the fuel filter has ever been changes; the regulator is built into it. If I have time later today, I'll clean up the ICV and MAF.

If that doesn't help maybe I'll run to harbor freight and pick up a fuel gauge.

I just took the car on a 400 mile trip; it ran perfectly and returned 31 mpg. Just likes to chug on startup...
 
Last edited:
Fuel filters can go a long time sometimes, but I have seen them cloged to the point of causing this kind of miss on start with as few as 30K miles. It depends on the gas you get, and that is a *&^% shoot.
 
Originally Posted By: Chris142
I'd look to a weeping head gasket that's fouling a plug with Coolant when it's sitting. I'd put a couple of stop leak pellets in the cooling system to see if that improves it.


I agree here.

Or possibly a weak coil.

Have you changed plugs recently? BMW's 100k spark plug service is generous...I changed my 545i's plugs @ 60k and they would have never made it to 100k without a misfire.
 
Last edited:
Here's an update.

I pulled the idle control valve out and cleaned it and the throttle body. Both looked like they hadn't been touched in 149,000 miles. I couldn't even get the flap in the ICV to move at first.

Anyway, put it back together. The boots looked great. No cracks or tears. The DISA valve was dirty, but I cleaned it up and it has no play and feels good.

When I started it up, the idle still misses a little bit. I took it out for a quick drive and noticed that the throttle tip-in was much smoother.

But when I give it a quick blip up to 1500 rpm, the idle gets rough and is accompanied by a fairly loud hissing noise. It sounds like it's coming from the DISA. After a few seconds, the hiss goes away and the idle smooths out. I can do this reliably; blip to 1500, hiss, chug chug chug, smooth.

I didn't think the DISA had anything to do with idle. Any other m54 nuts out there?

By the way, I changed the plugs at 135,000. They looked bad, and my city mileage went from 16 to 22.
 
Misfiring has very little to do with ICV being dirty, it's either your ignition, fuel mixture, or compression.

You mentioned you changed the plugs 10K miles back, did you use the exact OEM make/model of plugs? Potentially a weak coil?

A small intake leak can cause a misfiring, when the engine warms up and parts expand, sometimes the leak seals up.

Tight intake/exhaust valves can also cause a slight misfiring.
 
that hissing sounds like a large vacuum leak. Is the hissing present above idle speeds?

Just for run, when its cold, get some carb cleaner, and spray where the intake manifold meets the cylinder head. Note any idle changes. If it picks up, you have found your vacuum leak.
 
Last edited:
Status
Not open for further replies.

Similar threads

Y
VQ37VHR Motor bogging down at cold start; oil related?
Replies
18
Views
373
Hall
W
2010 Fusion Sport Misfires
2
Replies
22
Views
934
14Accent
N
My oil level is going up??? Really need help
2 3
Replies
51
Views
1K
Nick1424
9
2002 Grand Prix 3.1L, 4T65E trans slow 1st to 2nd shift
Replies
18
Views
434
CoachRoss07
H
Glitter or Bubbles?
Replies
9
Views
317
Marcozi
Back
Top Bottom