Author Topic: Cold start engine shakes and sputters (Read 27432 times)

bearsbmw · « **on:** November 14, 2008, 11:02:25 PM »

Ok this problem is driving me bonkers as I have been trying for a month to figure out the problem and I can't seem to get my finger around it ... basicly on cold start the engine shakes and sort of sputters a bit. Once it clears up, it runs very well after about a min... there is a few thing's that I can do that will clear this problem up befor I start in the morning and that is Unplug AFM or make a small vaccum leak

What the heck is going on !!

Thanks!

AcSchnitzer318is · « **Reply #1 on:** November 14, 2008, 11:23:27 PM »

This problem is driving tons of us up a wall. Get used to it... I've been dealing with it now for a year +.

B318M42W · « **Reply #2 on:** November 14, 2008, 11:38:20 PM »

here's my 2 cents... if you need to make a vacuum leak to "fix" the problem, then it means that the engine needs more air to get the "right" air/fuel mixture... so maybe...
- AFM is dirty or dying
- ICV is dirty or dying
- cold start injecter is not well operating
- fuel isn't "atomised" well enough???
- ECU's loop mode

first things to come to mind... hope it gives you an idea!
good luck

bearsbmw · « **Reply #3 on:** November 14, 2008, 11:41:20 PM »

Quote from: AcSchnitzer318is;60768

This problem is driving tons of us up a wall. Get used to it... I've been dealing with it now for a year +.

I was hoping someone would shed some new light lol with a new thread was expecting the deal with it part

Im too lazy to read the big thread on this same problem but did you replace your fuel regulator and knock sensors?

roundel318 · « **Reply #4 on:** November 14, 2008, 11:44:26 PM »

I like the cold start injector idea.....
Would a wonky O2 sensor cause this?
I wouldn't think so as it would probably cause trouble all the time?
Just thinking out loud.

bearsbmw · « **Reply #5 on:** November 14, 2008, 11:48:51 PM »

M42 does not have a cold start injecter
02 Sensor was replaced 2 x
AFM rueled out with a swap
ICV worked well when I put 12volts to it

bearsbmw · « **Reply #6 on:** November 14, 2008, 11:50:46 PM »

Quote from: AcSchnitzer318is;60768

This problem is driving tons of us up a wall. Get used to it... I've been dealing with it now for a year +.

nevermind about the knock sensors ... e30 m42 does not have my bad

roundel318 · « **Reply #7 on:** November 14, 2008, 11:56:06 PM »

How long does it run with your AFM disconnected before you shut it down, reconnect it and start it back up?

bearsbmw · « **Reply #8 on:** November 14, 2008, 11:58:18 PM »

5mins and hovering at 2000rpm ... I plug it back in while the car is runing and she drop's and idles perfectly

roundel318 · « **Reply #9 on:** November 14, 2008, 11:59:18 PM »

Do you have a spare ECU? Tried reseating the connector?

bearsbmw · « **Reply #10 on:** November 15, 2008, 12:01:05 AM »

reseting the connector ?? if you mean the ECU/dme then yes a million times with a battery unhook over night

roundel318 · « **Reply #11 on:** November 15, 2008, 12:03:06 AM »

Hot plugging anything that feeds to the ECU is a BAD idea.....
Just tossing that out there....

roundel318 · « **Reply #12 on:** November 15, 2008, 12:04:00 AM »

Can you run down a spare?
They go for as little as $40 on ebay.

bearsbmw · « **Reply #13 on:** November 15, 2008, 12:11:54 AM »

Quote from: roundel318;60779

Can you run down a spare?
They go for as little as $40 on ebay.

I guess that will be my next step ... would a grounding out signal wire from the O2 sensor mess thing's up? I remember way back when I was installing my wide band guage I touched the signal on the frame inside the car and it stalled the car but it started back up fine

tjts1 · « **Reply #14 on:** November 15, 2008, 02:05:01 AM »

Check the thin vac hose connecting the fuel pressure regulator to the throttle body. If the FPR is leaking or not receiving vacuum, the car will run like crap in open loop.