For the past two weeks, my 1997 328i's engine has seemed less willing to start when cold. The engine cranks normally but stumbles for half a second before it catches. After it starts, it runs a little rough for the first 15 to 20 seconds.

The engine starts up immediately and smoothly when it's warm. However, if the car sits for more than 6 hours, it exhibits the symptoms I described. The car runs smoothly and without hesitation otherwise.

The fuel pump and sending units were replaced three days ago to cure my crazy fuel gauge. Yesterday morning, before starting the car, I turned the key to the "accessory on" position to run the fuel pump and pressurize the delivery lines. After a few seconds, I turned it off and then proceeded to start the car. The engine didn't stutter before starting, and the rough running for the first few seconds was greatly reduced.

There is no telltale odor of a fuel leak. The fuel filter and spark plugs were replaced about 20k miles ago during an Inspection II service at the local dealer. The car now has 75k miles on it. I feed the car with Chevron mid-grade gasoline.

It seems like the fuel delivery lines are slowly losing pressure when the car sits for several hours. Could this mean the fuel pressure regulator is going bad? Or could I have a leaky injector?

Thanks in advance for your help.

Bump. Anyone?

Did you recheck the connections you made for the pump installation?

Regulator could be faulty, but it is highly coincidental seeing as how you just futzed with the fuel delivery system.

Usually when i have trouble after doing some work, i assume i screwed something up.
That goes for anything in my domain.

Thanks for the advice. I'll open things up tonight and check the connections. I didn't replace the units myself; my mechanic did.

The problem had actually been going on for a week before I had the pump replaced. There has been no change in the car's behavior since.

GP, didn't you just replace some of the emmissions control parts? The ones dealing with the emmissions while the car is cold? Could this be it?

Ken,

It's doubtful, as this seems more of a fuel system thing than an emissions control thing. The secondary air pump doesn't (or, shouldn't) affect driveability. I read the fault codes a few days ago and there were none.

Still, I'll have to check it out. I have a relative who owns a fuel pressure gauge - all I need are the right fittings.

Originally posted by G. P. Burdell
Yesterday morning, before starting the car, I turned the key to the "accessory on" position to run the fuel pump and pressurize the delivery lines.

that shouldn't be necessary since the fuel system keeps the lines pressurized specifically to prevent excessive crank times on restarts. check your fuel system for residual pressure. it is an easy check... take off your fuel rail plastic cover; you should have a schrader valve on the fuel rail. hook up a pressure gauge. compare your residual fuel pressure to specification.

I have a 96 328i with 78k miles on it and my car kind of does the same thing on starts. It takes longer than when it's warm. It doesn't really run rough except maybe for a few seconds. I haven't touched anything lately so I don't know if it's just common over years.

I have this (or something very similar) on my 99 M3.

If the car sits for > 6 hours it stumbles for exactly 30 seconds and then smooth as butter.

I've read many times that at least for the M, it is a software issue. The dealer has a flash update for the problem. (at least for OBDII M3's) Other's get the Jim C shark thingy and say it goes away.

I'm ignoring it like a lazy bastard for now...

This may not be your issue, but the symptoms sound identical.

never happened once on my 95 M3

I have something similar on my car, as well. It happens more when it's cold out, and if I try and drive in the first 15-20 seconds when things are a little rough, the car will usually falter (as if ASC+T is kicking in) or will stall outright.

I posted about it a month or so ago, and apparently it's a common thing. I've been Shark Injected for a couple of years now, but this problem only started happening this past winter. I may try unSharking/reSharking to see what happens.

So you are sharked and it still does it huh?

Anyone know the TSB number for the flash update @ the dealer? (won't go near my local dealer lot)

Originally posted by pikachu
that shouldn't be necessary since the fuel system keeps the lines pressurized specifically to prevent excessive crank times on restarts. check your fuel system for residual pressure. it is an easy check... take off your fuel rail plastic cover; you should have a schrader valve on the fuel rail. hook up a pressure gauge. compare your residual fuel pressure to specification.

Thanks, Pikachu. I saw the Schrader valve when I was poking around the engine compartment last weekend.

I know that I can get the appropriate fuel rail fittings (to connect the fuel rail fitting to a fuel pressure gauge) as "special tools" from the BMW dealership. Can I buy these fittings elsewhere, like from an auto parts store?

Mine does the same on my 328is. I have been playing with the SMT-UNI and when it is hooked up it did not seem to do it. I have not been able to get anything else to work for the SMT-UNI, so I am still using the stock ECU.

Originally posted by G. P. Burdell
I know that I can get the appropriate fuel rail fittings (to connect the fuel rail fitting to a fuel pressure gauge) as "special tools" from the BMW dealership. Can I buy these fittings elsewhere, like from an auto parts store?

are you trying to hook up a pressure gauge directly to the fuel line entering the fuel rail? on the m52, you are supposed to use a special tool to disconnect the lines,, but of course, you can get by with any sharp needle to depress the locking mechanism.

wouldn't it be easier to just hook up the pressure gauge to the schrader valve tho? the fuel lines entering the fuel rail are quite back breaking to get to and disconnect...

Yes, I'd prefer to hook up the pressure gauge to the Schrader valve. Sorry if I wasn't clear on that.

I did something really stupid. I had the same problem with the cold start. The shark injector solved that problem for me, but when I got my cams in, I was running slightly lean so the shop recommended that I take off the shark software and put it back on. I did it and ever since, I gotten the cold start problem back again. Now it won't go away.....

I thought a dirty ICV was the cause of this?

My '98 M3 does this as well. Have to let it idle for about 30 seconds or it almost dies with mild throttle applied.

some people have cleaned (or replaced) the ICV just to still have the cold start issue...

i have this same exact problem.. I let my car sit for about 8 hrs and when i try to start it, it will stumble very very slowly and sometimes catch and sometimes stall... If i crank it one more time after that it starts right away... Its really annoying.. I changed my fuel filter and the problem went away but came back in a about a week... what gives?

I'm thinking about unsharking and resharking my car. Does anybody happen to have the directions handy? I can't seem to find mine right now... If you could please post them, I'd really appreciate it. Thanks!

Any of you guy ever hear the old M5/M6 3.5l engines. Even the 4 pot M3, they all do this when cold. Don't worry about it, its a bimmer thing.

Bill

Yeah, I have the same thing on my 92 325i. I was starting to think it was a regulator problem. I've cleaned the ICV, to no avail...

Update:

The car starts up just fine now. It's been fine for the last few days. I didn't do a thing to it.

I was reading a bulletin on the TIS CD-ROM that said starting problems could be attributed to the switch from winter to summer gasoline formulations. Maybe that was the source of the problem.

Originally posted by G. P. Burdell
Update:

The car starts up just fine now. It's been fine for the last few days. I didn't do a thing to it.

I was reading a bulletin on the TIS CD-ROM that said starting problems could be attributed to the switch from winter to summer gasoline formulations. Maybe that was the source of the problem.

FWIW, my car seems to do better when it's warmer out, but on a cool morning, the problem returns. :dunno

Originally posted by geha13
i have this same exact problem.. I let my car sit for about 8 hrs and when i try to start it, it will stumble very very slowly and sometimes catch and sometimes stall... If i crank it one more time after that it starts right away... Its really annoying.. I changed my fuel filter and the problem went away but came back in a about a week... what gives?


Same problem, happened for the past 2 mornings now.

the first crank is either rough or stalls out completely.
the second crack is normal.

this happens to my car when it's wet out.. when temps are at dew point and car has not been driven overnight.

just to let some of you guys know, i replaced my fuel pressure regulator and my problem went away... don't know if it will work for you guys

Sharking/Unsharking: Go to Turnermotorsport.com, then to chips and software. The section for the Shark Injector has a link to the PDF instruction file.

Guys Check Your Electronic Throttle Drive System.that Is Diretcly Concerned With Choking And Throttle Stuttering While Putting Your Foot Down.I have the same problem although i put in 103 octane healthy unleaded racing fuel but only a quarter of a gallon mixed with shell 93 octane.The trouble the 103 octane cost 7.20 per gallon so i thought bugger that!!I need a sponser.However this fuel is really good for the engine and engine and fuel system parts as it thoroughly cleans it.I will change the fuel pressure regulator ,and do a shark injection to see what happens