M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: flypenfly on May 18, 2007, 12:27:22 PM
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On cold starts, it runs great, pulls strong, warms up quickly, stays cool.
If I turn the engine off, and then turn it on again without letting it cool off (say like a car wash), it stutters and coughs then dies UNLESS I give it a lot of gas.
So, it basically won't idle on hot restarts. It will drive ok if I keep giving it a lot of gas but sometimes still stuters. This lasts about 10-12 seconds after a hot restart, it seems to be fine after that.
Any ideas?
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No ideas guys?
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How many times has it done this? Was "like a car wash" a... car wash? Or does it do this also when you get gas or run into a store for a minute?
Have you checked ECU for any stored codes?
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Haven't checked ECU but no lights have ever come on. It happens every time. By car wash I was just giving an example, sorry if it seemed confusing.
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I'm going to take a stab in the dark. Are you using premium fuel? You should be. If not, start doing so. It's not the octane, the Motronic will compensate, it's the additives in a good grade of premium fuel that helps to keep the injectors & valves clean, and free of carbon deposits. A bottle of Chevron Techron in a full tank of gas will help. Also, I'd replace the fuel filter, unless it's recent, and check the fuel pressure, the pumps failed on these now & then. Let us know.....I was going to buy your car, but you changed your mind, damn...I wanted a RED one, lol.
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I know this issue is related to fuel but have never really seen an ultimate solution or steps posted ever to completely get the issue taken care of.
I have experienced this issue on m20b25s and m42b18s to date.
Most often it happens when I have been driving and let the car sit for a while.
The worst time it ever happened was when I actually replaced the fuel pump in one of my m42s to a better one :confused:
Some say it's due to some gases in the fuel, others say it's due to the fuel filter or fuel pump, some say it's due to leaking injectors.
It's one of those things I have learnt to deal with and currently it's not to so bad as the car eventually cranks anyway :rolleyes:
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I know this issue is related to fuel but have never really seen an ultimate solution or steps posted ever to completely get the issue taken care of.
I have experienced this issue on m20b25s and m42b18s to date.
Most often it happens when I have been driving and let the car sit for a while.
The worst time it ever happened was when I actually replaced the fuel pump in one of my m42s to a better one :confused:
Some say it's due to some gases in the fuel, others say it's due to the fuel filter or fuel pump, some say it's due to leaking injectors.
It's one of those things I have learnt to deal with and currently it's not to so bad as the car eventually cranks anyway :rolleyes:
I have this same issue and heards some where that it could be a bad o2 sensor. Not sure how or why but im pretty sure my o2 sensor needs to be changed anyway, so if someone knows which ford one i can use, i can try this out and let you know the results.
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I doubt the o2 sensor has anything to do with a hard cranking issue. I have used the generic and OEM sensors in the past...I personally prefer the OEM ones.
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Sorry for having to be anal about the "car wash", I just wanted to make sure it wasn't really a water related thing! ;)
I haven't had this car for very long, but I was under the impression it might have a stored code but not have the check engine light on. There's no reason for us to be guessing without that info first, just do the 5 pedal stomp thing and see.
Probably not the 02 sensor, the car should run just fine without it. And you would get a code if it were bad.
If the car runs great other than the first few seconds, I wouldn't think dirty injectors, fuel quality related stuff would be the issue either.
My GUESS would be a temp sensor, air or coolant, I don't yet know all the sensors on this car. And again, I would think the ECU would store a code. But the ECU is running in open loop when you first start the car, and if it's getting the wrong temp, it's miscalculating the mixture. Once you get moving, and it starts running fine, that's probably because it's gone to closed loop operation, running off the O2 sensor.
Idle issues are often due to vacuum leaks as well, so get a vacuum gauge and see if it's making what it should. They're cheap.
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Thanks guys, I'll check the above. This is a pretty tricky thing to diagnose over the internet.
As for fuel, I've already run a bottle of techron and I'm only running premium.
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Thanks guys, I'll check the above. This is a pretty tricky thing to diagnose over the internet.
As for fuel, I've already run a bottle of techron and I'm only running premium.
Just to clarify: I didn't mean fuel quality per se - I meant "something with the fuel system."
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I doubt the o2 sensor has anything to do with a hard cranking issue. I have used the generic and OEM sensors in the past...I personally prefer the OEM ones.
I dont believe its a hard cranking issue, the car starts up fine, however, it does seem like its not getting the right mixture. Almost like its getting too much fuel and flooding itself out. Once the car does cut out, it will start up fine and run normal, atleast mine does.
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..so this leads to either
(1) A case of not enough air. An AFM swap is an easy test for this or simply cleaning it or testing it.
(2) Excess fuel pressure due to a faulty FPR or fuel vapors not being getting rid off. We have a charcoal canister with the little valve thing on it. Perhaps a swap of this would help.
(3) Leaking injector seals could also cause this case that feels like "too much fuel" on start up especially if you notice black smoke. Rebuilt injectors are a remedy here.
:::::::::::::::Insert other options/tests here:::::::::::::::::::::::::::::
The 3 above steps are where I intend to look when I decide to try and tackle this issue someday.
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..so this leads to either
(1) A case of not enough air. An AFM swap is an easy test for this or simply cleaning it or testing it.
(2) Excess fuel pressure due to a faulty FPR or fuel vapors not being getting rid off. We have a charcoal canister with the little valve thing on it. Perhaps a swap of this would help.
(3) Leaking injector seals could also cause this case that feels like "too much fuel" on start up especially if you notice black smoke. Rebuilt injectors are a remedy here.
:::::::::::::::Insert other options/tests here:::::::::::::::::::::::::::::
The 3 above steps are where I intend to look when I decide to try and tackle this issue someday.
Wouldn't these affect the cold starts as well though? On a cold start, the car is perfectly happy and the engine purs (in a somewhat ticking way, hah).
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Wouldn't these affect the cold starts as well though? On a cold start, the car is perfectly happy and the engine purs (in a somewhat ticking way, hah).
Sometimes faulty components only show certain symptoms after prolonged use or sometimes or one component tries to compensate for the failure of another thus causing some of these odd things.
Like I said earlier - this isn't a guaranteed remedy and I haven't seen one to date. It might exist that we don't know of.
I am openly thinking solutions ;) and can wait till I find the golden solution (if ever) hence being hesitant to post in the beginning.
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As e9Nine mentioned, this seems to be a consistent problem with the M20 guys. I've seen lots of posts about this on R3V and E30tech. Maybe do a search to see how some of these guys diagnosed the problem. Just a thought....
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It boils down to finding if it's rich, or lean during a hot restart. One or more leaky injectors would cause a rich condition hot, but would make a great start when cold, due to a bit of xtra fuel. I've seen fuel pressure regulators that start leaking into the intake thru the tiny vacuum line. These could really mess with your mind.......I'm wondering if this just developed, or if it has been ongoing.
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It boils down to finding if it's rich, or lean during a hot restart. One or more leaky injectors would cause a rich condition hot, but would make a great start when cold, due to a bit of xtra fuel. I've seen fuel pressure regulators that start leaking into the intake thru the tiny vacuum line. These could really mess with your mind.......I'm wondering if this just developed, or if it has been ongoing.
Been on going for me. I believe rich or lean was the reason why o2 sensor was mentioned where ever i read it. And i've also been told that im running pretty rich so my fuel mixture is probably the cause of my issue.
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Its crazy to read through all of these responses about the ECU etc, which I'm sure it could be, BUT I like to start with the easy things, or basics first,, How do all your vacuum lines look? I'm thinking the car warms up,, the hoses get soft and maybe you've got some leakage there.. I would then look at the Idle control valve, and air flow meter.. THEN I would start looking in to coolant temp, and cam position sensor,, but I highly doubt a problem there.. Leaking injectors etc etc, I wont reiterate what others have said :) Good luck on it,, I have a funky idle when I start my car up, but I know my vac hoses are trash LOL
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I'm sure we could all benefit from a complete fuel & vacuum hose replacement. None of our cars are even near new, right? BMW used a rather poor, in my opinion, grade of fuel hose, and I replaced miles of it in the late 80's-early 90's. It would look fine, but it would "sweat" gasoline. Customers complained of a fuel smell after turning off the engine. Some 750's burned because of this. Vacuum hose wasn't any better. I used to replace all these with Mercedes hose, the stuff with the cloth braiding on the outside, then M-B started using exactly the same junk hose as did BMW.
In the same light, the ECU is a very dependable part. The problem usually does not lie there. Temp senders can go bad over time, and there's a good place to start. Check it cold & hot, as it can fail on either end of the range. Still, my $$$$ are on injector leakdown, or leaky fuel hoses, and the latter will be obvious by the smell and the gas stains in the area of the fuel rails. The air flow meter has a potentiometer under the black cover that can wear out, and cause driveability problems of all sorts. This usually worsens over time.
Lucky me, my iS runs like a champ. starts fine, hot & cold. I'm counting my lucky stars......
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Well i just change my vacuum hoses last year hoping that would've solved my problem but it didnt, I do have a few other things i know need to be changed such as thermostat and o2 sensor and possibly injectors so we'll see. Car has been running like this for quite sometime and still feels strong once it does cut out after a warm start so its not that big of a deal to me just yet. I'll just do it all slowly as money and time become available and hopefully one day, i'll have fixed the problem. If you guys get any results, please keep us posted.