Hot-start issues, possibly idle-related

[flipwils11]

Hi, new member here but I'm a regular on a lot of forums (mye28, bimmerforums, firstfives).

My wife and I bought this car locally from Rob about 2 weeks ago (link ) for a track car and there are some issues that have it stuck in our driveway now since I don't trust it to get me home.

Now there's a starting issue, something like a hot start but in my mind, it isn't even warmed up! It nearly stranded my son and I Sat morning at Caribou on the way to a car show. The Caribou is maybe 3 minutes from my house so the water temp gauge had barely moved. We go in Caribou and I come out to start it, cranks, but won't fire. 5-6 seconds of cranking, nothing. After calling my wife and telling her the situation, I give it a few more tries and then barely, barely get it to catch at maybe 200 rpm and I gently give it some gas and it idles. Called my wife back to tell her it was
running and promptly drove it home with no issues and parked it (switched to the E39 to drive to the show).

I have noticed a weird idle every so often. It will just go up to 1500-1800 rpm for no reason and then if you blip the gas will go back down. It was doing this right before I shut it off at Caribou but I couldn't get the idle to go back down and then I shut it off. Not sure if that is what made it not want to start then.

Also, later Sat in the afternoon, I tried to reproduce it. Car had been sitting since the morning when we took the E39 to the car show. Started it up just fine in our driveway, drove it around the block in the neighborhood, came back and parked it. Shut it off and then tried to immediately restart it. Same thing, wouldn't start again! I didn't mess with it and just left it.

I know from searching the boards that these M20 cars have an idle control valve. Last night I followed the troubleshooting guide on Pelican Parts for the idle control valve. I didn't have time to check the throttle body. I measured 20 ohms of resistance and 40 ohms on the terminals of the ICV mentioned by the Pelican parts FAQ. So the ICV seems to be fine.

Anything else I can check? I tried some search terms for idling and no-start, maybe I missed the right thread that will point to what is causing this.

[BenM]

Hey Adam, good to see you around here.

First thing I would is pick up a spare main relay and fuel pump relay. Its always good insurance to have them on hand and possible they aren't functioning properly. They should be mounted under a cover on the driver's side shock tower.

Another definite thing to check resistance on would be the coolant temp sensor, especially with the hot no-start issue.

Best of luck and you should really post some pictures of your stable (hint: M535i!!!) in the member's ride section.

Ben

P.S. the motronic system in your car is nearly identical to the '88 E28 528e (Motronic 1.1), so posting on mye28 might yield you some good help as well.

[BrewCity11]

Welcome to the site Adam. Sorry you got stuck with this problem right off the bat. Hopefully someone will chime in and give you a hand.

-Turk

[flipwils11]

Alright, talking with Turk and Rob offline inspired me to go take the car for another spin. And it's a beautiful day here!

It had been sitting since Saturday, and temp is about 75 today. The 1st start was not great, normal crank but didn't catch until maybe 5 or 6 seconds and the same as it did last Sat; barely idled around 200rpm then I gave it bit of gas and it idled normally. No high idle issues.

Drove the car about 15 minutes on some nice roads and came back home. Pulled in the driveway, stopped it, then tried to restart a minute later. Started right up with zero issues. Revved it a big, shut it off. Waited a few seconds, then restarted. Again no issues, started right up.

Emailed offline with Rob whom I bought the car from and I am running 93 octane which he thought might be something. I guess there's the possibility of bad gas but I fill up at the same station in my E39.

On a side note (had the windows down), passenger side window makes an awful clattering racket when you put it all the way up and it stops. A stripped motor or wind mechanism perhaps? Still goes up and down, but as soon as it is fully closed you have to pull your finger off the button immediately or it sounds like the motor is stripping a gear inside the door.

[jlevie]

My first suspicions would be a sticky ICV, sticky throttle cable or throttle body, or an intake leak. Depending on what year/model car it is, other parts could be added to the list of suspects.

[greese]

First, E30s are known for hard starting. My untechnical, based on nothing opinion is the DME remembers the temp on cold start. When the temp changes, it gets confused. Now that the weather is warm, mine is stubborn to start when cold (we live in similar climates). Bentley says warm starting problems are caused by faulty temp sensor. I would clean my ICV, throttle body and check for vacuum leaks first. I've lived with this problem for four years and only twice did it not start, both times were fuel pumps. Learn to live with it.

[greese]

BTW, I'm not a Noobie. I just don't post much. MY join date is Aug 2006.

[gtdragon980]

wow, sounds like my car, it does that sometimes also...ill try to start it up and it'll just keep on cranking but i gotta hold my foot on the gas for it to fire up. and i sometimes get that high idle issue too, i don't really know what is causing all of this but i dont really bother about it i just live with it lol

[flipwils11]

Drove it again last night with my wife and son. Went to dinner first and it started right up after dinner. Then drove it a while, went to the playground for my son to run around, and it had been sitting for maybe 45 minutes. When my wife tried to start it, it took several tries of cranking 5-6 seconds and caught finally at the very low rpm range as it has been. I had the passenger side window down and I could smell a lot of fuel.

This weekend might consist of a lot of troubleshooting time on the E30 since my M535i is still waiting on a good brake bleed (lost the gasket to my Movit bleeder) and a new brake fluid reservoir cap. But per Ben's request, here's a picture of my e12 love (6 years of ownership as of this month).

[twright]

Put a fuel pressure gage on it at the inlet to the fuel rail. Start the engine and the fuel pressure will be about 40-45 psi. Shut the engine off.

If the pressure immediately drops to 0, you found the problem. You need a new fuel pump.

If the pressure stays high (higher than 20 psi?) keep looking for another cause.

[Adrian_Visser]

that test is to check if the inline check valve ahead of the fuel pump works ( it is mounted on the outlet side of the fuel pump and is part of the fuel pump assembly), if the fuel pump delivers the proper volume and pressure there is nothing wrong with the pump and it doesn't need to be changed, an additional inline check valve can be purchased and simply installed on the rubber fuel hose coming from the pump, much cheaper than a whole new fuel pump.

[edoglas88]

Did the OP ever figure out his starting issues?!