Author Topic: First high idle and now no start issues (Read 3910 times)

jeff2051 · « **on:** January 04, 2012, 09:26:24 PM »

I did the vacuum line bypass on the new to me but not my first 1991 318is last week. I ran a line from the valve cover to the TB and ran the other line from the ICV to the boot. I left the water lines for another time when in the not to distance future. That along with a new valve cover gasket and plug wires fixed the rough running issues ......for a week. The other day it began running at 3500 to 4000 RPM's and if shut off would not start immediately but wouls start after a few minutes but would stall at first punch of the throttle eventually smoothing out. Had the same issue the other day but could get the car to idle normally by A.) disconnecting the lead to the ICV or B.) squeezing the vacuum line from the ICV to the boot. So I figured the ICV was bad. Found a used replacement tonight for it but now the car won't start at all with either ICV installed. After long cranking it will begin to sputter but no go. It's possible that I have two bad ICV's but my multimeter skills are not the best and I can not get a consistent reading from the test.

Any suggestions as to what the issue might be?

Geoff · « **Reply #1 on:** January 05, 2012, 05:26:36 AM »

it sure sounds like you may have missed a vacuum leak, or perhaps created one by moving that stuff around. after I replaced some hoses and stuff, I found that my intake bellows had developed a crack where its clamped to the throttle body, causing erratic idle and things. A good way to find a leak is to use gas from an unlit propane torch, or starter fluid, around suspect areas and it will have an effect on the engine if there is a leak. BUT of course the engine must run to use this method. I'd keep looking for a sneaky cracked hose or something along those lines
Geoff

DesktopDave · « **Reply #2 on:** January 05, 2012, 07:26:23 AM »

I've seen a lot of M42s with cracked throttle cable ferrules. Check the ferrule at the bracket on the TB. BMW issued a small spring clip to resolve that issue but seems only to have installed it on 5-series cars. A motor idling at 4000 rpm is unlikely to have a small vac leak. It'd be a big one. I'm suspecting a sticky TB butterfly. Disconnect the throttle cable & try to start the car again. Let us know what it does.

You have the FPR hooked up to the TB, right? I'd be tempted to run a fuel pressure test myself. If you don't have a fuel pressure gauge, you can run a quick test by disconnecting the FPR return hose from the chassis, putting it into a 2 liter bottle, and see how far it'll fill in exactly one minute. Should very nearly fill the bottle up.

If you do this test, of course follow normal safety precautions. Disconnect the coils, short the fuel pump relay, and have a fire extinguisher handy.

atdm3 · « **Reply #3 on:** January 05, 2012, 01:12:42 PM »

I did this mess under intake repair last week.
I had a weird idle issue after the repair but that was due to the small air hose from the Fuel pressure regulater attaced to the TB. make sure that hose is connected.
Did you clean your ICV? I ran brake cleaner followed by WD40.
Alex

jeff2051 · « **Reply #4 on:** January 07, 2012, 10:26:44 PM »

Latest update and thanks for all the replies. I was able to get to the car on Thursday evening after work and generally reviewed all connections and discovered that the intake boot was not seated completely on the bottom of the TB. Not sure how that came loose but it was and the car started fine and ran around that night just fine. Friday morning I took the car to work 42 miles one way mostly interstate. When I exited the interstate and stopped the idle had jumped to 4000 again and stayed that way the rest of the way to work. Upon leaving work that afternoon it started and has run since then. The only issue now is rough idle and hesitation at startup.

Go figure

I still have to take the intakes off and remove/replace the coolant lines, TB heater stuff and coolant tube but for now it appears to be running OK.

tfrain · « **Reply #5 on:** January 12, 2012, 01:27:39 PM »

I also have rough idle and hesitation, but it is only at startup. I have not done any of the "mess under the intake" mods, but I have removed and cleaned the ICV and checked the houses attached. All seems fine.

My suspicion is that I have a vacuum leak somewhere. Would that cause this issue? Can someone tell me, in order of most likely, where to check the vacuum connections? Also how much would it cost and where would I find part numbers to just replace every vacuum and emissions hose?

I know to check:
1. Intake boot - mine is pretty hard, should it be flexible? I don't see any cracks on it.

2. ICV hoses - the short one to the cam cover, and the other ones coming off the bottom, going under the intake.

3. The elbow from the Intake boot to the ICV as well as the line

4. The line from the front of cam cover to the Throttle body

Where else should I check?

My additional issue, and I don't know if it is related, is a smell of gasoline pretty much all the time. It isn't terrible or noticeable at all going down the road, but is when standing still. It is fairly strong. And I can smell it through the vents when sitting still as well.

thanks,
Tom

tfrain · « **Reply #6 on:** January 17, 2012, 01:09:10 AM »

my rough idle and hesitation at startup was cured by unplugging that standalone white/black wire outside of the loom on the firewall, under the cover, passenger side. You may already know about it, but it tells the car to read O2 Sensor data instead of potientometer (sp?) - at least it cured my hot start issues. I stumbled upon it on here a few days ago. That problem was really starting to get under my skin.

DesktopDave · « **Reply #7 on:** January 17, 2012, 07:04:11 AM »

Oh yeah...the CO pot for non-cat motors. That's a real gotcha with these cars, no doubt. Glad you got her running well again.

tfrain · « **Reply #8 on:** January 17, 2012, 09:08:44 AM »

I did thx. My next thing is the hose mod and replacing timing chain and sprockets. I must say that having an additional vehicle, while it costs me insurance money, is nice to have so I don't absolutely have to get the BMW back together sunday night. It is a luxury for sure, and I enjoy working on it when the pressure is off.

tfrain · « **Reply #9 on:** January 17, 2012, 09:17:27 AM »

Hey Jeff2051 - have you checked that cable? The black and white one that looks out of place under the plastic cover on the firewall? I can't find the dang thread now. It basically needs to be unplugged if you have a US car with Cat, otherwise it doesn't read the 02 sensor data and basically runs like crap on hot start for a minute or two. It was very frustrating and embarassing for me. Perhaps that is your issue as well??

victor.askew · « **Reply #10 on:** January 25, 2012, 12:23:59 AM »

Take an inspection mirror and look under the intake manifold to see that the intake manifold has seated flush with the head from end to end. Sounds like a large vacuum leak. Opps, I didnt read all of the posts, you found the problem. Grt.