Author Topic: Car won't idle - dies immediately (Read 3884 times)

WeOnlyHaveLime · « **on:** November 07, 2010, 10:59:08 PM »

Hey guys!

Just replaced the two fuel lines that are prone to leaking as I've had some problems with them. Fixed my fuel leak, but now the car won't idle! Put everything back together and while the car starts up just fine, it won't hold an idle and immediately dies once the revs drop. If I give it gas, it runs fine. Occasionally, it will idle for a bit but it's very rough. Went back through and checked all my vacuum lines, and I think I've gotten everything. This leads me to believe it's an issue w/ the throttle. How likely is it that the adjustment of the cable was messed up, causing the throttle to close completely when I release the throttle? If this is the case, how should I go about adjusting it? What did I do wrong?

Also, my friend who was standing by the engine bay when I started it back up noted that a small puff of black-ish smoke came from the area that the hoses are located when I started the car. I checked, and the area smelled like burnt rubber. Was this just old fuel on those lines burning off and singing the hoses a bit? What else could this have been? I feel like I've finally got this engine almost buttoned up and running right. There are just a few small little things that keep bugging me so I figured I'd ask some people who have likely seen this before! Thanks in advance for any help you can give me!

DesktopDave · « **Reply #1 on:** November 08, 2010, 06:10:31 PM »

Make sure you didn't cross the lines. If you have the feed & return lines mixed up it'll do just what your car is doing. Check that first before you mess with the cable.

Puff of blackish smoke? Vac leak? If you're car backfired maybe it blew out a hose? Fuel shouldn't be anywhere but in the rail.

WeOnlyHaveLime · « **Reply #2 on:** November 08, 2010, 07:30:08 PM »

Quote from: DesktopDave;98492

Make sure you didn't cross the lines. If you have the feed & return lines mixed up it'll do just what your car is doing. Check that first before you mess with the cable.

Puff of blackish smoke? Vac leak? If you're car backfired maybe it blew out a hose? Fuel shouldn't be anywhere but in the rail.

Cross which lines exactly? The fuel lines? It ran fine the first time I started it after I fixed the leaky fuel lines. I only took things back apart because I noticed a small coolant leak that I hadn't noticed while the fuel leak was going on. Put everything back together after getting that hose fixed and now I have the issues. I'm 95% sure everything is back together in the right places, but a connection may be bad or loose.

Sorry the OP didn't have that info.

Thanks!

DesktopDave · « **Reply #3 on:** November 08, 2010, 07:42:50 PM »

Yeah, that's what I meant. The fuel supply line to the rail and the fuel return line from the FPR. Sounded like the car wouldn't start right after the fuel line fix.

If I had to guess, I'd say to check the throttle position sensor, vac lines & idle control valve. A bad TPS could be signalling that the engine isn't idling when the throttle closes, so it goes too rich & cuts out only at idle. Vac leaks always cause idle problems, and a stuck ICV would do that too.

WeOnlyHaveLime · « **Reply #4 on:** November 08, 2010, 08:01:20 PM »

Quote from: DesktopDave;98497

Yeah, that's what I meant. The fuel supply line to the rail and the fuel return line from the FPR. Sounded like the car wouldn't start right after the fuel line fix.

If I had to guess, I'd say to check the throttle position sensor, vac lines & idle control valve. A bad TPS could be signalling that the engine isn't idling when the throttle closes, so it goes too rich & cuts out only at idle. Vac leaks always cause idle problems, and a stuck ICV would do that too.

Would a simple disassembly and reassembly cause any of that though? The car ran fine before and ran fine once after I replaced the lines. I'll check those things but I'm leaning more towards something I did wrong and less towards a part failing. I could be very wrong though. Thanks for all the help/suggestions!

bmwm42 · « **Reply #5 on:** November 08, 2010, 09:27:03 PM »

Mine did the same thing when i replaced the mess under the intake turned out was lose vac line to the icv

WeOnlyHaveLime · « **Reply #6 on:** November 08, 2010, 09:31:19 PM »

Quote from: bmwm42;98503

Mine did the same thing when i replaced the mess under the intake turned out was lose vac line to the icv

Yeah, my cooling/vac system is stock, so everything is still rather inaccessible at this point. I never got below the lower intake manifold as it never seemed like I needed to (fuel hose is accessible with only upper mani off, and coolant leak seemed to be coming from the line that goes from the small heater plate beneath the TB to the actual heater plate after the TB) but it's possible that I loosened something pulling the ICV and other things out of the way.

DesktopDave · « **Reply #7 on:** November 08, 2010, 09:32:44 PM »

It could have cracked a vac pipe. After 20+ years they get a little hard & crackly. Any damage to the vac lines will cause idle problems, but usually it's a surging idle, not a dead one.

There is a range of adjustment on the TPS (too bad they took out the idle adjuster screw, eh?), you could just dial in a little more or less throttle to deal with the flat idle until you figure out what's causing the trouble. Maybe squirt a little deep creep or WD40 in the throttle body & ICV to clean them up. Can't hurt to lube them a bit.