L-jet won't idle warm

Jim Chambers · 03-05-2002, 12:16 PM

My '75 1.8 starts easy when cold, needs no throttle to maintain idle. After car is thoroughly warm it will no longer idle. Only way to keep it running is to stay on the throttle. When engine is warm I can't keep it running long enough to get to the engine before it dies. Car is new to me. Just finished complete tune (plugs, points, cond., cap, new wires, dwell and timing are right). Messed with the air by-pass screw and makes no difference. Any ideas?

JRust · JRust's Garage

Hey Jim I've got a similar problem. Minr starts great & idles well when cold. Like yours it die's when warm & won't idle. I just took mine to the shop & should know the problem tomorrow. I'll let you know what we find. Possibly could be engine temp sensor?
Mine also is running really rich. Don't know if thats the same as yours but i'll let you konw either way. Also possible date for Pacific Northwest 914meet I mentioned a while ago May 20th. I keep you up to date

kenschipper · kenschipper's Garage

Have the same (or similar) problem here. Fine when cold, stop when its up to temperature and either won't start if you try in a few minutes, or won't idle until you drive for about 10 minutes.

Replaced the Auxiliary Air Regulators but didn't make a real difference. Thinking it might be the Cylinder Head Temperature Sensors but would rather know before spending the money.

JRust · JRust's Garage

Well one of my problems was my manifold intake hose/boots were
bad. Meaning they had stetched to much & were sucking alot of air in throwing everything off. I replaced them last night. Easy enough to do. Got kinda excited thinking that might fix my problem of it running rich. It might have but I'm not sure because it wouldn't start after I was done. I kinda figured I had more than one problem. I'm going to go thru & troubleshoot my fuel injection.
It just does'nt seem to be getting any gas. It has been doing this the last week & a half. Would run & drive allright except for the other running rich problem. Then it would decide not to start. turns over fine but would'nt fire up. I'd let it sit for a day & boom she'd start right up. So I'll try to start her tonight & see if one of my problems is fixed. Then start figuring out the next one. Good luck guy's keep me posted. I'll do the same

Jim Chambers · 04-10-2002, 09:00 AM

Problem solved at last. Checked all components according to
a great VW type4 FI manual found at manuals.type4.org/. All OK. Replaced most vacuum hoses. No change. Noticed fuel pump was operating with ignition (should not on L-jet).Borrowed air flow sensor from my neighbor Camp 914 Craig Laughlin's 1.8. Problem solved. Symptoms were: started easily cold, not idle when warm, could start warm only with throttle open, did not take fuel smoothly, only ran OK with slack throttle at steady rpm and could only keep it going at stop light with throttle part open. Installed different sensor, turned ignition on, did not hear pump, drove like it should. Fuel pump should have tipped me off sooner. Hope this helps someone. Craig is looking for a new sensor.