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Discussion Starter · #1 ·
Hey guys i've had this car for a while and its been my daily for years. Have something that's been bugging me that seems like its maybe popped up within the past two months. Its an 1987 mk2 golf with cis lambda. Really just a stock motor with some bolt ons . When I first start the car the car will idle cold fine and have no issue, But when its run for maybe a minute (not even warmed up) it starts to run real rough and the idle drops down to 750-800 rpm and will usually choke the car out if I don't give it gas. But if I hold my foot on the gas it will even out in maybe 20-30 seconds. So im puzzled as if it doesn't seem like a warmup problem? But I could be wrong. Ive checked for vacuum leaks and haven't found anything. I haven't don't a tune up on the car in some time so i'm gonna do it this weekend. This would be plugs, wires, cap, rotor, plug wires, and I was gonna run a can of seafoam through the system in the gas tank. Anything you guys think could be doing this? Could it be a tune up problem maybe, or a cis issue or vacuum leak?, or a cold start valve or a warmup regulator? Ive only really gotten the car to run good first starting if I got the idle jacked up to 1500 since this has happened, so a vacuum leak has been a strong question in my mind.

I want to try to get this fixed before it starts getting real cold up here in new York , so Im not sitting in my car in -12 winter mornings with my foot on the gas to keep this thing from buzzing itself off. :thumbup::thumbup: appreciate any input guys!
 

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thermal sensor

If the 87 has a WUR then I'd do the following:

Check for vacuum leaks at the injectors and all connections. Make sure you look closely at the boots and
rubber parts in the intake system. Check and replace any suspect rubber or plastic lines in the vacuum system.
Tune up the car: Plugs, cap, rotor, wires, air filter and a fuel filter.
Make sure the timing is spot on. If the distributor has a vacuum advance make sure it's not leaking, cracked diaphragm is possible..

Using a carb cleaner clean the valve butterfly (throttle body) and then remove the idle screw and spray a judicious amount of cleaner into the bypass. If the o-ring is damaged on the screw replace it. If you can get it, use a viton (green) o-ring, they last longer.

Check spark quality, you could have a weak coil. 3/8" jump to ground with a nice blue snap, weak yellow no good.

If all else fails get a gauge and look at fuel pressure and delivery, a weak pump is also a possibility.

Good luck
 

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Discussion Starter · #4 ·
well, i have done an entire ignition system tune up and no fix. Checked all boots and vacuum leaks and all are fine, even just put in a known good used warmup regulator. Cold start injector works good. Still no good with this bad idle ..... :banghead::banghead::banghead::banghead:
 
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