Jeff McVicar

everythig was fine and ran fine. I let it run for a couple of hours and turned it off. A week later I started it up and it started right up then after a minute the idel started tgoing up and down, like someone was tapping the gas.and its at a very well timed interval to boot. Any ideas??

Jeff McVicar

bump,,,,any ideas at all??

Ell

Check your vacume lines

Big Dave

Ditto on checking for vacuum leaks. A split rubber sleeve on my intake cause similar symptoms.

Do you hear any sort of hissing or whistling?

Does the problem go away if you step on the gas?

Gretch

Guy I know checks vacume leaks by opening the valve on a small tank of propane over the top of the engine compartment while the engine is at idle. If the engin speeds up when you do this, you have a vacume leak somewhere. I have seen him do it, it is a slick trick. To finish, he just starts plugging vacume at various points until the rpm bump up stops, and he has found the leak.

BrianG

A mechanic friend of mine uses Varsol in an atomizer spray bottle. Same idea.

Jeff McVicar

Thanks Guys for all your replies. I'll get on it and let you know how your diadnosis were. I sure do appreciate it a bunch.
Jeff

Jeff McVicar

Hey one more thought guys........like I said, it was idling fine when I turned it off. If I find no leaks, it there a throttle positioning sensor on an 83 that may have water in it ? I'm going out to work on it now.

Jeff McVicar

Well no vacuum leaks, there are two throttle positioning switches on the (throttle body for lack of the correct part name) if I depress the one on top the idle goes up to about 1400 and is steady as a rock. the bottom one is depressed when idle so I couldnt play with it without altering the throttle arm. Idling, the idle goes up to 1400 and seemingly swithches off the ignition almost and drops to just under 1000.......from 1400 to 1000 and back to 1400 takes exactly 1 second and is perfectly timed. It sure seems like an electronig control for the fuel injection system....any ideas again hahaha

WallyP

One common problem when you wash the engine - the water vapor from the warm engine will condense in the cooler distributor cap, coating the cap and rotor, and shorting out the ignition. Pop the cap off and dry both the cap and the rotor.

Frustrating when the car runs fine on the way home from the car wash, but won't crank that evening after you have changed clothes!

Jeff McVicar

hahahahhahaha no **** hahahaha. Thats pretty much exactly what i was thinking. I tried that already but I'll give it a closer look. That ia one quality cap compared to the gm stuff I usually work with.

Jeff McVicar

Thom I tried that and it looks like the cap and wires came as a unit and werent supposed to come apart hahaha I'm stronger than average and founf out when I broke the coil wire off of the hahahahha. ....check it out. if I hold the flapper open in the airbox it idles down and stays steady..... mean anything?

drnick

is power-washing ever a good idea? i thought these engines came from the factory with a special coating to inhibit corosion and that washing would remove it!

Jeff McVicar

Well I say when a engine is 20 years old and is covered with oil and road dust, its time to start over. After I get this ironed out I'll put a protectant on it.

Jeff McVicar

yeh i did hahaha I'mgoofy sometimesI was wondering why that thing was so hard to pull off haha some of the cap came with it haha. Yeh it does the same thing. it almost seems like its on a light switch......1400..off to 1000on to 1400..off to 1000 ect.... its so well timed its rediculous haha