High idle, rich running, with the occasional misfire

[hobbyshark]

Well guys I have a 1983 L Jetronic. I've replaced a majority of the vacuum lines in it and have new coil, cap, wires, and rotor. I've inspected the plugs and they don't seem to be fouled. Can anyone point me towards the next possible action to take?

[hobbyshark]

I've started checking the electrical connections on the MAF and at least one ground on the engine.

[hobbyshark]

Oh and occasionally the idle would bounce between 1000 to 2000 rpm. But it went away after I rooted around the engine tonight.

[stepson]

High idle usually means that you have unmetered air getting into the throttle body. Check that your barn door is seated properly.

[hobbyshark]

Would the 30 year old o ring around the MAF to throttle body be a the culprit also? Thing was hard as a rock when I looked at it.

[hobbyshark]

Any thoughts on the rich running and misfire?

[MPDano]

Originally Posted by hobbyshark

Would the 30 year old o ring around the MAF to throttle body be a the culprit also? Thing was hard as a rock when I looked at it.

Yup, that's an air leak. Replace it and see if it also fixes your rich condition. How is your O2 sensor. If it's original, time to replace that too.

[hobbyshark]

O2 is a recent replacement no more than 4 years I think. I also was looking at my used to be green now brown wire from the distributor. That's the last thing I can think of in relation to igniton. Of course there may be more.

[928 Bro]

Spraying carb cleaner while the car is on, in areas that you think might have a leak will prove itself right away. Idle will change right away

[stepson]

Originally Posted by 928 Bro

Spraying carb cleaner while the car is on, in areas that you think might have a leak will prove itself right away. Idle will change right away

Good idea but before spraying carb cleaner, check for fire flies under the hood (run the engine at night with the lights off to check for sparking from the ignition system) Since carb cleaner is highly flammable (duh!!), if fireflies are present, don't spray the engine with the carb cleaner. If no fireflies are present, just make sure you have a fire extinguisher handy.

A green wire problem can show itself in a number of weird symptoms. It's a possiblility to check after fixing the unmetered air leak at the barn door and checking for any others that may be causing trouble.

[hobbyshark]

I experienced some deadly fireflies this past year when I went to adjust the timing on my panzer. I rode the lightning and promptly got to work on the coil and wires.
The gaskets for the MAF arrive Tuesday. I hope to have them installed before I have to go back to work in the Bay Area.

[hobbyshark]

I will advise if this helps with the surge and high idle.
The other question I have would be should I pull the injectors and have them looked at? It looks like they haven't been pulled ever. I have had the fuel lines done. I didn't want to have my car looking like it got hit by an RPG by the side of the freeway.

[Dean_Fuller]

Originally Posted by hobbyshark

I will advise if this helps with the surge and high idle.
The other question I have would be should I pull the injectors and have them looked at? It looks like they haven't been pulled ever. I have had the fuel lines done. I didn't want to have my car looking like it got hit by an RPG by the side of the freeway.

So the fuel lines were replaced but NOT the seals? Old seals can cause a fire as fast as old lines. I suggest replacement ASAP just to be safe.

[hobbyshark]

The list grows....😐

[Danglerb]

High idle, too much air is going in.
Running rich, too much fuel is going in.

Too much air suggests a leak in some of the old rock hard rubber, replace it all. Idle could also be set high to compensate for some other problem, try setting it to the correct value.

Too much fuel can be a sensor issue or injector issue. O2 sensor is in the 1/4 exhaust headpipe, so it only "sees" one side of the engine. One lean injector on that side will make the rest run rich. Bad O2 sensor can make the whole engine run rich. Same for bad air flow meter. Its also safe to say if it hasn't already been done the injectors need to be removed and cleaned with new seals.

[hobbyshark]

Well the o ring got replaced and no noticeable difference. There was a definite change in the seal though

[stepson]

Originally Posted by hobbyshark

Well the o ring got replaced and no noticeable difference.

That is surprising

[MPDano]

Originally Posted by stepson

That is surprising

I agree. Try and spray carb cleaner around the rubber intake pieces while it's running. Also, there is a Diverter Valve near the Coolant reservoir that almost always gets bad due to the Diaphragm going bad.

[hobbyshark]

Ok looking at the part under the fuel injection rail between the coolant and windshield reservoirs. It has a threaded screw in the middle. I am correct about the part right or am I off base?

[hobbyshark]

Could the vacuum limiter be a culprit also? The symptoms of my woes are high idle unless I run it until hot. Shut down for about 20 minutes then back to a more normal idle at start up.