I've been trying to diagnose a problem with my 87 pickup with the 22R for some time now. The engine runs great from 1500 rpms on, but any lower than that and the engine idles roughly and has a slight miss. Also, when at fast idle, the engine has a severe miss that goes away when the gas pedal is tapped, bringing the engine off of the fast idle cam. A rebuilt engine has been installed, the carb was rebuilt by myself, and the truck still has a miss. Another thing is that I have the mixture screw turned out about 4 1/2 turns, 1/2 a turn more than factory, and this seems to help it a bit. But at the stock 4 turns, the engine has an even worse miss. Is it time for a Weber, or is it something else? I'm stumped

 

Bump!

 

Bump for ideas!

 

Bump!

 

75 views and not a single idea?

 

Bump!

 

Sorry, fuel injection would be my suggestion, or weber

 

sounds like a vacuum leak to me from somewhere. Assuming your ignition timing is set right at 0 degrees. Are you saying it only misses while the choke is engage?

 

Fuel injection would be nice, but there are no parts vehicles anywhere near me that are fuel injected

I can tell you for a fact that my timing is not at 0 degrees, although I am working on eliminating that as the culprit. As for the choke, the engine misses whether the engine is cold or warm so I'm not so sure about that, but it does miss worse when the choke is engaged on the fast idle cam, but not when you tap the throttle and step off of the fast idle. Also, I went around all the vacuum lines with an unlit propane torch and couldn't find any vacuum leaks. I'll put up a video of the engine missing as soon as I can secure a good camera

 

this is what is confusing, you say it doesn't miss when not on the fast idle cam. meaning choke is disengaged. basically saying only misses with choke engaged.

 

Or at idle

 

Here's the videos. First engine cold, then warm

http://www.youtube.com/watch?v=2aK4T4SO-J8

http://www.youtube.com/watch?v=w_lozv8Ty6I

 

sticking egr valve maybe ?

 

what did you do with the vacuum hose to the MC valve that was on the original air cleaner?

 

lmao good one XXX.

i too want to know whatchya did with it?

 

Doesn't have one

It's capped off, but the engine still missed when it had the original air cleaner

 

what about the egr modulator, all those capped off as well?

 

Yes they are

 

Any other ideas?

 

Mine had a miss at idle so I drilled out the idle mixture cap on the carburator. I adjusted it to get the highest idle speed possible and my miss was cured.