vibrating @ stop lights
 

OK, I still have an issue with truck running at stop lights, it doesn't feel like it wants to kill anymore, since changing the idle control valve. But after sitting a few minutes sort of has a slight kickback vibration feel. Hard to describe. As always thanks in advance.

90 burb 350tbi

Re: vibrating @ stop lights
 

dose it continue if you shift it to neutral? could be motor/trans mounts, vacuum leak, misfire... hard to tell without seeing whats happening first hand

Re: vibrating @ stop lights
 

I am running a new Edelbrock 4BBL. Mine did something similar at idle. In neutral or running through the gears, all was fine. We had one of the needles on the carburetor that seemed to have something in it. We removed the needle and sprayed some cleaner in the hole, then a blast of air... took about 3 or 4 tries but it eventually settled down.

Ran each needle down until the motor started to run rough, then backed off until it smoothed out. Been running fine ever since. I will be taking it to my buddy who runs a carburetor tune up shop and races Pro Stock... have him hook me up to his "tune-o-matic" diagnostic machine and dial in the carb and timing and all should be excellente'.

Re: vibrating @ stop lights
 

I had an 88 1500 with a manual there was an issue with the gearag trans Manuel. with truck idling its trying to compensate the idle for the gears slapping in Trans the fix was to up the idle.

Re: vibrating @ stop lights
 

Check for vacuum leaks. Hoses, valves, reservoir, egr valve and gasket, HVAC controls & check valve. Low/rough/surging idle with TBI is almost always a vacuum leak, a very small one. Also, after replacing the IAC, make sure you do the relearn/reset procedure. Another possibility is base ignition timing set too low and causing low idle or too high and causing low vacuum.

If its running fine but there is noticeable vibration in the seat when idling in gear, check the motor and transmission mounts. Old rubber clam motor mounts get soft and squashed down over time and the bracket on the engine rests on the cross member causing a rough buzzing vibration mostly at idle.

Re: vibrating @ stop lights
 

^Thanks guys, I will try to take a video tomorrow.

But I'm really starting to hate tbi engines! Took it out this morning for errands, got a fill up @ Murphy USA and it killed at the stop light after driving about an hour. It felt almost like it was about
to run of of gas. Started right back up, weird.
What is the best gas treatment system. Tried heet years ago seemed to make it worst.
Thanks again for you all taking the time to help me, it is greatly appreciated.

Re: vibrating @ stop lights
 

What is the difference with using a carb versus throttle body? Basically, do I just take the throttle body the intake manifold and put the carb on? Just wondering if it will bolt right up. I am limited on mechanical knowledge.
I have a edelbrock 1406 on my truck that I can swap out, significant gas difference?

Re: vibrating @ stop lights
 

Just thought about the fuel pump its in tank. So much for swapping from TBI to carb.

Re: vibrating @ stop lights
 

sounds to me like its just idling too low