Need Help With Random Idle Surge

bear601

New Member
Nov 5, 2011
17
0
1
ok ive got a 1990 ford mustang gt
5.0l bored to 306 balanced and blueprinted w/ forged pistons
1.6 roller rockers
gt-40 port and polished heads
gt-40 ported intake manifold
msd ignition
e303 cam
70mm throttle body
upgraded maf
k&n cai
24lb injectors
and a few other things im sure im forgetting to mention
anyway the car has no vac lines hooked up and runs strong as hell nice idle but ever
time i cruise in the car for a few miles the throttle sticks at what rpm i was cruising at.
so i replaced the iac ,no change still does it
replaced the tps, no change still does it
so i got a diagram of the vac lines started hooking them up and with them hooked up the car has no power, i mean no power
any ideas anyone

i was told bye a older gentlman that i needed to drill a tiny whole into the throttle body blade??
any help will be greatly appreciated
 
  • Sponsors (?)


See the "Surging Idle Checklist” for help with all your idle/stall problems. You can guess at the problem and throw parts at it, or you can use the checklist to help you find the problem quickly and inexpensively. It’s free and doesn’t cost anything: at last count there were more than 103,000 visits and still climbing

The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the fixes & updates. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.
 
Don't drill the hole. When was the last time you gave your intake system a good cleaning like the inside of the tb? If its really bad it could be sticking. That's what happened on my dads 94. I also clean my maf with maf cleaner every so often. Just a couple of things to try if you haven't already . Good luck!
 
First things first... If you suspect you have a vacuum leak, then get a gauge on there to confirm. Visually 'looking' at hoses is a poor use of your time and likely to be wasted.

I don't know where you live, but many parts stores rent such a tool.

If you find your vacuum is low, I would suggest getting a variety pack of vacuum caps/plugs from the same parts store and begin plugging off cruise-control, brake booster (while in garage), etc.

Findings vacuum leaks can be a bitch, and is only second to electrical problems on the Hemorrhoid Scale...be methodical in your diagnosis.