Hi guys Im new to this site and the mustang world. Bought a 91 gt and did a complete redo of the upper half of the motor. The car has 65k on the motor. here is the low down of the car. took it down to block and pistons.Installed a E303 cam,(yes I installed the dots cam at 6 and crank at 12), I put a new set of gt40X aluminum heads on,also put a gt40 upper and lower intake on(from a explorer),65mm throttle body from that intake,plugged the holes to the egr with high temp silicone bc deleting all the emissions on the motor, its got a bbk cold air intake with a 80mm MAS(calibrated to 24lb injectors which I also have installed in the car),roller tip rocker(1:6) from ford racing and a 1" spacer between the upper and lower intake.. Heres what I have the car wont come down from a high idle(1500) with the IAC hooked up. with it unhooked it will idle down then tends to surge and eventually die. I have a brand new 255lph fuel pump being installed in it as im writing this. I have a dyno and a tune set up for the car in 2 weeks but id like to have these problems fixed by then.The car doesn't idle for crap and has a major hesitation all the way through the gas. If I take it easy on the car it tends to be fine, but once I get after it, it hesitates very bad and tends to sound like a pinging in the motor. Any help with this will be GREATLY APPRECIATED!!!!! The car is timed at 14*. I have also moved the Air temp sensor to the intake bc the lower intake was not tapped for it so I read on here to place it in the intake which I have installed it so.
Need Some Help
- Thread starter Heath Wallenberg
- Start date
You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix. 
It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 134,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 134,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
I have similar set up , for egr delete get a simulator "cheap fix"or a tune it will fix some codes , as for idle e303 idles hard but won't surge , if your base idle is set correctly with screw on throttle body should not surge, sounded like you have unmetered air coming in check all clamps on Maf , I'd then say you could have vacum leak on hose or upper or lower intake gaskets,with fresh rebuild very possible , and symptoms are as above stated so , don't be to confident and assume you sealed everything properly we are human,,, after further reading it sounds like follow the steps above for idle reset will fix your problem , turn your tb screw one turn to open a bit more , as for idleing at 1500 with iac are you letting it warm up enough to come down to set after it's warmed , it is iac job to keep idle up until warm and will then slowly come down every car different
Last edited:
Run your codes first. Does sound like a TPS/IAC issue, but running the codes beats guessing. I assume with a 91GT, and the EGR deleted, your check engine light should be illuminated.
Grabbin' Asphalt
10 Year Member
I like my ecam idle lope, mine never surges at lights or stopping in the city.
I do have a SCT chip tune though
I do have a SCT chip tune though
Similar threads
