Engine 1993 5.0 surging idle . Modified engine

[Chad91gt]

Hi. So I'm finally back. Purchased a 1993 gt. Fully modified. Cam. Heads.intake. pulley. TB etc.. also with electric fan and full exhaust. My idle does alot of surging. Sometimes it will sit at 800
But then goes up to 1500 and sits for a min. Then sometimes goes back and forth. I sprayed catb cleaner to see if I can find a vacuum leak. No luck . Any other ideas .. I can use some help. Thanks .

 

[General karthief]

This will help if you do it step by step:
http://forums.stangnet.com/showthread.php?t=698148
Oh, welcome back!

 

[dcurtis]

I’d personally go through the base idle reset, disconnect iac, and advance plug, set idle at whatever your preference is for low idle, and plug it all back in, I’d clean the iac also and check timing, and set your tps voltage

 

[Chad91gt]

Thanks I'll take a look this weekend

 

[Steel1]

Not sure if you have a way to tune the ecm (chip, aftermarket ecu, etc.)
If not may be time to think about given your fully modified.

 

[Chad91gt]

How does that work? Chip is already programmed? Or a shop tune the ecu?

 

[Steel1]

How does that work? Chip is already programmed? Or a shop tune the ecu?

You could have shop dyno tune a chip for you that is plugged into your factory ecu (bring car to them).
If your into learning how to tune yourself and you want to keep factory ecu you could go with a piggy back
system like PMS or Moates quaterhorse.
The other option would be to replace your ecu with one from Stinger, Megasquirt or Holley etc, all these options
have varying levels of complexity and cost.

 

[jrichker]

Hi. So I'm finally back. Purchased a 1993 gt. Fully modified. Cam. Heads.intake. pulley. TB etc.. also with electric fan and full exhaust. My idle does alot of surging. Sometimes it will sit at 800
But then goes up to 1500 and sits for a min. Then sometimes goes back and forth. I sprayed catb cleaner to see if I can find a vacuum leak. No luck . Any other ideas .. I can use some help. Thanks .

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. It includes how to dump the computer codes quickly and simply as one of the first steps. 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 250,000 hits, which indicates it does help fix idle problems quickly and inexpensively.

 

[Chad91gt]

Thank you . I will check it out