adaven16

ok guys, without you knowing it you have fixed a lot of my issues with the stang over my three months of ownership thanks to the search feature. but now im frustrated and havent found an answer to this exact problem.

(The car is a 88 gt and is speed density) I have a surging idle that i cant get rid of. it is sporatic and doesnt always occur. sometimes it also dies when it surges too low. it always cranks right back up. also it has had a couple of lean pops under load. its had the issue since i bought the car a couple of months back, plus many more. a week ago, the thermostat went out and caused it to overheat on the interstate and thus blowing the head gaskets. this past friday i finished the installing the new head gaskets along with new high flow water pump, 180 degree thermostat, all hoses, belt, idle air control, O2 sensors, timing chain and cover, valve cover gaskets, fuel filter, new spark plugs and wires, new distributer cap and rotor, had the heads machined and valve job with new springs, coolant flush, all temp sensors, and all other appropriate gaskets. after all of this my idle still surges. also the car is not throwing any codes. I cant find any vacuum leaks and the smog system is completely removed.

my mods include: 306, bbk cold air intake, JE forged pistons and rods (lucky find when i took it all apart), bbk equal length shorty headers, mac pro chamber mid pipe, 2.5" piping, flowmaster super 44's, ported and polished heads (i know they suck but the machine shop owner owed me a favor so he did it for free).

could it be my fuel pump going bad and having trouble keeping up? any help would be greatly appreciated. thanks a lot

89mustangfive0

did you try cleaning your iac( idle air control) builds up with carbon..usualy easier to just get a new one for like 20.00 and throw it on instead of dickkin around with cleaning it...another thing is tr fordfuelinjection.com the slat and pepper shakers could use a cleaning... you clean those 10 pin connectors with contact cleaner and put some di-electric grease on it could also help to..

adaven16

yeah ive already replaced it. i did forget to check the salt and pepper though. thanks for the reminder. ill do that in the morning. and thanks for the link.

89mustangfive0

no problem good luck i have the same problem but i know there was some kind of recall where ford put on somekind of harness extensions on the salt and pepper shakers ( my buddys 90 gt he just picked up has them with the sticker from ford) its suppsoed to stop the surging idle..i called a local ford dealer and wound up cursin the guy out when he told me my 89 gt is old and out dated cause i dont drive a 2008.. i know its 18 years old but i was just looking for a simple answer lol

gothand

Where are you finding new IAC's for $20? [sm=jawdrop.gif]

lxman1

I hear ya!!!! About $32 locally.

Check the TPS voltage at idle. If it's too high, it can cause it to surge. Should be around .95volts.

Joel5.0

Suggestions for your speed density setup:

1. DIY KOEO/KOER/Cylinder Balance Self-Test

2. Summarized/Corrected Base Idle Reset Procedure

3. Proof a code 67 causes idle problems

89mustangfive0

i bought one from autozone it was like 20.00 plus tax

shawnk007

Check your TPS voltage. I had the same issue-bouncing idle and backfiring under a load. Turned out I had a bad TPS. Replaced it, and have never had a problem since.

87greyghost

Convert it to MAF it dont cost as much as you thing. THe most expensive part is the a9l computer and you can get that on ebay for a reasonable price. I had this problem also and just decided to go with a carb setup becuase someone is doin it for me for cheap. The MAF conversion shouldnt take but about 2 to 3 hours at most. Ive also been told that when you add mods such as heads. cam, bigger TB, it screws with that SD bad. Thats what i was told was wrong with mine is that i had a cam in it with SD and it was screwing up. Im not a certified mechanic these are just suggestions.