Idle Issues Please Help

[2l8iwn]

I am helping a friend workin on his coupe. I can only tell ya what i have been told about the car. It is supposedly a 93 cobra motor with trick flow upper and lower,msd coil, 75mm tb, 24lb injectors with cal'd maf, x-cam, headers, hi flow catted h, and flowmasters. Car keeps dying at idle. It will run for about 45 seconds real smooth and then surge so bad that it dies. Here is a list of things i have done. I have checked the tps with a volt meter and its ok, i checked the maf and its good. I checked the IAC and its good. I checked and reset the timing. I changed the plugs and checked the wires. changed the fuel filter. It had an O2 sensor broke off so i replaced it. I checked the connections on ect and act sensors. I am a little at a loss here. No check engine light and it seems to drive ok except full throttle is seems to lack power. I am going to check fuel pressure tonight but wanted some input on some other things to check.

thanks in advance.

[87stangbbb]

yeah fuel pressure is the only thing i can think of. my 87 didnt die at idle but took about 5 seconds of cranking to start. and ran like shit when you stepped on it

[2l8iwn]

now that i think about it the pump did sound a little suspect when priming. Well see.

[NXcoupe]

What maf is on the car(manufacturer)? What do you have the idle screw set at, what rpm will it idle with the IAC disconnected? Has the car been tuned? What's the initial timing set at with the spout out? What is the voltage reading you have on the TPS when you checked it?
Need this info to help, any suggestions without this info are not going to help.

[2l8iwn]

What maf is on the car(manufacturer)? What do you have the idle screw set at, what rpm will it idle with the IAC disconnected? Has the car been tuned? What's the initial timing set at with the spout out? What is the voltage reading you have on the TPS when you checked it?
Need this info to help, any suggestions without this info are not going to help.

Not sure on the manufacturer of the maf. I do know it has a white label and all the info was hand written. it does say that it is calibrated for 24lbers naturally aspirated. other than that i dont know much about it. To set idle i pulled the iac connector and set the idle between 400-600 rpm. Then plugged the iac back in and the car idles between 850-950. Not sure of a tune but i would guess not. With the spout out i have the initial timing set to 12 degrees. This throttle body has the adjustable slides for the tps sensor so i set throttle closed voltage to .90. The reading at WOT was 4.90 if i remember right. I looked at fordfuelinjection.com and they state when testing the tps that anything between .60 and 1.00 is acceptable. But i am no expert.

[2l8iwn]

I talked to my dad a little more. He used to be a ford mechanic, and he is bringing me a beep code scanner for the eec 4 , a vacuum gauge to check that, and a fuel pressure gauge to check pressure. Hopefully something will show its face when the car starts to surge. Ill post back the results.

[2l8iwn]

nxcoupe - The maf is made by massairsystems. it has www.massairsystems.com on it.

[NXcoupe]

Well, that's enough info, increase the initial to 14. What air intake do you have? Is there a bend before the maf?
Set the idle screw to around 800 and then plug the iac back in. That will help for starters, your iac duty cycle is probably in the 70% range right now.

[2l8iwn]

Ill change the initial to 14. The air intake is a mac cold air. There is a bend right at the fenderwell hole but nothing uncommon as it pertains to a normal cold air kit. I will reset the idle per your reference and post back. sorry i did not get the testing done last night as i orginally posted but the guy was unavailable.

[2l8iwn]

sorry guys i promise i will follow up with the solution to this. I just have not had a chance to catch up with my buddy to do some further testing. He did call and say that when he first starts the car and hammers on it that it does NOT cut out. Only after the car warms up. I am still leaning towards a fuel issue.

[2l8iwn]

update*** turns out that the iac was intermittant. we have since replaced and reset the idle to fords specs. Purrs like a kitten now.