Need Help With Engine Hesitation...

tblue

New Member
May 10, 2010
5
0
2
Tuscaloosa
I have an 04 GT, with 92k.

I purchased the car used. Here are the known mods
3.73 gears, cammed, 78mm TB, Off road H pipe, flow masters, tuner.....

Have had the car since April. The only problem with the car up until now is when I turned the A/C on the idle dropps below 500rpm and would have a hard time idleing.

2 weeks ago I filled up and that's when the problems started. I thought it was bad gas, but the problem is still there with the new tank of gas and after running seafoam through a tank of gas.

The car seems to idle fine, but has a very noticalbe hesitation/stutter under acceleration. It will smooth out some when the car warms up, but the stutter is still there.

I have cleaned the MAF and have driven with it unplugged, but the problem is still there.

I have cleanded the IAC and TB.

I replaced the fuel filter as well.

One thing I did notice is after I cleaned all these components, the car really ran well, I assume it was because of all the spray in the TB and IAC I used, but once all of that burned off the hesitation/stutter returned.

The car idles fine and revs fine,...it seems that from about 10%-50% throttle the hesitation happens, but anything about 50%-WOT it runs strong.

Maybe bad TPS?

Any ideas what I should check next?
 
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Check your coils...Fords engine seem to have week coils. I was having the same problem for about two weeks and just yesterday i changed them all out and the problem went way. i went with accel coil on plug... andy's auto sport has them for $200 a pack
 
I need to check all of the above, how do you check catalytic converters?

Your mod list says you have an off-road midpipe which means it has no cats.

You might want to check the O2 sensors. 10-50% throttle is still likely in closed loop so lazy or slow sensors could result in the car running goofy. Once you get into power enrichment the PCM goes open loop and basically ignores the feedback sensors.