Ok. I changed the fuel filter a few weeks backs and there was no change. Just recently however I now get an infrequent idle "sticking," where coming to a stop when in neutral or with the clutch in the idle will smoothly settle to 1000rmp, hang for a few seconds, sputter, and suddenly drop to its normal 750 and continue smoothly. This only happens 1-2 times a week. But it is noticeable when it happens.

 

My last car was a BMW I had set up for road racing. Sold it at 269k miles. They had "see through" gas lines in the engine bay, mine were STILL see through when I sold it. Over the years I saw numerous BMW with see through fuel lines which were no longer see through.

For a period of time BMW was selling Techron over the counter for engine cleaning. Until they found that the Techron was eating the engines when it couldn't find something else to consume.

There are quite a few fuel cleaners out there, look around. Right now i'm into Lucas Oil Products. I've been using their "Fuel Treatment" with fair regularity, but I just picked up some of their "Deep Clean Fuel System Cleaner" which treats up to 30 gallons. I'm going to use 50% of the bottle in two consecutive tanks. As far as the "Fuel Treatment" goes I'm certain that when i put in the tank that the GT and my FJR1300 that they both run noticeably better, definite improvement in acceleration.

 

It still sounds like a dirty TB but you may want to look for any air in-leakage in the plumbing for that JLT.

 

Any word on this? I have the same issues, the idle speed is all over the place, stalling, hesitation when accelerating, pinging at half throttle... this is driving me nuts. I've replaced the plugs, fuel filter, cleaned the throttle body twice, ran 2 tanks of sea foam, changed tunes, adjusted timing... I can't figure this out. The weird part is, I can disconnect the battery or reload the tune and it will go away and run awesome for about a hundred miles, then once all the relearning is done the power drops and the pinging starts. I hate to throw parts at it but I'm thinking I'll try a new TPS and new O2 sensors. Anybody got any other suggestions?

 

I have a Shelby GT That I bought new in Sept of '07.

It's my DD with about 40k miles.

I have had that same hesitation issue since day one. I brought it to the dealer's attention. Their old, "guru" technician said that it's "normal with a cold start".

I love that. Whenever they don't know what the problem is they call it "normal" or "They ALL do that."

Mine does it first thing in the morning. And after I let it set for a few hours, like when I use it at work to go to lunch. As I roll out of the parking lot, I'll stab the gas pedal with the clutch pedal pressed in and a loud BANG goes off. From then on it drives perfect.

I had just written it off to the Shelby GT tune they did in Vegas. But, I recently installed a 'Bama tune and it still does it.

I'm interested to find out the cause, too.

 

My 06 GT is doing the same thing, now that the mornings are a little cooler its gotten more noticable. It will sputter a little on the first acceleration when cold. I have everything new within the last 4k miles, plugs, coils, fuel filter, JLT 3 intake, frrp TB, Frrp intake manifold, Bama tunes 93 per, ford o2 sensors, new ford MAF.

 

Also ive used Seafoam both ways twice.

 

Sounds like an air intake leak of some type or a vacuum leak.

It also could be a dirty MAF or even spark plugs but I doubt that. I would go through the entire intake system and make sure no air is getting in or out through the intake.

The times that this has happened to me it has been a result of:

1. Cleaning a very dirty MAF. THe clean MAF read the air better and thus the tune was screwed.

2. Loose inlet piping of some type.

3. Bad fuel

4. Tune

 

It seems like the JLT intake pipe may be the cause of these air leaks. The pipe is too flexible, I over tightened the clamp connecting it to the TB and it made a dip in the pipe. Also the surface where the MAF atatches is not flat, its warped.

 

Any amount of air getting in or out that is not read by the MAF will screw up your car.