Lustang s197

So, I have been a few issues with my 2006 Mustang GT. What I have been noticing while accelerating is what I can only describe is this sort of thumping while accelerating. It's more of a feel than a sound, as if something is slipping. It's to the point to where it has an effect on acceleration. The only time I can get it to stop is when I really step on the gas pedal.

Right after I let off the accelerator, and also when I am just cruising at highway speeds of around 70 to 80 mph, it backfires a little bit. It sounds a little bit like someone hitting an empty jug with something.

I also notice what smells like a combination of a fuel and exhaust odor, mostly fuel though. It seems to be coming from the air vents when I first start the car up, or when I am idling at a stop light. Other than that, I can't pinpoint where it is coming from, and never notice it when I open the hood.

The backfiring started a few months back after I installed the long tube headers, and has gotten progressively worse since.

After replacing the air filter on the CAI, new plugs, new wires, the only thing that has helped has been switching over to the 93 octane performance tune and running the car on premium.

Doing that helped greatly, however, it's still running like I described, but to the point where it is now barely noticeable.

The fuel odor is of course as noticeable as ever. Any help would be greatly appreciated. It's been driving me nuts, especially on the highway.

waykooljr

Has the throttle body ever been cleaned? There are plenty of threads about cleaning the throttle body and it's easy to do.

Mine had a rough idle and was even stalling on me, cleaned the throttle body and it ran like new.

Nuke

What tune are you running and have tried a different tune?

Lustang s197

I was running on a regular tune when I was having most of these issues. I've since switched over to a 93 and started running the car on premium, and it seems to have solved most of my problems. The check engine light even went off. I plan on cleaning the throttle body and MAF censor tonight since I don't think they have ever been cleaned on this car.

I am still up in the air on whether I should still get another tune since I installed my long tube headers. The tunes I have now are the ones I got a few years back when I put my CAI in.

I'm too savvy with all of this computer stuff just yet, so any advice would be greatly appreciated. Thank you.

Bullitt2059

I would def get a tune to calibrate for the long tubes. I'm sure the car will run OK without it, but you're probably not realizing its full potential.
One other thing that may cause some hesitation is the fuel filter. My car had what seemed like some mid-upper range hesitation. changed fuel filter, and it was gone. Its fairly easy to change and worth doing if you're not sure its ever been done.

Dino Dino Bambino

You definitely need a new tune for three reasons:

1. The LT headers have increased the airflow through the engine so the tune needs to be adjusted accordingly.
2. The upstream O2 sensors are now further away from the engine and take longer to warm up, so the ECU needs to stay in open loop for a longer time during engine warm-up to prevent hesitation due to a lean A/F mixture.
3. If you have an offroad midpipe, the downstream O2 sensors need to be disabled.