hammeron

same here.

it does seem fuel related in a round about way. if there was a vacuum leak,
the initial open loop (slightly richer) startup period, could be masking the leak.

on the other hand if it is a bad o2 sensor, it would only manifest itself after
the car enters closed loop.

i think the loop timer is 60 seconds, on a stock calibration.

hammeron

that's an interesting question....

if you can trick the PCM into thinking that the engine coolant temperature
was low enough, it may be that simple. the threshold might be 140*F or
somewhere thereabouts.

MReesePT

I have not had time to run the data with the tuner, but anyone have any thoughts about a bad cat converter. I noticed that the right 4th spark plug had a new coil pack and may have been bad at one point (i have since changed all the plugs but not the coil packs)... The car makes a rattle like a loose heat shield only when cold and only lasts for a few minutes then goes away. I had someone tell me that he felt it could be a bad cat converter on that side.

Anyone have any experience with a bad cat that and caused them to loose power?


Thanks for all your thoughts. I am just trying do fix or try as much as possible before I give up and take it to the dealership and get bent over.

siggyfreud

A cat that is falling apart and clogging the exhaust would certainly rob you of power. But it wouldn't explain why your car runs normally for a few minutes and then takes a turn for the worse.

FastDEW

If it were a bad CAT, it would run poorly all of the time.

You need to data log. But it sure sounds like fuel starvation to me.

MReesePT

Finally broke down and took it to the dealership. The tell me that they diagnosed it as a throttle body problem. They were not going to replace the TB but there was a "kit" to replace what was not functioning properly. I took it as the TB was not opening fully all the time???

We will see how it runs tomorrow, will update if my big mystery was solved or just money wasted.

JDWalton

again, there is a data log of throttle position sensor, actual throttle position, and throttle % (pedal) But, if they get it fixed pretty cheap, I think you'll just be happy its done!

tx_zstang

Replace the fuel filter first; it's easy enough to do.
You cleaned the maf, that's a good thing to do as well.

Datalogging would show fuel pressure issues, which if a fuel pump or clogged filter is at fault, the pressure would drop.
Regardless, change that fuel filter!!!

MReesePT

Tx... did change the fuel filter, did not help.


THAT WAS IT!!!! THE MOTOR ON THE TROTTLE BODY GOT REPLACED TODAY AND MY STANG IS BACK!!!

Time to put the Steeda in and the custom tune from BAMA and really unlease the beast.

Thanks for the help guys.

JDWalton

steeda intake + cutom bama tune = win. Your gonna poop your pants with how much diffrent that feels.