Car issues after tune

[austin21]

Hi everyone,

Recently got my 99 Cobra back from the tuner, its got a procharger, comp cams XE-R series. It HAD a MegaSquirt MS3Pro however i decided to remove it and re-install factory since im not making crazy horsepower. The car did not do these two things prior. Also replaced the upper Intake Manifold and Throttle body as it had a 03/04 cobra throttle body on it.

Ive noticed two issues so far my tuner says is normal. Just wanted to get everyones feedback.

1. When slowly letting off the clutch in 1st gear to get her moving, the car seems to want to die as soon as it loses RPMs. I can feel the clutch just start to engage and if i dont give it gas, the car will die.

I've driven numerous manual cars, including a 3V mustang GT a few years ago and i could ALWAYS let off the clutch to get the car to start creeping forward. In this case any RPM drop the car seems to want to die. is this normal with my setup?

2. The return to idle after coming to a stop taking awhile to bring the RPM's back down. Its a slow decrease rather than an immediate drop. Apparently this is normal in 99/01 Cobras.

Its harder to drive the car with the car wanting to die as soon as it sees an RPM drop. I have to ride the clutch which i don't want to have to do.

Thanks for any input.

 

[robvas]

Take it back to the tuner, it shouldn't be stalling. How slow is the return to idle?

 

[austin21]

Take it back to the tuner, it shouldn't be stalling. How slow is the return to idle?

Ill try to take a video of it later today. Its pretty slow.

I know we put a new Idle air control valve on it.

 

[DSG2003Mach1]

I have a similar setup and took the tuner quite a while to get the return to idle right. It’s still acts up from time to time but it’s usually pretty decent

 

[01yellercobra]

JMO, but you should have left the MS3 in place. More potential and easier tune. But I digress....

The 03/04 throttle body is identical to the 99/01. If your tuner told you otherwise find another tuner.

More than likely it's just the cams. You're going to need to give it some gas to get moving. It's even worse if you have an aftermarket clutch. I don't know how lopey those cams are, but you're just going to have to adjust to them.

That's the dashpot decay rate. Your tuner can adjust it to return to idle quicker. It takes some tweaking to get right.

 

[austin21]

JMO, but you should have left the MS3 in place. More potential and easier tune. But I digress....

The 03/04 throttle body is identical to the 99/01. If your tuner told you otherwise find another tuner.

More than likely it's just the cams. You're going to need to give it some gas to get moving. It's even worse if you have an aftermarket clutch. I don't know how lopey those cams are, but you're just going to have to adjust to them.

That's the dashpot decay rate. Your tuner can adjust it to return to idle quicker. It takes some tweaking to get right.

I agree, however i was hoping to resell the MS3 to recoup some costs. Had to get the car retuned and my procharger serviced as it was leaking oil.

I already had a working factory ECU that was left with me when i inherited the car.

Not a lot of folks near me that know how to tune on that platform also. Which was another reason i decided to not retain it.

I think the reasoning behind replacing the throttle body with a factory style was it was an aftermarket accufab that was a single oval flap vs the factory style. Basically the car was getting too much air from what my tuner said. Between that and the butchered intake manifold i believe you saw a few weeks ago. Got both of those replaced.

 

[01yellercobra]

Ah. Ok. That makes more sense. The idle ports on the single blade don't line up with the stock intake IIRC.

FWIW, remote tuning the MS3 is easy. Something to consider down the road.

 

[austin21]

Ah. Ok. That makes more sense. The idle ports on the single blade don't line up with the stock intake IIRC.

FWIW, remote tuning the MS3 is easy. Something to consider down the road.

yes exactly! I didnt know how to word it. But she drives so much better now.

I drove the car today and it seems actually a little better when letting off the clutch. I think its just because i havent driven the car in almost a month and a half.

I inherited this car from my father in law who took it to a local shop called National Speed here in Richmond VA and they did a piss poor job. But i took it to someone else and the car is running way better so i am very happy. 460 whp is plenty.

Now to upgrade the audio system!