1999mustang2000

Ok well my car runs like total schit. It runs as if its missing and doesnt have much power at all. So today i go outside and look at all the codes it has.

Problem 1. When you start it up and give it some gas it hesitates then revs, the rpms come back down drop below idle rpm and then come back up.

Problem 2. The car has a huge loss of power, but only sometimes. Other time it runs awesome. If i unplug the MAF it runs good. I bought a new MAF and still have the same problem. It has a big *** aftermarket MAF housing on it. I wonder if that could cause it to run rich and like schit maybe it hasnt been tuned for it. (the MAF came with the car)

Problem 3. I cannot use my traction control at all. The light constantly stays on and will not go off. When i use my sct tuner and try to turn it on it still does nothing almost as if my pcm is bad and wont accept what the tuner is telling it to do.


Problem codes.
P0320 Ignition Distributor speed input
P0340 Camshaft position
P0350 Ignition coil
P0352 Ignition coil B
P1130 Lack of 02s fuel trim at limit
P1151 Lack of 02s lean
P0174 System to lean.

The car has highflow fuel rails stock injectors.

vanquish

I would most definately look into the MAF sensor. Running a random MAF sensor without being tuned for it would cause big problems.

1999mustang2000

Ok just to clear things up the housing is a 90mm housing with a stock MAF meter. will this still do it?

cliffyk

Yup, the sensor just samples a small portion of the flow and the total flow is determined from that sample and an assumption of the MAF inside diameter and flow characteristics. This is the purpose of the MAF Transfer Function table in the tune.

When the housing is larger the total flow for any given sample made by the sensor will be higher, however the PCM won't know that and will inject only as much fuel as required for what it believes the air flow to believe (from the transfer function)--hence the mix is lean.

I.e. either get a stock MAF housing, or a tune...

As to the t/c, the indicator is ON when the t/c is OFF--sort of a warning lamp. When you switch t/c off with a tune the lamp stays lit and pressing the switch does nothing.

This brings up another issue, when you used your SCT tuner to turn off the t/c you also loaded a tune into the PCM (it's not possible to just change one parameter--the whole tune has to be loaded).

Do you know what that tune was? Assuming you have "married" the tuner to you car, if you had previously loaded a custom tune with the SCT it will be that tune with the t/c off, if not it will likely be the stock tune with the t/c switched off.

I have no direct experience with SCT's tuners so this may be incorrect, as to which tune will be loaded, however it will be some entire tune not just instructions to turn off the t/c...

1999mustang2000

I have the 93 performance tune with the t/c off. but if i un-marry the tuner from the car i still cannot use the t/c

cliffyk

Are you certain you started with a stock tune?

If the car had a custom tune (with the t/c off) when you got it, and then you married it your SCT, then what the SCT thiniks is the stock tune will in fact be the custom tune that was on the car when you got it?

1999mustang2000

When i first got it it had a diablotuner i un married it then sold it bought a sct and married it to it and thats what it has now

cliffyk

That certainly improves the possibility that you stated with a stock tune. Unfortunately other than examining the tune with low level tuning software there's no way of telling it was actually a stock tune--with an OEM tune the t/c should be on (indicator LED off) at at startup and the switch should work.

1999mustang2000

hmm oh well. its not all that important, im just trying to get the car running good right now.

cliffyk

It is important because a tuner like the SCT makes changes to whatever it considers to be the stock tune, when you make selections like 93 octane, t/c off, etc.

If what it thinks is the base tune isn't then there's no telling exactly how the tune is configured--this and the big MAF may be at the root of the problems you are experiencing.