bizzare tuning problem - on the dyno now.

[MustangChris]

Hey all.

i have a 1996 GT with a 2004 cobra swap.

the thing was finally driven up on the dyno today and outside of massive belt slip they ran into one other problem. A problem I've never heard of.

The computer wont go into "idle" mode (?) ... 100% of the time it thinks its driving down the road. Throttle plate closed, open, neutral, 1st gear.

Anyone run into this issue before?

Many thanks,
Chris


Things to know:
2004 9 thread engine.
100% OEM when pulled from the cobra.
T45 transmission

modifications: (long-a$$ list, but the most important regarding this issue)
accufab TB + plenum
pullied+ ported blower
pullied crank
MSD 2 step
diablo sport chip
SCT BA 3000 MAF
Long tubes + cats
OEM ingnition


let me know if you need any other info!

 

[vermilion]

Tps? The communication between it an pcm distinguishes open and closed.


Sent by smoke signals

 

[MustangChris]

ty sir. I'll look up some info on that and we'll see what we can find out! :-D


keep the suggestions comin'!

 

[2002BLGT]

Datalog anything you can , VSS and TPS would be first 2 things to check

 

[MustangChris]

the tuners have it, so i'm sure they are loggin' it.... thanks for the advice guys! I'm just tryin' to do a little leg work for the guys, since im a bad ass customer like that... lol.

 

[Marvin97]

So is it not transitioning from open to closed loop?

 

[MustangChris]

that sounds like it might be accurate. (?)

they told me (in lay-man's terms) that the car, for whatever reason, doesnt understand that its parked, not moving, and supposed to be at idle.

 

[atlanticblue98]

In additional to possible tps... Iac working correctly?

 

[MustangChris]

we'll look into that! Thanks for the suggestion, Ryan...... ... God i hope its a cheap fix.

 

[Marvin97]

I would guess the tps, as far as I know it control the car switching from open to closed loop at about 60% throttle or so

 

[MustangChris]

gotcha.

this stuff is a little over my head.... when computers dont behave, it frustrates the hell out of me. lol.

whats the difference between open and closed loop?

 

[RichV]

Closed loop uses O2 sensors to control air-fuel via injector pulse. Open loop just used pre-programmed tables, does not care about O2 reading.

In a nutshell anyway, a little bit more complex with timing. Usualy, you are open loop at WOT, closed loop at part throttle. But, I understand that a lot of newer stuff does not have an open loop anymore. Not sure about your situation, I wish I knew more about the newer strategies.

 

[1997gtRioRed]

dont worry its probably something stupid like a broken wire or a dirty connector going to the tps, iac, ecm, ect.

 

[1997gtRioRed]

Closed loop uses O2 sensors to control air-fuel via injector pulse. Open loop just used pre-programmed tables, does not care about O2 reading.
.

i might be wrong, but i thought it was the other way around....closed loop is preprogrammed, open loop uses sensor input

 

[justinschmidt1]

i might be wrong, but i thought it was the other way around....closed loop is preprogrammed, open loop uses sensor input

No he had it right....

open loop is usually WOT or warm up...uses fuel tables

Closed loop is based off the sensors....

 

[1997gtRioRed]

No he had it right....

open loop is usually WOT or warm up...uses fuel tables

Closed loop is based off the sensors....

ah ok. thats weird though....you would think closed loop, it would be a closed system. and open would be, well, open to input.....hmm. whatever. ya learn something new erryday

 

[MustangChris]

Thanks guys!!! Learn new stuff everyday.