My TwEECEr helped me diagnose a problem

BlackVert

BlackVert

15 Year Member
Oct 3, 2003
5,589
9
98
Bethesda, MD
#1
On the way to work this morning, my CEL came on, and the car would rev too high after putting the clutch in. The light would go off while cruising and come back on at idle.

Great. :mad:

So I hooked up the notebook to the TwEECer and kicked off CalCon. It didn't take too long to notice that the Throttle Status (TS) was "part", even though the Throttle Position (TP) voltage was .880 and I had my foot off the gas. The TS should be "closed" under those conditions, not "part".

So I pulled over, popped the hood and checked the throttle. Sure enough, it wouldn't close all the way, because the cruise control (CC) cable was (is) either too short or the CC motor is not disengaging completely or something.

After disconnecting the cruise control cable, the CEL went away and now the idle is actually where I have been trying to get it all along, about 750.

The TP voltage is now .822 at closed throttle and the TS is "closed".

Looks like this may have been the cause of my idle problems all along. :bang:

Why would my CC cable be too short?
 
#4
I have one that IM gonna try today.

I dont know if my VSS is bad or it is the cable (or somewhere in the dash). [my speedometer and both odometers do not work---only thing in the dash not working]

My notebook drive crashed a few months back, and I havent loaded or touched the TwEECer. I just finished with it...and my mechanic suggested that to find out if the VSS is bad or the cable in the dash is, to hook up the TwEECer and datalog...If the speedometer works on the TwEECer, than it is NOT the VSS, and vice versa.

As far as the TwEECer goes, it is IMPERATIVE that you get the R/T with data logging!
RC
 
#6
BlackVert said:
It didn't take too long to notice that the Throttle Status (TS) was "part", even though the Throttle Position (TP) voltage was .880 and I had my foot off the gas. The TS should be "closed" under those conditions, not "part".
Click to expand...
This is pretty cool. For future reference, can you explain the dynamic to me a little better. If the CC cable was physically holding your throttle blade open (as if your foot was resting on the gas pedal, right?), why was your TPS showing its baseline volts?

I think I missed something but wanted to figure this out. :nice:

This is one reason I thought it would be cool to be able to stream stuff (to get an Auto X-ray, etc that can do this would go a long ways toward a TwEECer).
 
#8
HISSIN50 said:
This is pretty cool. For future reference, can you explain the dynamic to me a little better. If the CC cable was physically holding your throttle blade open (as if your foot was resting on the gas pedal, right?), why was your TPS showing its baseline volts?

I think I missed something but wanted to figure this out. :nice:

This is one reason I thought it would be cool to be able to stream stuff (to get an Auto X-ray, etc that can do this would go a long ways toward a TwEECer).
Click to expand...
As if my foot was resting on the gas pedal, exactly.

It started early on in my drive this morning when I was coasting down a hill (in gear), the light came on. Sitting at a stop light, the light would be on. Driving aroung part throttle, the light would go off. Coast (in gear) or stop, back on.

Also, the RPMs would climb between shifts and they came down slower than normal when I stopped.

The TPS was showing .880 volts, which I have, up till now, thought was the baseline volts. Now, with the CC cable disconnected, it reads .820 volts, which must be the baseline.

What caused it (the PCM) to finally figure out that the throttle was not completely closed? I dunno ... maybe the throttle return spring snapped it all the way closed once when i let off the gas quickly and the PCM caught it and made that the baseline?

At lunch, I bent the bracket a little so there would be some slack and reconnected the CC cable. It is happy again.
 
#9
wow you guy are having too much fun with those tweecer. Arent they a little difficult to tune with isnt it better to get a custom burned chip like a Diablo on the DYNO thats what i got. Just a ? cuz I thought it was real cool when it came out then I heard some bad stuff about it then, THEY said if you dont know how to tune with it you can really scr@w your tune up.
 
#10
yobi1kanobi said:
wow you guy are having too much fun with those tweecer. Arent they a little difficult to tune with isnt it better to get a custom burned chip like a Diablo on the DYNO thats what i got. Just a ? cuz I thought it was real cool when it came out then I heard some bad stuff about it then, THEY said if you dont know how to tune with it you can really scr@w your tune up.
Click to expand...
no doubt, there is a big learning curve. people can spend months just trying to track down one annoying behavior. grady knows what i am talking about there.

if you have a boosted app and you screw up the tune, yes you can break your motor. you can also do bad things to it if you forget to put the fpr hose back on or you do any number of other things.

sure, one option is to get a chip and be done with it in a couple of days. the car will run and you can be happy with it. will it be the best tune possible for your car? how will you know?

i have my reasons for choosing a self tuning option:
- it satisfys my intellectual curiosity
- i want to know what is going on inside my pcm
- i like knowing that i am in control of it and can change it when i feel like it
- when i am done, i can be certain that the tune is the best it can be
- it can help track down stuff like this pretty easily
- i'm a glutton for punishment
 
#11
You bring out a point on a few things I guess its not for everyone, especially if you are like me if it aint broke dont fix it kinda guy... What kinda of parameters can you adjust with that thing.
 
#14
yobi1kanobi said:
You bring out a point on a few things I guess its not for everyone, especially if you are like me if it aint broke dont fix it kinda guy... What kinda of parameters can you adjust with that thing.
Click to expand...
If we ever hook up Ill show you. Main ones (which are commonly used) are

1. delelte EGR (to get rid of CE light)
2. Turn off thermactor (if you removed smog pump)
3. Change temps at which the fans come on (low and high speeds)
4. Advance/retard spark (timing)
5. Change A/F amounts

And for us AODE guys, we can change tranny line pressures for firmer shifts, and we can change shift points (RPM in which auto shifts)

Those are just the basics.

RC
 
#15
94GTLaserRC said:
If we ever hook up Ill show you. Main ones (which are commonly used) are

1. delelte EGR (to get rid of CE light)
2. Turn off thermactor (if you removed smog pump)
3. Change temps at which the fans come on (low and high speeds)
4. Advance/retard spark (timing)
5. Change A/F amounts

And for us AODE guys, we can change tranny line pressures for firmer shifts, and we can change shift points (RPM in which auto shifts)

Those are just the basics.

RC
Click to expand...

Can #5 be done without the R/T model/
 
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