Drive by wire - intermittent operation??

[dontlifttoshift]

Kind of a strange problem.

GM crate LS3 with GM controller and harness. Ocassionally when the vehicle is started there will be no throttle actuation when pushing on the pedal. it starts and idles fine but will not come off of idle. It seems that if you disconnect the battery and reconnect (I should be in IT, right?) that everything works fine again....until it doesn't. No check engine light that I am aware of.

Any ideas, cuz I'm baffled.

Donny

[RJ66]

Hi Donny,
I have been working with drive by wire setups in many cars now, & the only common problem I've had with the throttle not responding has always been a bad pedal or connection by the pedal.

[dontlifttoshift]

RANDY! I aint seen you since the last time I saw ya. Time to update that avatar?

You were there the first time I got this call in Des Moines......when you had problems did it quit working all together, forever and ever?

I really haven't dug into this one real deep but figured I would ask around, I knew the smart guys were here.

[RJ66]

Same here Donny it's been like since then. The pedal in Jimi's AMX was just a bad pedal, replaced with new one & began to work just fine no issues. I've also had issues with connections down were it plugs into the pedal, but usually you get a code or light. I wonder if it has been programmed to not give a check engine light or throw a code if the pedal acts up? The other possibility could be connection by throttle body. Do you have another pedal to try?

I still like my Avatar.

[neki67]

I have had a more or less similar experience and with me it wasn't a bad pedal.

To put the ECM in a nice spot, I had to have the cables to the ECM make a sharp turn near the ECM. Now the cables entering the ECM connectors don't have much of a cable stress/strain relief built into them so the strain of the cables making a sharp turn transmits to the pins in the connector. The problem was very intermittent and everytime I wanted to trace it, everything worked (obviously). But after a few weeks of annoyance an aggravation I found out there was too much strain on the cables and pins. I decided to put the ECM in a (for me) less desirable position but now with no pull or tension on the cables. Guess what? The problem never occured again . . . . .

When you look at the connectors they look really sturdy but once you open 'm up, you'll see that there's no cable stress/strain relief (whatever you call it) built into them.

[dontlifttoshift]

Just an update...

I put another pedal in (TAC) and everything was going well as I tuned the trans more to my liking. Cycled the key on and off and noticed a lack of TPS signal. Long story short, it takes 10 to 12 seconds in order for the ecm to reset. It has nothing to do with the battery being connected/disconnected for any amount of time. Just 10 to 12 seconds of key off before going back to key on and everything is fine. If you wait any less time than that the fuel pump will not cycle and we will not have a TPS signal.

GM is telling me 2 to 3 seconds is a normal amount of time for the ecm to "reset"......I had never noticed that before but how often do you turn the key on and off that fast in normal use, not often I guess.

So it seems our problem is more of a quirk.

Donny

[Samckitt]

I had this similar situation in my 03 SIlverado, I would not get a check engine light, but the driver's information center would say "Reduced Engine Power". Pushing on the pedal did nothing, but would idle a little higher than what normal idle was. This would happen to me driving down the road, and any speed, driving along, then the info would show & no power. I would have to stop, shut off the engine for like 20 seconds & restart. Fought this for a while then replaced the throttle body & have not had the problem since.