Cruise control issue, decel ignition retard.

[RocketSled]

Good day,

I'm having a few issues with my 2004.5 G35. It's a tt car with a built bottom end, APS extreme kit, ID2000 injectors and the other standard parts.

My cruise control does not work. When I set it and lift my foot off of the accelerator, it seems something is happening with the closed throttle switch. Ignition timing retards to 1*BTDC. I can tell the throttle is opening by watching manifold vacuum drop, but the car acts as if it's in a decel fuel cut mode. Then the car will come back to life, accelerate back to the set speed (while ignition timing is locked at 1*) and then go back into the fuel cut. It will do this a few times and then the ECU seems to give up and it stays in the cut mode. If I hold the throttle just off the closed throttle switch, it operates normally, throttle control and timing.

Any time I'm off the throttle, wether the decel fuel cut parameters are met or not in the Haltech, timing locks at 1*BTDC. If I let the engine drop to idle and coast, the timing stays locked at 1* at idle. Blipping the throttle you can even hear the retarded timing. Right as the car comes to a complete stop timing jumps back up to table timing and the idle increases from 800 to 1200RPM until the ECU can compensate.

Any assistance is appreciated.

*EDIT*

I searched a bit more and came across this: viewtopic.php?f=24&t=4289

I plan to try that the next time I'm around the car. Any ideas if the timing retard is associated with this?

[CorrPerformance]

Have you set the parameters in this sector as described in this thread I have done so in many 350z and have had success with them thanks to Hal.
I have not heard of the timing drop issues that you speak off either.

Try this as well.
Set decel cut rpm to 10,000 (which will effectively eliminate decel cut) and test to see if cruise control works.

Good luck,
Alberto

[RocketSled]

I had a short amount of time to fool around with this today.

The change mentioned in the link thread worked for the surging and allowed the cruise control to work, sort of.

Any time the car is in motion, and my foot is off the throttle, ignition timing is locked at 1*. Even when active on the cruise control, timing is a steady 1*. If I put enough pressure on the throttle pedal to open the closed throttle contacts, timing is per the table.

This happens even if I change the paramaters enough to make decel fuel cut impossible (RPM 10000).

It seems to not be related to the decel fuel cut timing adjustment, though it does seem a base for that adjustment. If I set decel fuel cut timing adjustment to 1*, ignition advance will show 0* timing when decel fuel cut is active. If I set the decel fuel cut timing adjustment to 10*, -9* is shown in the logs when decel fuel cut is active.

When coasting to a stop, timing still stays at 1* until the car comes to a complete stop, then returns to table timing.

Any more help or suggestion is welcome.

[rcdash]

Have you enabled copy through settings and do you have copy through engaged for timing in the vacuum sites? Let the stock ECU control under no load and your car will behave better. Good luck.

[RocketSled]

I agree that what you suggested is a way around the issue, however, I'm more concerned with why the Haltech isn't giving me the timing I ask for in the first place. There has to be a reason it's falling to a static setting whenever off the throttle.

It doesn't seem this is a common issue, I can find no mention of it anywhere.

Is the standard to use copy-through timing in all of the off boost area of the maps?

[RocketSled]

By setting the APP 0% voltage box on the TPS tab of the Main Setup menu slightly below what the voltage actually is when the APP is 0%, I was artifically able to show the Haltech 1% throttle when I am completely off of the accelerator pedal. The static timing off throttle is gone.

A quick adjustment of the decel cut and everything is working great.

This took care of the issue during cruise control and when coasting to a stop with the engine at idle.

[str8dum1]

how did you do this exactly? i cant seem to type anything in those boxes..

and by lower voltage, you mean that say actual 0% is 0.69V. You would set it to 0.65V, correct?

Thanks, struggling with similar issues

By setting the APP 0% voltage box on the TPS tab of the Main Setup menu slightly below what the voltage actually is when the APP is 0%, I was artificially able to show the Haltech 1% throttle when I am completely off of the accelerator pedal. The static timing off throttle is gone.

A quick adjustment of the decel cut and everything is working great.

This took care of the issue during cruise control and when coasting to a stop with the engine at idle.

[RocketSled]

That's exactly right.

how did you do this exactly? i cant seem to type anything in those boxes..

and by lower voltage, you mean that say actual 0% is 0.69V. You would set it to 0.65V, correct?

Thanks, struggling with similar issues.