Idle & Off Throttle Hang - Sometimes

[antus]

Are you saveing the changes twice? Once one you finish editing the table - that saves them in ram but that does not save to disk - then you need to hit save in the task bar or pick file.. save as... to save the changes to disk.

[The1]

download 1.02 xdf ive fixed the lean cruise table.

[Monarols71]

Thanks N***l.
That fixed it. I wish I had 1/4 of you peoples knowledge. I can build the engines, but I can't (not these days) tune them.
We will give it a try tomorrow. Spare chip programmed and ready to go.
Any ideas on the slow to get back to idle problem??
Best Regards

[The1]

Don't worry I'm definatly no engine builder and am no programmer, can u post up a log of it doing it, is the iac passage in the Tb all clean?

[Monarols71]

Throttle body and IAC passages didn't have any build up at all, but I gave them a wipe out prior to, and after changing the motors. Motor pintle clean also.
Go to 7.16 to 7.19 in this log, and that has the slow back to idle issue. I have older logs, but the steps were way high before some great people told me how to adjust it. I must do some more logging after the lean cruise table is changed.

[The1]

I can see a DTC49.

[Monarols71]

Yeah. We live with an almost permanent DTC49. It doesn't seem to affect anything.
We have: - a new hall effect plate in the distributor, a new ignition module, new spark plugs, new HT leads, new battery, new alternator, checked all wiring, connectors, etc, etc, plus all the mechanical stuff that is new, and it still throws the fault. And yes, I've read through the post with the person with the VT 1 with the same problem many times.
We now have the SRS light on also, but that's my fault because of an integrated alarm fault and me not thinking at 6.15am trying to get the car to do something to get to work. Holdon to your wallet will have to fix that. Haven't had the car out of the drive trying to sort the alarm issue (I had to strip half the car to bypass it, and I know where every thing is ), so logging will have to wait.
The new .bin is in, so we'll see what happens tomorrow.
Cheers

[The1]

Well it seems to me DTC 49 (Cam or Crank Angle Sensor Intermitant) would most defiantly be your issue, the pcm uses the cam signal pulse to fire the injectors, without this it does not know which injector to fire for which cylinder, so it will just fire all injectors per pulse, as you can imagine this will use more fuel and probably cause power reduction and also the hang time coming back to idle.

In the logs the injector pulse time is not being decreased coming to a stop, as the failsafe to stop stalling, so you will have an increase in fuel which takes longer to bring the engine back to idle as all injectors are also firing, the IAC is doing it's job, it's bottoming out at 15 steps for while till all the fuel is burnt then comes backup to 25 steps to hold the idle speed.

I have seen this before on v6's, i dont have much knowledge with v8's so can't help you trying to fix the problem.

[Monarols71]

Oh. OK. Thank you.
I guess we've got to throw more parts at it. Or try and get an original distributor, as I don't think the cheap and nasties would be any better.
I'll start going through all the information that I have. There is a test for the distributor module here somewhere, as we had the original one fail, but that might not tell me anything.
Thanks for your valuable input.
Best Regards

[The1]

here's some info i have found in VT V8 Stuff.


DTC 49 - CAM/CRANK SENSOR SIGNAL INTERMITTENT

CIRCUIT DESCRIPTION:
During cranking, the ignition module monitors the crank sensor signal. The crank sensor
signal is used to determine the correct cylinder pair to spark first. After the crank sensor
signal has been processed by the ignition module, it sends a crankshaft reference pulse
to the PCM. When the PCM receives this pulse it will command all eight injectors to open
for one priming shot of fuel in all cylinders. After the priming, the injectors are left OFF for
the next eight crankshaft reference pulses from the ignition module (two crankshaft
revolutions). This allows each cylinder a chance to use the fuel from the priming shot.
During this waiting period, a cam signal will have been received by the PCM. Now the
PCM begins to operate the injectors by energising each injector based on true camshaft
position. With the engine running, the PCM monitors the cam and the crank sensor signal
pulses it receives and expects to see eight crankshaft sensor reference pulses for each
cam pulse. If the sequence of pulses is not correct for 15 occurrences, a DTC 49 will set,
indicating an intermittent problem with the cam signal or crankshaft sensor reference
signal.

DTC 49 WILL SET IF:· The engine is running.· The PCM does not receive 8 out of 10 cam sensor signals.