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engine diagnostic

Posted: Sun Feb 11, 2018 2:41 pm
by Cpur
Hi all,
Today we had time to log some runs in the 1/4 mile raceway.

Had some misfires, we logged a lot of things but nothing seemed to be the start of this misfire.

I also noticed that the Stack rpm was falling when the misfire occurs, so it was definitely an input problem.
Later we saw the engine diagnostic display.

I had 3 concerens here

cam sensor 10
rejected crack pulses 8
synthetic tooth errors 4

Does the Cam sensor effect anything after the engine is in sync and running?
Do rejected crank cause misfire?
Do synthetic tooth errors cause misfire?


Thanks and Regards

Re: engine diagnostic

Posted: Mon Feb 12, 2018 4:33 am
by Alex DTA
If the RPM is dropping, then it's a signal issue from the crank or cam sensor.
However, you don't have enough of either error to have had more than two misfires, unless the diagnostics have been reset? The number of wheel pulses would suggest not.

The ECU will reset if the there are more than 4 cam/crank sensor errors. If you've had a number of misfires, then this is not the problem.

Re: engine diagnostic

Posted: Mon Feb 12, 2018 11:27 am
by Rob Stevens
To add to what Alex says you have had 15 resets since last cleared, does that sound right? as in you turned the engine on and off 15 times.

Re: engine diagnostic

Posted: Mon Feb 12, 2018 11:49 am
by Cpur
If i have misfires next sunday should i try it in wasted not sequential.
Will this eliminated the chance of the cam sensor errors interfering?

Regards

Re: engine diagnostic

Posted: Mon Feb 12, 2018 1:32 pm
by Alex DTA
Yes.
Make sure injectors are not in sequential, and coils are in wasted spark mode, and cam control is off

Send me a copy of the map if you want me to check it for you

Re: engine diagnostic

Posted: Thu Mar 08, 2018 2:42 am
by Cpur
Hi All,

The missfires were probably coming from over boost cut. I need to check how does any cut work.
I saw that there are different cut patterns but i still didn't read this part.

Thanks guys

Re: engine diagnostic

Posted: Thu Mar 08, 2018 2:50 am
by Rob Stevens
The overboost is a full cut and has nothing to do with the cut patterns, the overboost cut maintains cut to all sparks until the boost has dropped below its set point again. It's pretty brutal in its operation,

Re: engine diagnostic

Posted: Thu Mar 08, 2018 4:19 am
by Alex DTA
I really need to make the overboost cuts clearer, as the answer to your question was there, and we all missed it.

As Rob says, it's a simple hard cut to the engine. It's to protect against failed waste gates/valves, which is why we don't use a PWM modification.