Trigger issues caused by noise? Heading for dragracing with big problem


6 posts in this topic

Posted (edited)

Hi

I hope someone can help me. Car is old vw beetle and i try to get more than 500bhp out of it. Had struggles past 3 years, but i really hoped to join my friends next weekend for my first dragrace.

On the dyno, with load, the car is "buggering" or misfires. My "dynoguy" says there is not clean enough trigger signal, so the ecu does not now exactly were crank position is and misfires.

I have tried 3 different triggerweel setups with VR sensors, and had several dyno attempts, also rerouted the shilded trigger cable so its far away from power wires.

I have a friend with same type V44 and i borrowed his ecu last night, but could not hear any approvements or see any on the log. I have log files if someone could look at them.

My "Dynoguy" also told me to log RPM-rate, so i did. But was this data mean? I really hoping for help.

Edit: I Have attached engine map and log from yesterday. Just started it on trailer.

min-ecu-Log 9-08-17 9;24;20 pm.llg

Turboroadster-09-08-2017.pcl

Edited by Turboroadster
Edit: I Have attached engine map and log from yesterday. Just started it on trailer.

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Posted

There is no sign of trigger error in your log but often if its noise related you will only see it under higher loads as ignition energy gets significant enough so that doesnt mean this is not your problem.

The two main clues to look for in a log that are indicative of trigger error is spikes or unexplained bumps on the RPM trace and unstable dwell time (dwell scatter). RPM rate can also indicate it but for that you more experience to know what is normal and what is abnormal.

What do you have for coils/ignition system?

How are the triggers set up - is the cam tooth well away for the gap on the crank etc?

Have you confirmed the polarity of the crank sensor is correct?

Have you ever had an oscilloscope on it to confirm if there is a trigger problem?

 

Also your fuel mapping is done a bit odd.  If you are using TP load axis on a turbo car you should really have the open loop afr target table turned on so that is can compensate for the different target over a range of boost pressures.  It looks like that compensation has probably just been "baked into" the fuel table now but it means the AFR will only match the target at one specific boost level.  That will be fine only if you intend to run the same boost level at all times.

 

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Posted (edited)

What do you have for coils/ignition system? 4x LS2 coils, with 36-1 on crank and VR sensor. Gap set to manufactors spec 0,2 to 0,4mm (with endplay)

How are the triggers set up - is the cam tooth well away for the gap on the crank etc? I am not sure how Cam tooth is positioned related to crank.

Have you confirmed the polarity of the crank sensor is correct? It is connected as instructions.

Have you ever had an oscilloscope on it to confirm if there is a trigger problem? yes, on my previous crank trigger system the voltage varied more than 50% on the teeth. Thats why i changed to this new crank trigger, but it was no difference.

I had to thrust our "dynoguy" for the mapping, i have no clue myself and he has a good reputation for doing it right on my friends cars. I have bought all ECU, ID injectors and the wire harness from him also but now it seems that he is not able to find out what is wrong, and its difficoult to get good support. Maybe i should find another tuner?

Is it easier to correct this if i make a Hall sensor instead of VR?

My friend with similar engine and ECU gave me his map for comperance.

 

Is there anything in these setups that can contribute to my problems?

 

Ign.table

4D ignition: Me=On Friend Off

 

Trigger 2(cam sync)

Pullup: Me= On, Friend=Off

Edge: Me=Rising, Friend=Falling

 

Digital Input

Pullup resistor: Me=Off, Friend= On.

 

Arming Threshold

Me= 0,5 to 6.0 Friend= 0,2 to 4.0

 

RPM Limit

End cut: Me=100% Friend= 75%

Start Cut TP100%: Me=60% Friend=65%

Start cut TP Low:Me=0% Friend=65%

Edited by Turboroadster
updated information

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Posted (edited)

What do you have for coils/ignition system? 4x LS2 coils,

Your Dwell table is a little lower than I would expect for LS2 coils.  Maybe the spark is weak?  Can you try adjusting your table to look like this:

 oqAPC0M.png

 

 

 

How are the triggers set up - is the cam tooth well away for the gap on the crank etc? I am not sure how Cam tooth is positioned related to crank.

Have you confirmed the polarity of the crank sensor is correct? It is connected as instructions.

Have you ever had an oscilloscope on it to confirm if there is a trigger problem? yes, on my previous crank trigger system the voltage varied more than 50% on the teeth. Thats why i changed to this new crank trigger, but it was no difference.

This can be quite important.  For the relative positioning of the cam/crank teeth I would have thought on an old engine like this the teeth should be accessible/visible?  Can you not turn engine so that the gap on the crank is pointing at the sensor, then check where cam tooth is?

I am not sure what instructions you used but unless the instructions came from link it may not be correct.  An oscilloscope is the only way to know sensor polarity is correct.

Do you still have any pictures from the last time a scope was connected?

 

 

Is it easier to correct this if i make a Hall sensor instead of VR?

Right now I'm not convinced you actually have a trigger issue at all.  If you have tried 3 different setups already without improvement its time to try to diagnose what the issue is rather than just replacing parts.

If the increased dwell suggested above doesnt improve the situation and you are really sure you have a trigger issue then the next step is to visit someone that owns an oscilloscope.  Most good tuners, mechanical shops and auto electricians should have one today...

 

I dont see anything wrong in the settings you listed .

Edited by Adamw

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Posted

Thanks a lot for help.

I will adjust the dwell table. My sparkplug gap is 0.6mm, i believe i could set it to 0.4mm also because i use E85 105 octane racefuel that is 30% "WETTER" than gasoline.

It is not easy to se the camtooth without pulling of exhaust/turbo/intake, but it easy to adjust the sensor.

I have found another tuner who is experienced with vipec, he has his own dyno and a Evo1 or 2 with 700hp.

He told me that that the LS2 coils also should be grounded in the heads, not just in chassis as today.

I will deliver my car to him on Monday with a printout of your replies. He will start troubleshooting, and if he finds and fix the problem, he will make it raceready.

You may also check facebook.com/turboroadster for updates.

 

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Posted (edited)

LS2 "Truck" coils?  Was the stock metal cage/mounting bracket that is grounded to the heatsink removed?  They're noisy without it and do tend to fire early if you run too much dwell.

Edited by JMP

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