Crank duration spikes (VVTI JZ GTE) | AEM
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SickBro
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Joined: 03/25/2018 - 08:51
Crank duration spikes (VVTI JZ GTE)

I am having issues trying to track down the root cause of spikes in the crank duration on my 1JZ GTE VVTI with the Infinity 5 Series. 

I have checked the following:

-Crank Sensor tested good

-Checked for obvious harness issues

-Tried every combination of cam and crank sensor pinning

-Cam/Crank are twisted shielded pairs with sheild drained to cylinder head

Any helpful insight would be appreicated, trying to get the car ready to dyno. 

SickBro
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Last seen: 3 months 1 week ago
Joined: 03/25/2018 - 08:51
File One  idle spikes last
SickBro
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file two  
AEM_NS
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Joined: 06/06/2014 - 09:31
You would never drain

Got another case of someone thinking they got a problem when they don't.  No errors and engine appears to idle fine. What lead you to think you have a problem?  The spikes in crank duration are normal and expected for a missing tooth crank pattern.

Also, you would never drain sensitive signal shielding to the engine. Should be drained back to a clean ground at the ECU.

SickBro
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Thanks for the response. I

Thanks for the response. I didn't spend much time, on it, but I tried to convince myself that the durations were related to the time between reluctor tooth edges but couldn’t exactly match rpm and number of teeth to the duration values. What are the units?

Good call on the shield grounds that was a fundamental mistake. The shield drains have been moved to the ECU sensor ground. Crank duration logs look the same.

I started looking into the potential for a cam/crank related issues to try and understand inconsistent sync times. Sometimes it syncs quickly and other times it cranks for several seconds before syncing. Do you have any recommendations to improve the sync consistency?

AEM_NS
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Joined: 06/06/2014 - 09:31
Units is usec/10 so a very,

Units is usec/10 so a very, very short period of time thus values are very large. Divide by 10,000 to get msec. It's period between teeth so period across 2 missing teeth will be 3x normal tooth duration.

Wrong again with the shield drain.  Sensor ground is for sensors.  Shield drain needs to go to a clean chassis ground with nothing else grounded to the same point.  Draining the shield to sensor ground is litterally putting all the noise caught in the shield onto the sensor ground circuit which isn't good.  Since you don't actually have a noise problem, I doubt you're going to see any discernible difference in the logs based on where the shield is drained but draining it to sensor ground is definitely wrong.

Logs man, take and post logs.  Logs will tell us what's going on during cranking and I can give you better, more concise, direct recommendations.

SickBro
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Joined: 03/25/2018 - 08:51
Dang I misinterpreted ground

Dang I misinterpreted ground at the ECU lol. The shields drain to the chassis at the ECU side now. Thanks again for the help. A couple start up logs are attached that were taken after the shield drain fix. The first one is several seconds before sync. The second syncs significantly faster.

crank1.itlog

crank2.itlog

crank1.itssn

crank2.itssn

AEM_NS
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Last seen: 1 hour 21 min ago
Joined: 06/06/2014 - 09:31
Looks like a possible missing

Looks like a possible missing tooth detection issue. Try changing the CrkMissThr table to 2.0 instead of 1.5.