Hot Engine Cam/Crank Sensor Issue | AEM
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darkness
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Last seen: 1 month 1 week ago
Joined: 06/07/2015 - 23:38
Hot Engine Cam/Crank Sensor Issue

1994 Toyota Supra 2JZ-GTE

Series 2

 

I have been running V2 for 3 years now and up until now I had no starting issues. Recently my car will start just fine cold, but after shutting off and trying to start when the motor is up to operating temp the car will not start. I have replaced both my cam and crank sensors with brand new ones from Toyota. I have logged the channels in my start tab and I can see that with a cold motor, STAT Craninking is on (1) and the car fires up. When the motor is warm (140F-190F) STAT Craniking is off (0). I can also see in my logs during cold startup I am getting cam and crank signal, but during hot startup I have a crank signal and no cam signal. The hot start issue has come out of knowhere as I have not changed anything on the car. I have searched this issue and found others with similar issues and you recomended swapping the crank sensor input to the cam sensor at the ecu to eliminate a cam wiring/sensor issue. I can and will try that but because I can cold start, my faith in that fix is low. I will post logs below of the cold and hot start from my start tab. If it helps better I can log under the advanced pickups tab that offer more insight to the sensors.

 

 06-27-18_Hot Start.daq

06-24-18_Cold Start.daq

AEM_SB
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Last seen: 2 months 2 weeks ago
Joined: 06/07/2014 - 14:29
The OEM sensors on that

The OEM sensors on the 2JZGTE engine are 2-wire variable reluctance (VR) sensors. VR sensors generate a stronger voltage when they are cold than when they are warm. They also generate a stronger signal at high RPM than at low RPM.  In other words, the combination of a hot engine spinning slowly will result in the weakest signal from the cam sensor, since the cam spins at half the speed of the crank.

The Series2 ECU has options to adjust the trigger level for the cam & crank sensors; note that trigger level is the minimum signal voltage that is considered valid (not noise). In the 'Adv Pickups' tab, try changing the value for Cam H Sens Level. This is set to 0.00 Volts in our 6100 Supra MT calibration, which actually sets the trigger threshold to a default value of 0.20V.  Try changing this to lower values, such as 0.14V or 0.08V.

 

Also note that the VR cam & crank inptus on the 6100 EMS was designed to work with the OEM cam & crank sensors found on the USDM twin turbo engine. The distributor from the non-turbo GE engines, and the cam/crank sensors from the newer VVTi engines (includign the turbocharged ones) are known to send weaker signals and may require hardware modifications to the EMS input circuitry to work properly.

 

Hope that helps,

SB 

darkness
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Last seen: 1 month 1 week ago
Joined: 06/07/2015 - 23:38
Solved, thank you. Setting

Solved, thank you. Setting the Cam H Sens Level to 0.08V worked and the car now hot starts at 195F. I am going to pass this information along to a couple other V2 supra owners loacally who are having similar issues.

dre99gsx
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Last seen: 10 months 1 week ago
Joined: 10/11/2015 - 20:50
Seemed to help on another JDM

Seemed to help on another JDM non-vvti hot-start issue as well.  Was cranking for many seconds not wanting to start only when hot.

dre99gsx
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Last seen: 10 months 1 week ago
Joined: 10/11/2015 - 20:50
Seemed to help on another JDM

Seemed to help on another JDM non-vvti hot-start issue as well.  Was cranking for many seconds not wanting to start only when hot.