Starting Issue When Hot
04-04-2021, 11:01 AM
#31
Sorry for bumping and old thread, but I feel my input will be welcomed.
I have been dealing with identical issues with my car with the AEM V2 unit. The AEM will not stat sync if the cranking voltage falls below 11.2v or so. With a fully charged battery, the voltage was dropping to the low 10s during cranking and it would fail to fire unless I used a jumper. Heat increases resistance even further and the engine compression is higher when warm, so it makes sense that a hot start would pull the voltage low enough to prohibit the EMS from stat syncing.
Observed that the only grounding point from the battery to the vehicle is that mickey mouse OEM negative strap. I ditched that and ran two gauge 4 wires from the battery: One to the original ground location, and another to the engine block engine bolt hole next to the VTEC solenoid. Ran an additional ground from the body to this same location. After this, the car starts up crisp and the problem has gone away. Cranking voltage never drops below 11.3v now.
The OEM ECU is designed with neglect and car aging in mind, so it is more tolerant to low voltage cranking, but with enough corrosion and aging of the wires, it may still cause a no-start condition when hot even in a largely stock car.
It is worth it to inspect and upgrade the grounding points when encountering this situation.
I have been dealing with identical issues with my car with the AEM V2 unit. The AEM will not stat sync if the cranking voltage falls below 11.2v or so. With a fully charged battery, the voltage was dropping to the low 10s during cranking and it would fail to fire unless I used a jumper. Heat increases resistance even further and the engine compression is higher when warm, so it makes sense that a hot start would pull the voltage low enough to prohibit the EMS from stat syncing.
Observed that the only grounding point from the battery to the vehicle is that mickey mouse OEM negative strap. I ditched that and ran two gauge 4 wires from the battery: One to the original ground location, and another to the engine block engine bolt hole next to the VTEC solenoid. Ran an additional ground from the body to this same location. After this, the car starts up crisp and the problem has gone away. Cranking voltage never drops below 11.3v now.
The OEM ECU is designed with neglect and car aging in mind, so it is more tolerant to low voltage cranking, but with enough corrosion and aging of the wires, it may still cause a no-start condition when hot even in a largely stock car.
It is worth it to inspect and upgrade the grounding points when encountering this situation.
The following users liked this post:
indi00 (04-07-2021)
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