pagoda69

I am going to be storing my 98 993 in my garage for about 4 months while we are away. Will disconnecting the negative on the battery hurt the OBD or any of the relays?

Jonttt

I disconnect my battery for c9mths every year with no ill effects at all, been doing it for years.

pagoda69

Thanks for the quick reply. On my older cars I always disconnect the battery with no issues. I've heard that if you do that on a 993 it could be a problem for the OBD. I'm glad to hear that you've had no issues. I hate leaving a battery tender on a vehicle for long periods.

GT917

No problem.

Two points to take care about after reconnecting the battery:
1. remove the DME relay then turn the ignition key for a couple of seconds: it will send oil in the hydraulic system before the engine starts. After that, replug the DME relay.
2. let the car standing with the engine being launched. The engine slowly heats, it enables the calculator to re-align itself.

pagoda69

Thank you. Glad to hear that it's OK to disconnect the battery. Good tips on restarting.

ronnie993tt

Leaving it on a trickle charger plugged into the cigarette lighter is easier and eliminates re-start "programming" issues.

pp000830

Hi Pagota,
When you disconnect the battery the ECU adaption adjustments are lost so it will take a few miles of driving before the idle smooths out. Also, the results of the non-continuous emissions tests will be lost and will reset over time as the car is driven. This does not influence engine performance. The test results (readiness flags) will need to be completed again and result in a PASS status before the car is taken in for an emissions inspection if they are still done in your state.
Andy