The Flyin' Miata Techline

Troubleshooting ground problems.

Time for another one of TurboDog's Tech Tips from Flyin' Miata. On high mileage cars (so far only on 90-97 models) we've had a few exhibit some strange behaviour under acceleration or when shifting. The tacho needle drops, power falters for a second, then comes back on. There is a harness that goes from the chassis to the intake manifold on the passenger's side of the engine. This harness contains fuel injection wires, cam sensor wires, etc. Each time you accelerate, the engine rocks and tugs on this harness. Often wires will fatigue and break within the harness, causing intermittent problems. To test for this problem, start the car and start wiggling the wires trying to simulate the engine rock. If the tacho drops or engine falters, you've narrowed down your problem. You'll need to slit the covering over the harness and carefully examine the wires to find the offender(s). Good luck!

As always, feel free to disseminate these tips if you think they are useful. TurboDog would like credit if you do.