Thread: 97 D1 3.9 V8 electrical issues, engine stalls when hot. pulling my hair out!

Before changing the base idle, clean out the throttle body and the throttle blade. oily gunk can build up on it from the crankcase ventilation.
After you have done that look at the base idle which should be 550-600RPM. You adjust by blocking off both sides of the stepper, and turning the screw on the throttle body , out for more.
The stepper should then compensate for the AC.
Maybe replace the load relay also, although never really heard of this as a problem.
the stuff above will not affect running other than idle.
Regards Philip A

Originally Posted by PhilipA

Before changing the base idle, clean out the throttle body and the throttle blade. oily gunk can build up on it from the crankcase ventilation.
After you have done that look at the base idle which should be 550-600RPM. You adjust by blocking off both sides of the stepper, and turning the screw on the throttle body , out for more.
The stepper should then compensate for the AC.
Maybe replace the load relay also, although never really heard of this as a problem.
the stuff above will not affect running other than idle.
Regards Philip A

You would know better than I with these, but it seems that it's warming up fine then dying and won't restart till everything's filled down. Dosnt it sound like MAF adjusting symptoms? Otherwise I'd say amp or coil overheating but he's changed them.
Cheers Jim

Originally Posted by Steve269

I gave the car a kick in the guts this morning and it started, so I warmed it through and started more probing of sensors while running. Nothing untoward was noticed until I turned on the A/C, the engine began to stall so I turned it off and the engine recovered. I switched the A/C on again ready to give the engine some throttle but it stalled and wouldn’t restart.
I’ve looked at the wireing schematics and the only thing I can see common to the A/C circuit and the circuits that include TPS, ECT, EFT, MAF, Fuel Injectors etc is the “Engine/ Ignition Load Relay. Is it possible this relay is at fault? Has anyone come across any similar occurrence? Or am I missing something?

I would replace the relay, also look for wiring faults due to a LPG EFI cutoff relay either present or removed. I had a car come in a month ago with a very similar problem where a LPG cut to the injector feed was rejoined with a non waterproof connector, and that was corroded.

but it seems that it's warming up fine then dying and won't restart till everything's filled down. Dosnt it sound like MAF adjusting symptoms? Otherwise I'd say amp or coil overheating but he's changed them.

Well yes but I was just referring to it stalling with aircon on and it only takes a few minutes to clean the throttle body etc.

His main problem certainly sounds like something to do with ignition.

The MAF, I don't know. the motor will run with the MAF adjusted over a wide range. It's just that the CO will be high if the MAF has too much initial voltage . In fact you adjust the MAF to 1volt when you fit o2 sensors. I don't know if he has checked the MAF by putting a multimeter across the signal and earth and seeing if the value rises with the engine revs.
It could be anything even the ignition switch having a bad contact which heats up or the power relay.
Another more common problem is the bunch of in line resistors just near the battery. (whoops RRC talk there . I don't know if later D1 has them)
Regards Philip A
Maybe also check that the injectors are getting power when the car stops. Each bank fires all at once so a short or bad connection in the loom could stop it.

IÂ’ve made a little progress, found the main engine Relay had cooked itself, checked harness etc no obvious reason why it had other than old age. Replaced that not expecting any miracles.
Continued testing all engine sensor circuits and attempted to trace the gas system circuit but that needs more time and thought.

IÂ’ve found when doing a continuity test of the TPS circuit that two of the wires are arse about. According to my Hains manual the red/black wire from ecu goes to blue on tps and yellow from ecu goes to green on tps. However IÂ’ve found they are crossed at the tps end of the harness. Will this confuse the ecu or is it that basic itÂ’s not going to bother it?

IÂ’ve also checked if power to injectiors while running on gas, there is power to the A bank but I didnÂ’t have enough time to see if they were firing or not before the engine cut out again. MAF also has power to it while on Gas.

This is the 14cux manual it's for RRCbut it's the same system. Have you got the RAVE Manuel or just the haines Manuel?

https://o.b5z.net/i/u/6064257/f/14cu..._injection.pdf

You need to check that the TPS produces a varying voltage with throttle position on the plain red wire in the engine loom. The other wire should be a steady +5V from the ECU.

Thanks for the replies.

I’ve got the hard copy Hains manual and the 14CUX on PDF set up on my phones book thingo app.

I’ll check those voltages later when I get it running again.