The car is a 1985 Volvo 360.
Last June, some serious welding had to be done in the front footwells (both sides) to get it through the MOT. It has since been erratic in cold starts. Lately it won't start at all. The usual test show there is a spark and that fuel is getting through. I'm wondering if perhaps the ECU (which is under the dashboard) might have been adversely affected by the welding.
Any ideas, anyone?
You can fry the ECU but it'll normally fail in a far more obvious way, it's far more likely to be a temperature sensor.
Something else: ECUs either work or they don't, there's very rarely an inbetween.
A sensor somewhere perhaps?
Or, if it was the welding that caused it, a melted cable somewhere.
Cheers,
Colin.
that's why you disconnect the battery or put one of them welding anti-welding clamp meter things over the terminals to stop it from frying any eclectics
it could just be something else though
Yes. Any pro welder should have put a voltage limiting clamp across the battery.
How exactly would disconnecting the battery save the ECU? The damage is alleged to be caused by voltage surges from the welder, disconnecting the battery would not stop the surges, it would just mean that there was no longer a bloody big capacitor connected to damp them out.
It doesn't make any difference, it's the voltage difference on the grounds that fries the electonics, which if you connect the clip next to where you're welding won't happen. The voltage limiting clamps on the battery don't do anything usefull about that either.
That's hat I always thought, yet some swear blind that you must disconnect the battery to avoid damaging the electronics.
The message from "SimonJ" contains these words:
I've often wondered that.
Many people swear on many things :-)
Just to update everyone who replied, it started first thing this morning, possibly because the outdoor temperature is somewhat warmer than it was the last few times I tried to start it. Which narrows the problem down to either the cold start injector or the thermo time switch (I think).
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