8 replies to this topic

[David106]

Hi all,

 

We are rebuilding our MPi after having been dismantled, repainted and partially re-assembled. It's been resting in the garage for 5 years now and we are trying to start it up for the first time. There have been no changes to any part of the engine, only the fluids and the filters.

 

Current situation is:

 

The battery is fresh, when the key is turned the fuel pump does not work. The starter motor does work when the key is further turned.

 

We've checked the wiring (apparently ok), the fuel pump (ok), the fuse (ok) and the relay module (ok). It happens that the relay module does not receive the input signal from the ECU (so the relay for the fuel pump does not activate). So it seems the issue might be something related to the ECU.

 

Another symptom that we overlooked for a while is that as soon as the battery is connected (the ignition key is not even in place) the needle of the temperature gauge goes completely up. The engine has never started so its temperature is just room temperature.

 

Since the ECU gets the temperature reading from the sensor and it gives signal to the temp gauge, it seems to us that both issues are somehow related.

 

Could it be that the ECU is preventing the engine from start as the measured temperature is so high? Any idea on what to look at next? 

 

Thanks a lot in advance,

David

[Steve220]

Check the ECU's earth. If MEMS hasn't got a good grounding, it can be problematic.

[Steve220]

Another thing to try is the inertia switch, that cuts the fuel pump if it's knocked.

[David106]

Thanks Steve220, forgot to mention that we also checked the inertia switch and it is working properly. The ECU's earth is the enclosure itself, right? We'll check that!

Cheers,
David

[David106]

Hi all, found this thread about the temperature gauge reading high, apparently the reason could be the sensor wires connected to earth when they shouldn't. Do you think this could be applicable to a ECU driven temp gauge?

http://www.theminifo...e-reading-high/

Many thanks for your inputs,
David

[David106]

Another clue, we've disconnected the cables from the temperature sensor, one of them gives 11.7v and the other one 12.3v, measured between the connector and the engine (earth). Should both cables to the temperature sensor give positive voltage?

Cheers,
David

[David106]

Another clue, we've disconnected the cables from the temperature sensor, one of them gives 11.7v and the other one 12.3v, measured between the connector and the engine (earth). Should both cables to the temperature sensor give positive voltage?

Cheers,
David

The air temperature sensor in the inlet manifold behaves the same way, both cables have positive voltage. So both are either ok or wrong :/

[David106]

Hi all!

 

After quite a loooong time, I've managed to make some progress on this issue.

 

I bought a pscan.uk diagnostic tool that didn't manage to communicate with the MEMS2J ECU in the car. I removed the ECU from the car to perform some more tests but it didn't work either. At that point in time, either the ECU or the pscan tool were faulty. I managed to buy another ECU from a donor car and repeated the tests over the bench. It turns out the old ECU is dead and both the pscan tool and the new ECU work well.

 

Having a dead ECU may well be the cause for all the strange things that were happening but, what damaged the ECU in the first place? Might it be that, after stripping the car down and putting it back together, something was so wrongly connected that it damaged the ECU? Any advice as to how to proceed?    My biggest concern is that the new ECU will be damaged as soon as I plug it in.

 

Any piece of advice is more than welcome.

 

Thanks!

[Steve220]

Have you ever connected the battery backwards?