ECU trouble or not? Swap ECU?

[Canuto]

Hello :-)


ECU (?) playing up, intermittently. Probably. Impossible to demonstrate the problem.


I am quite new here, although I have been lurking for a while…


I have an intermittent problem. I guess it originates from excess of water in the plenum. Maybe. I have never seen it being wet. I have read and searched a lot in this forum, and found almost what I search for. But I still can't quite figure out what is wrong. Nothing is definite. The car is not dead, it just plays tricks on us when we least need it.
I hesitate to start swapping old parts for new parts just to see if the problem comes back or not.

Problem:
The Rover sometimes refuses to start after we have parked it for an hour or two. Maybe less or more as well, but never a problem if it is parked for a whole day or night. Never a problem if it is parked for only 15-25 minutes, either.
After short trips never a problem.

And it happens quite rarely. Typically if we have a plane to catch, like last time, or we are on our way to somewhere and we have driven for several hours already.

When trying to start it, the starter motor turns like normal. The rover will start the next day, anyways. Like nothing has happened.

I have made sure the plenum is bone dry the last 4-5 months. I have checked, and I have prodded. Still, of course, the weather has been cold and water may evaporate slowly.

I suspect there is something wrong with the ECU, but I am not sure.
Can it be "half broken" (=sometimes broken, sometimes ok) even if all water is totally out and evaporated, after having been wet at some point?

-->> Should I open it to check the internals for bad soldering, anything looking suspicious? (I am not an electrics specialist…)
-->> I consider ordering a new ECU at Rimmer Bro (we are really fed up with this problem now, and we hesitate to use it - it sits in the garage at the moment) , but of course it costs a bit. If I use the correct age and type of car when ordering, is it just a job of swapping one for the other, or is there something to consider? (except for disconnecting the battery of course).

The multiple pin plug of the ECU looks and feels 100% ok and fine. Nothing looks bad from the outside.
The Rover runs very nicely when it runs. No signs of any problem.
Except at one point in time (a couple of years ago) when failure warnings turned up on the display, in error. Bulbs that were broken here and there, but they weren't. I disconnected the battery, and reconnected it. Problem solved. Only once this, but it might have been a symptom?

Car:
Rover 75 V6 1999
Norway

I am quite new here, although I have been lurking for a while…

I would really appreciate it if someone could point me in the right direction.

Kind Regards
Knud

[shodan70]

give marinabrian or big russ a pm about this they are the ecu gurus on here

[75Connie]

Have you had the ECU read for faults?

[radi8or]

Could possibly be cam sensor, common on V6, starts when cold, won't when hot.

Easy to check, get engine hot, remove sensor and place in fridge for 15/20 minutes, if it starts probably the problem, if not the problem is elsewhere.

Cam sensor Here, courtesy of Mango Man .

Easier to eliminate first.

[Canuto]

Hello again, and sorry for not replying sooner.

This camshaft sensor business seems so spot on for me.
Thanks a lot!!!
I really hope that is the reason.

I have looked at it, taken it out even, and it is really easy to change. It doesn't look quite the same as the one Rimmer has for sale, possibly a newer type.
There is only one on the engine, isn't there? I mean it's a V-engine, and in theory there could be two?
I have never done anything on a v-engine before (or an engine newer than 40 years old for that matter...)
I think I will order the sensor, and seal, from Rimmer and try.
Easier than trying something on the ECU, anyways.

Only thing, this morning (cold engine) it hesitated to start. Only 3-4 seconds longer time with starter motor, but clearly 4-5 times longer time than normal. I nearly turned the key off, but it gave a cough and then it started.
Maybe the sensor is just getting worse - which sounds logical to me.

I have not had the ECU checked for faults as such. I have discussed this at the garage, and I suppose they have done what they could in the first place. It's not a Rover garage and has never been one, so I guess the tools are limited. Wouldn't one need a special ECU tester for Rover 75 to carry out a proper ECU test?

Knud

[Undercover]

Originally Posted by Canuto

Hello again, and sorry for not replying sooner.

This camshaft sensor business seems so spot on for me.
Thanks a lot!!!
I really hope that is the reason.

I have looked at it, taken it out even, and it is really easy to change. It doesn't look quite the same as the one Rimmer has for sale, possibly a newer type.
There is only one on the engine, isn't there? I mean it's a V-engine, and in theory there could be two?
I have never done anything on a v-engine before (or an engine newer than 40 years old for that matter...)
I think I will order the sensor, and seal, from Rimmer and try.
Easier than trying something on the ECU, anyways.

Only thing, this morning (cold engine) it hesitated to start. Only 3-4 seconds longer time with starter motor, but clearly 4-5 times longer time than normal. I nearly turned the key off, but it gave a cough and then it started.
Maybe the sensor is just getting worse - which sounds logical to me.

I have not had the ECU checked for faults as such. I have discussed this at the garage, and I suppose they have done what they could in the first place. It's not a Rover garage and has never been one, so I guess the tools are limited. Wouldn't one need a special ECU tester for Rover 75 to carry out a proper ECU test?

Knud

Only one cam sensor needed as all four cams turn together via the various tming belts.

A basic code reader will allow you access the the engine fault codes and this will flag up any other faults. if you buy one and use it, clear ALL the fault codes first and then run the engine and see if any fault codes reappear; you don't want to be pulling your hair out fault finding faults that are no longer there.

[Canuto]

Thanks a lot.
This cleared more than one thing for me.

I see Rimmer has one;
http://www.rimmerbros.co.uk/Item--i-43913DRAPER
but it is for petrol-engines post 2001.
I couldn't find one for older engines at Draper, either.
I am quite naive in this electronics stuff. And I could really use one of those, I guess, as I guess more and more will happen to the Rover as it gets older now.

I am concerned about if the tester does fit the car both physically with the correct plug and also if it actually can read the Rover's fault codes. Maybe this is easier than I have thought. Only thing now might just be if I need to find a tester that can read cars from before 2001 (my Rover 75 is a 1999 model).
Knud

[Undercover]

Originally Posted by Canuto

Thanks a lot.
This cleared more than one thing for me.

I see Rimmer has one;
http://www.rimmerbros.co.uk/Item--i-43913DRAPER
but it is for petrol-engines post 2001.
I couldn't find one for older engines at Draper, either.
I am quite naive in this electronics stuff. And I could really use one of those, I guess, as I guess more and more will happen to the Rover as it gets older now.

I am concerned about if the tester does fit the car both physically with the correct plug and also if it actually can read the Rover's fault codes. Maybe this is easier than I have thought. Only thing now might just be if I need to find a tester that can read cars from before 2001 (my Rover 75 is a 1999 model).
Knud

Don't order a new one just yet. Have a read of this thread, pop it out and give it a clean first and try the 'washer' trick to move the sensor slightly away from the camshaft. http://www.the75andztclub.co.uk/foru...ad.php?t=74797

I am sure any KV6 camshaft sensor will work as it is just a magnetic pickup.

[75Connie]

Originally Posted by Canuto

I have not had the ECU checked for faults as such. I have discussed this at the garage, and I suppose they have done what they could in the first place. It's not a Rover garage and has never been one, so I guess the tools are limited. Wouldn't one need a special ECU tester for Rover 75 to carry out a proper ECU test?

Knud

Hi Knud

It would obviously be best to have the car checked on a Rover Testbook T4 machine. But failing that, If the car is OBDII compliant, a simple OBD reader (available on eBay for about £10) and a piece of software (Torque Pro seems to be the favourite on an Android phone cost approx £4 assuming you have the phone) might just save you some grief, by reading the fault codes relating to engine running, and allowing you to clear them.

AFAIK, (but any number of experts on here will be able to confirm or otherwise) petrol engines from model year 2000 and diesel engines from model year 2004 have to be OBDII compliant according to EU regulations. As yours in a 1999 car, you may be lucky and it may be compliant. Its worth checking out. I think there's a label somewhere on the front of the engine bay that tells you if it is compliant.

Hope this helps.

[Canuto]

Wow, thanks. I'll go out and check for labels.

Knud