Help! engine cuts out at 1800rpm

[M-G]

Help, I had a flat battery earlier this week in my 2000 450 and jump started the car to get home. After half a mile the engine cut out at 1800rpm and restarted after 2-3 seconds. Nursed the car home at 30mph in 4th = 1600rpm!

Swapped the battery as it was knackered and was advised to check the fuel relays in case I had dislodged one whilst jump starting. I pulled out both relays and pushed them back in. I can hear them working when the ingition is first switched on.

I tried to drive to work this morning and all was fine for the first half a mile then it started cutting out again. The strange thing is that when stationary the engine revs without a problem over 1800rpm.

Any clues on what to look at next or should I be taking it into the dealer?

[greenv8s]

To change the battery you would have had to go into the passenger's footwell where all the ECU wiring is? I'd spend half an hour checking all the fuses and relays are seated OK, ECU plugged in properly, no obvious physical damage to the wiring. If that doesn't fix it, time to call in the experts. Probably nothing major, but you can spend an awfull long time trying to track this down (and risk damaging other things in the process) where somebody with more experience and knowledge of the system may go straight to the problem.

[M-G]

I think this is probably wise as I had to scrabble round in the garage to get the battery out and changed. I did try to put everything back in the right place, but who knows I might have dislodged something else.

I called the local dealership and they suggested the coil as it could be breaking down under load (ie a seperate issue and nothing to do with the battery change).

I think a good half hour checking the connections may be in order before I look at the coil

Thanks
Mark

[trefor]

Are you in the AA/RAC? If not, join. Call them out (I think you have to wait 24hrs after joining?). They will do all the basic diagnostics without you needed to pay a dealer. Yet. Hopefully it's something simple like the ECU not being completely plugged in. Does sound strange that the problem always happens at 1800rpm. The other thing is the 100A Fuse between the alternator and battery. Maybe the movement is causing it to break connection while when stationary it is fine.

[jonmartin]

This is very odd I was going to post something very similar, my 10 year old chim has needed jump starting a few times of late. just got it back from getting some other bits fixed and they said battery/altinator were fine (mind its a 50 mile drive there). I have also been having problems with the engine threttening to and a few times actualy cutting out whilst sitting idle in traffic (usually idles at 1k).
If you find the cause of your problem I would love to know. Im going to struggle by until mot/service in May.
Cheers!
Jonmartin

[trefor]

jonmartin said:

This is very odd I was going to post something very similar, my 10 year old chim has needed jump starting a few times of late. just got it back from getting some other bits fixed and they said battery/altinator were fine (mind its a 50 mile drive there). I have also been having problems with the engine threttening to and a few times actualy cutting out whilst sitting idle in traffic (usually idles at 1k). If you find the cause of your problem I would love to know. Im going to struggle by until mot/service in May. Cheers! Jonmartin

For the idle/stalling bit have you cleaned you stepper motor? Details available if you do a search on this forum.

[M-G]

I thought of the stepper motor, but belive its cleaned as part of the service and this was only done 8 monhts ago. Would it get that dirty in 8 months and 4,000 miles?

I need to check my breakdown cover when I get home tonight (part of the insurance to see if I'm covered for home start).

Thanks

Mark

Ignore the top part of the post as I have just realised trefor you're advise was for jonmartin!


>> Edited by M-G on Friday 16th January 16:51

[shpub]

Yes.

[M-G]

Ok, I'll have a look at that too then! Wife's going to be happy with me this weekend, she thought we were going shopping!

[M-G]

Ok, I've cleaned the Stepper motor, which wasn't that dirty and checked the fuses and connections. The fuse for the ECU was not pushed in fully so I made sure it was in properly.

went for a run every hopeful, but still the same problem after half a mile.

I switched off and restated and that seems to clear the problem for a minute or so and then it returns.

Should I look at the coil? I noticed a post a while trawling through the archives that the black coils with no makers name on are supposed to cause problems. I have one of these fitted!

[harleywilma]

M-G said:

Ok, I've cleaned the Stepper motor, which wasn't that dirty and checked the fuses and connections. The fuse for the ECU was not pushed in fully so I made sure it was in properly. went for a run every hopeful, but still the same problem after half a mile. I switched off and restated and that seems to clear the problem for a minute or so and then it returns. Should I look at the coil? I noticed a post a while trawling through the archives that the black coils with no makers name on are supposed to cause problems. I have one of these fitted!

guess youve checked the dizzy cap and air flow meter?

[M-G]

Called the RAC last night and they came out to look. The RAC chap suggested it was the airflow meter but had no way of checking as the fault was when moving and not stationary. I took him for a run to demonstate the problem. He confirmed it was an ingintion cut out at 1800 rpm. He had no other suggestions, apart from have it towed to the dealer so they can investigate the problem!

Will get it towed tomorrow and see if they can sort it out.

[MAC5]

HI all,

Had a similiar problem with mine just a couple of weeks ago. Had been messing about changing the battery 3 times in Total!. It appeared whilst doing this i had disconnected some wires. Problem was solved by V8 devolpments.

Good luck

MAC

[M-G]

Problem solved!

A mate from the Suffolk club suggested that when the car was jump started it some times upsets the ECU and needs resetting.

I unplugged the ECU for 30 minutes, reconnected it and hey presto the problem has disappeared!

Thanks to you all for your assistance.

Mark