A few issues - advice sought

[Danblez]

So, there are one or two issues with my new Chim.

Firstly the car is hanging on to revs randomly. I have read a lot about the stepper motor which was cleaned before purchase but I will give it another go. I will check for any air leaks too, anything else I should be checking? The odd thing is as soon as the car is at a standstill the revs step back down pretty quickly but if moving anywhere between 1500-2000 revs is normal. Is it part of the engine management that revs should be maintained higher than tickover when on the move?

More worrying is a brief cut of power under acceleration. It feels as though electrical power has been cut for a fraction of a second. Definitely worse when cold but does it randomly when warm. Will the RoverGuage help me identify this?

Finally there is a thrumming noise from the rear end when moving. At first I was worried it was the diff but now I have heard it more I think it may be a wheel bearing. I will get the car jacked up and and have a feel of the bearings, anything else I should be checking?

Thanks a lot
Dan

[ianwayne]

Yes idle speed is elevated once speed above about 5 mph. It helps between gear changes, but should still drop to about 1200 rpm.

I had hunting idle speeds, sometimes 3k rpm. Turns out I had a 'cheap' new stepper motor fitted. If somebody has bought that ones that are £13 or so, they do not respond properly. Biting the bullet and paying £90 for a genuine one solved my snags.

[Colin RedGriff]

Danblez said:

So, there are one or two issues with my new Chim.

More worrying is a brief cut of power under acceleration. It feels as though electrical power has been cut for a fraction of a second. Definitely worse when cold but does it randomly when warm. Will the RoverGuage help me identify this?

When this happens are the radiator fans kicking in or possibly some other electrical component starting up?

I had a very similar thing happening whenever my cooling fans kicked in. Turned out to be one of the earth points not being clean and tight. I would systematically check them all, it's not necessarily the earth directly associated with the component. On my Griffith it was the drivers side earth bolt on the transmission tunnel inside the car that was not fully tightened, but the front chassis point on the drivers side also needed cleaning up.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Danblez said:

Finally there is a thrumming noise from the rear end when moving. At first I was worried it was the diff but now I have heard it more I think it may be a wheel bearing. I will get the car jacked up and and have a feel of the bearings, anything else I should be checking?

Check the diff mounting bushes are tight - there are two at the front of the diff one each side these are easy to check and change. More difficult is the top diff mounting which is a complete bugger to get to and change.

Edited by Colin RedGriff on Monday 12th January 18:58

[Danblez]

Thanks both.

Colin, the cutting out is completely random but always under acceleration. I am going to swap out the ECU and FP relays and see if this helps. I will also check the earths.

I will also take a look at the diff mounts cheers

Edited by Danblez on Tuesday 13th January 12:54

[ben2083]

Hi,

I had exactly the same fraction of second cut of power during accels at random for a few weeks, tried a few things to no avail and then one day it cut out all together and wouldn't restart. Bit of fault finding showed it was the fuel pump relay. Swapped that for a new one and it was fine. Odd one as the stutter is that sharp that I was convinced it must be ignition related but was definitely the FP relay.

Make sure you get the right relay with the diode in or your get queicsent drain issues.


Ben.

[Danblez]

Cheers Ben, have bought the correct Bosch one so fingers crossed!