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+--- Thread: Over revving and other issues (/showthread.php?tid=5860)
RE: Over revving and other issues - Stuart Rees - 01 Sep 2018
Ye... strange and unfortunate the problem came back last week Tris. I had the ECU last time but the motor seemed to solve the problem. Glad we found the root cause of the high revs today.
Stu
RE: Over revving and other issues - Nick H - 01 Sep 2018
Sounds like you found the cause of the issue. I seem to remember if the idle motor fails or shorts out it can blow some of the electronics in the idle ECU.
Hopefully it’s a relatively straightforward fix.
Nick H
RE: Over revving and other issues - Chris Williams - 02 Sep 2018
Good news, well done chaps. You may have to twist his arm but Rich is a wiz at that kind of stuff. Not sure what's in the ECU but as it's 80's tech I'm sure it's fixable if he can get the parts.
Chris
RE: Over revving and other issues - Chris Williams - 02 Sep 2018
Quote:But now it looks like I need a rather expensive idle ecuhttp://dmctalk.org/showthread.php?16612-Misc-Parts-For-Sale
RE: Over revving and other issues - TristanC - 02 Sep 2018
(02 Sep 2018, 21:09)Chris Williams Wrote:Quote:But now it looks like I need a rather expensive idle ecuhttp://dmctalk.org/showthread.php?16612-Misc-Parts-For-Sale
Cheers Chris.
Spoke to Arran and he’s got rebuilt ones on the shelf with modern components, sounds like the way to go to me. £120 with my idle ecu as px
I’m happy with that. I should have it within the week.
RE: Over revving and other issues - Chris Williams - 03 Sep 2018
Quote:Spoke to Arran and he’s got rebuilt ones on the shelf with modern components, sounds like the way to go to me. £120 with my idle ecu as pxFair enough, cant go wrong at that price.
Chris
RE: Over revving and other issues - TristanC - 08 Sep 2018
New ecu installed and all seems well again now.
And also replaced the bearings in the idler pulleys today too. Nice new SKF bearings.
The old ones were very noisey indeed.
I was lucky they didn’t totally give up the ghost!
Angle drive sorted too.
Just need to change the oil again and I can take her out ! Whoop.
Thanks to you all for the input and especially Stu for giving me his time and also bringing parts along to help narrow down the revving issues.
Tris
RE: Over revving and other issues - Nick H - 09 Sep 2018
Good Job Tris.
Those idler pulley bearings could have been the reason for your belt issue.
When I worked for a race team we had a French mechanic who had worked extensively with the PRV
Engine. I remember driving into work one day and Gilles heard the car and knew just from the sound the pulley bearings were starting to go. He explained they can jam momentarily and then free off thus damaging the belt. But when you look visually you often find all looks good.
Nick H
RE: Over revving and other issues - TristanC - 09 Sep 2018
I think you’re right Nick.
Here’s some pics of how worn the AC belt was. (It was new just a month or 2 ago)
And a new belt for comparison.
![[Image: 90CED0B1-A034-48CF-8A8C-4B7FBA7639F3.jpeg]](http://newdelorean.co.uk/wp-content/uploads/2018/09/90CED0B1-A034-48CF-8A8C-4B7FBA7639F3.jpeg)
![[Image: BE1CBCFB-3FC5-4791-825A-26F6249A92AC.jpeg]](http://newdelorean.co.uk/wp-content/uploads/2018/09/BE1CBCFB-3FC5-4791-825A-26F6249A92AC.jpeg)
RE: Over revving and other issues - Chris P - 09 Sep 2018
Could you let us have the bearing numbers please Tris? I'm planning on changing the belts on MGJ, so may as well do the whole job.
RE: Over revving and other issues - TristanC - 09 Sep 2018
Sure Chris, here’s the link:
https://simplybearings.co.uk/shop/p6819/SKF-62022Z-Metal-Shielded-Deep-Groove-Ball-Bearing-15x35x11mm/product_info.html
Cheers
Tris
And for future reference, in case this link becomes inactive in the future, the specs are
Inside Diameter: 15mm
Outside Diameter: 35mm
Width: 11mm
d
=
15mm
D
=
35mm
B
=
11mm
Dynamic load C
=
8.06 kN
Static load Co
=
3.75 kN
Fatigue load limit Pu
=
0.16 kN
Reference speed
=
43000 rpm
Limiting speed
=
22000 rpm
Weight
=
0.045 kg
d1
=
21.7mm
D2
=
30.4mm
r1r2 min
=
0.6mm
da min
=
19.2mm
Da max
=
30.8mm
ra max
=
0.6mm
Calculation factor kr
=
0.025
Calculation factor f0
=
13
RE: Over revving and other issues - TristanC - 09 Sep 2018
Well that was short lived.
Back to 1500 rpm again!!!!
Backfiring, rough running and 1500rpm
She will idle nicely for 5 mins, then creep up.
Turn her off, leave a bit, try again.... idles fine, then creeps up again..
Take out the bung from the mixture screw hole, idle decreases. Yes decreases....!
Oh Lordy.
RE: Over revving and other issues - Chris Williams - 10 Sep 2018
Quote:She will idle nicely for 5 mins, then creep up.On it's own? as in you don't do anything, not driving playing with it,blipping the revs?
Turn her off, leave a bit, try again.... idles fine, then creeps up again..
Quote:Take out the bung from the mixture screw hole, idle decreases. Yes decreases....!Obvious I know but either the bung or remnants' of plug are not pushing down on the operating arm is it?
Chris
RE: Over revving and other issues - TristanC - 10 Sep 2018
Yep, on its own after a few minutes warming up. Or a few mins after a restart after 15 mins being off
When I noticed the revs decrease with the bung in (Stu also saw this) I put my finger over the hole and had the same result.
———
I’ve been advised to disconnect the o2 sensor and adjust the mixture to bring the idle down. This being based on the fact I’ve been tweaking the mixture screw through out these issues.
I guess as a means to try to get the mixture correct again....
RE: Over revving and other issues - Nick H - 10 Sep 2018
(10 Sep 2018, 15:26)TristanC Wrote: Yep, on its own after a few minutes warming up. Or a few mins after a restart after 15 mins being off
When I noticed the revs decrease with the bung in (Stu also saw this) I put my finger over the hole and had the same result.
———
I’ve been advised to disconnect the o2 sensor and adjust the mixture to bring the idle down. This being based on the fact I’ve been tweaking the mixture screw through out these issues.
I guess as a means to try to get the mixture correct again....
Tris, Just to clarify “Revs decrease with bung in place”?
If this is correct that’s what I would expect. The revs will increase if unmetered air
enters through the CO adjustment hole.
Possibly the O2 sensor is contaminated by running rich.
Nick H