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| the old girl is poorly,; rough idle and stalls when pulling away | |
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| Tweet Topic Started: Wed Feb 21, 2007 11:38 pm (892 Views) | |
| kentronix | Wed Feb 21, 2007 11:38 pm Post #1 |
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I'm only really here for the Kitchens
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right, the background. The car has been off the road for about 10 days, the battery was already very low due to lots of short journeys with lights/heater/demister etc,... anyway, the battery went totally flat and I had to jump it, I have since got a new battery just in case. It may be unrelated but you never know, always worth a bit of background Since then it starts fine runs fine for a bit and then roughly when I suspect the whole block is getting to running temp the problem starts. At speed it runs ok but much less power. At idle its really lumpy, so much so that it may conk out if I drop into drive at rest (theoretically its a 2.6 auto). I can keep it running by two footing and ensuring it starts in 1st rather than 2nd, once up to 3k revs it sounds fine, no lumps but it has much less power. The lumpyness doesnt sem to be missing cylinders, it isnt that regular. And the conking is so severe it is unlikely to be just a cylinder not firing. Idel has dropped from 700 to about 500. It is also very severe when it stops, I feel the engine move. It may just be what happens when you stick a 3.0 in a relatively light car but it jolts the car quite a bit when it conks. I have read a bit ad the ovp sound a likely option but the fact that it does actually run at high revs suggest perhaps elsewhere ? I have checked all the ht leads and sprayed wit hcarb cleaner but it didnt help. Any ideas ? |
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| Cosmo2.5-16 | Thu Feb 22, 2007 12:00 am Post #2 |
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Part of things
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Did you check the fuse in the OVP relay, if you have being jump starting it you might of blown the fuse, Its a 10 amp fuse. Check this first. |
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| kentronix | Thu Feb 22, 2007 12:12 am Post #3 |
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I'm only really here for the Kitchens
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ovp is somewhere behind the battery near the ecu right ? From what I read I assumed if it is ok in the high revs than it probably isnt the ovp. Although just coz one person says in on the net doesnt mean its true of course how do i find the ovp ? Checking the fuse is easy enough but is there an easy way to test the unit ? |
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| Cosmo2.5-16 | Thu Feb 22, 2007 12:56 am Post #4 |
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The OVP relay lives beside the ecu's, over on the passenger side of the engine compartment behind the black plastic thats behind the battery cover. It's a tall relay with a 10 amp fuse at the top of it. Check the fuse first and we'll take it from there. |
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| pentoman | Thu Feb 22, 2007 4:16 pm Post #5 |
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Resident OVP Expert
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Never heard that bit about high revs and the OVP. It's not true. Just yesterday I totally removed my OVP and drove around for a while just to see how different it was (answer: not very, except the ABS didn't work). I've realised I'm getting to uber-geek levels now, but on my early 8v the OVP is on the outside of the ABS/Injection ECUs i.e. the right side as you look under the bonnet. On my late 16v the OVP is on the inside, i.e. the left side looking in under the bonnet. If you can get a torch in there it's a bit easier. It just pulls out pretty easily. Check the fuse. They are simple, yet when I tried to fix the one on my 16v (resoldered it and everything) I failed and had to buy another one. However if you jump started the car that apparently takes out the OVP fuse very often, and the symptoms sound exactly like OVP related failure. |
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| kentronix | Thu Feb 22, 2007 4:19 pm Post #6 |
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I'm only really here for the Kitchens
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I can't find the OVP Took the battery out, behind it I have the ECU's, A funny thingie over the right hand side, a black large relay unit over the left and a selector switch similar to the S/N one for fuel type. I checked right down behind the black realy thingie and there is nothing there. Any ideas ? I checked over the other side of the car by the fuses and the extra relays and its not there either. I assume its meant to look like this ? http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...em=160086673749 Some pics of my ecu area. ![]() ![]()
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| cossie connoisseur | Thu Feb 22, 2007 4:26 pm Post #7 |
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there can be only one ;-)
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Bottom pic look at the left there is the top of it in the picture. it slides into the ECU housing
Its between the fuel pump relay and ECU housing! silver body, retangular |
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| kentronix | Thu Feb 22, 2007 4:36 pm Post #8 |
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I'm only really here for the Kitchens
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a ha, got it. I thought that was the side of the ecu. Cant get it out but will try again a bit later, I really ought to do some work for once Here is a pic in case anyone else is dumb enough to not find it ![]() I flipped the top open but cant get the fuse out, and the unit itself is held in tight, I assume I have to take the ecu's out to get to it ? |
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| cossie connoisseur | Thu Feb 22, 2007 4:43 pm Post #9 |
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there can be only one ;-)
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The clear cap is on tight but does come out with a little force. The OVP slides out vertically but be caredfull not to strech any wires. The pins will be very firm in the terminal block but with persistance (and removing other things in there to get to it better) you will get it out. Might i add that you take the ECU's out and there bits in there and give them a clean cos it DOES make a difference to the running of the car
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| kentronix | Thu Feb 22, 2007 4:49 pm Post #10 |
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I'm only really here for the Kitchens
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phew, a bit of effort and 2 scraped knuckles later
Got it out, the fuse is fine, is there a way to test the unit ? |
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| cossie connoisseur | Thu Feb 22, 2007 4:51 pm Post #11 |
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there can be only one ;-)
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Yes you can but you need the right info and equipment so mercedes may be able to help. If you know them they may be able to do it for free
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