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C4GP 1.6THP EGS box - power loss no obvious cause |
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mwj666
 
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  Member No: #49862
Joined: Nov 13 2017Location: Cheshire |
Greetings all, a bit of an odd one: Bowling merrily along at about 60mph in my partner's C4GP yesterday and suddenly it just lost all power (no error lights). In desperation I knocked it down 2 gears and floored the accelerator and it promptly started running OK again. Then half a mile down the road did exactly the same (but fortunately we were only 200 yards from home by then) Hooked up diagbox today and there are NO ECU codes that look remotely relevant, (which in a way was a relief as I was half expecting the P0087 HPFP error). There were P2299 (brake pedal signal inconsistent with accelerator peal position) on the engine ECU which I suspect is 'historic' as it says the car was doing 16kph at the time. On the gearbox ECU there are P0925 the gear does not engage (but says the car was in neutral so not relevant) U1208 Info sent by engine ECU invalid value received - AFAIK that should trigger the ESP/ESR warning light but NOT put the engine into limp-home. On the off chance P2299 was relevant I've checked the full range of accelerator travel in diagbox and the 2 tracks seem to follow each other exactly in sync (I assume track 1 should always be double the value of track 2) and similarly both the brake pedal sensors seem to be faultless. Tracking the fuel pressure didn't show any errors either (sits on 50 bar +/- 1 bar max) I'm far from a novice mechanic but will confess to being stumped - if it was a good old-fashioned car with carbs I'd say it felt like a fuel line vapour lock (it was pretty damn' hot yesterday) but AFAIK injection systems can't suffer from that. Any and all suggestions (other than 'part-ex it quick') welcome at this point  !Thanks |
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Ap0qalypto
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  Member No: #52161
Joined: Sep 21 2018Location: Republic of Serbia |
That's a very odd one, when my crankshaft position sensor was giving up, from time to time I would get sudden loss of power, for a short time(couple of seconds), I didnt have any error on the dashboard. Once I have removed brake pedal switch, didnt put it back correctly and my rear brake lights were on all the time. First thing I noticed is the lack of acceleration, since ECU thought that car was slowing down but at the same time I was hitting acceleration |
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mwj666
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Member No: #49862
Joined: Nov 13 2017Location: Cheshire |
Thanks - well that is a feasible-sounding suggestion, and is more ideas than I've had about it so far despite much head scratching  The car only does very nominal mileage (a couple of thousand miles a year) and spends the rest of it's time sat out in all weathers so I suspect my first port of call might be checking and cleaning up the connector to the CPS since AFAIK it's not difficult to get at. It wouldn't be the first problem I've had with corroded connectors - and it'd also fit with this happening when the car is really, really hot having sat in traffic for half an hour in 30 degree heat ! Or I might just replace the damn' thing, they aren't expensive and it is 17 years old now anyway (it's a 2009 car) I shall investigate - ty
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Ap0qalypto
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Member No: #52161
Joined: Sep 21 2018Location: Republic of Serbia |
Their BSM(next to engine ECU) is prone to failure, I have replaced mine couple of years ago. Its simple plug and play though | ||||
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mwj666
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Member No: #49862
Joined: Nov 13 2017Location: Cheshire |
OK, having now got a version of Diagbox that will actually talk to the car properly and read the logs (I was on 5.02 ) - there is a single P0925 error in the ECU faults log that happened at around the correct mileage. Nothing whatever logged on the gearbox It's not recurred and the other day I took the car for a 20 mile pretty mercilesss thrashing round the local roads and the motorway with no problems whatsoever. Smacks to me of a bad connection somewhere given when the error happened everything was absolutely scorching hot! Doubt it's the position sensors on the front of the box as they were replaced about 5k ago and I very thoroughly smothered the connectors with grease to keep any moisture out given their extremely stupid placement right on front of the box. Next step find a wiring loom diagramme for the EGS box and go over every connector |
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Ap0qalypto
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Member No: #52161
Joined: Sep 21 2018Location: Republic of Serbia |
Check two big connectors which are going into gearbox ECU. They should have special grease on them, which prevents moisture. You can see then from the top, looking down. On 2.0hdi its visible once you remove engine air filter housing | ||||
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mwj666
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Member No: #49862
Joined: Nov 13 2017Location: Cheshire |
they are filthy - but I wouldn't say it is 'special grease' just accumulated road muck  Funnily enough they were top of my 'easy things to check list', the car does only nominal mileage but lives outside and in winter everything gets pretty damp under the bonnet so query corroded connector I thought, good clean up and a liberal coat of white lithium grease
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mwj666
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Member No: #49862
Joined: Nov 13 2017Location: Cheshire |
Hmmm... is there a secondary locking catch for the front EGS ECU connector? I've popped the yellow locking tab on the LHS out and it's still not budging, it wiggles side to side a bit but is flatly refusing to pull upwards. Understandably I am loath to apply too much GBH to it! Clearance to the underside of the battery tray is pretty minimal so I can't see if there's a secondary catch at the rear of the plug and taking the tray out would be a right faff (the box would also promptly forget all it's learned settings when power is removed) |
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Ap0qalypto
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Member No: #52161
Joined: Sep 21 2018Location: Republic of Serbia |
I dont think there is another one, it has like pull type of connector. On the other hand, I have never dared to remove them
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