reward for knowledge.....
i know this isnt g but i am going crazy, i will send whoever comes up with the answer to my query either a fine bottle of port/wine or healthy supply of beers if they can solve my issue for me, i will present my case in the medical format...
Patient: CLK 230K Cab 1999
History of presenting complaint: When engine warm and driving along at motorway cruising speeds, if i slow down to merge a to another road or slow for a junction, when i put my foot down again, the car stutters, doesn't like it then sets itself into rough running, reduced acceleration and generally ill health. this can be solved by stopping, turning engine off and on. but as you can imagine, not many places for this when on motorways.
Past Surgical History
- Replacement with genuine parts - MAF, Air filter, all pipes cleaned (to stop MAF contamination as well as brass breathers to stop it happening again) o2 sensor in exhaust manifold.
Investigations:
Hooked into diagnostics at local specialist, no faults came up but after an hour they figured it could be do to with the throttle positioning, but would want 1-2 hours with the car to go through and pin point the problem, thoughts on this?
Differential Diagnosis: i initially thought coils, but then thought it would make it run crap the whole time(?)
Prognosis of Owner: poor due to irritation levels in the pursuit of perfection
Any help would be great, i made i video of how it sounds tonight but didnt come out well so can exacerbate the symptoms again and re-record if anyone thinks that may help
Kind Regards, and thanks for any help
Tommy
I would have thought your best bet would be to read the codes and see where they lead you, but it's a shame you don't get anything back from there. Maybe the codes are being cleared by your reset procedure?
Also bear in mind there are at least 2, if not 4 O2 sensors, but again they can normally be tested for correct function, or will definitely throw a code when they go bad.
It sounds like the initial fault causes the engine to go into limp mode, so whatever is faulty, it just triggers that limp mode. Maybe your best bet is to wait for things to get worse, so the problem can be identified. Not very helpful I know!
Ps. might be worth looking at a new fuel filter, just in case.
You don't say what mileage your car has done, but I would also recommend replacing the fuel filter. When partialy blocked it can create the type of intermittent fault you are describing. It is also very difficult to detect on a diagnostic machine.
try the experts?
Tom
Had a similar intermittent problem to this on a VW LT 35 Van, from new. Dealers changed MAF sensors and all sorts. Only sorted when outside of warranty, changed to Indy servicing and got to root cause right away. The intercooler had a leak, as evidenced by oil streaks, and was confusing the sensors. Swapped it out been fine ever since.
Regards
David
had something very similar as well in our chevy. i did all the things you mentioned (MAF, Coils, leads, plugs, pipes, o2 sensors, etc.) after a long process of elimination, it was the maf that was off, but also we had a few vacuum leaks which gave incorrect readings/datums to the ECU. Try checking these before going any further. good luck/ph
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sorry i forgot to put mileage... 122,000 now (been cranking the long distance commutes up a notch!) had the fuel filter changed at 109,000 when i got the car.
Spider i saw your chat messages, dont know if i have the correct mobile number, I only use shell fuel in it or BP, optimax everynow and then as a treat to myself from me.
Would a tine crack in the exhaust manifold cause these symptoms?
Tom