99 Passat Engine Problem

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Thu 5 Jan 2006 20:40
99 Passat Engine Problem - Jimmy123
99 1.8 20V, 91000 miles on clock, fully serviced and timing belt kit changed at correct time, no problems untill recent.

I had run the tank down and following this the engine seamed to surge or as if you were braking but only during motorway cruising, seamed OK around town. Decided to get a full service and change fuel filter, but now it is worse? Been thinking of things like: Flow level meter, fuel pump, temperature sender, type problems. There are no warning lights on dash board so I'm stumped? Reluctance to go to dealer dueto cost, but the backstreet boys can run up an equally large bill.

Any help would be much appreciated!

Jim
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Fri 6 Jan 2006 07:20
99 Passat Engine Problem - Andrew Moorey (Tune-Up)
Noting the mileage I would plump for lazy Lambda sensor. It wont put up a fault code as it is still operating within its parameter but is cycling slowly which presents a long 'go lean' signal to the ECU which correspondingly wakens off the mixture until it sees an equally long 'go rich' signal which has the effect of giving an acceleration surge and so on. Not noticeable round town. Simple test is to get up to operating temp then, in neutral, raise the revs to 2500 and hold your foot steady. A lazy sensor will show up by cycling the revs independently by as much as +/-500rpm.
Andrew
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Simplicate and add lightness!!
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