Vauxhall Vectra B 2002 Z18XE - Loss of power

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Thu 2 Feb 2012 18:52
Vauxhall Vectra B 2002 Z18XE - Loss of power - keithleonard


Hi The EML came on in my car making it run lumpy hesitant and misfiring, after checking it read faults code for the MAF Sensor. After talking to my local garage I replaced the ECU, Coil Pack and MAF, The car ran fine for about two days, then it started to cough, misfire and lose power, flat as a pancake. After a while the EML reappeared. A compression test and fuel pressure test were both fine. I have since disconnected the Lambda Sensor and Knock sensor making no difference to the performance at all. Please any help and advice would be very much appreciated !!

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Fri 3 Feb 2012 20:32
Vauxhall Vectra B 2002 Z18XE - Loss of power - The-Mechanic
What code did you get when you had it checked ? Was it P1555 by any chance ? This code can in some cases (depending on the diagnostic equipment used) point towards the MAF sensor, but in fact is caused by the throttle body air bypass port being blocked which in turn gives a false reading at the MAF (hence the trouble code).
What usually fixes the problem (well it did on my identical Vectra) is cleaning out the throttle body.
Take the throttle body off, get some carb cleaner (or use petrol and a cloth) and clean the carbonised gunk from the body above and below the butterfly flap.
Also a common problem is the idle air by-pass port gets blocked up (like this one was). When you take the throttle body off, you'll have a small bore rubber hose going from the rocker cover to the lower right hand side of the body onto a small brass stub. This allows air to by-pass the butterfly when on idle and it gets blocked easily as condensation builds up in the hose and dries / hardens, causing the blockage. I used a small straight pick tool (you could use a thin, strong steel wire or 2~3mm drill bit) and cleared it out by working it through the crud in the stub. Give it a blow out with compressed air and spray some carb cleaner down it to make sure its clear.
Bolt it all back together, check the fault codes and clear them and roadtest. If it was the same as mine, all should be OK with no hunting and the emissions light should stay OFF.
All the best,
Graham.
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