golf mk4 gti 2.0 poor idle high emissions

**sparkyjohn2005** · 06-10-2008,10:47 PM

help! my golf gti 2.0 is running really rough idleing and is putting out high emissions also guzzling fuel took out the spark plugs which were just replaced and were pretty sooty changed the coolant temp sensor but made no differance can anyone tell me whats wrong?

**Crasher** · 06-10-2008,11:04 PM

A fault code read may indicate a faulty lambda sensor (very common on this engine) but the problem can be caused by a faulty Air Mass Meter (or MAF as some call it) DO NOT DISCONNECT the AMM to test it, that will just store a fault code and not help you. Get a code read done and come back with the results.

**sparkyjohn2005** · 06-10-2008,11:13 PM

ok thanks mate shall i book it in at vw garage or will any auto diagnostics place do?

**Crasher** · 07-10-2008,01:34 PM

Anyone who can read and clear codes. Get a print out.

**angelo4913** · 13-01-2009,12:50 AM

Hi all, i have the same problem as listed above and was wondering if anyone had solved it? any suggestions? i have serviced the car, replaced air flow mass sensor, changed HT leads... bit stuck now as diagnostic does not say what the problem is specifically. just reads: misfire, high emissions etc..

Thanks
Angelo

**Crasher** · 13-01-2009,10:14 AM

What is the car year, engine code and the fault codes you are getting?

**angelo4913** · 14-01-2009,02:37 AM

Hi, it is a 1999, 2.0 golf gti, it has recently come up with emissions workshop, it is running really rough, has very high emissions, getting very poor miles per gallon. it says misfire recognised on snap on diagnostic, but i can not work out what the problem is. i was thinking maybe it was a lambda sensor.?

**Crasher** · 14-01-2009,01:01 PM

Where did the leads come from? Which brand and part number of plug? What is the engine code? These are very prone to coil pack failure, is the fault code clarified as a particular cylinder or just random/multiple. Yes, the lambda sensors on these are very prone to failure but you would have an associated fault code.

**fray** · 03-02-2009,09:54 PM

has this problem being solved? i have the same problem, also got a decat pipe fitted, my car cut out today and showed emmisions on the screen? any help would be great
thanks

**Crasher** · 04-02-2009,10:21 AM

Fitting a decat pipe to a car with a post cat lambda sensor is really stupid. Of course it will show an emissions error, the second sensor is there to monitor the performance of the cat and the signal is also used by the ECU to apply correction valves to the mixture to fine tune the running so that cat is running efficiently. How did the people who did that expect the car to pass an MOT? On the 2.0 8v, removing the cat will give no appreciable power gains whatsoever. You will have to fit a cat and probably two new lambda sensors (or at least the pre cat sensor) and see how it goes from there. The only way to stop it getting upset is to fit a lambda cheater to the post cat sensor input which fools the management system into thinking the cat is still there but it doesn’t get around the legality issue.