Engine problem V5 B5 Passat

[tombei the mist]

Engine surging / hunting heavily when under load from cold start and during warm up. Most pronounced between 1500 -2500 RPM.

EPC and EPS lights come on steady together and engine begins to run very rough / surging when just reaching operating temp.

Turn off engine and leave for a few minutes and restart. EPC and EPS lights remain extinguished and car runs OK with minor hunting. Taking to VW dealer for diagnostics. Don't have access to VAG-COM. What could be possible causes?

Faulty Engine speed sensor, temp sensor, dirty Throttle Body perhaps? Any help is greatly appreciated.

[paul b]

Engine surging / hunting heavily when under load from cold start and during warm up. Most pronounced between 1500 -2500 RPM.

EPC and EPS lights come on steady together and engine begins to run very rough / surging when just reaching operating temp.

Turn off engine and leave for a few minutes and restart. EPC and EPS lights remain extinguished and car runs OK with minor hunting. Taking to VW dealer for diagnostics. Don't have access to VAG-COM. What could be possible causes?

Faulty Engine speed sensor, temp sensor, dirty Throttle Body perhaps? Any help is greatly appreciated.
I helped a fellow forum member out with a V5 Passat, he came to my house and we rigged his car up to my VAG-COM. His was hunting awfully (I wouldn't have enjoyed driving it at all) so he changed the MAF with a Bosch one. Big mistake, the car remained the same so a few weeks later he put a genuine one in and the car was perfect.

Having said that, because you have warning lights on, it means you are guaranteed fault codes, so once its been scanned there should be something to work on.

Paul

[tombei the mist]

Thanks Paul. I suspect that it's got something to do with the MAF or engine temp sensors. I'll provide feedback when I get the diagnostic results on 5 Jan 09.

[paul b]

Something I should add, faulty MAFs don't usually give fault codes unless they are disconnected. We'll know more following that scan. :)

Paul

[tombei the mist]

Diagnostic came up with TB as the probable cause. Looks like the problem was a split vacuum hose with a cracked connector. The hose runs across the TB. Had the 60K km major service done also. Now running well but will monitor with a cold start tomorrow.

If the problem reoccurs then VW suggest a TB change. Not keen to go down that route given that they want $2400 for a TB in Australia. I'm sure if I had to change it, which I think is unlikely, I can source and have fitted elsewhere cheaper.

[paul b]

Good luck with it! :beerchug:

Also, if you know the exact fault code number, and the problem persists, you can key it into Ross-Tech's Wiki (http://wiki.ross-tech.com/index.php/Main_Page)and see what they suggest when you find this fault code.

Paul