Replacing an engine ECU advice

[xpeterpx]

I've been trying so solve the unsolvable and have exhausted all other possiblilites on my lumpy idling problem(-see my earlier post).I know it a long shot and extreme but I'm fortunate enough to have had a spare one offered by a mate whos breaking his mk4 so just thought it might be a simple plug and play/recode operation as I have full vagcom access.
 

[Ben_1uk]

I've been trying so solve the unsolvable and have exhausted all other possiblilites on my lumpy idling problem(-see my earlier post).I know it a long shot and extreme but I'm fortunate enough to have had a spare one offered by a mate whos breaking his mk4 so just thought it might be a simple plug and play/recode operation as I have full vagcom access.

I wouldn't have thought this would solve the problem. Have you tried the usual?

- split leads/hoses
- coil pack
- spark plugs

Have you scanned it to see if it chucks out any fault codes???

[xpeterpx]

Yes mate went over the breather pipes at the weekend and couldn't spot anything sinister.Also changed the fuel filter to eliminate that too..
http://www.golfgtiforum.co.uk/index.php?topic=121046.0

Scanned many times with the full registered version of vagcom and comes up clear every time!

[Rhyso]

i'd be very surprised if it was an ECU problem - you don't tend to hear of them going wrong 

is it not something like a gasket or seal perished??

[xpeterpx]

Possibly,but where would I start with checking? Are there any 'notorious' ones on the mk4 I could start with?

[Ben_1uk]

I can't remember the name of the valve (think it might be EGR), but that can sometimes get clogged up with crap and cause performance problems???

[Rhyso]

Possibly,but where would I start with checking? Are there any 'notorious' ones on the mk4 I could start with?

inlet and exhaust manifold gaskets maybe??

I can't remember the name of the valve (think it might be EGR), but that can sometimes get clogged up with crap and cause performance problems???

i believe they are fitted to diesels only mate

[Ben_1uk]

Just read the original thread - it was the TB I was on about :embarassed: and yes, it's been cleaned already!

[dai-cymru]

whats the bsi unit?

[Ben_1uk]

whats the bsi unit?

The BSI unit controls a number of basic functions including indicators, ignition lights on with the key, cluster readings and also aids in starting the engine by talking to the ECU to engage/disengage the immobiliser .