WOT issues on 3B

[Knight Rider S4]

Right I have my latest 3B with strange issue , i have just built up the top end and its running smoooth as ,no rattles so on

BUT under load different story

Took the car for a proper test run today and it was only boosting up to .7bar with MRC ECU(should be 1.3)..another thing when I go WOT it pops and farts alot and feels retarded ..I have changed over the MAF thinking it might be to blame but no real change

If it was a ABY I would say it had a dodgey coil , any other 3B owners had coil failure which caused same fault?

Cheers


Steve

[DJones]

Right I have my latest 3B with strange issue , i have just built up the top end and its running smoooth as ,no rattles so on

BUT under load different story

Took the car for a proper test run today and it was only boosting up to .7bar with MRC ECU(should be 1.3)..another thing when I go WOT it pops and farts alot and feels retarded ..I have changed over the MAF thinking it might be to blame but no real change

If it was a ABY I would say it had a dodgey coil , any other 3B owners had coil failure which caused same fault?

Cheers


Steve

Have you got the correct rotor arm?

[Rocco]

Distributor,sparks plugs,spark plug wires

[Knight Rider S4]

dizzy not long replaced all working , this was done by previous owner ...never really checked to see if it was a wide arm rotor arm or not will double check that and see ..leads are good so is cap, plugs arent old either..MFTS cause this?

[Knight Rider S4]

Think I maybe sussed it ..When I was working on engine the only thing that i thought might be suspect is the knock sensor beside the thermostat, wiring was all twisted and kinked I took it off and straighten it out and put back on ...This is a strong candidate for fault

[denniselbows]

don't think it would be down to the knock sensor as when one of mine went it just went flat as in limp mode and didn't miss fire or anything only time i have had a miss fire is when my rotor arm tip burnt off. which only hapened when coming on boost. does sound ignition related though

[avants2turbo]

you say youve just rebuilt the top end? Is the cam to cam timing or cam to crank timing off?

[Knight Rider S4]

Everything is bang on timing wise on car, runs fine when not under load and rev's fine just when going WOT it goes to ****...will check the dizzy to make sure it is all good ..going to replace the knock sensor just so it is out the loop as I know it was not in best shape

[istoo]

not sure on the 3B but on my 7A the dodgy knocksensor will stutter on the way up the revs but after 5000rpm its goes perfectly.. a possible minor help... maybe.

[S2central.net]

I'd say knock sensors worth a test first... Check they are ONLY 25Nm tight first of all. Also check TPS as well but do not also discount fact you might have a good ol' boost leak. Always worth resetting ECU after applying remedies - just in case any faults are stored. Easier to do with VAGCOM and such

[Knight Rider S4]

Update on this

Swapped the knock sensor over from another engine and that has stopped the popping and farting but boost is only 0.8

Plugged vag.com and the only code came up was F60 but think this came about due to poor running before ...Cleared the code and took the car for a run to see if it would reappear but nothing came up

So looking about for boost leaks came across the Charcoal Filter ...it seems to be missing the seal top and if I put my finger over I get a vacuum feel to it ..Will this affect boost ? Have put picture up of one that is right ..missing the rubber top off mine



Was trying to check measuring blocks with vag.com ..been a 3B it's a PITA as it is only capable of single reading, channel 7 seemed to be the most irratic as it floated from 65 to 135 ..trying to find channel info off s2central but struggling to see it just to confirm what it is

[newsh]

Vac connection to ecu ok?
I know you said timing is all good but does that include the dizzy marks? These are critical.
Tried unplugging MFTS? (great fun on a 3b...)

Vacuum is only seen by the carbon can at idle so prob not an issue apart from the vac not being applied to the petrol tank.

[newsh]

Is the WGFV operating? Head under bonnet, listen to the valve at idle and give it very brief WOT, should click.

[S2central.net]

Channel 7 - are you sure ?

http://www.s2central.net/vagcom_4.html

[Knight Rider S4]

Vac connection to ecu ok?
I know you said timing is all good but does that include the dizzy marks? These are critical.
Tried unplugging MFTS? (great fun on a 3b...)

Is the WGFV operating? Head under bonnet, listen to the valve at idle and give it very brief WOT, should click.

.

Vac connection is all good to ecu , dizzy marks are spot on as I did it when the head was off (timing cams ), Going to try and unplug the MFTS and see if that helps , great fun?..what should I expect to see with it unplugged

Done a full output test on vag.com everything working as it should


Sure it was channel 7 Paul..cheers for the link will double check all of them and make sure they are in parameters