16v issues after head rebuild...

[_Meth 0]

Just had my rado off the road for a few weeks taking the head off and pulling it apart etc, its all back together now and starts and runs but ive got a few issues I could do with answering if anyone can help?

 

1) I fitted the 50mm manifold when putting it all back together, I know its supposed to be a little flatter low down and pull harder at 5k + but its totaly flat all the way through the revs? I only fitted the top part, not the second section that fits to the head itself - could this be why? I also used the original throttle body from the 42mm manifold as the one that came with the 50mm had a few bits missing - is this ok?

 

2) The pipe that runs from the back of the airbox to a heat plate on the exhaust was badly damaged and falling apart, so have removed that and not fitted it back... how important is this hose? Should I find something to replace it? Or do I need to blank off the hole in the back of the airbox? Or should it make no difference?

 

Thanks in advance guys! :D

[_Meth 0]

Just to clarify - there is no pull at any point realy through the revs - feels flat as a fart...

[farrantino 0]

check the metering head flap to make sure its not sticking, or it could be the fact that the two inlet half's haven't got a good seal, also double, if not triple check the timing.

[farrantino 0]

just had another though, if you took the head off, did you put new injector seals in, as these will just draw more air than needed in.

[_Meth 0]

Did have a leak from the two manifold halves but sealed that up, double checked the timing - its bang on the 2nd mark on the crank pulley with the cam marker, and bang on the 1st line with the timing light. Didnt replace the injector seals, but didnt remove them... reckon they need replacing?

[boost monkey 0]

why did you use half of each manifold?

[Supercharged 2]

Meth - can you please update this thread ASAP!

 

http://the-corrado.net/showthread.php?52126-2011-Corrado-Forum-Calendar-A-few-Still-Available!/page26

[_Meth 0]

Replied.

 

Honestly, I have no idea why I used two different halves :lol: I had the first section laying around and have had for a while now, figured Id give it a shot. Am going to swap back to the original tomorow - hopefully thatll solve the problem.

[davidwort 0]

easier to swap just the top half I guess but the step from 50 to 42mm is going to do something pretty odd to the induction :scratch: not exactly what VW intended :lol:

[_Meth 0]

To be honest it wasnt because it was easier, its because ive seen pictures and heard people talk about it and ever only seen the top half - it didnt occur to me that its stepping back down to 42 again before it enters - thatll just be causing a bottleneck and getting rid of any pressure there!

 

Lol I feel suitably embarrassed :bonk:

[pumbaa 0]

Can you post a list of exactly everything you changed?

 

Check all vacuum lines, though i think your problem is the 2 different manifold halves. surely whichever gasket you used will not mate correctly to the incorrect half?

 

You could try testing all injectors to see if they're spraying, as above check the metering head flap if moving, check all plugs and leads and quadruple check the timing. Also check the woodruff key hasn't sheared on the cam gear.

[_Meth 0]

Ive just swapped the manifolds back over and now it wont start at all...

 

Well it may start and run realy realy rough and try and die, if i hit the gas a bit it revs up high and then just cuts out =/ im realy confused now because all ive done is swap them over! the only thing I can see that I dont remember before is the little black cylinder on the end of the intake manifold with a plug on the back (the bit that slots on a rubber onto a metal bit) is now buzzing a lot with the ingition on, and I dont remember that...

 

Any ideas?!?! :@

[swiftkid 1]

I believe the cylinder next to the inlet manifold is the isv and it should be buzzing.

 

Make sure the plug underneath the throttle body is fine and not falling to bits, causes all sorts of havoc if the plugs arn't making contact properly. Make sure the injectors are seated properly, you could pull them out individually and just prime them to make sure they are firing firstly.

 

Seeing as you have had the head apart, check, double check and triple check you put the timing back exactly, check the cam timing and the belt to make sure your not a tooth out, then check the dizzy. There is a guide over on clubgti to time them up properly.

[_Meth 0]

Am jsut about to take it all off again and double check the lot :(

[swiftkid 1]

Well you don't have to take it apart, just check the timing first to make sure its right. Pretty straight forward, hang on i'll try find the link for you

 

edit: few things to check

http://clubgti.com/forum/showthread.php?t=186796

http://www.clubgti.com/forum/showthread.php?t=86157

http://clubgti.com/forum/showthread.php?t=195423

Edited February 22, 2011 by swiftkid

[davidwort 0]

big vacuum leak somewhere, you sure all the pipes and hoses for thevac system and idle are all properly connected and no splits?

[farrantino 0]

Check the Vacuum pipe on the back of the manifold, check for splits and so on, this also will cause you hell.

[pumbaa 0]

Sounds like a vacuum leak to me. May be a silly question but there is a pipe that runs from the isv to the large air intake pipe that connects throttle body to airbox?

[pumbaa 0]

If you upload a picture of the engine bay i could try to circle things to check or see if anything looks missing.

[_Meth 0]

Just checked the clubGti link and the timing was out by a tooth - its now perfect with cam gear marking and marking on the flywheel - but the marking on the crank pulley is a bit behind, is that right? Am I right in assuming thats the marker to check for ignition timing?

 

It now starts but idles about 500rpm and sounds like a bag of nails! darent run it :(

[swiftkid 1]

If I were you I would set the markings with the crank pulley but make sure the slack on the cam belt is the right way, ie so when the engine turns first off it doesn't alter the timing.

 

If its running at 500rpm it may be that the dizzy is out, if you have got a timing gun you can check it. If it was right before it might be worth checking for vacuum leaks as well as that will make it idle like a bag on nails as well.

Make sure you turn the engine over a couple of times after you have messed with timing to make sure there's is no valves hitting pistons!

[_Meth 0]

And the timing light - should that be checked against the mark on the flywheel or on the crank pulley also? Ive looked at 3 different guides for all of this and they seem to give conflicting info... the crank pulley mark and the flywheel mark are in different places =/

[swiftkid 1]

They shouldn't be!!! you should be able to check either because they are both connected to the crank and fit on 1 way. It is the marking on the plastic cover your timing it with? As that doesn't point directly downwards, its offset slightly

[boost monkey 0]

Why are you checking timing at all? I thought all you did was bodge two different manifolds together?