Strange Engine Powerloss

[Frankieflowers]

Sometimes things break at the right moment - extremely lucky dude!

Hi Jay. I was reading this thread because I am witnessing a loss of power between 3000 and 4000 RPM. I had to take the cylinder head off and send it to get welded because of a crack on the fourth cylinder exit. We basically took the parts off and put new gaskets and bolts on the engine. We didn’t modify anything concerning the turbo or the front mount intercooler system. When we started the engine after the fix we heard the tweaking high pitch weird noise coming from the turbo area. My partner said that it could be oil missing in the turbo pipes that could make the turbo bearing run dry. I don’t think it could damage it at low temperature on idle. So I thought it could be the new balls and gaskets that needed to adapt on the downpipe for example? What else could it be? The turbo was fine before we took the head off. We change the timing to 10 but put it back to 0. Nothing really changed besides having more power on the top. The turbo isn’t working as it should. There is an air blow noise but all the pipes and silicon hoses are apparently tight what could it be? Consider that my partner took the metal clip off the EFI pipe because it was too hard to put back and put a metal clamp instead. Just to be sure I went underneath the car to check it if it was loose. I don’t think it could be a problem because it’s where the air gets sucked in the turbo. The pressure gouge gives a constant pressure and as I had and tightened hoses before I could definitely see the boost under its nominal level. This time the boost is right where it should be but the acceleration power isn’t right. Siri be the knock sensor thing you were talking about? Too much air in the fuel mix? What could have been changed so drastically from before and after we took the cylinder head off? The set up is the same and we just put everything back together. I hope that you can help. Thank you

 

[Frankieflowers]

Here’s the result. New bolts and gaskets. The engine runs great but there is a fun y noise and loss of turbo power around 3000/4000 RPM.

 

[Jay]

There's a number of things it could be (or a combination of a few) so I can only give you a steer..

The noise can be traced to the turbo yes? If so check the free play in the impellor shaft. If the seals are damaged it could cause the blades to make contact with the housing. Seals could have been damaged by the lack of oil as suggested if the turbo hasn't been primed prior to engine start.

Don't quite follow what you are saying about the timing - it should be set mechanically at 0 degrees then adjusted to 10 degrees BTDC with the distributor, just doublecheck this is the case.

Also check that the intake camshaft has been tensioned. It's very easy to forget the service bolt during cylinder head removal (a lot is going on at once).

Always worth going around the intercooler couplers as one could be pushing open on boost.

Probably a lot there that's not the issue but report back if you find anything mate.

 

[Frankieflowers]

Don't quite follow what you are saying about the timing - it should be set mechanically at 0 degrees then adjusted to 10 degrees BTDC with the distributor, just doublecheck this is the case.

Yes that is exactly what we did. .0 with the mechanics and +10 on diagnostics mode.

 

[Frankieflowers]

Always worth going around the intercooler couplers as one could be pushing open on boost.

Probably a lot there that's not the issue but report back if you find anything mate.

Yes the phenomenon is weird. At first when we installed the front mount intercooler my partner missed a few screw clamps on the hoses so they were making air blow noises and boost was low.
Now it is different. On mid revs there are power gaps between 3000 to 4000 RPM. Boost (picked on the hot pipe) is normal but could it be lowing from somewhere else? Could this happen if the efi pipe Isn’t tightened right? Probably not but could it disturb the waste-gate from working properly?

 

[Jay]

Just another thought - pop the efi pipe off and make sure the rubber seal is seated properly. They can be a nightmare to refit at the best of times, seen a few interfere with airflow.

 

[Jay]

Wouldn't be uncommon for it to get caught during fitment (firsthand experience lol)

 

[Jay]

Oh and whilst it's off check that you can spin the turbo blades freely and there's no play or noises.

 

[Frankieflowers]

Oh and whilst it's off check that you can spin the turbo blades freely and there's no play or noises.

Will do. Thank you. I will do what you said and also tighten the turbo bolts that may be loose.

 

[gorganl2000]

Just another thought - pop the efi pipe off and make sure the rubber seal is seated properly. They can be a nightmare to refit at the best of times, seen a few interfere with airflow.

this is very true...back in the day i used a little oil/grease on the inside of it to help it slide on

 

[SKINY]

this is very true...back in the day i used a little oil/grease on the inside of it to help it slide on

Will be doing that later too lmfao