loosing boost pressure :(

[cheshire190e]

Hi everyone, I have a problem with my car loosing boost pressure, initially I thought it was down to a faulty boost controller but I have since tried another boost controller and I still have the problem.

On standard boost the car works fine but when the boost is turned up to 1bar either with a greddy profec or a manual controller the boost hits 1bar but then slowly falls back down to standard boost pressure even with the pedal hard into the floor.

Would anyone have a clue whats goin on because its confusing the hell outta me?

It hits 1bar at about 3k and then falls back to about 7psi by 7k

Its an sr20 redtop with a t25g.

Cheers

Matt

[BBB]

What's the rest of the spec? FMIC, dump-valve etc...

You've checked for hose leaks etc I presume?

[arry]

Sounds like the actuator isn't up to the job anymore.

[cheshire190e]

Its a redtop sr20det. t25g. standard wastegate, its got a FMIC 3" exhaust and decat and a big cone filter.

i'll try a new actuator I think. Would anyone know if there the same on the t25g as a t25?

[BBB]

Before buying new bits I'd check all the hoses and clips, pressurise the pipework to check for leaks and block up the dumpvalve to see if that was leaking at high pressure. That'll cost you nothing. If that's all okay, then start changing parts.

[cheshire190e]

ok will do mate, i don't actually have a dump valve but ill see if the actuator is holding pressure ok. Which pipework should I check? all intercooler pipework or just the small pipes to the actuator etc

[BBB]

The best test is to block all the way from the turbo exit to the throttle plate, this checks the FMIC connections. Have a search for a thread by Si which even lists which jars to block the pipes with :D

As for the actuator, take off the feed pipe that goes to it (small bore jobbie) and connect it to a footpump. Watch for the arm that goes to the wastegate moving as you raise the pressure. Another way to check is that that arm should be hard to move by hand if the internal spring is working properly.

[cheshire190e]

ok cheers mate ill give it a go. Could it also the the recirc valve dying, would it be worth blocking it up?

[BBB]

That's what I meant by dump valve ;) You just have a recirculating dump valve. The standard valve leaks at pressures above 1 bar. Block that up as another possible cause of leaks and see what happens.

[cheshire190e]

ahh i get you :) ok ill give it a good test later on. Hopefully its something simple its really bugging me as to what it can be.

I also have another question, the standard solenoid that is just above the chassis rail by the side of the turbo, one pipe goes into the accordian hose just before the turbo but the other port is just left disconnected.

Does this need to be connected to anything?

Cheers

[BBB]

The standard boost solenoid is now just junk and you can remove it from the car entirely, just cable tie the wiring neatly to the ABS unit. Remove all the pipes that came from the solenoid and block up the hole in the elephant trunk with a suitable bolt or end of a pencil, depending on how pikey you feel.:wack:

Your set up should be as clean as possible with short pipe runs. Boost pressure source --> EBC or MBC --> actuator.

[cheshire190e]

ok cheers mate i'll get that ripped out then. where is the best place to get the source for the boost pressure from?

I think mine is plugged onto a port at the throttle flap but not 100% havn't had the car long

[BBB]

Ideally, the control side of a boost controller should sense the pressure straight after the turbo as this keeps the pipe lengths really short and avoids spiking. Apex (trader on here) and I'm sure others, do a boost pressure nipple that you put into the flexible hose just after the turbo exit and then run the pipe to the EBC solenoid.

[cheshire190e]

ahh ok, so ideally you want the boost source pressure to be inbetween the turbo and intercooler. I could probably tap a nipple into the hard pipe to the intercooler

[cheshire190e]

just pulled out and blocked the little pipe going from the original boost solenoid to the accordian hose. I'll do the recirc valve later. Is there a guide on blanking the recirc on a redtop anywhere?

[cheshire190e]

right small update, I've pulled off that solenoid and blanked the holes. I also don't have a recirculating bov it must have already been removed. Unfortunately the problem still occurs.

I have started to think it might be a weak actuator for the wastegate but I have just descovered a crazy noise which sounds to do with the fuel system.

So maybe this is my problem, not getting enough fuel.

Here is a video of the problem, any help would be greatly appreciated. Cheers

http://www.facebook.com/v/10150291281180548

Thanks again

Matt

[BBB]

Please tell me you don't have the standard pump in there :(

[cheshire190e]

No its got a walbro pump, if that link doesnt work here is a different one

http://m.youtube.com/#/watch?desktop_uri=http%3A%2F%2Fwww.youtube.com%2Fw atch%3Fv%3DnxJO5pONtLY%26sns%3Dfb&sns=fb&v=nxJO5pONtLY&gl=GB

[cheshire190e]

No its got a walbro pump, if that link doesnt work here is a different one

http://m.youtube.com/#/watch?desktop_uri=http%3A%2F%2Fwww.youtube.com%2Fw atch%3Fv%3DnxJO5pONtLY%26sns%3Dfb&sns=fb&v=nxJO5pONtLY&gl=GB

[cheshire190e]

Anyone know what the noise could be? its worrying me as i have to use the car daily

[cheshire190e]

take it i'm the only person who has experienced this crazy noise then.

[docwra]

I cant hear it at work, but if boost is dropping off like that ID bet its the actuator. Mine had actually bent its mpounting plate a while ago which was making for very interesting driving. :wack: