robj2502

First some background on the car:

So I have a 2001 JDM bugeye STI, It has a sports cat downpipe and full 3inch exhaust (TSL pulse extraction) this is the only engine mod. It has done 44ish thousand miles and has been serviced on time. Also think the fuel pump may have been upgraded recently and the MAF has been replaced (both by previous owner) but not definite on these points. It hasn't been mapped

My problem is that the power seems stepped when in the higher gears or like the car is coming off boost for a second and then coming back on boost almost a hesitation mid boost. I am very aware of it on the motorway when in 6th gear where you go to overtake or any overtaking for that matter where you keep constant pressure on the throttle. Seems less/not there in gears 123 and worse in 456

Any one got any ideas where to look or what it may be?

Car has no fault codes, Idles well etc etc

SAM-UK300

iTrader: (8)

My guess would be maybe some sort of boost spike/cut? I know if you completely remove cats on newage then you must have a remap (to stop the spiking) but I dont know if this also applies to sports cats?
I'm sure somebody with much more knowledge than me will be along shortly...

JGlanzaV

iTrader: (3)

Did you sort out Tys refunds or parts?

SAM-UK300

iTrader: (8)

Not sure who Ty is, if it is that cannon Fodder fella then yup, he had the parts...

JGlanzaV

iTrader: (3)

Good stuff

I would be thinking it might be worth cleaning the boost solenoid?

FMJ

iTrader: (2)

You are going to need a decent quality boost gauge. You may be over boosting and that can be disastrous for your engine.

robj2502

I was thinking of getting it remapped anyway just to take full advantage of the exhaust. But didn't want to turn up to wherever I get it done with some silly boost problem and waste everybody's time!

I will check this but so far every item/hose I have removed around the engine has been clean/free from oil and crap

Oh dear hope it isn't this!! any one got a boost gauge they can lend me??

Also what is the standard boost pressure supposed to be?

Thanks for the help guys

JGlanzaV

iTrader: (3)

The solenoid might just have some dirt in it, I would personally use some crake cleaner wizzed through it and see if its any better, although i dont know if thats any good for it! Im sure someone can confirm

FMJ

iTrader: (2)

I would have thought the solenoid has a rubber seal inside it which may be dried out or damaged by brake cleaner but who knows. People always talk about cleaning them with it. Just make sure you refit the hoses the right way around after disconnecting them.

A boost gauge is always handy with these cars as it gives you a warning that something isn't right. Basically if one of the little vacuum lines to the wastegate actuator or solenoid has a tiny hole or split the turbo will be allowed to produce too much boost. As the boost gets too high it then drops back and climbs again and in some cases feels like a stutter as you are on full boost. This sounds a bit like what you are describing but it may be other things. If you have too much boost it can melt pistons in a worse case scenario. If its still fine now then everything is probably still ok but don't drive it at full boost with a problem like this as you may cause damage.

I would definately get a boost gauge and see what is going on. You want the boost to rise steadily to the correct amount (you will have to look that up as im not sure) and then stay there or maybe drop off by 1-2 psi as you get towards the red line. If it goes too high look for split vacuum lines. If it's not high enough you could have a blocked line, boost leak, dirty solenoid etc.

Or of course the hesitation could be sensor related, plug, coils etc. Its hard to say but I would want to know what the boost is doing from personal experience where having a boost gauge literally saved my engine.

robj2502

I will have the boost solenoid off and check and if it is dirty I will decide what to clean it with from there but agreed that I am not sure about brake cleaner but will see.

I was looking at getting gauges for boost and for oil temp/pressure so may just accelerate getting the boost gauge as like you say it is a good to know what is going on.
I will definitely have a look at the condition of the lines that go to the wastegate and solenoid to check for leaks as it does sound like some of the issues I have been having are caused by this.

Having a look across the web it would appear that my car came with the VF30 and should make around 15psi however maybe someone could confirm this?

Again thanks to everyone for your help so far