Very unusual boost problem
 

Please help!

I own a standard (as far as I know, other than cat back exhaust) 2001 RS which used to always boost to about 9 x10 kpa on the stock boost gauge.

Nowdays sometimes I get full boost and sometimes I dont.

I usually get full boost out of it in second gear but sometimes I dont it will just stay at about 4-5 x10 kpa and not go higher.

I hardly ever get full boost in first gear just the same amount of half boost that I get in second sometimes, unless I spin the wheels...then for some reason the boost creeps up until the wheels grip again then it usually goes down again even though i am full throttle right through the rev range.

I am guessing its electrical because at times it holds full boost but I have no idea.

Cheers

This sounds like a typical issue with the Turbo Control Actuator/System. To move the actuator quickly, the system uses 2 solenoids for vacuum and pressure (to push and pull the actuator). If one or the other isn't working properly, the actuator cannot react fast enough which is really apparent in the lower gears like 1st and 2nd.

The problem you'll have is you probably have the "black box" for the solenoids unlike the North American models. If they can be separated, see if you test each solenoid to see which one may not be working properly.

Hey Eston,

I have almost an identical problem. I'm taking my car to Carl Hayward on Wednesday (UK) next week to get it sorted. Should be a couple of hour job as they have to take out the rat's nest etc.

Theres no guarantee we'll have identical solutions, but when I've found out my problem, I'll head back on and let you know where it was going wrong.

Hope that will help!

Cool thanks for the replies guys. cjj I hope we do have the same problem. I look forward to hearing back.

Hey cjj any luck getting your boost problem fixed?

*cough* go non sequential *cough*

I used to get random boost issues then i went non sequential (manual boost controller) and its worked right every time so far, and I changed it years ago.

Going non-seq is ok if thats what you want to do, but I'm not sure I'd do that as a trouble shooting method.

Like Mahjik mentioned its probably one of your solenoids.

To properly fix the problem go to Degeesamans web page, download the vac hose diagram, replace all of your vac tubing if yours is old, test each check valve, your vac and pressure chambers, and each solenoid and actuator. Replace what is bad and your problems will be solved. Take your time and you'll have a well functioning twin turbo system (assuming stock or near stock boost levels).

*EDIT* Just noticed you have a higher series FD. I'm not sure if you can individually replace the solenoids from the "black box" or not.

This might help diagnose it or narrow it down a little. It has helped me numerous times with boost problems. It might at least give you some stuff to check and make sure it's not something simple. I had a similar problem and it ended up being a bad gasket between the elbow and the TB that would sometimes seal perfectly and let me boost in 1st gear then once hitting higher boost it would blow past the seal and cause my boost to drop. lol can't wait to go single.

http://www.autosportracetech.com/RX-...leshooting.htm

Problem solved
 

It was a check valve. Troy from Mildren Automotive (Adelaide, South Australia) fixed it in a hour.

Thanks for your help guys