Hi, changed the Dumpvalve on my 97 sti the other day as thought I could hear it leaking when on boost. Changed it and it spooled up a bit earlier but it hit 1.78 boost straight away so have driven it off boost since. I changed the dump valve back earlier to the one that was on there originally, but it still over boosted to 1.55 bar boost today so just drove it off boost home again.

I'm booked in on Monday to see JGM as I presumed it was the map that had been done with the leaky dump valve and now fitting the one that didn't leak was causing it to spike.

Anyone point me in the right direction where to look first?

Thanks

Tim

EDIT: Is the APEXI POWER FC definitely not self learning? I have been told by someone on here that it isn't, but would like some more assurance as have seen a couple of websites now that say it is with the boost control kit (which I presume I have or comes as standard with the hand controller/ecu? or is it the 3 port solenoid)as I have different boost settings - does everyone have this that has one?)

My friend has also told me to: to try and find is the MAP sencor this is what tells the ecu what pressure/vacuum is going on in the engine.I am not sure if the pfc uses a separate map sensor just to read/help control the boost or it uses the original map sencer on the car (if it has one as standard)to the ecu?
If there was a leak in that pipe it could confuse the ecu and it would not be able to hold the boost correctly.

 

Could well be the map, but do the other checks too, check pipe work and clean out the solenoid etc. Or obiously, turn the boost down!

 

Don't think it'd be the map as its been fine since i've had it (3 odd weeks) Had a look at the pipes and can't see any splits or anything. My drivers side FMIC pipe has possibly got a small hole in it where its been rubbing against the frame, but don't think that would cause the spike would it?

I will clean out the solenoid tomorrow.

Forgot to put earlier that the boost setting was on the lowest cycle setting its supposed to be hitting 1.2 bar and using 20% cycle, but hit 1.55 today.

 

check the pipe from actuator to boost solenoid.. if that has a hole of leak it would cause overboost..

you need to sort the hole in the intercooler pipe too mind but it would cause under not over boost

Simon

 

Thanks Simon, will check that pipe tomorrow, light was running out when I looked at all the possible pipes I thought it might be this afternoon, so will check that tomorrow.

I'm going to try some quicksteel on the pipe tomorrow if I can get hold of some.

I'm just wondering if the PFC and the self learning i've read about would lead to the old bov overboosting for a little while as i've read it self learns? If it is the case how long would I have to run it for until it reached the normal boost it used to get.

 

If the pinhole isn't on a bend in the hard pipe, then you may want to cut the pipe and re-join it with a silicon hose and 2 jubilee clips - That way, you are guaranteed to fix the leak, and it should stop the pipe from rubbing through again

The powerfc should be fuel cutting if you are getting 0.25Bar over the boost setpoint

 

no it will not relearn..

there is a very fine closed loop control on the boost to try and keep to the target boost but it needs to be close.. you will damage the engine if you allow it to boost that high

Simon

 

Cleaned the boost solenoid and all pipes out today and its solved the problem.

MANY THANKS!