Hi....

Ive got a few boost problems with my rx7 (95 FD)..

I have checked the FAQ and read through the trouble shooting so please dont have a go

The problem im getting is intermittantly the boost takes a long time to build up...example...

Ill be cruising along at 60 mph in fifth then floor it and the boost will shoot to .8 bar (runnung base map on apexi ecu)..thats fine no problems there..

Then ill be cruising again at 60mph and floor it but this time the boost takes along time to get to .8 bar (just creeps up on the commander display) but WILL get there over approx a 10 second period..and the car does feel flat.

Ive ran a boost check and get .8 .7 .8 (a little low i know but not to fussed until i get it mapped)

Now the problem is intermittant so i dont know how im going to find it....any one got any ideas
Ive checked the obvious vac lines etc - all ok (would be there all the time anyway)

thanks

gavin...

 

8i have the same prob. and the exhaust kinda makes a different sound when it happens, and the car feels really powerless, im allso running apexiPFC on basemap

 

take a look at your 1 way check valves on the rats nest. se if they are still functional

 

[edit:] definitely check the check valves first - the worst condition the check valves see is when boost pressure is in the manifold - so it would make sense that if one was leaking, it would deplete the vacuum tank under boost and make it slow if you immediately get on the throttle again. You need a vacuum pump to properly test them, but IMO it's better to just replace them all. Hardware store variety works ok, but Dale Clarks check valves are probably ideal.

Intermittent is a bugger - I'm guessing an intermittent solenoid failure. when it's not doing it, try reaching in a unplugging a hose to the vacuum and pressure chambers. Make sure they're holding ok. Then when it starts to misbehave, see if the same thing happens - if not, perhaps a solenoid or check valve leaks when hot.

It's a bugger to find it, too - one method is to remove each solenoid and test it to hold vacuum/pressure and coil resistance, then put them in an oven (say, at 220F for 20min) and test them again.


Dave

 

Dave Disney has documented this one:

https://www.rx7club.com/showthread.p...isney+solenoid

All you need to know. It's problems with the turbo control system - either you've got a bad check valve, or the solenoid itself is bad. Start with the check valves, then try the solenoids. See my sig for check valves .

Dale

 

thank you ever so much for your replys


Ive read through Dave disney's fix and have come to the conclussion that i actually dont have a problem...

This is taken from his fix page..

Ok, now for a couple of notes. The turbo system goes into twin mode when you pass the transition point (about 4500 rpm at WOT, later for partial throttle). It does not return to single mode until you go below 3000 rpm. So, if you go past the transition and then coast down to 3100 rpm or so and floor it again, it will be a little slow building boost because both turbos are still on-line. It is supposed to work that way.


Now that is exactly what im getting...Little did i know that once i go past 4500 with WOT that the car then stays in twin until i drop below 3000 rpm....

thanks guys

gavin..

 

Thank YOU for actually reading the information that was supplied. It's sad to see someone take the time to dig up a link to a resource and the person never reads it.

Dave

 

You can adjust the rpm of both the transition and the return to sequential mode (somewhat) with the datalogit. For some reason, that aspect of the twin turbo system seems worse with the PFC than with the stock ecu. The quirk is occasionally annoying in daily driving but behaves exactly how you want it on the track.