mkrx

Hey guys, this is my first message here since im kinda newish rx owner.
I have already ran into problems i havent solved yet, I got this weird boost problem i think i have a clue but havent got time to work it on yet so im asking bit help on what to look when i start to disassemble my car.

Boost is running fine 0.7 bar at primary turbo, but after secondary turbo kicks in at 4500rpm my boost drops to somewhere 0.5-0.6bar, but sometimes it boosts normally. And after acceleration when i step off from the gas pedal and for example change gear 2 to 3, i got about 0-0,1 boost, so not much .
Now if i take my foot off of a gas for a while and push it again im getting normal boost again. Im thinking could it be blow off or charge relief valve stucking into open position or wtf?
other prob i got is seatbelt warning light isnt going off when i fasten my belts. It just keep ticking..

FD3S -93

Fsunoles06

Your boost problems could be several things, such as a vacuum leak somewhere. Have you replaced your vacuum lines? rx7store.net sell a Hosetechniques Kit to replace all the vacuum lines underneath the Upper Intake Manifold and everywhere else vacuum lines are running in the engine bay.

One of your vacuum hoses may have just popped off somewhere, look for any loose hoses.

I also suggest you do all the reliability mods (stickied in this section) if you haven't already.

As far as the seat belt thing goes, check underneath your drivers seat and make sure the connector is intact and not ripped apart or disconnected. This is your seatbelt sensor I believe.

mkrx

Thanks for your answer, Vacuum hoses have been replaced with silicone ones. First thing im going to do is take upper intake manifold off and check if theres any hoses popped out. I also checked the wire under drivers seat and that is intact too. only mods i got are greddy intake, knightsports downpipe, catback exhaust and boost gauge and newly replaced vacuum lines. I got koyo radiator and pfc under order now so waiting them to arrive..

Fsunoles06

also make sure all your check valves are in good shape and since you just had the vacuum hose job done, verify all the hoses are connected in to the correct solenoids and nipples. Search for vacuum hose diagram.

You mention sometimes your car boosts normally, is there any particular gear you are in when this happens. Generally 3rd gear is a good "testing" gear for your boost pattern, but you could reach very high speeds.

Cant be very much help on the seat belt though. Maybe remove the gauge cluster and check things out.

Fsunoles06

also, when you take your foot off the gas in between gear changes, your boost is going to drop off

mkrx

Yep i think its not about gear its more about when both turbos are working at high rpm and then stepping off at gas and then pushing gas again.. Then it does that it will boost only 0-0.1 bar.. under 4500rpm car works just fine no boost problems, and usually when i accelerate the boost pattern is normal. its just when i let off gas and push the gas pedal again quickly, for example in gear change.. though i have noticed that it usually happens in full acceleration from 2nd to 3rd gear. About seatbelt problem i found with search that there could be short in CPU #2, gotta check that out

mkrx

yea ofc boost drops when i take my foot off in gear changes i know that , but boost doesnt rise up again when i start to accelerate..

paperjam

Someone pointed out to me (in another post) you may not be reserving vacuum pressure in the pressure tanks which may explain why you get boost originally and then no boost on deceleration and then accelerating again.

Check out this link also -

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