Just hooked up an autometer boost gauge, so I took my car out for a test run.

VAC is around 20 HG


Boost is fine in all gears except first , in first it only shows 5 PSi of boost, vacuum tube was hooked up from the MAP sensor using a T fitting...


any suggestions on what it might be

 

bump

 

nick..
theres an extra nipple on the uim for your boost gauge..
its on the passenger side next to the bolt that holds the throttle cable bracket...

 

Are you testing your boost pattern at WOT?

 

I've never gotten as much boost in 1st and 2nd as in 3rd, 4th, 5th. I'm still puttering around and procrastinating the troubleshooting process. But I'm not sure if it's not normal.

Dave

 

Many people have noted there is a different reading that is obtained from that nipple verses using the MAP sensor line. IMO, read the line to the MAP sensor since that's exactly what your ECU is reading.

Nick13B,

Someone else had a similar problem before and their issue turned out the CCV. Might be worth looking into.

 

pressure tested both nipple to read exactly the same..
idle and under load...
did not however measure if theres a drop once you share a line...

 

Sharing the line should be nominal. Here's some more info about people having different results:

https://www.rx7club.com/showthread.p...hreadid=291618

 

You could have a slow actuator. What happens in the 3rd gear WOT test?

 

Not trying to hijack the thread but I didnt feel like starting another one and clogging the board. I to am having boost problems and this is what I am noticing

1.) a little bit of white smoke when I start the car (sometimes) and it just passed emmissions with a high fuel concentration (the only bad spot).
2.) compression is sightly down like .5-1.0 (on a cold engine)
3.) I am only getting around 4psi of boost from the car
Other than that she is driving like a champ.

Any help would be greatly appreciated. Please, no wild guesses, my shop is doing enough of that.

 

check your c clips n all the actuators and also check the intercooler couplers.I mean take them completely off and stretch them all out.Only 4 psi indicates that either your wastegate c clip fell off.Which has happened to me.
Or that you have a massive boost leak somewhere.I also had a torn y pipe coupler which was venting boost heavily.Has the car been like this for a very long time? or has it gotten progressively worse?

 

It has just been like this, not getting worse. I have replaced all the vacume (sp) hoses already and havent found a leak.

 

Thanks for all your suggests guys.


Well I just installed the boost gauge myself today so I wouldn't know if it has been a problem for a while.

Mahjik: whats does CCV stand for?


and where is the waste gate located? anyone have pics? or pics of that clamp he said might have fallen off?


AMP: hey dude, I just used a T-fitting and I ran a line from the MAP sensor, because everyone was saying the readings are more accurate.


ALSO: I do have the stock BOV venting into the atmosphere and not the intake box, could that cause it?

 

no.the stock blow off valve venting to the atmosphere is essentialy what the aftermarket ones do.but its just not adjustable.Unless its leaking boost.but I hear that they are usually problem free.You never know though.

I also had a ccv problem myself.The ccv stands for charge control valve.Its the valve in the back half of the y pipe that opens at 4500 rpms to allow the secondary boost to come online.If you do not have a vacuum hose routing diagram I suggest you get one asap.It will help you out greatly in figuring out what the heck were talking about.I dont think that it may be the ccv because when I had a split vacuum hose at my charge control solenoid my charge control actuator wasnt working and therefore the ccv door was staying closed.The car felt fine up untill transition.If you dont know already the transition from single to twin turbo happens at 4500 rpms.So at 4500 rpms I was not boosting worth a damn but before that it was working fine.I dont think its your ccv.But I could be wrong.

If you havent really worked on your car I suggest you get familiar with it quickly.Mainly because you will be saving a shitload of money that you would otherwise spend on a mechanic that may or may not know what the **** hes looking at.You can check all the actuators fairly easily if your car is either on a lift or if your intakes are completely off.Provided you know what an actuator looks like.Theres a website that actually documents everything that you should check in order to diagnose problems with the sequential system.What you will read on there is that you have to get the primary boost working correctly in order to be able to fix anything on the secondary boost.But being that you have primary boost issues I would check all the stuff that I have mentioned and then also visit this website.I hope this helps you out. check this link out.
http://www.autosportracetech.com/RX-7/rx7stuff.htm

 

Read through it, the only problem is being able to get under my car. Thats one of the crappy points about living in a condo. Someone was staring at me yesterday when I was installing the B&M.

 

because you were working on your car? I ****** hate ************* like that.People need to learn to mind their own ****** business these days.Thats how people get their asses beat the **** up.Sorry.Had to vent.

Well If youre afraid of jacking up the car then remove your intakes.I got it to the point where I can remove both intakes in a matter of minutes with a flat tip screwdriver.You will also have to remove the heat shield on the pre catalitic converter if you still have the precat.
What mods do you guys have so far? It will help me out a little in figuring things out a little.
Also remember to make things easier on yourself once you remove something.If you can make it easier to remove for next time by all means do it.Because there will be a next time.Thats almost a guarantee.

 

I already have a DP....the first thing my shop thought of when it registered 4psi was a clogged pre-cat so they put on the dp. Ok, saying that I got the intakes out of the car (not a big deal to do, done it on many a car), what should I be looking for on a top down viewing angle?

 

with the problem with mine, Im gonan go with a vacuum line blew off, but im thinking it might be the CCV because in 1st I can watch the boost slowly drain off, and the problem is intermitten, sometimes it does it, sometimes it doesn't