No boost in first, could exhaust leak be culprit?
 

***I'm only boosting on the acuator spring my Greddy ProfecB Spec II is OFF***So, I installed my MP, which replaced a High flow cat, and now I'm not getting boost in first gear, and barely any in second, but seems to boost just fine in 3rd and 4th. Now I'm not going WOT, but I am just noticing where I should be boosting under mild accel, its not boosting.

My mods are: Greddy Profec B specII EBC, Intake(blitz dual i believe), blitz boost guage, PFC(no commander), 1300cc secondaries, cosmo fuel pump, streetported motor(emissions, aws, etc removed) with ~3k miles on it, 3"dp mp and PFS singletip catback. I just recently changed to all 9s sparkplugs. As of right now its running on the default PFC map, it will be tuned as soon as I put my smic on and get it running fine then it goes to the dyno.

Could an exhaust leak cause this? The car was boosting perfectly fine under this same kind of driving(I never take it to redline and usually only boost up to ~4k rpms since my rear turbo is leaking some oil(burns a litttle bit of oil on startup sometimes)). The car didn't have a gasket between the DP to HFcat to catback, and the high temp silicone was in its place, do I need to clean that off and get gaskets for the exhaust?

No I'm not worried about my motor, it works just fine so don't bring that crap into my thread. My turbos may be in question though, I don't doubt that they could kick the bucket any day.

Synopsis: No boost in first, hardly any in 2nd, 3rd and 4th seem fine. Just put midpipe on, exhaust leak cause this?

its hard to tell but sometimes it can be a bad check valve to the vacuum chamber. what is your boost pattern?

did you try the troubleshooting tips?
http://www.autosportracetech.com/RX-7/rx7stuff.htm

also, with a midpipe I would expect higher boost or at least creep. Was your system working normally before the install?

Yes it was boosting fine, I did notice that it would break up up top, but in the lower revs(<6k) it boosted straight to around 7-8psi and held great.

I am not pushing my car near hard enough to see if it is creeping or not, and that isn't whats worrying me. I just don't understand why I am getting no boost in first, little in second, and good in 3rd and 4th. :o

Could be a leak. Are you running sequential or non-seq?

Sequential. I did NOTHING under the hood of the car, and yesterday prior to the install it boosted just great on my way home from work.

No, unless it's between the manifold and turbo but a clogged exhaust can cause this problem. I dont think it's the case for you since you replaced your DP and MP.

The low boost in 1st and 2nd is pretty common however there are many culperates and remedies for the situation. You may want to check your primary turbo intake hose and make sure its not colapsing Also maybe check your vacuum lines behind the pressure tank in front of the upper intake manifold.

Seems weird that this happened after a midpipe install, I will check some old threads to see if I can get you any more info, I would suggest doing the same.

Good luck bud.

Hmm, so I went to advance to get myself stuff to stick my emblems on and I noticed that it may be driver error. I don't think I am giving it enough gas for it to boost because of how ridiculously loud it is? I dunno nothing seems mechanically wrong.

if your sequential, you should be seeing a 10-8-10 psi boost pattern. Not 7!!!

You had a problem even before you did the mp.

You need to read the link I gave you and troubleshoot the problem. There is no way around it.

also if you are only seeing 7psi check this:
http://www.autosportracetech.com/RX-7/symptoms.htm

Look at the check valve going from the y-pipe to the pressure chamber. Check for cracks and that it only allows air to pass in one direction.

Or go for a drive and build some boost and pull a hose of the pressure chamber and you should hear air coming out. If you don't hear air, you have a bad check valve or a cracked/loose hose somewhere further down the line.

Thanks Poss for correcting 7racer ;)

I find that it takes a lot more of the accelerator pedal to get boost in 1st or 2nd. In 4th and 5th it takes very little. Since you say you're not pushing the car, I think that's the reason you're not seeing low gear boost.

Doesn't make since going from a high flow cat to a mid pipe (it that's all that was done it shouldn't have affected you boost) at least not to where you wouldn't have any or make it lower.

Thats exactly what I think it is, and I am pushing it even less because of all the Boost Creep hype, and I discovered that after I took a trip to Lowe's. Thanks everyone for the input.