I was at the track yesterday with my 93 R1 and i ran some really bad times, my 60 times werent that bad, so i checked the boost guage and while racing i saw that the boost didnt climb above about 1 - 2 psi. I got pissed so i took my car out on the street and didnt launch it, i floored it and the boost raised up to about 9 psi (which is still low, but one thing at a time) and came down normally. The problem only occurs at high RPM's. If i floor it, it gives me the right amount of boost in 1st when i dont launch it, but when i redline and shift, there is 1 psi (if any) boost in 2nd gear. I was thinking this could be from a crack in the vacuum chamber, the crazy vacuum hoses (one in the wrong place, cracked, etc.), or the check valves. If anyone knows what the hell is going on please let me know. (it's a '93 R1 with a mazda direct remanufactured engine, new stock turbos, new vacuum hoses, gaskets, catback etc.)

 

Your car didn't work correctly so you pushed it even harder? WTF?

Check all the clamps around the intake pipes, make sure all hoses are connected and not split or damaged, same for solenoids and electrical connectors. That is my generic answer to your problem, it's very difficult to troubleshoot questions over the internet. How's your idle?

-s-

 

Check this link http://www.autosportracetech.com/RX-...leshooting.htm

 

I have the exact same problem except it goes up to max 6-7psi when I'm shifting through gears like in a quarter mile race, although the boost is set at 10psi with a mbc.

I'm suspecting the vacuum chamber is either leaking or the hoses/checkvalve are leaking. Anybody have any thoughts on this?

 

I did some troubleshooting just last night. It's tedious, but cheaper than replacing every check valve, tank, and solenoid (which comes to $1000 if you're counting).

Start with an extra pressure gauge. I have one with a 1/8" barb fitting that does 30inHg vaccuum through 10psi pressure. (15-20psi would be better, but hey it was Autozone). Also, 8' of 3.5mm vacuum tubing, another 6" of tubing, and a nylon 1/8" Tee. Then, I tapped into various lines in the system, and did a boost test. I started by removing the bolts holding down the pressure tank (in front of the UIM) so i could flip it out of the way for access to the solenoids.

Using a long bent-needle-nose pliers, screwdriver, and rag, I was able to pull over and move the tee with the engine still running and not burning my hands. Most of the turbo control solenoids are easy to tee into. Having the engine warm is important since many solenoids only misbehave when hot.

When I get home I'll post some pics of the setup (which is simple, really) and show where I tee'd in. If I get bored this weekend I may tee into more places just for learning's sake.

Dave

 

I ended up taking the UIM off and testing the pressure/vacuum chambers and all associated check valves and they were all ok, but I did find a silicone vacuum hose all dry and torn up which I thought for sure was the cause of the problem. But after drag racing last night at the strip I noticed I have the same problem.

Next on list is the Turbo Control Solenoid...what do guys think? I'm thinking the heat is causing a lazy reaction.

BTW, it goes up to 7-8psi during drag racing, but on the freeway at WOT it's 10psi and if I let off at high rpm and floor it again it goes right back up to 10psi instantly. So the problem is only when I'm shifting through gears at high rpm's. Hmmm... if it was the Turbo Control Solenoid, shouldn't it keep me from going 10psi even on the freeway??

Thanks guys.

 

Did you ever resolve this? I'm having the same problem, good boost if i punch in low rpm and pull the gear, but shifting into the next gear results in low/wavy boost high rpm, i'm thinking i have a bad check valve to the pressure tank

 

I actually wrecked the car before i had a chance to fix the problem. I did replace all the check valves with ones from usplastics.com, for like 5 dollars, that helped the boost pattern. I never got around to checking the wastegate actuator, I do believe that might have been the culprit.

and that autosportracetech.com helped a lot, look above for the full link

also, make sure to check the charge control actuator, and the turbo control actuator.

i got a mityvac vacuum and pressure tester, worked great for this application

 

I am 90% sure that the solenoid is your problem. I had the exact same symptoms with mine. Swapped out the solenoid and the issue was resolved.

 

My boost has been perfect since I changed all the silicone hoses and check valves. I also installed a midpipe and tuned my PFC, so it's hard to say what it was that fixed the problem.

If I were to put money on it, I think it was the check valves that were the problem with the 7psi boost problem.

 

Throw it all out and go single!!!