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Boost is stuck below 5 psi help please

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Old 04-15-09, 04:05 PM
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Boost is stuck below 5 psi help please

Hey guys I am kinda new to the rotary thing so bare with me if my questions seem really stupid.

I bought a 94 base model back in November that had a blown engine and a world of electrical problems and have system by system got the car up and running. Last week I took the car to get smogged and failed horribly so I pulled the UIM off and popped the injectors out to find one of the primaries wasn't firing. I had spares so i swapped em out and reassembled the rats nest and UIM. As I test drove it I immediatly noticed that the car was easier to get going from a stop (I didn't have to rev the car hardly before popping the clutch). The car sounded better and had no more gas smell from the back like before. The car was boosting 8-10 psi from like 3k-8k rpm pretty evenly before I fixed the injector problem but now that I tested it it only hits like 4-5 psi and sometimes builds no pressure at all even at WOT. IN neutral the car produces 0psi when it should be 4psi. I pulled all the IC hoses off and the Y pipe coupler off and thouroghly inspected and reinstalled all of them with high quality clamps very tight and still same problem remains.

Here is what else I have tested and tried: Vacuum at idle is 16-20 in/hg, tested CRV and ABV both are good, after hard run there is no pressure retained in pressure chamber, all vacuum hoses were replaced 2k miles back.

I am 99% sure all vacuum hoses are hooked up but it may be possible that they arent hooked up right. Any ideas which hoses could be causing my problem?

Also the precontrol and wastegate soleniods are right next to each other and I may have flopped the connectors.

Not sure where to start. I can pull the UIM pretty easy but its hard to see where all the little hoses go on turbo side of motor and I don't know if a swapped hose could cause this problem.

Wierd thing is the problem just started after injector fix so I suspect the problem was my doing although experience on other engines tells me this kind of problems can sometimes come out of the blue.

Any help would be greatly appreciated.
Old 04-15-09, 04:23 PM
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After driving the car, disconnect the line to the pressure tank (on top) and the vacuum tank (under/between the alt and PS pump). You should hear an couple seconds of hiss indicating they are holding pressure and vacuum.

Definitely poke around looking for loose hoses while you're in there.

As for the coupler clamps - don't overtighten. It's not loose clamps that cause leaks in most cases, it's tears in the couplers. If you overtighten the band clamp you can pinch the coupler and create a tear.

Dave
Old 04-17-09, 12:49 PM
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[IMG][/IMG]Dave you are the man. I had already tested the pressure tank hose quite a few times and no hiss but yer post reminded me that the problem was around that area most likely. Went out and got a Mityvac cause you need one if u have a FD ffs. Got a good hose diagram from the sticky posts and followed the simplified diagram. Tested the check valve that feeds the pressure tank and it was good. Found that output hose from the pressure tank goes to the solenoid for the turbo control actuator and so I put the Mityvac on the hose comin from the tank and it just pulled free flowing air so I knew either I had a split hose or a misconnection. After poking around with a flashlight found my problem:

The hose that feeds the vacuum tank and the hose that goes out of the pressure tank were flip flopped.

Easy fix thank god. Didn't even have to take the UIM off. Yay Mityvac.

So now I start it up and I noticed the vacuum was slightly higher at a steady 20 in/HG at 1200 rpm

Revved engine in neutral a few times to redline and around 4-5k it hit 5psi whereas before it was only goin to 0.

Pulled it out on the street and floored it and all I had to say was holy s**t what a difference. Was pullin 8-9 psi now and the power was a day and night difference. Made me feel sorry for the rx8 guys for sure.

I still think there may be a slight boost leak since it's not reaching 10 psi usually. I suspect the elbow pipe that goes to the throttle body because I noticed the o ring was a little crushed and it has a little play at the flange so I'm gonna investigate how to do a boost leak test.

Well thanks for the help and I hope my experience helps someone else in the future since it's not hard to misroute a hose when doing a vacuum hose job.
Old 04-17-09, 12:50 PM
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BTW that Vince sales dude kicks Bliiy Mays' ***
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