So I finally installed my alta boost gage and water temp. For some reason my car will only pull about 10psi at WOT through the first three gears... Seems low considering the 15% pulley that is installed. At first I was thinking there was a problem with the gauge, i.e. kinked hose, loose fitting, etc. After triple checking all the fittings and using wire ties on everything I can confirm that is not the case. I installed the boost gauge hose to the bottom of the FPR so I know the source is good.

I then turned my attention to the (stock) BPV. There is still strong spring tension by that I mean it is rather hard to push the BPV lever back all the way and there is no slop. I was also very careful to make sure that clamps around the SC seated well and were tightened evenly. I have also heard that if the BPV the car will go into limp mode if you hit redline and the BPV is faulty, I tried that and nothing happened. There are just over 52k mi on the car, I guess the BPV could be bad or not closing fully?

My current train of thought is towards the belt or the SC itself. I bought the car used about a year ago and have yet to replace the belt but I probably will do that this weekend. Is there anything else to check? any thoughts?!
Also the car is an 02 R53, 53,000 mi, WMS pulley, aribox, and full exhaust (if that matters)

 

First off, how well does the car pull? What I mean is does the car have some umph to it? If it does, then are you sure the gauge is working properly. I'm not talking about the connections. I mean the gauge itself. Another thing to check are the plugs. The bypass valve could be bad, but I doubt it.

 

the free flowing exhuast is going to lower it a little but not enough to only see 10psi. Does the boost rise with rpms. On cold mornings I have seen 17 psi at redline, but today at 90+ degrees I was only seeing 14 psi at redline. At temps in the 60's - 80's 15 psi is normal for me. With the DT BPV the boost hits sooner than with the stock BPV too. Did you check the intercooler boots?

 

Sure seems to have plenty of umph! I have only driven one other mini s and mine seems faster. I have a friend with a modded eclipse and my car seems to pull almost as hard... I thought about the gauge and hooked it up to my air compressor (with only 14psi in the tank per its gague) line pressure was about 12-13psi and the boost gauge showed 13psi. So it should be good, though i have not had the chance to hook up a mech gauge yet... What would i be looking for on the spark plugs? damage to the electrode?

as for the air temps, i live in CO and we havent see a day above 70 since I installed the gauge! boost does increase with RPM's and it does ramp up quickly if i stomp on it but when cruising i am frequently in vacuum; seems like the BPV is working... the intercooler boots are seated and tightned evenly, no leaks there. Thanks for the help!

 

1) definetly replace the belt and eliminate that doubt.
2) what scale is yr gauge?

 

If you live in Colorado my guess is altitude has something to do with it. I read somewhere around here that Randy Webb experienced similar boost pressure from 15% pulleys. I might be wrong, though... I get 15 psi constantly (at WOT) with the 15% and I have a header and exhaust so I doubt your exhaust has anything to do with it. Then again I am at sea level.

 

The belt is next on my list. Boost is in psi, and vacuum is in/hg; prosport gauge kit sold by alta.

 

I think by what scale he was asking; at how many PSI does the gauge peak.

 

Yikes... installing the boost gauge rocks!! However.. IF connections are soft and cause air leaks .. it will show the 10 psi when it should be 15-16 psi! Holes or leaks in the IC will show up also.. 12 to 13 PSI vs the 15-16 psi!! go back and check all the connections.. and the way you routed the vac hoses..I suggest AFTER you do that.. and IF the readings are the same... THEN get worried about the rest of the system... yes??

Just me..............................

Thumper

( zeeya on the Dragon!!)

 

Definitely change the belt as others have stated. As for the plugs, what I was talking about are the right type. I know I had Bosch Platinum +4s in mine and after a while, the car didn't not produce a lot of boost, but basically because the plugs were terrible !!!

 

belt

 

ah good call! 25psi

 

i boost 17psi max in hot humid texas weather with wms 15% pulley and 2% crank pulley and catback. if youve double checked your connections the only thing i can figure is the gauge itself its "miscalibrated". by that i mean messed up. dropped or something that contorted the workings of the gauge. because ive heard of stock mcs' boosting 11psi or so.

also have you checked the intercooler couplers for leaks? that seems to me to be the most susceptible place for a leak of some sort

i would think that if your belt was slipping youd feel it, unless its a gradual slip. when my belt does slip i notice, it feels like im losing traction, total loss of power

hope this helps

 

i have a fifteen and noticed that my belt tensioner had no holes showing on it when i put on a new belt and when i took the car to redline i only had 10psi boost (i had 15psi with the old belt) however i could not feel a diffence on how my car pulled. i put the right sized belt on with one hole showing on the tensioner and now the car goes right up to 15psi

 

thats so bizarre doesnt the stock pulley boost 10?

side note: i suppose the other possibility is the bypass valve like you suggested,

that doesnt hardly seem possible though seeing as its directly connected to the throttle body and if that wasnt closing completely youd know

good luck, keep us posted

 

i have a 15% pulley