Okay if the normal boost pattern is 10-8-10 on a anolog boost gauge should it be the same at all altitudes ? I am getting a 12-10-12 reading at 4800 ft ??

 

It should still be 10-8-10 since the gauge doesn't read atmospheric pressure

 

What all is done to the car (mods)?

 

No mods ! Was going to put a Mazda trix downpipe on that I have obtained !

 

Altitude should not matter as stated above. When I moved to 7000+ ft my boost patterns were the same as when I was living at 900ft. We will need to know mods to the car to help you if you would like more help in diagnosing the reason it has this higher boost pattern. At assumption you have a PFC it sounds like someone tuned it to run that boost or at minimum has adjusted the boost settings.

 

It is a 94, everything is stock, has a Mazda dealer installed remanufactured engine with 13,000 miles, purchased car two months ago from California. Have put about 2500 miles on car since then with no problems, except I replaced the pillow bushings because i didn't care for the annoying clunking noises. I finally got around to installing a boost game (mechanical) and the 12-10-12 and sometimes 12-10-8 is what i was getting when I did the third gear test run, and this started to make me worry. As a result I disconnected the wastegate and precontrol soleniod electrical connectors to limit the boost to the wastegate spring.

 

Have you considered that your mechanical boost gauge is off relative to the factory sensor? Unfortunately, without a DIY scantool (which a couple people have done) you can't log what the factory ECU is seeing for boost pressure (measured pressure). Nor can we see the calculated target boost pressure, or the "boost pressure error" used in the feedback system. All of these things can be logged on more modern cars, like Evo and STi, but we don't have that capability here. So what if the computer is doing what it's supposed to do after all? Just because we don't understand it doesn't mean it's broken. The reason why I am suggesting all this is because you say your car is truly 100% stock, and I am taking that at face value. It's probably been running like this for years and has never had any problems from the higher altitude.

If it were my car I'd plug the factory boost control solenoids back in and keep driving it like there's nothing wrong. The factory tune on a completely stock car is plenty safe. It works fine on 91 octane (not sure what you have available there), it has knock control, and it has a rich mixture under boost. If anything goes wrong you will still have knock retard and overboost fuel cut to protect the engine. It was engineered and tested to run in all sorts of ambient conditions. That's why there is a barometric pressure sensor built into the factory computer to make additional compensations for changes in altitude and weather.

What I wouldn't do, unless you are really prepared for it, is any horsepower-related modification. Stay stock stay happy.

 

So you do not recamend installing a Downpipe ? I planned on installing the downpipe to remove some of the heat out of the engine bay and to get rid of the pre-cat !

 

A downpipe may not be a big deal considering the JDM models didn't even have a precat. One thing can lead to another though.

 

I had a 10-8-10 boost pattern before I installed modifications, and I live at 5,000ft

Altitude shouldn't have an effect on max boost pressure, because the w/g will allow the turbo to reach it's set boost level regardless of altitude.

 

Possible your gauge Is off buy a cheap one and see what it reads mechanical gauges are just a spring and a valve basically. If the valve starts leaking it willnread low if spring is loosing it's springiness it would read over.

 

Get (or borrow) another gauge, and test to see if results are the same. Your gauge is likely off. It's also possible that your new engine has something different from stock.

 

I'm at 7k ft, and my boost pattern was nowhere near 10-8-10. Also, transition happens at >4500rpm. I have PFS intake, IC, plus DP and CB. I discussed this alot here:

http://www.nopistons.com/forums/inde...10&t=9291&st=0

and here:

http://www.geocities.ws/laracers_vr_..._problems.html

Also, Tom Huerta at Rotary RX in Albuquerque (~6k ft) didn't seem to think there was anything wrong with my car.

Bottom line is I added some valves, one of which is controlled by a profec-b, to keep boost levels at ~10psi. Transition is still at ~5000rpm though. The car feels strong, and I don't have any complaints. 1/4-mile is 13.6s.

Hope this helps. Good luck.