Compressor Surge in Mazdaspeed Protege + Check engine light

[Sever]

Hey everyone, I went to look at a car last night, here's the craigslist link:

http://phoenix.craigslist.org/evl/cto/802678605.html

It's a 2001 ES, and the whole drivetrain, front suspension and brakes are out of a Mazdaspeed Protege. I took a hard look at the car and got to take it for a drive, but there's a couple issues that worry me.

There's compressor surge or flutter. I looked at all the plumbing. Everything looks stock except for an aftermarket intake. I don't have any experience with turbocharged cars though so who knows. Could the aftermarket intake be causing the flutter? The BOV recirculates on these so I shouldn't hear anything. If the owner had turned up the boost, could that cause the surge, and how would I look for a boost contoller?

The seller claims there's no catalytic convertor. However, there appears to be one there, but it may be a gutted one. The seller is sure the previous owner said there's no cat and that it wouldn't pass emissions. The check engine light is on. The car is really quiet.

The car steers drives and brakes great. There is a steady rumbling noise that gets worse at higher rpm's. Like the wheel bearings or something. At 45mph it's really bad. When I come back I'll jack the car up and spin the wheels, but what else could it be?

I really like this car and it's a blast to drive, very quick. I can't go forward until these issues make more sense to me. I'd love any help you can give.

[MD323]

take it to an autozone or other auto store that will retrieve the code for free, so you know why the CEL is on. the missing cat claim could be to cover the fact that the CEL is on due to something a bit more major.

also if the bypass vavle is bad or not hooked up properly you could get surge, but not from turning up the boost ( well as little as the FE will take before giving up the ghost)

[XelderX]

If it has an Injen CAI on it you will hear a lot of compressor surge. It's normal...enjoy it. Get the CEL code checked and let us know what it is. You may also want to confirm that it has the MSP stock ECU in it. If it's running off the ES ECU there will be some major problems very soon.

[Sever]

Oh, good advice, thanks. I'll find an autozone around. The seller says it's the MSP computer. Wouldn't it have to be for the digital speedo to work? It reads 38k miles, which is the mileage of the motor, not the car. I don't think the car would run as great as it does with the ES ecu.

Any idea about the rumbling noise?

If it has an Injen CAI on it you will hear a lot of compressor surge. It's normal...enjoy it.

It could be, or just some cheap CAI. Why would it be ok? I get that the intake makes everything louder, but if the car is surging I need to fix it, right?

How do I check if the bypass valve is sticking? I'd try and check the turbo for play but I don't think I can get at it.

Thanks guys.

[XelderX]

The ECU doesn't control the odometer. It has it's own memory. The circuit board from the donor car could have been put into the ES dash though. I wrote a how-to on doing that so that people could change gauge clusters without changing odometers. It probably does have the MSP ECU or it wouldn't be getting anywhere near enough fuel. What kind of intercooler does the car have? The MSP had a small sidemount intercooler right beside the radiator. The only way to get rid of the compressor surge is to completely change the BOV/bypass valve arrangement. The stock setup surges, but you can't hear it very well. The stock setup with an intake will be very noticable. Even my setup with an HKS SSQV and a full FMIC surged a little.

[Sever]

It's the stock intercooler. Everything is factory except the intake. So the intake doesn't cause the surge, it just makes it louder? Weird. I wonder if under a harder load the valve dumps more aggressively.
I'm going down there tommorrow to take the car to autozone, then jack it up and check out the wheel bearings. If I want the car I need to buy it this weekend, he has somebody driving up from tuscon to look at it tommorrow. It's a great deal, I just have a bad job right now and I can't afford to get hosed. Really the drivetrain alone is worth $2500, the car is a freebie. In fact $2500 is what I was going to spend rebuilding my stock BP before I wrecked my car!