I need some assistance in troubleshooting a possible wastegate problem. I have a friend that is looking to purchase a CYM with a RX6 single turbo. The owner says that his RX-7 will not make over 10psi and if the turbo tries to produce more boost than 10psi, he gets a "stuttering or sputtering" condition. The owner thinks it's wastegate related. Quite frankly i don't have enough experience with single turbo 7s to comment on it. The car in question has the following mods:

rx6 kit, heat sheild, and custom cai
mazda comp rad with samco hoses
pfc
avcr
boost and temp on the column
sparco steering wheel
gab super r shock with gc coilovers 550 ff 450 rr
Pettit front sway
m2 toes and arms
m2 cb, pettit resonated ss midpipe
pettit smic
j&s knock with fuel monitor
etc.....

The owner says that by "boring" out the wastegate hole it might relieve the problem. Anyone else experience this problem or be able to offer any other suggestions on:

1) what the problem may be
2) how to fix the problem
3) any other information that may be useful

Thanks in advance.

Darril

 

1. when the valve sees extreme temperature, the shaft seizes with the guide

2. hone it out, so it has room for thermo expension

3. the nut retains the valve gets viberated loose, either put more locktite or put a little weld on it.

 

1. when the valve sees extreme temperature, the shaft seizes with the guide

2. hone it out, so it has room for thermo expension

3. the nut retains the valve gets viberated loose, either put more locktite or put a little weld on it.

 

damn... double post... sorry guys

 

or send it to xs and have them upgrade the brass valve guid with a stainless steel one. but the rx6 kit comes with a 10 psi spring stock. so i think that if it is holding boost fine until 10 psi then the wastegate is fine and its something to do with the ignition or the boost controller. what kind of ignition amp does it have?

 

my rx6 has a 7 psi wastegate, but I agree it sounds like an ignition problem. Change the plugs. Could it be knock?

 

If the wastegate valveguide got stuck the turbo would over boost. Definitely sounds ignition in nature. Check the J&S unit. Also check plugs,coils,wires and if present aftermarket ignition amplifier. Good luck

 

Ok i went to go look at the car. Heres what happened.

The owner was pretty much keeping the car under 10lbs via throttle. I asked him to boost it to 15psi so i could see what the car did.

As soon as the car goes over 10psi it sputters and surges. When it hit 15 psi the turbo and exhaust note became extremely loud and when he let off something made a very loud "POP" noise. I don't know if it was backfire or what. I watched the LED J&S for the stoichmeter and it never registered lean, although that may or may not mean anything.

I see what you are saying about the wastegate not being the culprit if it's boosting up until 10psi fine.

Another observation i made was that the car had an unusual amount of carbon buildup/soot on the back bumper. Obviously it's running rich. Could the car running excessively rich have anything to do with the surging experienced past 10psi? The car has a PFC but no Commander hand held.

TIA

Darril

 

THis is typical of a car that is tunnnnnned very rich. I am talking about lower than 10.

When tunning you put enough fuel so that it is rich and you will be slower and even buck a little. As you lean it out with a wideband as a guide the ride gets so much smoother.

Just a thought.

Chris