kborro01

iTrader: (3)

After a couple months, I finally got around to working on the 90 T2 again. After the rebuild and restoration and chasing down every problem resulting from 4 years of being broken down, I finally got it started. From day one, it's been blowing huge amounts of smoke. I tried to drive it thinking that maybe it was just residue from engine rebuild, but it never got better. I finally got around to pulling the TID and other air management stuff and looked into the turbo and it's filled with oil. I rebuilt the turbo as part of rebuilding everything using a master kit from G-pop, checked and confirmed all the clearances were good, then put it back together, now the oil thing. I saw the thread concerning venting and turbo blow by, but my configuration is stock. I have another turbo to put in and see if that works, but it seems like something is missing inside the turbo to bypass that much oil.

AGreen

iTrader: (11)

You may have missed the chra to backplate gasket. It's a little square cut o-ring.

kborro01

iTrader: (3)

I might have found the problem, or two problems. One was it looked like the o-ring may not have been seated correctly, but the other potential problem I'm not sure about. When you pull the front compressor wheel and housing back plate, there is another plate that covers the oil gallery that has channels machined on one side and flat on the other. Within this is a bushing that s flat on one side and beveled on the other. I had it installed with the beveled side out and it didn't look like the plate was sitting flush but up about 1/16 of an inch. if I put the beveled side down, it sits flush. Not sure if this could be the main culprit or not and I can't find any pictures clear enough to tell for sure. Anyone have any thoughts and if that plate wasn't sitting flush, could it cause the problem. I want to make sure I have it right before I put everything back together.

RXSpeed16

iTrader: (41)

Chamfered edge points toward the chra. It sits on the journal bearings which normally has a thin film of oil and centers the shaft. If you install it the way you described (chamfer away from the chra) the rotating assembly will have a way too much drag and the backing plate will not seat all the way. Recently assembled one this way and saw exactly what you are seeing now. Haven't used it yet but it assembles correctly now.

TLDR: you found the problem.

kborro01

iTrader: (3)

thanks to all, I'll post how it turns out, probably going to take a bit to blow all the oil residue out of the exhaust system

kborro01

iTrader: (3)

Well, one step closer to actually becoming road mobil again. Finally got everything put back together. Lot's of smoke still, so I pulled out the entire exhast system from the downpipe to the mufflers and it was coated inside with oil that had blown through, so I'm leaving that off for now. I'm going to put my 91 NA exhaust system on it when it's time to put it back together. I figured out my surgin idle by looking more closely at the FSM. I noticed that I've been doing the TPS adjustment from the middle of the procedure and I never actually did the first part where you check for voltage and adjust the TPS bracket. After I did that and then did the rest of the adjustment, no more surging idle. Now I'm trying to chase down an idle issue with the car not being able to run below 1000 rpm. I can get it to adjust down with the test plug grounded and cranking on the BPAV, but once it gets to around 1000, the car just dies.

Tyler3

Try adding on an oil catch can. I found a little oil in my intercooler and water in my turbo. (I just bought the T2 motor) It's a rotary though so they are really strong motors, a little oil would be nothing to worry about, but if it's really a lot then I would try to get that fixed.

kborro01

iTrader: (3)

The idle issue is a little different than what I've seen described in other posts. It doesn't go up and down at a cyclical rate usually associated with the TPS hunting or a vacuum leak. It throttles up to a point and then decelerates. Then idles slowly back up and decelerates. Other posts I've read sort of indicate this is a fast up and down of the throttle. Mine is a slow build to about 2000 rpm and then a drop. I've also noticed that I can't kick the throttle down at start up. When the car starts normally it goes to about 3000 and hangs there, but you can kick it down with a tap on the throttle. Mine goes to about 3000 and stays there until it warms up and then slowly decelerates and starts to cycle until the car is completely warm and then decelerates and shuts off. I'm thinking a problem with Accelerated Warmup System, one of the solenoid valves on the rats nest is sticking or maybe the thermo wax on the throttle body. TPS's are metering good and no ECU colds.

kborro01

iTrader: (3)

How The Fc Idle System Works - NoPistons -Mazda Rx7 & Rx8 Rotary Forum

This is a pretty good write up on No Pistons about the ISC Components and what they do.

Tyler3

After it warms up what does it go down too? That is actually pretty common.

kborro01

iTrader: (3)

The idle starts off high as normal, about 3000. When I nudge the throttle, it doesn't kick down. As the car warms up, the idle slowly declines until after about five minutes it shuts off. I thought it was the BAC, but that really doesn't do anything until the car is warmed up and then you can adjust the low side idle. Now I'm searching the forums for some clues. I don't think it's the ACV because that's just a secondary air source that's mostly for emissions. Any one have any thoughts?

RotaryEvolution

iTrader: (30)

the thermowax is active until the car is fully warmed up, so it sounds like your thermowax is set too high and then once warm your idle air screw or idle curb set screw are set too low.

ignore the BAC, people tend to put too much blame on it when its job is the last in a line of many others that are much more important. once the car can idle on it's own, then worry about the BAC.

kborro01

iTrader: (3)

I'm going to have to go through the FSM and see exactly how it's supposed to work. From dunking a spare Tbody in hot water, I noticed that the silver tab extends and pushes a cam down. What would be the symptoms if the wax wasn't extending which I noticed on another tbody that I also dunk.

RotaryEvolution

iTrader: (30)

if one isn't extending it is probably seized up from age, if a thermowax is seized in the cold/closed position then the idle will always stick high in the 2k+ RPM range.

once warmed up and the plunger extended then the cam comes off the throttle and it is running off of curb idle settings.

kborro01

iTrader: (3)

I checked the thermowas by putting the Tbody in the oven for a few minutes and it extended as it was supposed to, but I had to make a couple of adjustments the line up the indicator to the center of the cam. I also had to adjust the secondary opening measurment. One thing I found as I was disassembling the Tbody and UIM. The large o-ring that goes on the intake side of the t-body was missing. Would this cause the car to start out at a high idle and slowly decrease to stall. I know that the ECU takes the air flowing over MAF to calculate how much fuel should be programmed, but if it has an airleak at the intake point, that air amount is not being measured and could cause the car to lean out to the point of shutting off. I also noticed there was about 1 cup of oil settled in the bottom of the UIM from where the turbo blew oil up into the intake.
Before I put it all back together, I'm going to go ahead and do the ABS delete as it's easier to get to the lines with the intake off. I'm keeping the ABS brake booster and Master cylinder so I'll have to make a few brake lines. I got the ABS delete kit from Mazda trix and not very happy with the way it just kind of dangles there, Once I get it all completed, I'll post a couple of pic on how I did it.