the wastegate is causing the spikes. it needs to be ported and a new flapper needs to be installed. the wastegate is the weak spot for the S4 TII's

 

I may just have to put up a WTB thread for a large ported S4 turbo so I don't have to worry about porting myself...as I don't have the tools for it. Getting the turbos swapped out would be an interesting time.

 

the turbo is easy enough to remove. takes me about 1/2 hour/45 mins to get the turbo off of my 10AE. porting isnt bad, you just need the right porting tools. i believe mazdatrix sells them...not too bad on price if i remember correctly

 

If you could throw me up a step by step/write up on removal of the turbo, you would be saving me so much work and headache on attempting to fail at it...hehe

 

well...i can see what i can do on that... remove the acv, bacv, and egr valve (if you still have any of those). remove the intercooler and the piping to the turbo as well as any heat shields you may have. remove the air box, turbo inlet duct, and the downpipe. remove the coolant return line from the turbo (leave it attatched to the water pipe). unthread the oil feed line from the hard line at the turbo, remove the coolant feed line from the turbo completely, and remove the oil return line from the flange at the front cover. unplug the oxygen sensor and remove the four nuts holding the turbo to the exhaust manifold. you''ll need to get at the frontmost nuts with some extensions and a swivel and the rearmost nuts you get at with a wrench from underneath the car. you can choose to drain the coolant if you's like. i never did as it was fresh coolant and what i needed drained into my catch pan when i removed the coolant return line. from there its just a matter of feeding that sucker out of the engine bay. its not too bad once you do it once and get the hang of it.

 

Awesome man, that helped a whole bunch. Gave me a lot of pointers. I just know there are like 4 or so bolts on the exhaust while I think 4 more to the manifold...when I tried to get my ratchet in there, I couldn't really see what I was doing, lol. Let's hope I can get this done one day soon. Neeeed a port job bad.

 

three nuts on the downpipe and four on the turbo to manifold. its tight but you can get it if you are patient.

 

Great, I'm not a very patient man I'll start the car up and give it a shot at removing the turbo this weekend. Do you have ratchet sizes and such?

 

Niceeee, I like the color of that car. I wish I could get me a RX-7 like that, they are plentiful enough around here but almost 99.9% of them are under maintained or beat on by kids. (not saying I don't beat on my car myself but I take care of it!)

 

Yeah, that's the problem with most of them. Some kid gets a hold of them and hacks them up to hell. That's kind of what ended up happening here. Behind the stereo is a mess of wires that are just disgusting to see, a million wires under the drivers seat where he took off his amp and subs. A car that has been boost creeping as if that is how it's supposed to work..

Poor thing *pets*

 

i know what you mean.. here's the story of my 1988 10AE:

http://www.rx7club.com/showthread.php?t=720132

the car looks even better now, being 100% 10AE (all anniversary parts in place) and running excellent!

 

Cool, have fun working on it!

 

CyberPitz, if you need any N/A FC parts, i've got a whole car: http://www.rx7club.com/showthread.php?t=793220

 

any updates?

 

yea, I have an S4 converted to S5 only but hell, she does the job well ^^

 

Wow...This brings back soooo many memories....

I miss and highly regret getting rid of my '88 RX-7 GXL...

 

Well, nothing really big has happened to my baby recently. Money being tight and all.

I still have to learn how to tune my SAFC2 haha. Next order for business is finding out why it's not idling on cold start...hell, it won't even take gas to keep it alive. It will die 5ish times, then work out of nowhere. I was told to check the thermowax, so I gotta figure out how to do that. Then I will check to see if the BAC is doing anything.

I will probably spend 700 bucks and get a BNR Stage 1 turbo, so I can have a ported wastegate. That will also fix the spout of smoke coming from the turbo under heavy boost. It's going to be a while till the car is where I want.

 

i would lean more towards the BACV as being the culprit. if you do not know how to test it let me know and i'll post the procedeure and ohm readings for it.

 

Don't even bother with the BNR stage 1. The stage 2 kit is like 50$ more expensive, and the stage 3 50$ more expensive than the stage 2.

And if you're running the stock fuel system with stock injectors i would not recommend turning up the boost. The factory injectors run at about 75-80% duty stock, they run out of leeway very quickly and you definitely don't want to run super lean one day because the boost was turned up.

 

Hmm, why thank you! That's what I was curious about. I will probably drop 750 secondaries in there sooner or later I want to make this a reliable machine before I do power work to it. Also, if I went for the Stage 2, would I need to do any sort of fuel modifications? I only have the Walbro 255 atm with the rest of the system stock.

 

As long as you get supporting injectors and a good tune the walbro should be perfect. BNR turbo's are low boost, highly responsive. There are not many people who run the BNR's for our RX7's past 16psi.

 

Sweetness. I'll probably think about getting the stage 2 then...

I decided to play with the car a little bit. Discovered my BAC wasn't even plugged in. That explains why I couldn't change the idle from 600 rpms. While trying to crank her over, it would start the die. Every time. That's not anything new. Usually after 5 times, it starts up and runs great *Thermowax suspected...*. Well, after 10 times, the battery is flat dead. I look around the engine bay..."Why is this unhooked from the turbo?!" Stupid vacuum leaks.

 

Ya unhooked things suck. I completely removed the BAC/water running through the throttle body. Without the BAC the car doesn't want to idle when turning it on, but giving it slight throttle for 30 seconds and it will idle on it's own.

 

Well, here's exactly what I deal with on first startup.

It will start, rev to 1k and die. If I give it the FAINTEST touch of gas, it dies. I could give it a lot of gas and it will still die the second I touch the pedal. I have to keep starting it to where it will just let me push the gas to hold idle.

That's where the thermowax idea came in. I just have to find some way of getting to it and testing it!

 

you'll need to remove the throttle body to fully expose the thermowax....i woul dlook more into the coolant temp switch