1990 Rx-7 Convertible project
05-05-12, 12:17 PM
#101
Senior Member
Join Date: Feb 2010
Location: Norway
Posts: 504
Likes: 0
Received 0 Likes
on
0 Posts
This story seems just like mine, lol, except I already got two new front shocks, one new exhaust muffler, new rear brakes, a rebuild, new AFM, new ECU.
Guess what? Still runs like **** :P
I haven't given up, and I am the only 7 owner in a radius of 1000 miles. And I live in Norway, meaning all parts take 12 days to arrive from California (MazdaTrix and RacingBeat)
Good luck!
Guess what? Still runs like **** :P
I haven't given up, and I am the only 7 owner in a radius of 1000 miles. And I live in Norway, meaning all parts take 12 days to arrive from California (MazdaTrix and RacingBeat)
Good luck!
07-03-12, 09:46 AM
#104
Junior Member
Join Date: Jul 2012
Location: Oregon
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
i am about to buy a 88 convertile, its got an oil leak where the motor meets the transmission, i realize its a big fix, is it worth it to buy the car for only 1000??? 
still runs now fine
still runs now fine
07-04-12, 12:07 PM
#105
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
I would say $1,000 is alittle high if its leaking oil from that part of the engine. Thats a pretty big fix especially if its a cracked iron or something serious. Ive bought an Rx-7 for $300 before that ran alright too. If its in nice shape and you really want to fix the problem it has then go for it but honestly you probably can find one cheaper you just have to know what your looking at or getting yourself into.
07-17-12, 08:55 AM
#106
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
I found a vacuum leak at the lower intake manifold. I'm ordering a new gasket when I can afford it and seeing how it goes. Also decided to do the throttle body mod once it comes time.
07-18-12, 12:21 PM
#109
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
Yea, progress has been slow since I lost motivation to work on the car but I am slowly regaining it. Why do you advise against the TB mod? Ive read mixed reviews so Im stuck in the middle, trying to get as much legit info on it as I can. Gsharp, thank you and mine is for sale haha.
07-18-12, 01:45 PM
#110
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
I probably should say why I planned on the TB mod and its because my engine came out of an automatic Rx-7 and went into a manual Rx-7 so the TB is different. I had the idea that if I eliminated the secondary plates and the double throttle diaphragm on the auto TB it would run smoother and eliminate my bouncing idle (I thought the plates were out of adjustment or just weren't working right since the vacuum is different between the auto and manual). This forum is so loaded with misleading info I don't know what to believe. That was before I figured out where the vacuum leak was so that plan might be scrapped depending on how the car runs with the new lower intake manifold gasket installed.
07-30-12, 07:04 PM
#112
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
Does anyone wanna tell me why doing the throttle body mod is such a bad thing? i understand that i cant drive the car until it warms up or i cant romp on the throttle under 3,000 rpms or the car will bog due to the plates being removed. those 2 things are okay with me but is there any other problems or things i should know about before i go ahead and start this mod?
07-30-12, 07:15 PM
#113
^ It's a waste of time. The main part of the mod is taking out the thermowax and eliminating the coolant passing through the TB. This mod claims to "cool the intake" by not having heated coolant running through the TB. It's a crock of ****! The entire intake is aluminum, it's going to heat soak regardless of the coolant passing through! You're in pennsylvania, you have the same weather that I do in NY (pretty much). I don't know about you, but when it's cold I still enjoy my car. I put my thermowax and BAC valve back onto my heavily modded car. I can start my car in the winter! I can drive it fine when it's below 30! It will idle on it's own perfectly!
07-30-12, 08:02 PM
#114
I have to add a TON of fuel to my acceleration enrichment map for my engine to rev properly. Even then, it's hard sometimes to get the right amount because the Rx7 throttle body is fairly large, and it's getting a TON of air all at once. It's almost exponential how much more air enters as the throttle plate is linearly opened. At least I assume it is, since my accel enrichment graph is exponential, unlike the majority of the graphs I've seen.
I understand that it's desirable because it's essentially a free mod, but doing this makes the car drive like such a piece of **** all the time. It sucks, I did it, I regret it. If you value being able to not buck around like a huge idiot when you're driving slowly (like in a parking lot) then don't do it!
I understand that it's desirable because it's essentially a free mod, but doing this makes the car drive like such a piece of **** all the time. It sucks, I did it, I regret it. If you value being able to not buck around like a huge idiot when you're driving slowly (like in a parking lot) then don't do it!
07-31-12, 08:45 AM
#115
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
so basically you guys are saying it doesnt do much of anything besides make the car run like crap. i planned to do the mod because i figured my 2ndary throttle plates werent opening and closing right due to the engine being from an automatic and the whole throttle body and thermowax set up is different. i guess i figured simplifying the throttle body would help my high idle. on fc3spro.com they say then the fast idle cam can become jammed on the cam roller and lead to high idle. it made me think, maybe my fast idle cam is far out of adjustment and is doing exactly what fc3spro claims will happen. any other way to set the fast idle cam other then letting the engine warm up alittle and setting it? i think that really might be my problem now and you guys gave me enough info not to want to do the mod anymore. the weird part is i read a lot of good things about the mod too like better throttle response above 3k
07-31-12, 05:58 PM
#116
Maybe the secondaries being removed help, I don't know. I was buying up TB's when I saw them cheap, hoping to find one fully functioning. I never did find one with the secondaries in order, so for me I never "felt" what they do. You can always take them out, but leave the thermowax in place. Don't forget the dashpot! A lot of people take that off as well, not helping the situation.
08-01-12, 01:05 PM
#117
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
Cool so maybe Ill try taking only the secondary plates off and leaving everything else intact. Good thing about my plates is the screws are not mushroomed from the back so they can be taken out and put back in with no problem if taking them out doesnt work too well. Another forum member told me that its a possibility my thermowax is bad or out of adjustment and I was thinking that my fast idle cam is getting jammed on the cam roller and was leading to my high idle of 2k to 3k along with the TPS out of adjustment.
08-01-12, 07:20 PM
#118
The secondary plates operate on vacuum. There's a constant (not ported) manifold vacuum source attached to a vacuum delay check valve, then it goes to the double throttle diaphragm. So when the engine is at idle, it has full vacuum (around 20 inches). When you snap the throttle plates open, vacuum drops down to 0 or close to 0. The vacuum delay check valve slowly allows vacuum to die off from the double throttle diaphragm, slowly opening the secondary plates. When vacuum returns, the delay check valve opens, and allows full vacuum to return to the double diaphragm actuator, thus snapping them shut.
If you find another vacuum diaphragm that is operational (and you can find one from almost any vehicle from the 80's or 90's, you can modify the bracket for it to work on your car. I used one from a 92 prelude on my NA.
Or you could just wire them open until then. That way, you won't have to ruin the bushings or seals if you want to return the system to original. You also will not lose ANY airflow that way. There is no noticeable difference in power with them wired open, and even less power (low end torque) with them completely removed.
If you find another vacuum diaphragm that is operational (and you can find one from almost any vehicle from the 80's or 90's, you can modify the bracket for it to work on your car. I used one from a 92 prelude on my NA.
Or you could just wire them open until then. That way, you won't have to ruin the bushings or seals if you want to return the system to original. You also will not lose ANY airflow that way. There is no noticeable difference in power with them wired open, and even less power (low end torque) with them completely removed.
08-01-12, 07:27 PM
#119
If you pull the entire TB off, you can really look at the thermowax. When I was testing and adjusting mine, I would run it under hot water so that it acted fully open (car fully wamred up at idle). Then looking at the FSM, I determined what position it needed to be in. After, I would run it under cool water and throw it in the freezer 
This way I could see where it was in it's minimum cold position (start-up position on a cold winter day). I went back and forth a few times until the correct positions were found and it operated smoothly. None of that getting stuck business!
Hey, it worked
This way I could see where it was in it's minimum cold position (start-up position on a cold winter day). I went back and forth a few times until the correct positions were found and it operated smoothly. None of that getting stuck business!Hey, it worked
08-02-12, 10:05 AM
#120
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
Im going to have to look into finding another diaphragm from another car or wiring the plates open for the time being. I actually do have my throttle body off the engine as of right now. I was looking at the thermowax set up and that upside screw for the thermowax was screwed all the way in so the piston part from the thermowax was not extending at all. I didnt tighten, not even touch it, so it must have been the previous owner on the engine messing with things. Another thing I realized is the cam roller isnt aligned with the markings on the fast idle cam but I think that could be because its not warmed up. Im going to try loosening the screw to the thermowax so it can extend during warm up of the engine and pour hot water over the fast idle cam/thermowax area to try and set the fast idle cam properly. From what I can remember the fast idle cam has to be around like 77 degrees or something like that to set it properly. I really am appreciating all this help guys. Im starting to find out what the source of my high idle was and Im excited to fix it and get this car on the road before the end of summer!
08-02-12, 11:18 AM
#121
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
Poured hot water on the thermowax and fast idle cam. Set the fast idle cam so that the cam roller was in between the markings on the fast idle cam. I noticed the thermowax did not extend at all as I turned the screw and poured the hot water on it. The water was very hot but not boiling hot so either my thermowax is no good or I didnt use hot enough water. Hopefully the thermowax is good. If the thermowax is no good I might just go through with the throttle body mod until I can afford to buy a new throttle body from a manual Rx-7.
08-05-12, 02:44 PM
#124
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
Got the thermowax off today. The screws holding it on were seized I needed to let them soak in rustbuster for a day then had to borrow a impact screwdriver to get them out. I soaked it in boiling water, the piston extended alittle suprisingly, it is now in the freezer. Im going to repeat one more time. So now that I know the thermowax does work I think all I need to do now is set my secondary throttle plates to the correct position, re adjust the fast idle cam, adjust my TPS, get a LIM gasket, finish the exhaust and the car should be ready for inspection. Anyone got anymore advice on what I should be looking at next? Maybe I missed something.
08-06-12, 09:40 AM
#125
Brap Brap Brap
Thread Starter
iTrader: (3)
Join Date: Jan 2010
Location: Pennsylvania
Posts: 981
Likes: 0
Received 0 Likes
on
0 Posts
So I boiled and froze the thermowax repeatedly. I put it back on the throttle body and dumped boiling hot water on it to try and set the fast idle cam properly by the book which is a Haynes manual and I was looking at the online FSM. The fast idle cam does not seperate from the cam roller once the thermowax is hot as if the car was warmed up. I tried multiple times to try and set it the right way using all of the adjustment screws and had no luck. I pretty positive the thermowax is not fully extended and I'm about to go through with this TB mod after all and deal with the side effects of it until I can buy a new TB/dynamic chamber.