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HIGH END power question

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Old 11-27-01, 12:10 PM
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is there any kind of mod like that that I could do to my 88 tII that would keep the boost down because I dont like the idea of natural boost. I'd rather be in control of how high my boost would be. could I take a wastegate off of something like a talon or stealth tt because my junkjard just got one in.
Old 11-27-01, 01:50 PM
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Originally posted by ROSHX7


I had the EXACT problem as you at FIRST. My car would RUN great up to about 6800rpm, then it would misfire and pop and seems like its choking! But I SOLVED THE PROBLEM! The culprit was the TPS sensor. At WOT, the resistance reading was going to 15K, where it should only be 5K (1K Idle & 5K WOT)...so the computer was going haywire all confused. I swapped in a good TPS Sensor and PROBLEM WAS GONE!!! I really THINK its your TPS as well, swap in a good one and see how it goes! Good luck.
I'll try that on my gxl but I dont have quite the same problem as the other dude, my car just doesnt pull as hard, it doesnt studder or anything it just slows down, the car starts to pull hard at like 4 k then at 5500 the vdi kicks in hard, i can feel it in any gear if i go WOT. but soon as i get around 7 k the power drops.
Old 11-27-01, 08:53 PM
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c'mon i know one of you rx-7 gurus might know what kind of wastegate might work. Do the talons have a small wastegate on them like we do or what. because i want to do tid filter and exhaust to maybe have quick spool up but i want to be able to control the boost by a controller not naturally.
Old 11-27-01, 09:33 PM
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tIIforever...

In order to keep boost from rising on the 87-88 TII we take the turbo off and PORT the wastegate passage out larger and undercut for better exhaust gas flow. I made it huge and replaced the disc seal w/ larger one machined out of a boinger exhaust valve. You could also replace w/ '89+ TII turbo that has dual wastegate ports and better designed exhaust manifold as well; a direct replacement from what I've read. I have RB down/mid pipe and TID and boost 7-10psi.
Old 11-27-01, 10:49 PM
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Originally posted by ROSHX7


OH MAN!!! I'M SCREWED. I guess I DO HAVE a 1990 Turbo off a 1990 RX7 afterall! I couldn't EXPLAIN why I couldn't get more then 5psi out of it naturally, but your explanation TOTALLY EXPLAINS the reason! THANKS!..., so you say that the boost is controlled by the ECU? I was puzzled, and so I THOUGHT I might have a Cosmo Turbo, because my turbo is JSPEC. Cause after I put this turbo on, I was hoping to get 12psi natural boost, cause on my 1987 Turbo I got 10psi naturally. But then when I only got 5psi, I was LIKE WTF, to the people at ROTORY MOTORSPORT (the people who sold and installed the turbo for me). So the guy there told me that he thinks that turbo came off a 1990 Automatic 4-door rotary car from Japan and that's WHY I'm stuck at 5psi. WHO KNOWS?! So I ended up having to use my Manual Boost controller to bring the boost up to 12psi!
the fact you only got 5psi and have to use a controller is a good thing! don't be mistaken. boost creep is not natural! it's evil. the correct way is with the controller.
Old 11-28-01, 03:55 PM
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Ok i need a new TPS --
where do i get one??

Thanks...
Old 11-28-01, 03:56 PM
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Old 11-29-01, 01:01 AM
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I checked Maztrix for a TPS for the 89 and they want 350 bucks... **** that noise...

What can I do to mine to fix the problem cause that is ******* annoying...
Old 11-29-01, 07:15 AM
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Interesting subject! As far as the TPS goes, you might check any local junkyards...Although I don't know if that would be a reliable way to go?
Old 11-29-01, 08:53 AM
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what do you mean for undercut the exhaust. and do you have a picture of it anyone?
Old 11-29-01, 04:06 PM
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Here is another question about TPS --

I checked mine today, and it seemed to be working properly, it wasnt sticking or anything... but i dont know a whole lot about the TPS... So could someone plz briefly expalin to me how it is supposed to work...and what to check for when trying to ensure proper functioning..??

Thank you...
Old 11-29-01, 04:40 PM
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Originally posted by ROSHX7


I had the EXACT problem as you at FIRST. My car would RUN great up to about 6800rpm, then it would misfire and pop and seems like its choking! But I SOLVED THE PROBLEM! The culprit was the TPS sensor. At WOT, the resistance reading was going to 15K, where it should only be 5K (1K Idle & 5K WOT)...so the computer was going haywire all confused. I swapped in a good TPS Sensor and PROBLEM WAS GONE!!! I really THINK its your TPS as well, swap in a good one and see how it goes! Good luck.
Hey Rosh -- what resistance did you check, this problem is REALLY bothering me... I dont want to plunk down the 200 bucks for a new TPS seeing as how that IS more than 10% of the cars cost -- I just would like to know what exactly did you measure and from where...I need to get this problem solved...

Thank you
Old 11-29-01, 05:00 PM
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Originally posted by Rx7-88na


Hey Rosh -- what resistance did you check, this problem is REALLY bothering me... I dont want to plunk down the 200 bucks for a new TPS seeing as how that IS more than 10% of the cars cost -- I just would like to know what exactly did you measure and from where...I need to get this problem solved...

Thank you
Well, don't BUY a new TPS...go down to the junkyard and pull one off another 86-88 RX7 instead. Make sure its good. The way to test it is you need a Multimeter or OHM Meter. If your checking it on your own car, 1st bring the car up to operating temperature, shut it off, then insert the two test leads into the back of the connector of the TPS sensor. Get the K ohm reading at IDLE and at WOT. At idle it should read about 1K ohm and at WOT it should read 5K ohm. YOU can only ADJUST the idle value...turn that screw that near the TPS to get the IDLE K ohm down or up close to 1K OHM. Also check that as you open up the throttle, the resistance rises normally till it gets to 5K at WOT. If you are getting way more then 5.5K ohm at WOT, then your TPS is junk.

If yours is toast and you gotta get another one, go down to the wreckers...plug your ohmeter test leads into the TPS connector and crank her over to WOT..if you get around 5K and the value progressively rises to 5K as you gradually open the throttle, then you know that TPS sensor is GOOD.

HOPE my lame explainations make sense! If your more confused then ever, then HOPEFULLY someone will post a LINK to the site that shows you how to do it.
Old 11-29-01, 05:04 PM
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EH guys, i don't know WHAT THE HELL HAPPENED, by I got all that HIGH END POWER NOW on my TII. It PULLS HARD like a bastard to redline and past redline! All I did was tighten the screw on my BOV so the spring is harder...I think that fixed some boost leak at high rpms and I also PLUGGED up the hose that connects the airpump to the ACV. I use to have a little K&N breather filter there, but now its completely blocked off. I don't know which one did it, either the elimination of some BOOST LEAK or EXHAUST LEAK @ the ACV hose that did it! Either way, I'M THRILLED!!!
Old 11-29-01, 08:46 PM
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Rosh-SWEEEET, I bet it feels great! TIIforever-undercut means that the WG hole that you see from the exh. pipe side of the turbo is one size and it gets bigger as toward the engine side. You could really use a reverse taper bit to do this more easily. The undercut will aid flow by creating a smooth approach to the WG hole and by having a minimum amount of restriction. There is alot of material there, so go to town-I guess the thinner it is the more prone to cracking, so use some judgement.
Old 11-30-01, 01:41 PM
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Originally posted by ROSHX7


Well, don't BUY a new TPS...go down to the junkyard and pull one off another 86-88 RX7 instead. Make sure its good. The way to test it is you need a Multimeter or OHM Meter. If your checking it on your own car, 1st bring the car up to operating temperature, shut it off, then insert the two test leads into the back of the connector of the TPS sensor. Get the K ohm reading at IDLE and at WOT. At idle it should read about 1K ohm and at WOT it should read 5K ohm. YOU can only ADJUST the idle value...turn that screw that near the TPS to get the IDLE K ohm down or up close to 1K OHM. Also check that as you open up the throttle, the resistance rises normally till it gets to 5K at WOT. If you are getting way more then 5.5K ohm at WOT, then your TPS is junk.

If yours is toast and you gotta get another one, go down to the wreckers...plug your ohmeter test leads into the TPS connector and crank her over to WOT..if you get around 5K and the value progressively rises to 5K as you gradually open the throttle, then you know that TPS sensor is GOOD.

HOPE my lame explainations make sense! If your more confused then ever, then HOPEFULLY someone will post a LINK to the site that shows you how to do it.
Okay -- i understand the concept but i DO NOT know what two points you want me to check the resistance across... you said the back of the TPS connector, there is a 8-pin DIN there... what two connections am I looking for?? thank you...
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