ROSHX7

My friends modded NA seems to pull harder and harder as he hits redline, loves the topend. My TII on the other hand, is really strong 3000rpm-5500rpm...but after that seems to run out of steam specially approaching redline. Is that the WAY it is, or I'm I running TOO RICH topend? Please let me know, so I can address this issue with my car and fix the problem.

live4boost

iTrader: (2)

thats weird do you see your boost drop off. It should bulid up boost and hold it until you shift.(unless you are past redline.) There are many things to check. spark plugs, coils, fuel supply. Mainly check out secondaries. Im sure there are others but give a little more detail on the symptoms. Oh yeah don't forget compression if it has some miles on it.

Scott 89t2

is your boost dropping off? probably is. the stock turbo is choking it at higher rpm. then again have your tunned your 680's at all with anything? or did you just stick them in?

does the N/A pull harder then yours? if so then you have a problem but you just mean that it just keeps pulling harder as opposed to falling off right?

I think you need to shorten your sig a bit too... takes too much of my screen just list the main stuff.

and get rid of the 5w-30!! run 20w-50 in the summer, I'm running 15-40 right now. and I guess run 10-30 when it gets colder in dec, jan.

ROSHX7

Sorry guys, I'll chop down my SIG..its is WAY to long like you said. Actually I'm NOT losing boost high end...its stays rock solid. BUT, I just threw in my injectors...I don't have a FUEL TUNING computer like an S-AFC or anything, so I'm guessing I'm running REAL RICH top-end. My Car is really BAD on gas...I get only 300km on a full 60L tank just normal driving. I think I need to lean out my TOP END for sure..!

Scott 89t2

yeah at 10psi it's probably pretty rich. time for a S-afc more $$ but it will probably give you a nice power increase once tunned right. there is a guy in town with a wide bacd o2 sensor who doesn't charge to much he just sits in your car and tunes as you drive. much cheaper then a dyno and it's all you need. he just oped up a shop in van. I think it's called L&R racing. he spent a bit of time on adrains car a while back trying to get it running.

Freeway

He tunes while you drive? How so?

Freeway

Rosh,
What can's are you running on there right now? I can't identify them in your sig.

Xentrix

This is an interesting topic, my gxl starts to lose topend around 7k from 2nd gear up. What gives??

power mods:
RB header, pre silencer
Greddy Power Extreme
K&N Cone filter with cold air box and extra venting into box
Removed the 'fart can' hose that connects below the 6 ports and runs up to a filter below the washer bottle.

HWO

I'll explain why aye.......

you mates NA gets into its power band, where the engine is becoming more and more volumetric efficent as it gets up towards redline, so the more it revs the better it breaths. Your T2 on the other hand has a small turbine wheel stuck up its **** which it choking the hell outta the exhuast flow once you get over 6000rpm. If you put a large T04 onto your T2 and gave it a bit of the good ole die grinder to the intake and exhaust ports treatement, then your car would also pull harder and harder as it gets up the revs

Keith

That's funny. My 87 TII, complete with the small turbine wheel stuck up its ..., pulls like crazy to well above 7500 rpm in first, second, and third gear - I'm too chicken to take it up there in fourth and fifth (Yeah, yeah, I know I'm a wuss!!). As a matter of fact, it pulls so strongly in first that it'll hit 7500 rpm at least in the time it takes for my foot to react to my eyes seeing it pass 7000! imho, that is NOT the way it is! I agree you need an S-AFC or something, 680's will definitely be rich compared to stock 550's! Also, high rpm power loss can be associated with exhaust/intake restriction. If you still have a cat on this car, make sure it isn't blocked. Make sure your intake air filter is clean. Did you ever run the car with the stock secondary injectors? If you did, did it run out of power like it does now? Because if it did, you may have low fuel pressure. If that is suspect, change the fuel filter, and check the fuel pump intake in the fuel tank. Check for sufficient voltage to the fuel pump. Check the pressure regulator.

For comparison purposes, here are my mods:
Apexi Air intake, Bonez downpipe (2.5 inch, I believe), High-flow cat, HKS 70mm cat-back, electric fan. The rest is bone stock!

Just my 2 cents worth!

Irv, Keith's dad

ROSHX7

Hi Irv, yeah your RIGHT, I did run with stock secondaries before and it lots power at the HIGH END just like NOW. I've since then changed the FUEL PUMP and FUEL FILTER and did the 12V rewire mod and still it didn't change much. So the LAST PIECE of the puzzle is the FUEL PRESSURE REGULATOR, so I'll swap that out for a NEW one and see if that makes a difference! Thanks!

ROSHX7

LIKE WHOA!...cool, I'm going to check this OUT. Where is this shop?

Thanks Scott!

ROSHX7

"can's"??? Not quite sure what you might MEAN by that, but I take it you mean the EXHAUST?...I ditched the 5zigens for some OBX Racing 'Greddy Power Extreme' style mufflers.

Scott 89t2

check the pressure with a gauge before you go to all that trouble. it's not that easy to change. I'm sure it just needs some tuning.

A TID mod would probably help, give you more power down low too. but it might raise you boost a psi or 2. well from what your boost is without the controller.

BLUE TII

iTrader: (9)

Rosh, how are you keeping down to 10psi? I have ported wastegate on my 87 TII RB down/mid pipe Wabro and rewire Greddy boost and A/F and TID mod. I run just over 10psi on a cold moist night and 13:1 is most lean so far in 5th. My TII pulls very hard up to revlimiter in 1-4th, 5th does take longer. 650s are probably a bit too rich (but the low and midrange would be the most rich, not top end), but I think the problem may be intake related for you-TID made a huge difference on the high end for me and made turbo more responsive as well. Do you still have the restrictive, narrow, rubber, s shaped factory TID?

Freeway

yup, that's what i meant. I like the look of them, how do they sound are they really loud? I'm looking for new "cans" but I don't want something that effects something like conversation while driving.

BLUE TII

iTrader: (9)

OK, I saw you have 90 turbo w/ dual wastegate passages in another post-that keeps the boost down. I say TID for you!

ROSHX7

No man, I got rid of the restrictive stock intake completely! I got 3 inch tubing that I built out of plumbing supplies that goes to my MAF and my HKS filter. My BOOST is something BEYOND ME! I got this 90 Turbo system off a AUTOMATIC JSPEC car from JAPAN, I think a 4 door car of some sort that uses the 13B as well. So its a J-SPEC 90 Turbo. Anyways, it RUNS solid 5psi stock, no matter what I do to my car...even if I ran an OPEN EXHAUST, it won't go any higher! I can't get any NATURAL BOOST out of it. And I already have a 3" downpipe, NO CATS, 3" exhaust piping to mufflers and a 3" INTAKE! So I had to use my Manual BOOST controller to set it at 10-12psi.

ROSHX7

The 5zigens I had was REAL LOUD, so much that my neighbors complained and I set off every single car alarm in my building while parking!....made the car sound like a CIVIC almost...high pitch, wuuuuuuuaaaaaaaaahhhhhhh type sound. This new setup is WAY NICER....real DEEP TONE...more like a low WOOOOOOO similar to the RACING BEAT, but a bit louder, and MUCH quieter then the 5zigens. I LIKE A LOT!!!!

ROSHX7

I don't even know what that means 'dual wastegate passages', so for sure I don't have that! I have a dual exhaust, that's about it in forms of dual.

Rx7-88na

You know -- Ive got the same problem in my 89 GXL -- the power runs strong to about 6800 then it gets real shaky and it sounds like the engine is choking what gives?

I asked this question before and I got ZERO responses... so is it my fuel pump? FPR? or something else like injectors?

Please Help...

BLUE TII

iTrader: (9)

In '89 Mazda changed the RX-7s wastegate to dual orfice to eliminate boost creep, kept the same 5lb spring and incorporated an electronic boost control into the ECU for the higher boost pressures. I would imagine this is the turbo you have; you think you may have the Cosmo (13bt sedan) turbo?

Xentrix

YES I WANT TO KNOW WHAT THE DEAL IS! I have mods, but before the mods the car ran strong all the way to redline.

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!

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.