lax-rotor

iTrader: (1)

Did search and did do these things already (The car is a slightly modified 87 GXL):

Symptoms: The car will accelerate fine up to exactly 3500 RPM and will not move past that if I hold it at WOT. However if I back off the throttle a little bit it will accelerate slowly to redline. There seems to be a specific point in the throttle that the car does not like to accelerate past 3500 RPM.

The first time this happend I cleaned out the TPS and it seemed to fix my problem until the TPS failed again. So I did all of this to try and remedy the problem:

Cleaned all stock grounds found on AaronCakes website. Ran new ground from EFI grounding location on engine (Underneath the intake manifold, on top of the housing). Ran back up ground off the pressure sensor.

Bought brand new TPS. Calibrated and set.

Did a poor mans check on the AFM: Pushed the flapper door while the engine was on and it bogged down signifying to me that it's functional at least.

Checked 6PI--Functioning perfectly well.

This is where I think I found the problems but I'd like your opinion on it: While removing the upper and lower intake manifold I noticed that the injectors contained quite the amount of debries in the little metal mesh at the top of the injector. I do plan on sending them out to be cleaned soon (as soon as my shipment from MazdaTrix comes in). Would this debries be the cause of my stumble? Could a clogged fuel filter be the cause of it as well and would be the indication of the debri in the injectors?

The stumble itself is rather abrupt as soon as you hit 3500 (and only happens under load), but once hit is fairly smooth and doesn't stop the car from being drivable.

Any help or insight would be greatly appreciated.

Apac tii

Sounds like you are on the right track. Dirty injectors are never good same with the fuel filter, I would replace the fuel filter to be safe along with cleaning the injectors.

lax-rotor

iTrader: (1)

Is there anything else I should look for in the meantime?

arghx

iTrader: (3)

do you have a clogged cat?

lax-rotor

iTrader: (1)

That's a negative I'm pretty sure. I had a clogged cat that I hollowed out, and have one empty main cat. I only have one pre-cat that I'm not sure about. But the engine runs, and idles very well. (Minus of course the hesitiation).

Should I just hollow out the last cat?

jal301

iTrader: (4)

I recall reading an online article about "How to buy an rx7" which explained this problem (and solution) in detail. It has something to do with a poor/corroded electrical connection within the computer. Let me see if I can recall the article.........

jal301

iTrader: (4)

Aaaahhhhhhhh........here we go. Just past half-way down the page, see "Emissions Control Unit (ECU)"

So I would suggest finding the unit and first, checking the grounding. Then, pulling it and checking the soldering joints inside.

Good luck - hope this helps. Let us know how you make out.

http://www.aaroncake.net/rx-7/buy1.htm

lax-rotor

iTrader: (1)

I do not think it's the ECU for a few reasons:

1) The ground has already been repaired with the attachment of a new gound at the EFI grounding point (Which also happens to be where the ECU grounds out as well--I've noticed marked improvement in all the electrical systems with this ground).

2) The hesitation seems to me less and less electrical since I can get past the hesitation without incident at partial throttle. Unless the corrosion of the ECU is extremely specific in area then I highly doubt an electrical incident is causing this hesitation for me. Note that it's not at 3800 but at 3500. Granted it might just be the Tach is 300 off, but I find that rather peculiar since there's really nothing electrical going on at that RPM other than the primaries working almost at their peak pulse width just prior to the secondaries coming on.

It seems to me that I have significant problems with the hesitation only under load, and only when the throttle is pushed more than halfway. I'm fairly certain that means it's a fuel issue. This also seems to tell me that my car is not in "limp" mode because of my ability to pass 3500. Of course I have little experience with that specific mode and would need confirmation on that fact.

I'm hesitent to do any work on the ECU because I would rather just replace the unit with a standalone and not have to worry about it any more. That being the case I may have to just suffer through partial throttle accelerations until the summer and I can afford a stand alone and a new harness.

FCTIIMike

My car does the exact thing, I am thinking it has something to do with the secondary injectors? Anyways let me know what you find, because this crap is bugging me to.