peel_n_out

lemme tell you the symptoms. very little power under 4,000 rpm. when i do get to 4,000 then it starts to sputter and eventually goes. It runs better in cold weather (sux for a vert). Car stops running after about 20 minutes of driving and i have to wait about 7 hours to start it again.
things it cant be: coils, wires, spark plugs, belts, pulleys, vacuum hoses, solenoids.
btw its a 88 5 speed. any suggestions

RRTEC

iTrader: (13)

Check the Compression. Sounds like you lost some seals or springs.. 7 hours to start it back up sounds like flooding due to poor compression.. Compression test will rule out worst case senario or confirm it....

peel_n_out

do i have to do that at mazda or can i from home?

RRTEC

iTrader: (13)

Free and less accurate way is to pull the EGI fuse from under the hood, and remove one set of spark plugs top or bottom. Have someone crank the motor and listen for 3 even poofs on each housings.

The Wankler

iTrader: (14)

=== poof, poof, poof ===


LOLOLOLOLOLOL I like it!

SureShot

Or you can just listen carefully to the starter gear noise when cranking.

R..R..R..R..R..R even pulses in sets of 6 is good
R..R..r..R..r..R uneven pulses is bad.

peel_n_out

ok started working on the car again last week after taking it to mazda. compression was 9 or so. the air meter was bad and they also said that the intake manifold gaskets were leaking. i replaced the air meter. I did the gaskets (and exhaust manifold gasket). they were so brittle they crumpled as soon as i took the manifold off. AND NOTHING. car runs the same.

mazda joins the list of mechanics stumped.

anyways i noticed while the manifold was off that the exhaust gaskets at the cats were all bad and the exhaust manifold was covered in rust. can an exhaust manifold be "bad". can this cause no power under 4000 rpm?

one more thing i noticed is one of the auxilary ports wont move...the bar is stuck vertically. isnt this port for high revs?

RRTEC

iTrader: (13)

If your 5th and 6th are stuck it does cause driveablility issues... But I haven't experienced flooding and what not from bad actuators...

dopefishlives

Given the information you've posted, this, while it may not resolve your issue is a comprehensive list of things that should be done before continuing.

Replace air-meter
Replace all intake manifold and throttle body gaskets as well as check vacuum lines
Replace O2 sensor
Replace Air filter, fuel filter, pulsation dampener and spark plugs/wires
Check your injectors and seals for leaks or clogs (Witchunter can clean and test a full set for $60 shipped)
Remove and clean the aux port (6PI) sleeves and clean them and the port with brake cleaner. Oil the sleeves and ports lightly and reinstall, paying attention to orientation.
Remove, clean and test 6PI actuators for movement or seizing.
Replace your OEM cat converters with hi-flow or replacement units


Once all this is done, if the problem isnt resolved than continue diagnosing. These are all items that can hinder your performance and be hazardous in the manners you've mentioned. You said you got 9's on the comp test from Mazda, that is good, now you just need to assure the problem is resolved before one of several bad things DO occur.

Possibles:
-If the air meter or o2 sensor is faulty. which can cause inaccurate air/fuel adjustments
-Intake gaskets leaking or a vacuum leak will cause unmetered air to enter or metered air to leave.
-Plugs will be fouled or burnted depending upon your fuel conditions by this point, replace as well as the wires to assure good conductivity.
-The fuel filter if clogged will not allow enough fuel to get to the rails, a clogged air filter can imped performance and allow various nastys to get into the engine.
-The PD(pulsation dampener) and injector seals can sometimes leak, this is a major fire hazard and should be taken as a priority before continuing to drive the car. The leaking can also cost fuel pressure and lead to poor spray patterns and fuel loss.
-If the 6PI system is not functioning you'll loose power on one or sometimes both ends of the RPM range. This is the most common power-loss point however it doesnt cause stuttering in most cases. Given that one of the ports was stuck, I'd completely remove and clean both, assure easy movement before continuing to diagnose your issues.
-Another MAJOR point of power loss, drivability issues and overall poor running conditions of an engine (particularly rotaries) will be the cat converters. If they have overheated and clogged than the exhaust is heavily restricted and will cause erretic engine response, power and idle.

EDIT: As far as the manifold, unless it cracks or somehow warps beyond the ability to seal, the exhaust manifold will not fail. Since it is made of cast iron and is uncoated, the surface will rust quite a bit, I wouldnt be too concerned unless the rust had managed to work a hole in it somewhere. I'd look at the catalytic converters as they commonly will fail due to excessive heat and clogging of the 'honeycomb'

I hope this helps, if you lived closer I'd more than gladly offer up a hand -- I love working on rotaries and will always spare some time if I have it to give. Post up your results, maybe some more history on the car and the maintenance of it as well as some images of the engine, the intake track, exhaust and ports.

peel_n_out

I ordered a fuel pump and filter. it has not arrived yet but i decided to take off the old pump first. Found a nest under the panel! My car is garaged so it must have been there quiet a while. anyways, other than that the connections were corroded. hopefully I will get more pressure and solve this problem. i need to buy a camera...

My5ABaby

iTrader: (7)

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/troubleshooting-your-car-ecu-340578/

90WhiteVrt

Check your timing.

peel_n_out

thank you for the link. i like it better than the kamikaze approach. i will try it if the fuel pump doesnt work.
and yes...i checked my timing

peel_n_out

I used the diagnostic checker. it functioned properly but there was no error codes. not even as i turned on the car and it sputtered and died. so the last thing it could be is the exhaust system i guess. i have new fuel system, cleaned injectors, coils, wires, plugs, intake manifold gaskets and exhaust gasket, afm, vacuum hoses,....and new paint....its hard to imagine the exhaust being the problem because when i bought the car it didnt even have mufflers and it ran ok. but i guess it could be clogged cats i guess. idk

peel_n_out

i've been busy at school and work, both full time but i got time to work on the car again. The exhaust fine. I tested the tps and something isnt right. i did this right, right?: warm up car. leave key in acc. put probes into top and right slots in green checker. ohms should read 1. Mine read 0. i tried to adjust using the screw but it would not go up...am i doing this right?
the thing is that one time when i tried to guess where to turn the screw the car almost ran ok for a minute. is my tps garbage or did i screw (pardon the pun) this up.