I have worked day and night for about 7 months on fixing my rx7 i have done everything that i can think of and the only thing that is left that i could think it might be is the compression. My problem with my 87 Rx7 S4 non turbo is that it wont start up right away like it should and if it did it wont idle right. I have cleaned the fuel injectors, my starter is good, my alternator is good, I have cleaned alot of the carbon out of my intake, i got another tps, i changed all the emission hosing, I have new spark plugs, I changed out the ignition coils with s5 coils, and I changed spark plug wires. If there is something else that i need to check please tell me because it is bugging the crap out of me. My compression test was 60 on all but i didn't open the throttle body i dont know and it also doesn't suck in enough air for it to really do anything i put my hand in front of the throttle body and it didn't want to suck my hand in and i can tell you it isn't sucking enough that the air mass unit sensor isn't clicking and i don't know if i should have a the air box connected or not but i don't.

 

60 psi on both rotors? that isnt good at all. Try it with at WOT.

 

get a new motor it would probably be more cost effiecent ...lol

 

so yeah ummm i looked up in a book that the max psi for a non turbo is 84 and i have 60 if i open the throttle up that means that i will probably have like a little under 84 right if i am right then that mean that bad compression isn't my problem my problem is my engine isn't sucking in enought air if i'm right on that then i need to know what the hell is the part that is stoping this from happening.

 

dude you seriously need to call me or brad .. you have more than enough resources locally to diagnose your baby.

 

it would really help.

 

i know this is a bit obvious, but have you redone all your grounds?

 

Considering the compression is the same across the board I would stop worrying about it.

Variables that affect the compression readings overall include the cranking RPM, elevation, and wether you had the throttle open or closed.

Start looking elsewhere for your problem, I suspect vacuum leak(s)... that's usually what makes these things not run right.

There is also potential for sensors to fail, like the coolant or air temp sensors, I believe the thermoswitch in the radiator also controls some cold-start parameters... but I'm not positive, it's been years since I mucked with the stock ECU.

 

I feel your pain brother.

I spent a year trying to get mine to work right. The problem? I read the Factory Service Manual. I'm going to say something now that will probably **** some people off, but I don't care.

I've worked as a tech (yes, professionally) for well over 4 years now. I've worked on alot of cars. I've read thousands of service manual procedures. Never.... ever.... have I come across one so vauge as the Mazda FSM. It leads me to pondering its ambiguity for hours. Get this- instead of testing sensor voltages, the manual tells you to test the sensor's resistance. Then, waaay on back farther on it will tell you to use Mazda's diagnostic breakout box (which of course eeeverybody has one ) and check their sensor readouts. Their logical test procedures are a joke.

If you're having a problem with your vehicle not starting up right away, here are some things that I came up with while testing mine.

1) The switch to turn the fuel pump is in the mass airflow meter. Use a voltmeter or a test light to determine that it's coming on relatively soon after initial cranking.
2) Make sure the fuel pressure comes up soon as well.
3) Check vacuum leaks.
4) Check fuel leaks
5) The ect sensor on my 88 was fine. It was the wiring in the back of the plug that got me. The wires pulled away from the plug just enough to where they weren't contacting the ect sensor, but they were still physically inside the connector. There are 2 wires that go to the ect (in the thermostat housing). Backprobe the ecu and measure their voltage. It's a normal 5v ref sensor, so it should read anywhere *with the key on* between 0.5v and 4.5v. If it's 5v or 0v (or very close to) there's a problem.
6) Intake air temp could also give a slight problem, but it's not very common, and the side effects of a bad one (or wiring) is not too tragic.
7) Make all the proper adjustments. Timing is set right on, tps is adjusted properly, idle speed is around 750 rpms. Make sure you jump the terminals of the initial set coupler when setting timing.

Everything else you've already done was a great start. Plugs, wires, etc. Make sure you change your fuel filter if it hasn't been done recently.

(side note... before you do all of this, recheck compression. Warm the engine up to normal operating temp, shut it off, disconnect the CAS, remove top 2 plugs, and floor the accelerator pedal.)

 

ok.......and whats this suppose to do?

 

i really appreciate it to all of you guys really the only problem that i'm having is getting it start like running it doesn't have a problem staying on so far but just starting it now i haven't done the grounds but i have checked them. Now the vaccum leaks if i'm right would be the little housing right because i replace all of them accept for this one piece that i didn't think was a big deal it is a green little piece that goes in betweent two pieces of hosing and goes in front of the throttle body opening. Now i will check that stuff. when i do i'll tell you what i got.

 

just for anyones info i still have 60 psi with the throttle body open it didn't do any good so ummm yeah that is compression and well i heard that max is 120 psi but my manual says 85 psi

 

so really umm any thing else that i need to know before i stop this.