To do the test properly you need to turn the engine over by hand and leave the CAS plugged in and installed. The 0 to 5 volt change on the G/Y wire will only be noticeable if the engine is turned over by hand in a slow manner. If the CAS were spun quickly it would be similar to the engine running and the voltage on the G/Y wire would change so fast the meter would not register it.

Now yesterday you told us the reading on pin 2A was .3 volts which will prevent the car from working properly. It has to be close to the 4.5 to 5 volt range as stated in the FSM. Secondly, the vref reading at pin 2A is an "output" voltage so what ever reading you get at the ECU pin should be roughly the very same at each sensor it connects to. Now voltage can drop as it passes through the wiring but the voltage you are reading is coming from the ECU so if it starts out at 4.2 then it can't possibly increase further down the line. Decrease, yes, increase, nope. You are telling me it is increasing which makes virtually no sense at all. When you take the reading from the ECU make sure you are using a proper ground for the Black meter lead such as the mounting bolts at the front of the ECU.

 

Ok ill turn it by hand and the voltage issue may have been operator error lol I used ecu as ground however I was also charging battery which may have caused increase/ issues with readings

 

Ok how u test ecu ? According to all data looks like u ohm check between cas and terminals almost like u wear amp checking it. Or do u disconnect cas and ohm the cas 4plug

 

You disconnect the largest ECU plug which has the Green, Blue, White and Red wires. With no key in the ignition and the meter set to ohms you place one meter lead to the Green wire and the other lead to the Blue wire and it should read between 110 to 210 ohms. Do the same thing for the Red wire and the White wire.

 

Is that for ecu .... Sounds like cas which I already checked. I got within the spec.

 

My bad as I thought you were asking about the CAS. To check the ECU the only thing you can really do is check each wire and compare the voltage reading to the specs listed in the FSM. Did you ohm the CAS at the CAS pigtail or the ECU plug as it is more important to do at the disconnected ECU plug to prove that the wiring is good up to that point.

FSM ECU specs. (post #3).

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/88-rx7-wiring-diagram-968998/

 

I did it at the cas in plugged ill try at the ecu unplugged, but hey I turned engine by hand key on amd gr/y was changing voltage I think there problem theo cause I got up to 800mv I think not sure of the scale I was on.

 

Did you ever test for spark on the leading coil? If not then you should give it a try.

 

Just tried both rotated by hand and tried with spare cas and got nothing

 

You still need to ohm out the ECU plug related to the CAS and when checking for spark turning over the car w/the starter is probably best. Also, if you try to start the car does the tach bounce. If it does then the trailing coil is firing. The Brown/Yellow wire at the trailing coil is the wire which alternates from 0 to 5 volts when the engine is turned over by hand much like the G/Y wire of the leading coil.

 

Ya I was thinking about checking cas at ecu wires ill do it tomorrow. And ill check that brn / yel wire so Ur saying I can in plugg be/yl and see 0-5v. On h/yl it is fluctuating but I don't think its enough. The tach is non op

 

Translation: unplug the trailing coil that has the Br/Y wire and rotating the engine by hand w/key to on should indicate 0 to 5 volts over and over.

 

Hey the coils and one of the main grounds are grounded by the screw threads correct because the chasis is painted so they're not really grounded except where the screws go thru the.body right. I am going to buy a master tape and die/ thread repair kit and chase them should I get metric ....

 

Oh ua and there's a resistor of some sort that goes to b/y wire and get grounded next to coil but there is another by the starter which Idk where it goes its a y/r wire which has power to it .. and I habe another one of thise resistor things one wire not plugged in Idk if it should be grounded or not

 

As far as the y/r wire at the junk yard they have one of those resistor things on the starter but its nut hooked to anything so I thought is ask

 

The coils ground by contact w/the fender. If this ground is not sufficient the igniter in the coil will not fire at all.

There are no factory grounds near the leading coil and the only grounds near the trailing coil are a group of five or six grounds in a single plug connected to the strut tower.

The resistors as you call them are condensers and the one connected to the B/Y wire is for the circuit involving the coils and injectors while the one connected to the Y/R wire is for the oil pressure gauge. They help to smooth out fluctuations in the signal sent to the oil pressure gauge and tach.

Condenser pic in post #1, 1st thumbnail.

https://www.rx7club.com/showthread.p...=condenser+pic

 

U don't happen to know thread pitches on most of the bolts .... Metric or standard

 

No, but I'm sure they are metric.

 

1 pair was 165 other 167

 

Going to clean up the threads tomorrow afternoon. Wiring seems good max ohms 210 and mine are posted in above post from ecu harness unplugged

 

Tried the br/y wire went .012 to .028v while rotating engine by hand with 4wire plug disconnected. Going to but new nuts and bolts for coils and clean threads some more but I'm thinking bad ecu...

 

..

If the CAS checks out okay and the grounds at the ECU are good this sounds about right. When checking for the 0 to 5 volt changeover at the coils are you using the negative battery terminal as the ground for the multimeter or what?

 

Ya

 

Going to grab ecu now. Isn't there some kind of ballast resistor by air box

 

That would be for the fuel injectors.