I am pulling my hair out. I have just spent the last 2 days trying to get things to fire on this car. Bottom line is this.

When I use the starter to crank the car over and ground a plug wire to the strut tower........NO SPARK

WHen I hook up an extra CAS that I have to the wires on the CAS and turn the gear by hand.... SPARK!.

PLEASE, PLEASE PLEASE!! any ideas. I am about to dump this car and go get something else. I love RX7's but this one is making me look stupid. THe car is completley rebuilt and now it won't start.

Frustrated to say the least.

 

I think the starter is pulling the voltage down so much that the spark is very little. When you spin the cas with your fingers you have no load on the battery etc and you get a larger spark.

Pull or push start the car.

 

could the first CAS be bad maybe?

 

I had the car hooked up to a jumper on a truck when cranking it and still no spark. So I don't think it was pulling down too much. I will try it again though. I thought the same thing about the other cas and I pulled it out to test it. Same result ,when using the starter to crank. No spark. Could this be an ECU problem?

 

just switched the ecu to an s5 NA ECU from the TII and still no spark. I guess that eliminates the ECU possibility. I don't get it.

 

OK, it looks like I may have found the problem. I tested the ignition switch and in the "ON" position, I am getting the continuity that the FSM says I should have. This means that electricity is flowing through to everything that it should. Including the injectors, fuel pump, coils, CAS and all. That is why I am getting spark when the key is set to "On". OK, change switch positions to the "Start Position". I had my son hold the key to start of course with all of the plugs undone to the ignition switch (there should be 4 on an S5, I am not sure about the S4). There are actually 5 plugs on the column, but one is for the turn signals. In the FSM, it should to test continuity (ohms) across certain plugs/terminals. I did this with the key set to start, and lost continuity across the terminals where it was supposed to be.....No continuity, no juice to the ecu, plugs, CAS, injectors.....you get the idea. So, FSM says replace the ignition switch. I am doing that today and will post tomorrow whether that was indeed the problem. I hope that it was. I tell you what, after 2 days of rechecking every wire back to the ECU and installing 6- #4 wire grounds, this had better be it!!

 

A cheap way to figure out if this is the problem, would be to go to the Main Relay. Pull the plug off that has four wires. Jumper the White/Red to the Black/White and then the Black/Green to the Black/Yellow. Now everything is powered up and turning the key to Start can't have any effect whatsoever on power to the coils/ECU/injectors etc. Takes but five minutes to do the above.

 

Thanks Hailers. I will give this a try. Can you think of anything else that might cause this problem. What about the ignition module down by the heater blower? I looked for the last night and couldn't even find it. Maybe that's the problem. Well then again, I just know what I am looking for.

 

I know of no Ignition module near the heater blower.

My suggestion is just that. There was another fellow in the last four months that had your same problem, but I don't remember how or what solved his problem.

But if you jumper the four wires on the Main Relay's large plug, then everything should be there for starting..............but I gave him the same info and I'm not sure it worked or not.

You might disconnect the two wire plug on the Main Relay also. Just disconnect it, nothing more. No REAL reason to do that except superstition. humor.

Be sure to unjumper the four wire connector when your through or it'll drain the battery later in the day.

EDIT: oPPPS. One thing I missed. You do have to turn the ignition switch to start to supply power to power the fuel pump. But the other things like coils, ECU will be powered by the jumper job you do on the main relay plug. And of course you have to use the ignition switch for power to the starter itself, that's a given.

 

Nothing doing Hailers. I tested the main relay like you said and still no spark when cranking. I even put in a brand new ignition switch to no avail. I started double checking some wiring because I had to extend the harness for the JDM motor. All of the traces look good back to the ecu. I found a wire on the relay by the trailing coil that was pushing out when the plug was pushed on. Fixed that..nothing. I did remove the emmission equipment off of the car when I rebuilt the engine. I just left the wires for all of the solinoid rack bundles up. I wonder I should have to jumper this or not.

I noticed one guy who was having the same problem said to check for voltage at the "3J" plug on the EGI computer. I have a 3 j, but it is the wire that feeds the CSA (Cold start assist) which is removed because the jdm motor does not use this. It has no sensor in the oil pan for this device. The 3J wire right now is just sitting there not connected to anything. Should I have to jumper the plug on the CSA to fool the computer?

Heres a strange thing on the spark. When I measure the voltage to the coils with the key in the "on" position, it has 12 volts. When I go to crank, the voltage does not go away, it drops slightly because of the cranking, but does not go away as the spark would indicate.

I have placed the NA EGI computer (N351) in place of the N370 that I am using and it seems to have no effect. So I am kind of eliminating that as the problem.

So I guess the question is this. Should I jumper the wires on removed emmision equipment?

Should I jumper the CSA wires?

Could it be a bad MOP that is causing this. (even though I have tested it.

Could it be a bad MAF causing this (even though I have tested it)

I am getting spark at all 4 plugs when cranking the CAS by hand in the ON position. Actually, it is a very HEALTHY SPARK as I found out last night!

 

Pin 3J on a series four would be batt voltage to the ECU. Actually if you had a series four you could disconnect that wire and the engine would start and run good. IMHO he should have been more interested in pin 3I which is voltage from the Main Relay and the ECU does need that (series four).

On a series five 3J is for the AWS solenoid which has squat to do with starting the enigne/spark.

None of the Emissions solenoids, including the ones on the ACV, have anything to do with starting. They all recieve 12v thru the White'/Blue connecting with the Black/White wire at the Main Relay. BUT I notice that that White/Black wire also feeds the ECU on pin 1B. That pwr is needed for the ECU to work.

If you can, backprobe that wire at 1B (BW) and go to Start. See if that wire still has 12vdc when the key is put to Start. That might be worth doing. If the 12v disappears then the ECU can't do much of anything. You might check pin 1A for batt voltage also if you want. That batt voltage isn't vital to starting on pin 1A.

About the MAF. Some people have had problem with the MAF killing the spark. But take note, the engine will and should start with the MAF disconnected. The ECU does not use the MAF during Start until the rpms get over 500rpm. Engines crank at approx 200rpm FYI. So I'm saying, yeah, disconnect its plug and give it a try. Can't hurt anything and might help.

A bad OMP should not cause a non start, unless it's killing the 5vdc ref voltage while cranking. Hmmm. I won't hurt to disconnect it like I suggested with the AFM.

Something is killing the spark but only when the engine is turning over. So, the OMP and AFM might be the things. OMP turns when the engine cranks and the AFM moves a bit aft as you crank. Kinda makes some sense. You have spark when they Don't move. A sliver of a possibility here. Disconnect both and give it a go.

I'm almost as lost as you are and the fellow who I tried to help on a like problem a few months ago.

P.S. I'd still be interested if 1B loses voltage as you crank the engine. But do the disconnect of the OMPand AFM first.

 

Thanks,

I will give this a try this evening. I really appreciate you input on this issue. I think that the possibilities are narrowing.

 

First of all, I have no series five. BUT I remember just a week ago how someone said they had connected the OMP elec plug to the TPS???? I don't know if this is possible or not, just FYI type thing.

A jpg attach with nothing to do with the words above, but related to your problem.

 

It is possible to switch those two plugs because I think that they are the same male plugs. WHat may be more likely now that you mention it is the following.

I had to re-do the plugs on both the OMP and the TPS AND the CAS. I had to pull the wires completley out of the plugs to properly attach a new wire to them. They had dry-rotted away on the casings. Anyway I had sliced off the end of an OMP/TPS/CAS harness from the NA and had it sitting there. In my diagnostic frenzy, I picked this one up thinking that it was the OMP harness. Using that one to compare to, I had a bunch wires in the "wrong" holes on the OMP harness. I switched them around. NOW I am wondering if that was really the end of the OMP harness and not the TPS or CAS harness.

Guess I will find out tonight!

 

The engine should start with the TPS, OMP disconnected.

The engine won't have spark with the CAS plug screwed up. BUT, you have spark when spinning the CAS gear by hand, so you did NOT screw that CAS plug up at all. At least I'm fairly sure of that. At least ninty percent sure.

I'd disconnect the OMP and TPS to see what happens. I know I can start my car without the TPS plug and I'd bet my next ten years paycheck that the OMP can be disconnected with no start problems. It just ain't a player in starting.

The TPS will default the ECU to .....ah I forget. Full open if memory serves. NOT a problem with starting at all.

 

Ok, spent another frustrating evening under the hood/dash/everywhere last night trying to identify the issue with the no start.

I traced the AFM, the TPS, the Knock sensor, and anything else I could think of to no avail. I disconnected the AFM, the OMP, the TPS and still no spark when cranking.

Maybe it's the ground for the computer. Right now, I have the one black wire that connects to the nut under the computer. Is this all that there is besides the ones in the engine compartment? Like I said, I added 6 number 4 wires for grounds and power to various areas. I can't imagine this being the problem.

The only thing that I have not tested is the power signal coming from the ECU to the igniters. The way I look at it on the S5 Turbo, Pin numbers 1G, 1V, and 1H are the output signal from the ECU to the igniters. How much voltage should I have coming from those to the igniter? ON the leading coil, I am assuming it is the OTHER wire other than the black with yellow that I measure. I will measure at the ECU and the end point. Remember, I measured the voltage to the coil while cranking and it is NOT shutting off power to the coil while cranking. Should I have power to it with the key in the ON position. I am assuming not, since it needs a pulse from the ECU while cranking. I also do not know which pin to measure voltage TO the ecu ( I am assuming 12 V) with the key in the On position and then cranking to see if cranking makes me loose voltage to the ecu or not. Again, thanks for all of the help. I am determined to fix this BEFORE I set fire to the car.

 

There's white two socket plug that goes to the Lead coil assy. One wire is black/yellow and had 12vdc anytime the key is put to ON. The OTHER wire in that plug triggers a ground to the coil/ignitor assy and that gnd is what causes the ignitor to work. I Really would not mess around with that *other* wire at all. You know the coil/ignitiors work because you spun the cas and you got spark.

You need to check the pin I suggested in a post above to see if your losing power to the ECU once you start cranking. That was pin 1B at the ECU, a black/white wire.

The grounds for the ECU are located on the engine..................but I'm not familiar with where on a series five. I'd have to look it up. Anybody that knows where it is on a series five, give a holler.

On a series four there is one gnd for the EM harness and it's on top of the rear rotor housing. ON a series five there are Three ground points for the EM harness. One is near the ECU and the other two seem to be on the top of the engine, according to the series five FSM.

 

I tested the ECU power last night and it is getting power while in the on position and when cranking. There seems to be no signal coming out to the igniters. I finally decided to pull the engine harness out last night. I unwrapped the whole thing to see if I had wired something wrong since I had to extend the harness for the JDM by about 18".

It is interesting what I found. I found that I had wired the B/W wires from Harness FEM02 into the black wires midway up the harness. I think I did this because I thought they were one and the same. On the wiring diagram, it shows 3 solid black wires coming off of FEM02. On FEM 02 itself, there is actually 1 solid black and 2 black with white so i assumed (not a good thing) that the B/W and the B were the same, just ground wires.

I also found out why my blower motor was not working. By studying the diagram, there is a thermo switch that is used on the American harness/ecu that is not used on the JDM motor. Originally I just left that wire sitting. I suppose this is to turn the fan on only when the water temperature is warm enough to keep you from getting a Cold/ Warm blast of air when you turn the car on. It looks to me like it grounds to make the blower come on . I suppose that if I just ground this wire somewhere, that it will turn the blower on when the car is turned on.

So right now I am very carefully checking all connections on the harness and making sure that everything is right before I plug it back in. I should have this done this weekend and I will let you know how it turns out. I am hoping that the B/W..B wire thing was the problem.

 

OK, I removed the wiring harness this weekend and checked every single wire in it. I found that I had wired a b/w wire to B and checked everything else out. I had also used some radio shack shielded wire for the signal from several of the devices in the engine. Although I got the biggest wire I could get from them, I think that the internal wires wires were much to skinny to carry the signal. I salvaged some heavier sheilded wire from another harness.

Anyway, late last night I got it back together. Tried to fire it up and I HAD SPARK!!

Unfortunatley I only had it on the front coil. The back is giving me nothing. I also lost injector fire and fuel. I guess now knowing that the harness is pretty close to right, I feel like I can test the ECU for 12V at the plugs for the injectors with the ignition on and some other things.

I am closer I think, any other ideas?

 

Refresh my memory. This car was a series five non turbo and you put a Turbo engine in the car and used the JDM EM harness on the engine. You lengthened the harness a few inches. IS what I just wrote right?

The ECU you have, what number is on the ECU?

Since you got the spark on the LEAD coil, have you tried to reinstall the non turbo ECU to see if that made a difference?

There's one thing that has me a bit worried. You mention FEM-01 and FEM-02. Your working on a series five. On the series five I believe they use terms like X-10, X-11 for those plugs. So I'm wondering if somehow your looking at a series four diagram and that's confusing things??????

You have the series FIVE wiring schematics?

 

This is an NA car using a JDM motor with an American NA harness. It is an S5 with an N370 ecu. I tried the NA N351 ecu BEFORE I changed the wires. I can try that this evening. I did take some non essential wires out of the harness while I was at it. For instance, the cruise control wire from FEM 02, 01, the temperature sensor (the JDM does not use one), the plugs for the vacuum relays and the like.

 

One thing I noticed on the series five wiring diagram, is on that series they have two BW wires for grounds. They come from pins 3A and 3B. And then they use a pure black wire for the grounds for all the sensors. Well, it ties to the BrB of all the sensors anyway. Just mumbling.

Anyway, it's not a normal thing on a series FOUR car to have a black/white going to gnd. On series FIVE it seems normal in some areas.

 

By the way, I am using a 1989 wiring diagram. The car is an 89 NA. I did mess up my NA wiring harness early on in the project and bought another one that may be a latter year. I had purchased an S4 Turbo harness (that I still have) and couldn't use it before I realized the differences between the two.

 

With regards to the BW going to ground, I did notice this when I pulled the harness apart. Going to the ground on top of the rotor, a BW and Solid B were BOTH going to this ground. It looked factory, but I disconnected it thinking that I did it. I did think it odd to have a BW going to ground.

 

Ok. I have a 91FSM from a download I did a year ago or so. So I guess the 91 and 89 vary a bit.

The FSM for the 91 shows two of the ECU gnds on top of the rear top side of the engine. They show to be seperated by a few inches from each other for some reason or the other.

The series five na harness should have worked on the turbo engine with, if I remember right, by just changing two wires.

The NZCONVERTIBLE in the attached thead describes the two wires: https://www.rx7club.com/forum/showth...5+non+turbo+to