pyrojohnhippy

This is a "sequal" to the post I posted last night asking which ecu to get. I guess the real question is and problem is.... How do I get signal to the injectors? I have pictures of car in previous post. Everything is functioning in my car like it is supposed to before start up, but the injectors aren't firing off, and when I had a diagnostic run on the ecu repair man said that there is no signal going to the injectors. Now he is getting this when he has a N370 Hooked up. He sais it needs another N370 and that will fix the no signal to injectors problem. This mechanic doesn't specialize in sec. gen. rx-7 nor mazda's, but he does know quite a bit about the car and has helped fully patch together the wiring harness...lol.... I'm told that the wiring going from the ecu to the injectors is complete, and that if something were there to control it (like a new'used' N370) the engine would start and run. it was a mess when I got the car so I'd like to think he isn't swallowing my money... even though I have like $5 to my name right now... lol... Need help plz!

Any suggestions much appreciated!!!!!!

Thanks,

John

WAYNE88N/A

You're not really getting a voltage signal TO the injector, you're getting one FROM (or through) them. Picture the injector circuit all the way to the ECU as being almost a completed circuit- you have power from the main relay, you have the component that's using the power (injector), and you have all of the wiring necessary to make the circuit work, except for one tiny item- the ground. This is what the ECU supplies, by switching it on to complete the circuit (getting the injector to "fire") and switching it off to stop the circuit, tens of times a second (depending on rpms, of course). Check each injector "input" at each pin at the ECU (voltage, to ground). If you get battery voltage there (12v) with the key on, then the injector power, coils, and wiring are good. Next stop will be the ECU, or the ECU's grounds (the gang ground on the rear rotor housing, specifically).

Note that you also need the "trigger" input to the ECU for injector firing, which is the CAS's job...

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

pyrojohnhippy

Wow, extensive information!!! Thank you!!! I'm going to have to print it out and give it to the mechanic. I appreciate a word from the wise!


Thanks,

John

The Spyder

iTrader: (8)

Your in oregon? Who is the mech? I might know some people that can help .

pyrojohnhippy

"Today's Auto" I'm in se Salem, Oregon. The Mechanics name is Robert somethin he's the manager. It'd be nice to get this thing fixed, cuz I don't have a running car, I really wanna drive it, And I need a job ^.*!!!! I don't know how compatent the mechanic is that is workin on my car though.

The Spyder

iTrader: (8)

Shoot me a PM, I have a few names I can look up, theres a great mech down in salem who can help ya out. He was on the forums, but is taking a break right now.

Sounds like quite the project, I can give you a hand if you need it. Im about 20 minutes away. Hit up the Northwest Section of the regional forums. Theres a bunch of us around .

HAILERS

IF your mechanic failed to install the ground ring for the ECU on top of the rear rotor housing.......the injectors will not operate. Once more....the GROUNDS FOR THE ECU are on TOP OF THE REAR ROTOR HOUSING. This has happened on this forum before. Same symptoms.

pyrojohnhippy

Ok, thank you very much HAILERS. I will relay that to the mechanic tomorrow morning. Thanks!!!!

pyrojohnhippy

Okay!....... Well I just got back from the mechanic and boy am I ****ING PISSED!!!!!!!! I found out what my total for all this work has come up to.... $437.90 just for them to tell me that the current ecu's for the car wouldn't work. I provided them with that other N374 and they told me same problem. So when they told me the total today I almost knocked out the mechanic. There was a bit of argueing involved and them reasuring me that they have been doing their best to fix up my car... THEY WERE WATCHING TV WHEN I WALKED IN THIS MORNING!!!!! FFFFFFFFFFFFFFFFFFFF! So here is what I did. I handed him a printout of the responses I got from WAYNE88N/A and HAILERS and the mechanic replied by saying... "I checked all the grounds!!! I have it grounded correctly that's the first thing that I looked for" I had the vice president of the mech shop take me out to look at the car and point to the ground going from the rear upper rotor housing to the ecu... and he couldn't find it... and then we went back inside and the mechanic said..."you can't see it from above, you can only see it from underneath... when the car is lifted." Then he proceeded to tell me this:

"The current ecm, the N370 has no spark or pulse and has a check engine light. The N374 show's no injector pulse but has spark and no check engine light. The ground is there, the N374 wouldn't get spark if the ecu wasn't properly grounded. You need to get a new N370 in order to make these problems go away. I don't know what you told these people online but obviously they either misinformed of the issue or they just are giving incorrect feedback on the problem."


The car has been with this mechanic for almost 3 FULL WEEKS and no progress!!!!!!!! I'm selling stuff to pay for this... I need a good mechanic... I'm lost... this is all to depressing... anyone know what is really going on???? This is what the engine currently looks like after the mechanics messed with it.....

pyrojohnhippy

I guess I'm going to go ahead and purchase another N370... If that doesn't make a difference I'm thru with this thing... I was so looking foward to even driving it!!!! I've spent a total of $2500.00 on this car already... I have like $500 left... I don't think I really have any kind of a shot here... realisticly... I had my hopes so high too....

The Spyder

iTrader: (8)

Get that car out of that shop now. That mechanic is a ******* moron. I can see theres NO ground wire in the pictures you have provided. I would question all his work upto now and if we can find anything else wrong because he did not know what he is doing I would seek a refund!
I have friday afternoon and night free and between what I know, the local rotards, and the people here I can help you without you having to spend your savings on the car. I hate mechanics like that.
Ill give you a call later. This is getting rediculous....

WAYNE88N/A

Good luck, man. Most auto mechanics don't have a clue unless they can plug a Snap-on scanner into a connector somewhere and have it tell them what to change. Such is life. Between all of the guys on the forum, you have access to the best rotary mechanics in the WORLD. Use them

pyrojohnhippy

Just got off the phone with the mechanic... He pretty much sideskirted the whole grounding issue... confusing my lack of knowledge about cars explaing that all the a/b negative/positive connections are right, and that he couldn't find anything to support the fact that the ecm is actually grounded to the rear upper rotor housing. He has it grounded somewhere... I have no idea where.... I don't know how I'm going to get the car off the lot... I can't afford to right now... towing is too expensive I'm so hosed!!!!!!!!!!!!!!


arf life sucks...

WAYNE88N/A

I'm going to need the S5 guys with the wiring manual to back me up here, because the pins might be different...

For troubleshooting only, just in case that rear rotor housing's ground is defunct, either you or the mechanic can supply a "new" ground for the ECU by using jumper wires from the ground pins at the ECU to one of the many metal studs sticking up in the immediate vicinity of the ECU. A piece of copper wire that you could shove into the back of the pins and then bolt to the chassis ground (with a ring terminal would be nice) would do the trick. Make sure the wire is small enough to fit inside the hole, yet large enough to remain there without falling out. That would settle the discussion between you and the mechanic once and for all.

On the S4 ('86-'88) cars, the ground pins are as follows (all of these wires should be black, BTW):

Pin 3G- small plug on the left, 2nd one over from the left, upper pin.

Pin 3A- small plug, upper right corner

Pin 2R- middle plug, far left, bottom

Pin 2C also has ground potential, but does not attach to any outside chassis spot, so don't physically ground this one...

Double check me on this, S5 gurus

HAILERS

The ECU is grounded to a ring terminal on top of the rear rotor housing. It is located UNDER the throttle body. You cannot see it. It is NOT that simple little grond that runs from near the wiper motor to the engine.

In the 87FSM, on page 50:22, which is a schematic, you can see that the grounds for pins 3A and 3G go to ground point 24. Ground point 24 is on a ring terminal on the top of the rear rotor housing. It cannot be see without removing the throttle body. Again, it is NOT that simple *** wire running from near the wiper motor to the engine top. It is under the throttle body.

WAYNE88N/A

Hey, you're not an S5 guru... S4, maybe

Do you happen to have the ECU pinouts for the S5, Hailers???

If you know where to look, and you have a flashlight, you CAN see that rear rotor housing ground with everything installed...

HAILERS

So if you can't see the ground ring under the throttle body, then you'd think someone has already gone to the ECU and pulled the smallest plug off and put a meter on pins 3G and 3A and seen if the gound is somewhere in the .1 ot .5 ohm range or less. Might also look at 2R and 2C on the second largest plug while there.

You mention that one ECU will cause the plugs to fire. That does make me think the grounds are probably good. It wouldn't take long to look at the ECU though. Attached is a jpg out of the 87FSM showing ground point 24. It is a ring terminal on top of the rear rotor housing that can only be seen with the throttle body off, but can be checked from the ECU as described above.

EDIT: In case someone misses it, on the JPG I drew on large red line to the ground number 24 and another thinner line to the actual ground point on the engine and attached red dots to the original fsm line from the 24 number to the actual ground point. NO. It is not that clear where the ring terminal is in that picture, but it IS located on the top of the rear rotor housing about three inches to the left of BL 0.

And WAyne is right (for once{humor}), if you know where to look, and the intercooler is off, you can with a mirror and flashlight see the ring terminal. But like I said, if you take a meter to the ECU plugs you can confirm the grounds being good/bad.

This is a series four, isn't it???????????? Gotta go look and re-read a bit.

WAYNE88N/A

Actually Hailers, I can envision the ignition working just fine without that housing ground...As long as the big boy is connected down by the starter...

EDIT: Scratch that, I'm smoking something. The ECU won't function at all without that ground connected SOMEWHERE to ground...

HAILERS

Ok, It dawned on me. It's a series five. Same principle. Probably different pins on the ECU though. I don't have a series five in front of me. The grounds still in the same place. I'll get the right pins for a series five in a little while. This is starting to resemmble(sp) work. Uggggh!


EDIT: Ok, pins 3A, 3B, 3C and 3D are grounds on the series five. There, done.

HAILERS

Well just run out to your car, depin the grounds from the ECU, and then tell me your car started. THEN I'll believe that. Ain't a gonna start, I can tell you that right here and now. The grounds for the computer/internals in the computer, are......on the rear rotor housing.

WAYNE88N/A

Yeh, I already edited my work. Had to go do some plane stuff, took me a while to get back

Thanks for the S5 ECU grounds