WAYNE88N/A

harley, the ground tab at the back of the engine (on or near a tranny bolt, with a wire going to the firewall) is NOT the one we're having a "civil discussion" about...although without that one in good shape you're probably screwed, too...ground #24 is on top of the bracket/ standoff for the "rat's nest", in fact it is under the bolt that secures that particular area of the bracket...if you look at the right side of the dynamic chamber, underneath you'll see two 12mm bolts that secure it to a bracket, side by side, about 2" apart. directly below that point is #24 (I've never tried to find it with the TB & everything on, but I know it's gotta be a bitch to see it with everything in the way)...HAILERS had a good idea earlier- read the ground from the ECU pins when you're having trouble and compare this to resistance readings when everything is running smoothly- that way you won't have to take the TB off to access it (unless you get a bad reading when it's acting up)...heck, all this "animated discussion", and we're not even sure if this is your problem...(sigh...as long as we're learning...)

allforjesus06

clogged injectors. send them to a shop to get cleaned.

allforjesus06

or/also make sure that the connection to the wiring harness to the injectors are secure. to check the primaries you have to take the upper intake manifold off, but i think it'd be worth it.

allforjesus06

double post, sorry.

HAILERS

I want to say that the rolling the car a couple of feet ...is superstition??? Maybe not but that's all I see there.

The water temp switch on the filler neck is for the auxillary fan..if you have one. I don't see that being related to the problem.

And like the man said....gnd 24 are on a ring connector and BOLTED to the rear rotor housing with a bolt. I don't think you can touch it without removing the dynamic chamber. Better to ohm out the wires at the ECU going to the ground.

WAYNE88N/A

harley, did the problems start soon after that temp sensor was put out of commision? you said the plug was just "sitting there", there's no way it (terminals/wiring) could be touching ground? what components have you ruled out as being the problem?

harley71105

OK, on the superstition....she WILL crank (or at least has twice) when moved....not starting then moving and starting isn't superstitious, I'm just trying everything I can think of....Now, Wayne88 that ground on the right side (under) the dynamic chamber, is that driver side or passenger, cant see much under the UIM...yes it may have started when I changed the fan sensor and it is not grounded out...dirty injectors? I think not, could be wrong, she runs too good....all good ideas though, guys...the fifty dollar reward still stands...

WAYNE88N/A

have you taken a good look at all the accessible harness runs in the engine bay (FALCOMS mentioned this a while back)...gently move/ pick up the harness, especially at areas that contact the frame or engine, and look for chaffing damage to the bundles...just to verify, when it's NOT starting, everything is as it should be, except the "light-off", right? same voltage gage reading, same twitch on the tach, same starter sound, etc...have you read out those ECU pins to ground yet, as HAILERS recommended? that's going to be a very important number to know for us to continue troubleshooting...I would take a damn good look at the harnesses with a flashlight, first, though...

harley71105

Ok...I'm going to check out the harnesses, I'm not much for testing the ECU Though but like I said I have two spare ECU's and in the past two years have switched them all out and the intermittent failure has occurred with each one of them....

gambone

iTrader: (3)

Ok Mr. harley my name is steve gambone and I do this for a liveing and was a mazda dealer tech. the one thing that I have learned about Jap cars that go realy lean or rich is to look at the PCM coolent temp sensor. check the connector for corrowtion then I use a reostat and dial in the rite rang and sub it for the sensor. most posable is the sensor has a bad spot in it's rang

harley71105

OK...can anyone tell me where the PCM coolant temperature sensor is...maybe it is in the manual...shouldn't be to expensive....I'll just buy another one...if thats not it...then I have another extra part handy...

WAYNE88N/A

I think he's refering to the water thermo sensor, behind & below the alternator- should have a green plug (check the plug body real good, too- they tend to break a lot)...usually throws you into a limp mode, runs like crap when it's bad, but I've heard some guys actually couldn't get their cars started when it crapped out on 'em...you can check the output of it at pin 2I at the ECU- it should be .4 to 1.8 volts, at idle...you can also play with the plug backshell while the car's running to see if it's an intermittent electrical open

harley71105

Thanks Wayne....I have plenty to checkout now thats for sure....I'm a little vague on where the injector harness is....is it under the UIM or on the other side of the dynamic chamber?

WAYNE88N/A

man, I'm sorry I ever started calling it that now...it's actually part of the engine EGI harness, near the end of the run, so it's only got a couple of wires in it, namely the injectors, and a couple of other sensors...the section we've been hashing over is under the TB/ dynamic chamber, sitting on top of the engine (I think that water thermo sensor feeds into it too)

Icemark

See that is the problem from the start with why I took exception to your's and other posts.

The ground on the back top of the motor is the Primary ECU ground...

NOT THE INJECTOR GROUND...

and to be sarcastic (again) any air craft mechanic that had been working on rotarys since guy 1989 should know this.

WAYNE88N/A

all right, Icemark- water under the bridge, man. I still think it's that ground the ECU uses for the injectors, among other things, but we're here to try to help people out, not to insult each other and argue semantics...

Icemark

Actually I looked through more in depth since I got home, and the ground to ground 6 is only on the 88 and later models and the auto versions (which would not be there on an 88 GTU as well).

harley71105

Icemark, I respectfully regret to tell you this, but I have 2 (two) 88's. One SE with an automatic and the 88 GTU
with the intermittent under discussion, and THEY BOTH HAVE THAT #6 GROUND...manuals and production planning are not always in sync...they even parts from different mfgs during the same year....I think you probably know that...since there don't seem to be a lot that you don't know....but those grounds are on BOTH of mine....sorry

Icemark

No, I don't think you understood what I posted...

All FCs have ground #6.

but they don't all use #6 for feed to the ECU.

There are a half dozen or so other things that use ground #6, its just in your case, your ECU would not (but your blower, door switches, front wiper motor, heat/defrost/fresh air/etc do.

SilverT2

IF your shure your fuel pump is working. Then...

1. get a pad and pen
2. document were everything goes
3. rip everthing down to the short block
4. internally clean the **** out of the uim and lim
5. send injectors of to RC Enginerring to be cleaned
6. replace all injector grommets or air bleeds if needed
7. block of al vaclines and block off EGR, and Bac valve
8. Reassemble with new gaskets and torque to spec.

Thats the best I can do, I hope you get it started..

harley71105

Yes, Icemark, I did misinterpret what you wrote, thanks.
T2silver, it is only an intermittent problem....otherwise a good plan to dissassemble if needed, but otherwise she runs too good to go through all that just yet...I probably would wind up with more problems than an intermittent no start....thanks

HAILERS

Actually its called THE EMISSIONS HARNESS, in the FSM.

The Water Thermo Sensor is on the backside of the water pump housing. It's identifyed by a Green colored jack on it. Hey! Give it try. Either change it out or buy a pot and adjust the pot to see if that helps.

Ground point 24 is one and three eights inches left of centerline on the rear rotor housing. It is located on the rear portion of the rear rotor houlsing. It is on a *boss*. It is held on with a bolt. The wires are black in outer color. If the car starts ever, then they are connected most likely.

By the way, I think you've already soleved your problem. Give yourself a fifty buck tip. Here's the deal. Where ever you park the car, allow a couple of feet in front of the car so you can roll it fwd a couple of feet and start the car. Preferably on a downslope.

HAILERS

Actually its called THE EMISSIONS HARNESS, in the FSM.

The Water Thermo Sensor is on the backside of the water pump housing. It's identifyed by a Green colored jack on it. Hey! Give it try. Either change it out or buy a pot and adjust the pot to see if that helps.

Ground point 24 is one and three eights inches left of centerline on the rear rotor housing. It is located on the rear portion of the rear rotor houlsing. It is on a *boss*. It is held on with a bolt. The wires are black in outer color. If the car starts ever, then they are connected most likely.

By the way, I think you've already soleved your problem. Give yourself a fifty buck tip. Here's the deal. Where ever you park the car, allow a couple of feet in front of the car so you can roll it fwd a couple of feet and start the car. Preferably on a downslope.

HAILERS

Actually its called THE EMISSIONS HARNESS, in the FSM.

The Water Thermo Sensor is on the backside of the water pump housing. It's identifyed by a Green colored jack on it. Hey! Give it try. Either change it out or buy a pot and adjust the pot to see if that helps.

Ground point 24 is one and three eights inches left of centerline on the rear rotor housing. It is located on the rear portion of the rear rotor houlsing. It is on a *boss*. It is held on with a bolt. The wires are black in outer color. If the car starts ever, then they are connected most likely.

By the way, I think you've already soleved your problem. Give yourself a fifty buck tip. Here's the deal. Where ever you park the car, allow a couple of feet in front of the car so you can roll it fwd a couple of feet and start the car. Preferably on a downslope.