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Discussion Starter · #1 ·
I get the feeling you guys don't like early/ 1G probe GT's but I have to ask as I am getting nowhere. My early production 89 Probe GT has an issue with the injectors only getting a signal for less then 2 seconds then shutting off per noid light. The original computer was a F231 with bad injector drivers. I replaced the computer with used wrecking yard F222, F230, and F231 computers w/apparent same issue. I would assume I need to buy a good remanufactured unit and try again. Which 1st generation computers are actually compatible? Per my ford electronics/vacuum troubleshooting supplemental manual on page 48 I have an additional circuit w/a resistor and diode plus a capacitor added to the oil pressure sensor circuit which runs to an "idle switch" on the eca. Car is tired w/crappy oil pressure if that works as a cutoff however bypassing the sensor and grounding the wire through an incandescent test light makes no difference. Both efi relays are supplying power to the computer and flapper door so the injectors are shutting down on the computer side when cranking/run. I want to buy a known functional eca but don't know which of the F part numbers will definitely work on this early car. I tried to research this question in your archives but could not find where anyone has previously asked it...
 

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I get the feeling you guys don't like early/ 1G probe GT's but I have to ask as I am getting nowhere. My early production 89 Probe GT has an issue with the injectors only getting a signal for less then 2 seconds then shutting off per noid light. The original computer was a F231 with bad injector drivers. I replaced the computer with used wrecking yard F222, F230, and F231 computers w/apparent same issue. I would assume I need to buy a good remanufactured unit and try again. Which 1st generation computers are actually compatible? Per my ford electronics/vacuum troubleshooting supplemental manual on page 48 I have an additional circuit w/a resistor and diode plus a capacitor added to the oil pressure sensor circuit which runs to an "idle switch" on the eca. Car is tired w/crappy oil pressure if that works as a cutoff however bypassing the sensor and grounding the wire through an incandescent test light makes no difference. Both efi relays are supplying power to the computer and flapper door so the injectors are shutting down on the computer side when cranking/run. I want to buy a known functional eca but don't know which of the F part numbers will definitely work on this early car. I tried to research this question in your archives but could not find where anyone has previously asked it...
I like them better than 2G probe GT's.

I have read and reread you post a couple of times, now I will completely ignore it and ask.
Have you pulled the ECU codes?

You need to check the wires between the distributor and ECU, there are 6wires at the distributor, two join together and become one in the harness = 5 wires at the ECU, these wires are for the pickups in the distributor, the ECU uses their signal to fire the two injector banks, the ECU will fire the injectors for 2 seconds and wait for a signal from the disi to know which bank the fire next. If it receives no signal it stops firing the injectors.
The fact your injectors get a signal for two seconds suggests the injector drivers are working in the ECU.

Chances of you getting 3 junk yard ECU's and them having the same problem as yours are pretty darn small.

I don't understand what you mean by "Idle switch on the ECA" What is ECA?
Are you saying the Probe has a low oil pressure engine cut set-up from factory?

The Mazda F2T just has an oil pressure switch that turns on a light in the dash, the probes have a gauge, does the wire leaving the oil pressure sensor go to the ECU also? If it does remove it at the ECU harness plug and wrap it in tape.

I really think your issue is signal from one of the 3 disi sensors.
You need a multimeter that test for continuity.

To test the wires, unplug the distributor, take a long piece of wire and stuff it into one of the pins of the harness connector for the distributor, run the other end into the car, connect it to one end of the multimeter and use the other end of the multimeter to to find that wire at the ECU harness connector. If any of the 6 wires at the disi don't have continuity at the ECU connector than that the problem.
To test the disi sensors, remove the disi from the head, connect the multimeter to the blue and white wire pins at the connector, spin the disi 360* and check for continuity change. do the same for the red and yellow/blue wire, and for the green and yellow/blue wire. (you will have to try both yellow/blue wires with the red or green wires because they are seperate in the disi but the same in the harness.
 

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Discussion Starter · #3 ·
I have already installed a new correct NOS F220 6 wire distributor along w/a billion other parts. The factory books all call the computer an eca aka electronic control assembly and since I don't know the correct descriptors among tuners/builders of these cars I sound like a moron. I am bumbling through this as other than my Lancia's my other cars are all old school carbureted big blocks. I take it this 1st generation is called F2T and is associated to the 2.2 engine? Once this thing runs again I was going to pull the engine and rebuild it since it leaks oil and antifreeze and is tired. That being said I will follow your above described procedure as it is all about getting the injectors to fire. I have a John L Fluke multimeter so can systematically check each as described. Many have told me that Mazdas have a low oil pressure cutout switch however I realize this 1st year 1989 car has different wiring that the rest of em which does not help since wiring diagnostics is my weakness. The 2 wire connected to the oil sensor on one spade terminal split with one going to the analog gauge cluster and the other going through a resister and a diode to a splice that connects to the computer under the dash at pin 1E. This wire shares and "idle switch" which simply completes a ground. I am heading to work in an hour so I will update in a few days when I have a minute to follow your instructions. Thank you for taking the time to point me in the right direction since every last thing has been replaced except for the vane/flapper door assembly which troubleshooted fine per the 6" thick factory book I used as a guide, sort of. With the noid light installed one at a time in each injector connector all of the cylinders fire 5 times before they stop getting a signal
 

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Wasn't razing, just making sure we all use different terms and make up our own, if you research you get 50 different results.
I did an engine swap on my 88mx6 GT, the car wouldn't start, I modified a bunch of thing and had no clue what the problem was. I swapped everything to the point every single piece was swapped, still the same problem your having, paid one of the shops nearby to diagnose, he brought in e ford electronic tech, they told me as much as you have discovered... kept changing parts and finally got my hands on a factory workshop manual, step one is check the wires between the dissi and ECU. On the 88mx6 there was an issues, pulled out the harness that was in the 88mx6, same issue, untapped the harness and found the spot the single yellow blue leaving the ECU crimps to 2 wires had corroded and cracked. Pulled the tape off the harness in the MX6 and it was the same problem. Connected the wires and the car ran, wish I knew about step one first.

That and thousands of other experiences have taught me that just because it's a new or different part doesn't mean its a working part and can introduce more problems than solutions. Trouble shoot then replace is the easiest was.
 

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Discussion Starter · #6 ·
Ok, round two. All 3 pickups/sensors are fine in the NORS Ford distributor. The white/red wire from EFI relay 1 is intact all the way to the injectors. Moving on to the blue and white wires for the internal crankshaft position sensor the blue wire is intact using an ohmeter at the 6 pin lug at the distributor and at the yellow "connection 1" plug (1 of 3) that go into the computer. However the associated white wire is showing as open, if the one I have attached to with the power probe in the above picture is actually the correct one at the computer end. On the pro on demand schematic it shows that the white wire should be at position "P" on the plug. The solid white wire I have attached the probe to is the only solid white wire on it. Can you advise if this "4th from the end on the upper row" is position "P" as described? I ran a jumper as advised from the 6 pin connector at the distributor to this power probe wire piercing attachment and upon trying to start found no change. almost runs for 2 seconds then just cranks. Not sure what else controls the injectors drivers.....
 

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Discussion Starter · #9 · (Edited)
Now that I had enough nerve to ground the red/white STI plug as there are 5 unused plugs just sitting there in that corner, I have codes of 01 for Ignition Pulse and 34 for Idle Speed Control Solenoid Valve which per another thread here in MX6 world are 1989 only Probe Codes. Any recommendation on how I should interpret "Ignition Pulse" since it did not give codes 03 or 04 for Cylinder Identification Sensors A or B?. The spacing and length of the flashes matches the info provided in the thread in that the 1st one was a quick single flash, then about 4 1/4 seconds until I had 3 long flashes, 1 second pause then the final 4 fast flashes until repeating the same pattern... As far as the distributor testing the blue and white wires were straight-forward for the crank position sensor but am I to try all combinations of the remaining wires w/the ohmmeter for the 2 batched cylinder sensors. It is not sinking in with their being 5 wires. Again the mechanical stuff is where I accel/understand but some of the wiring issues make my brain turn-off.
 

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Try downloading the 89 wiring diagram from this link:
Index of /
It is on this page and also under Mazda

You are pointing to the correct white wire.

Schematic Font Parallel Engineering Rectangle


Font Rectangle Parallel Number Pattern


Code 34 is the same on the 89 mx6/626 GT, this can cause idle to surge while the ECU chases the preset rpm but can't hold it. This will not prevent the car from starting or running.
The 1989 WSM has no mention of Code 1
The 1988 WSM Has Code 1 : Ignition Pulse (And the 89 ECU will throw code 1)
The only thing the probe has different (That I can recall) are the oil pressure sending unit instead of a switch and the oil level sensor in the oil pan and the wrong logo on the valve cover.

Font Parallel Rectangle Number Pattern


Font Rectangle Parallel Number Screenshot

Page 105 and 106:
Font Parallel Pattern Rectangle Number

Font Parallel Rectangle Pattern Document




Before trouble shouting the igniter you should check the grounds for it, on the mx6 they are next to the battery bolted to the inner fender with an M6 bolt 10mm head. There should be four or 5 ground wires meeting together in a plastic plug, the wires are all black with green/gold dashes on the MX6. If this ground contact is loose, corroded or bad the igniter wont fire and the car wont start. But a bad ground here give very weak spark and the engine doesn't usually try to fire twice and give up.

I really hope I am not wasting your time here but I suggest you grab 1 role of black electric tape and start removing the tape back from the distributor plug toward the injectors, follow the two Yellow with blue stripe wires. Eventually you will find them wrapped in green and or yellow tape (about one foot back from the dissi), this is where they are crimped together in the harness and two become one. They are crimped with what looks like a lead cube and the yellow green tape is all that was keeping corrosion out off the wires, the heat cycling of the harness makes the tape turn gooey and that causes the exposed wires to corrode. Even if they still carry continuity there is a chance the can't carry enough current, cut the splice cube out and strip back the wires until you find nice shinny copper, take 1 piece of = or larger size wire and use it to connect the 3 ends. I recommend solder, shrink wrap and tape to make and cover the connections, some people don't like using solder and say it creates resistance but I have never had any issues from soldering wires on wire harnesses, compression and crush connectors I have seen them fail time and time again after the wires corrode or a couple break the rest slide out of the connector and even when the plastic sheath is cut off the connector and it's properly sealed in tape the metal tube still develops condensation.

When you retape the loom over the harness, stard where you stopped stripping tape, tape around the wire bundle a couple time them put the loom over with the tape coming out the seem of the loom and start taping over the loom, tape back over the end of the old tape (where you stopped removing it) and work your way forward to the dissi. When you get to the end flip the tape and go around the harness sticky side up for 1.5 turns then flip it again and do 1.5 turns sticky side down. cut the tape do not pull and break it and don't stretch it too tight while wrapping the harness either. The tape will never unravel this way.


I have had the exact same problem a few times and have purchased cars with this problem over the years, fires up and dies. It has always been harness related for me.
I have had/seen igniter ground problems a few times also (not enough spark to run or start the car).
And I have had a couple ECU's die on 88-89 GT's, the car runs like ass, sputters and missfires, wont rev beyond 3000 rpm, the higher the rpm goes the slower the car moves, if you shift second it stalls...

One of the members here Zach had the fired up and dies issue, he said he found continuity between all the Dissi wires and ECU but changed the harness and it worked.

This was my first post on MX6.com:
Car starts but runs rought and stalls NEED HELP ! TRIED...
In my defense I had no workshop manual or online copies to work with and I joined mx6.com to the day I posted the thread. So all I had was pile of parts and a bunch of guessing.

Maybe for you it's not the dissi wires but it could still be a signal feedback issue caused by the harness.
I say you have gone this far, undo the two other connectors near the ECU on the harness and pop the rubber grommet out of the firewall and move all the connectors to the engine side. Remove the 10mm nut holding the harness to the firewall and free up enough slack in the harness so the ecu connectors are easily accessed at the same height as the intake manifold. Now you can work with a multimeter and check all the ECU to sensor connections. Check the grounds in the engine harness, one bolts to the engine lift bracket next to the throttle body, one bolts to the intake manifold on the passenger side after the #1 injector, I will be honest I don't know where these grounds go but I think they bridge off to ground stuff like the knock sensor, the IAC/BAC valve... and they may go all the way back to the ecu and are used as the injector ground pulse signal for injector bank A and B. The SDS extra injector controller I run does that, it operates two injectors and has two grounds that need to be connected to 2 different ground points on the engine. The injectors are connected to a switched 12V source directly and the unit pulses the ground signal it gets from the block to the injectors.


Try downloading the wiring manual from the link, I tried it recently sometimes it opens in pdf and sometimes it doesn't. Also click on Mazda and grab copies of all the 88-92 GT turbo manuals you can find, it's all very similar and good to have.

Wire diagrams are a pain in the ass at first but the aren't that complicated, I prefer the Mazda WSM to the ford ones but fords part code indexing is better except the fact they used the same code for a ford probe as a pinto.

For the most part any wire of the same color and the same size in the harness is connected/same wire/same signal, even though two separate ground wires of the same color might not meet in the harness they will carry continuity between each other once connected to the frame.

The color abbreviations are fairly simple
R=red
B=black
L=Blue
G=green
Lg=Light green
R/L = red with blue stripe.

If you look at the first workshop manual page you will notice that every device there are two doted lines with two arrows on every wire leaving the device (Knock sensor, crank angle sensor, injectors...) these dotted lines and arrows mean there is a connector there and the EM-26 for example, EM is the harness, 26 is the connector at the dissi.

All the connector pinouts are drawn out at the connection side not the wire side.

The grounds can be a little more complicated because they don't have pinouts just connections in the electronic diagram.
Take the ground 8 for example on the same page. It goes to the knock sensor and also goes to a dotted line on the knock sensor, 5 of the 6 dissi wires and the O2 wire. This represents that ground point 8 connects to a grounding sheath (braided metal sleeve) that wraps around all these wires somewhere in the harness, it does not make contact with any of the wires, it shield then from noise/electrical signal interference. I have seen electrical wire disconnected at both ends in building conduit that's pick up voltage from the 3phase 575V next to it simply from electrical radiation (Not an issue for devices running on power from the conduit but dangerous to work on and requires tracing wires and shutting down more breakers until the wire is safe to work with).

Shit you might just be the unluckiest guy and have a bunch of bad ECU's but I do not want to see you purchase another ECU have the car not start, then you set it on fire and walk away with this look on your face:
 

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Discussion Starter · #12 ·
Now that you guys have focused me on codes 1 and 34 I am realizing that the 2 black cutoff wires at the throttle body are for the IAC so they are not even/have not been hooked to the red and white wires since I bought this thing. It ran ok when I got it and the guy drove it onto my trailer at the time and then I drove it for about 2 months until the fateful day I did a full throttle pass down the freeway and it died when I let off the throttle and have problems ever since. I priced a NOS IAC and they want over $600 for it but being it is a saturday can't verify it is even available for this early turbo car. Is there a trick to troubleshooting the IAC electrical part and if so can the two wires be connected either way. I would rather buy a used one so that the plug is correctly done as the female half of the plug on the harness side is intact. Cleaning the IAC is a no brainer of course.
 

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Morgan, now i only need the connector 3 ecu pin out , looking at wiring diagram , i made out the following
3A-ground
3G-ground
3E-inj 1&3
3c-inj 2&4
ignition -3-B

those are all i could make out of it from that pdf diagram. if anyone know the other pin goes to on connector 3?
 

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