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Discussion Starter · #1 ·
Hello, I got my 91' Mazda MX6 GT on the road a few months ago thanks the help of some kind people on here on where to find parts and was hoping I could get a little more help today on getting it started and running again. I have already made sure it is getting air by taking the charge pipe off bypassing the turbo, it had air. I also removed the fuel line after the filter and made sure that had good pressure, it had fuel. I still haven't time to test for spark or timing. I did change the old ignition coil but that didn't help... Anyone have a good idea why it could have just stopped starting like this, I had just drove the car and never had a problem starting before all this.
 

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1- How could it not get air?

2- If your getting air and fuel there are only two things left, spark and timing.

3- Have you pulled the engine codes?
1st Gen FAQ: How to check the ECU Codes. And what are they?

4- Aside from fuel and engine/head failure the other issues that wont throw codes are a broken timing belt, broken lead plug wire (coil to dissi), distributor rotor failure and ground wires.

5- If the timing belt didn't break it isn't mechanical timing.

6- Check the rotor and lead plug wire.

7- Most of the ignition (spark) system is grounded to the engine bay side of the inner fender next to the batter through a white plastic plug it will have 4 or 5 small black wires running to it and is bolted to the body with an m6x1.0 10mm head bolt.
These grounds can corrode and so can the brass connector bolted to the body. If these ground connections loose or make poor contact the igniter gets no ground signal and won't fire the coil.

8- Start with 7 and figure out 1 with time and experience So 7, 2, 3, 4, 5, 6, 1

9- If you solve this issue please add the solution to this thread so it's not another dead end thread.

10- Details help diagnose car problems, so far you have given us "Car wont start, it's got air, it shoots fuel out the fuel line, changed the coil, still wont start".
 
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Discussion Starter · #3 ·
1- How could it not get air?

2- If your getting air and fuel there are only two things left, spark and timing.

3- Have you pulled the engine codes?
1st Gen FAQ: How to check the ECU Codes. And what are they?

4- Aside from fuel and engine/head failure the other issues that wont throw codes are a broken timing belt, broken lead plug wire (coil to dissi), distributor rotor failure and ground wires.

5- If the timing belt didn't break it isn't mechanical timing.

6- Check the rotor and lead plug wire.

7- Most of the ignition (spark) system is grounded to the engine bay side of the inner fender next to the batter through a white plastic plug it will have 4 or 5 small black wires running to it and is bolted to the body with an m6x1.0 10mm head bolt.
These grounds can corrode and so can the brass connector bolted to the body. If these ground connections loose or make poor contact the igniter gets no ground signal and won't fire the coil.

8- Start with 7 and figure out 1 with time and experience So 7, 2, 3, 4, 5, 6, 1

9- If you solve this issue please add the solution to this thread so it's not another dead end thread.

10- Details help diagnose car problems, so far you have given us "Car wont start, it's got air, it shoots fuel out the fuel line, changed the coil, still wont start".
Thank you for the tips on diagnosing, sadly my check engine light went off because I disconnect the battery before so no codes to help. I did try to check anyway but got no flashes from the check engine light. I went out today and checked to make sure the timing belt was good; it looks great and is spinning. That rules out timing for the most part. Next, I pulled plug one and used an extra plug to check for spark (grounded the plug to the battery) and sure enough no spark. I pulled the distributor cap off just to make sure that was spinning, and the camshaft didn't break. That looked good as well, but I still cleaned up the contact points to insure good connection. So, I am left with checking the grounds still, I will be doing that very shortly and getting back to this thread. I do have one more question though, I noticed this little device called the Igniter next to the ignition coil and was wondering if that could have gone bad?
 

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your problem is ignition related, you claim you replaced the coil, did you plug in the resistor balast back on the bottom, and also check the igniter, disconnect the igniter plug and check for corosion, usually green
 
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Discussion Starter · #5 ·
So, went out to check for corrosion and there is some green slime on the igniter but whipping it off didn't help, what's the best way to clean it? Also, when I went to try and start it, I got the check engine light back and it flashed for code 42 being the (Turbocharger Boost Control Solenoid Valve), would that keep it from starting and what could have gone wrong there?
 

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Discussion Starter · #6 ·
your problem is ignition related, you claim you replaced the coil, did you plug in the resistor balast back on the bottom, and also check the igniter, disconnect the igniter plug and check for corosion, usually green
I did find some green slime corrosion, is that what you mean? and what is the best way to clean it?
 

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Discussion Starter · #7 ·
I did some more testing since earlier and here is what I found; All the grounds look clean and tight, I will be pulling them all off and cleaning them when I get time and it's not so hot out, I live in Florida. I'm just going to rule that out for now. Also, I did some more testing with a multimeter. I put one side to ground on the battery and the positive side to the inside of the wire that goes from the ignition coil to distributor cap. When OFF position 0v, when ON position it got some voltage, and then when cranking it was at a little over 12v. Is this normal? If so that mean I am not getting spark across the distributor cap over to the plugs. I made sure the rotor was clean and the leads on the cap, so I just don't know what to do.
 

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Code 42, the turbo solenoid valve. Will not affect the car starting or running, most people running boost controllers remove it because it lowers boost at low and high rpms.

So you checked for spark at the plug wires and now your wondering if it's the rotor.
Take the spare plug and test the lead wire from the dissi for spark, I recommend using a bolt head to ground the plug to and not the battery.
Using a multimeter meter to test ignition spark isn't very accurate, the multi meter can't display the voltage fluctuations a quickly as they happen. Spark is related to amperage not voltage, you can have 12V that isn't strong enough to light a peanut bulb. An almost dead car battery can still put out 12V on a gauge or meter but won't have enough amperage to light dash gauges. So you can pick up a weak spark on a multimeter, one that's probably so weak it can spark a plug. By testing the Lead ignition wire using a plug you are eliminating the resistance of the cap-rotor-cap-plug wire, the spark should be stronger that a normal plug wire test and 4 times as frequent.

The ignition coil has two wires running to it one should be 12V+ constant when the key is comming from the main engine fuse in the black box next to the battery and the other should be pulsed signal from the igniter, this one can be tested using a multimeter and should put out a pulsing voltage of about 6V when trying to start the engine.

Cleaning corrosion can be done using electrical contact cleaner, personally for harness connectors I remove them from plug and clean them with a soft wire brush a the bench grinder or replace them. If the male pin connectors are part of something like the AFM or Igniter I would use an emery board nail file to clean the corrosion of the contacts.

You should use Dielectric grease on your connectors, it has many automotive uses, can keep spark from arching down the boot and water from getting in, protects connectors from water and corrosion, can be used on the outside metal of female spade/pin connectors to prevent them from corroding...

What is Dielectric Grease? | Blain's Farm & Fleet Blog

The 88-92 F2T is OBD1 although this is an onboard diagnostic system it also represents the type of computer that runs the engine, EEprom ecu's like the F2T don't run a Xmile diagnosis after reset, they are quite simple, if you unplug something it will flash a code, reset it and if the unit is still unplugged it will still flash a code. I don't know what triggers code 42/how the ECU monitors it, I know that if it's not connected it triggers the code, the solenoid has 2 wires, 12+ and Ground so either the ECU monitors the amperage traveling the 12+ or it only uses ground as a feedback wire and the solenoid is grounded through it's metal body, that means their is full continuity between the ground wire and solenoid valve, I don't think this is the case because I modify them and use them as adjustable electric boost controllers and they would always stay on if they grounded the electric solenoid through their body, I always pulse ground through relays and trigger the relays using toggled ground and run ignition switched, fused 12+ constant to all the crap I add to cars, why? because you can take a ground signal from anywhere and run it to the relay or toggle... more of the wiring will be to and from the toggle and relay and therefore most of the wiring can't short to ground due to chafing, rubbing pinching... Notice how factory wires have tons of plastic brackets that protect them from movement, friction and contact with anything. Have you seen any custom car build anywhere ever where they tapped plastic brackets to the wire harnesses and drilled holes throughout the body to attach them. (With exception on the permanent mount air compressor I have in the trunk, it's motor grounds through the body, when I first install it I wired it to trigger through ground and it just stayed on).


The ignition isn't the most complex on these cars, the ECU gets a pulse from the sensors inside the distributor and sends a signal based on that to the igniter that amplifies the signal and sends it to the coil. There are other signals the ECU uses to choose the timing delivered to the igniter but the dissi sensors tell it RPM and physical engine timing (cam/rotor position).
So distributor, ecu, igniter, coil.
1 - check the connectors at each of these, make sure there is no corrosion and good contact.
2- check the wires between each of these and make sure there is continuity.
3- check the signals (volage, ground...) at each connector.
4- Check each item for proper function.
 
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Discussion Starter · #9 ·
Code 42, the turbo solenoid valve. Will not affect the car starting or running, most people running boost controllers remove it because it lowers boost at low and high rpms.

So you checked for spark at the plug wires and now your wondering if it's the rotor.
Take the spare plug and test the lead wire from the dissi for spark, I recommend using a bolt head to ground the plug to and not the battery.
Using a multimeter meter to test ignition spark isn't very accurate, the multi meter can't display the voltage fluctuations a quickly as they happen. Spark is related to amperage not voltage, you can have 12V that isn't strong enough to light a peanut bulb. An almost dead car battery can still put out 12V on a gauge or meter but won't have enough amperage to light dash gauges. So you can pick up a weak spark on a multimeter, one that's probably so weak it can spark a plug. By testing the Lead ignition wire using a plug you are eliminating the resistance of the cap-rotor-cap-plug wire, the spark should be stronger that a normal plug wire test and 4 times as frequent.

The ignition coil has two wires running to it one should be 12V+ constant when the key is comming from the main engine fuse in the black box next to the battery and the other should be pulsed signal from the igniter, this one can be tested using a multimeter and should put out a pulsing voltage of about 6V when trying to start the engine.

Cleaning corrosion can be done using electrical contact cleaner, personally for harness connectors I remove them from plug and clean them with a soft wire brush a the bench grinder or replace them. If the male pin connectors are part of something like the AFM or Igniter I would use an emery board nail file to clean the corrosion of the contacts.

You should use Dielectric grease on your connectors, it has many automotive uses, can keep spark from arching down the boot and water from getting in, protects connectors from water and corrosion, can be used on the outside metal of female spade/pin connectors to prevent them from corroding...

What is Dielectric Grease? | Blain's Farm & Fleet Blog

The 88-92 F2T is OBD1 although this is an onboard diagnostic system it also represents the type of computer that runs the engine, EEprom ecu's like the F2T don't run a Xmile diagnosis after reset, they are quite simple, if you unplug something it will flash a code, reset it and if the unit is still unplugged it will still flash a code. I don't know what triggers code 42/how the ECU monitors it, I know that if it's not connected it triggers the code, the solenoid has 2 wires, 12+ and Ground so either the ECU monitors the amperage traveling the 12+ or it only uses ground as a feedback wire and the solenoid is grounded through it's metal body, that means their is full continuity between the ground wire and solenoid valve, I don't think this is the case because I modify them and use them as adjustable electric boost controllers and they would always stay on if they grounded the electric solenoid through their body, I always pulse ground through relays and trigger the relays using toggled ground and run ignition switched, fused 12+ constant to all the crap I add to cars, why? because you can take a ground signal from anywhere and run it to the relay or toggle... more of the wiring will be to and from the toggle and relay and therefore most of the wiring can't short to ground due to chafing, rubbing pinching... Notice how factory wires have tons of plastic brackets that protect them from movement, friction and contact with anything. Have you seen any custom car build anywhere ever where they tapped plastic brackets to the wire harnesses and drilled holes throughout the body to attach them. (With exception on the permanent mount air compressor I have in the trunk, it's motor grounds through the body, when I first install it I wired it to trigger through ground and it just stayed on).


The ignition isn't the most complex on these cars, the ECU gets a pulse from the sensors inside the distributor and sends a signal based on that to the igniter that amplifies the signal and sends it to the coil. There are other signals the ECU uses to choose the timing delivered to the igniter but the dissi sensors tell it RPM and physical engine timing (cam/rotor position).
So distributor, ecu, igniter, coil.
1 - check the connectors at each of these, make sure there is no corrosion and good contact.
2- check the wires between each of these and make sure there is continuity.
3- check the signals (volage, ground...) at each connector.
4- Check each item for proper function.
Okay, that makes sense because I do have a boost controller. It was hooked up by the last owner, so I didn't know much about it. I did get around to cleaning the grounds and ensuring the connectors to the coil were clean. I don't think it is corrosion anywhere because I am in Florida, and it was running and driving the day before. I will test for that 6v pulsing next to see if it is the igniter.
 
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