won't start
Thread Starter
Racer
Joined: Mar 2002
Posts: 309
Likes: 6
From: Troy Al
won't start
My '93 coupe turns over but does not start. I maintain between 40-20 lbs on the fuel pump guage. A spark at the plug. Also it failed the either down the throttle body test. No codes. This seems a strange problem. Any solutions appreciated.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
Timing is off, check to see if the distributor is tight. High miles car? Mabe you jumped time. Is the spark strong? Could be module or coil.
Thread Starter
Racer
Joined: Mar 2002
Posts: 309
Likes: 6
From: Troy Al
102,000 miles. ICM is suspect. Because it is over $100, I may have to wait a week or 2. I have another coil to try. The last opti I changed, about 200 miles ago, I put the MSD cap and rotor on a new A/C dist. I am suspicious of the rotor button coming loose because they warn to use loctight on the screw. I did. But I have terrible luck with this car.
No noid light. Maybe it's time to get one...
No noid light. Maybe it's time to get one...
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
If you don't have a noid light, place some fingers on 2 of the injectors, while someone cranks. You should be able to feel the vibration when they open and close.
Opti, glad I don't have one.
Opti, glad I don't have one.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
It is a good idea to check the injector drive with a noid light. It will not only tell you that you have drive (or not) to the injectors, but will also verify that the opti is putting out the low resolution pulse and the ECM is clocking it thru. That same opti pulse is used for the drive for the ICM from the ECM.
Check the spark off the coil compared to a plug wire. Should be the same which is 1/2" spark to ground.
Also check your coil wire where it goes thru the water pump to make sure it's not sparking or grounding out killing the spark.
Check the spark off the coil compared to a plug wire. Should be the same which is 1/2" spark to ground.
Also check your coil wire where it goes thru the water pump to make sure it's not sparking or grounding out killing the spark.
Thread Starter
Racer
Joined: Mar 2002
Posts: 309
Likes: 6
From: Troy Al
Noid lights seem to come in lots of styles and prices. Most kits come with 6. It that ok, or do I need 8? Does this stick on over the injector to test? Will the cheap set do the trick, or do I need to look for some specific ability?
Of course a bigger question is, if the rotor button had worked a little loose inside the dist. would I still be getting fire? I plan to test the coil output today. I put a MSD blaster on back when I did the last opti. I still have the old stock coil on it to compare.
thanks!
Of course a bigger question is, if the rotor button had worked a little loose inside the dist. would I still be getting fire? I plan to test the coil output today. I put a MSD blaster on back when I did the last opti. I still have the old stock coil on it to compare.
thanks!
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Noid lights seem to come in lots of styles and prices. Most kits come with 6. It that ok, or do I need 8? Does this stick on over the injector to test? Will the cheap set do the trick, or do I need to look for some specific ability?
Of course a bigger question is, if the rotor button had worked a little loose inside the dist. would I still be getting fire? I plan to test the coil output today. I put a MSD blaster on back when I did the last opti. I still have the old stock coil on it to compare.
thanks!
Of course a bigger question is, if the rotor button had worked a little loose inside the dist. would I still be getting fire? I plan to test the coil output today. I put a MSD blaster on back when I did the last opti. I still have the old stock coil on it to compare.
thanks!
You can always make a noid light with a LED and a 680 ohm resistor in series with it. Got to get the correct polarity of the LED connecting it to make it work and light up.
You can hook up the original coil just for testing. Don’t need to mount it, just hook up the connectors and let it hang. It will work just fine.
"Generally", if the ICM is defective, it will put out its full output or nothing at all. It usually does not have a weak output that would lower the amount of spark you get.
Usually the rotor is going around in one piece or not. If it came loose and broke, you would get nothing. Either it works or it does not. And of course you know there is no timing question here. The opti goes on in just one position and all timing is performed by the ECM and related inputs to it.
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Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
The high side (of injector) is the voltage supply of 12 volts from the bus via the injector fuse. So it will always sit at 12 volts. If the low side does not go to ground for the injector pulse, then the ECM is not providing the injector drive.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
You can check injector pulses by disconnecting one injector connector and probing the two pins with a voltmeter. One pin will be battery voltage and the other will be the pulses from the ECM (the engine needs to be running). You can see the voltage reading jumping around on the pin with the pulses. On my car that's the light green or light blue wire. All 8 injectors are connected together inside the ECM so it doesn't matter which bank or which injector you test.
This is what the injector pulses look like on my car at idle:
This is one of many ECM waveforms I posted on my web site at:
http://home.earthlink.net/~cliff_har...waveforms.html
This is what the injector pulses look like on my car at idle:
This is one of many ECM waveforms I posted on my web site at:
http://home.earthlink.net/~cliff_har...waveforms.html
