Intermittent no start condition - Page 5

Rich Biebel · 09-19-2013, 09:33 AM

The sensor outputs a very low voltage and it would be millivolts......

A Fluke can read this accurately....

I just had some trouble with the ABS sensors in my GMC....

They do the same thing.......and can easily lose low speed output from rust building up under them. I found the info readily available online as to what they should read just by turning the wheels by hand......and a little work with a file and a wire brush.....and Viola....all better...

That was after I had already replaced both sensors and they were probably good.....

John Nechiporchik · 09-19-2013, 09:44 AM

Mike/Joe/Kirk,
I did the test of the crank trigger as Joe stated. Simple and effective.
Next, I spoke to MSD and the tech rep indicated the ohms reading of the MSD pickup (test leads on purple and green wires) should be between 65 and 85 ohms. This is for the non magnetic pick-up.....magnets are in the wheel, not the sensor.

Will test mine tonight along with using my newly acquired noit light to test injectors.
Also got a few other areas to check (connections, grounds etc) tonight.

buzzinhalfdozen · 09-19-2013, 12:50 PM

Rich , I believe there is a special coverage for the wheel speed sensors you can check with your local GM dealer as it varies year to year. We clean and apply a compound to the knuckle so rust doesn't redevelope. John, good deal testing this stuff is not hard at all, but does require a few items, sounds like you're on top of it. Joe Oh and sorry bout that wrong resistance spec, I was shooting from the hip on that, which is the spec GM uses withtheir sensors must have got stuck in my head.

Steve Williams · 09-19-2013, 05:20 PM

Quote:

Originally Posted by Kirk Morgan

I have been working on this stuff since it all started, Certified mech for 30 years. I went to a A/C Delco class many years ago and learned that the magnet type makes A/C voltage when cranking. I believe the spec is 3 volts. I can dig out my old books to confirm if needed. That will confirm signal strength which can cause intermittent problems.

Kirk

This is exactly what I was referring to when I spoke of voltages and weak signal.

John Nechiporchik · 09-19-2013, 08:54 PM

FED 387....after testing every circuit I could test....it appears that the only logical conclusion I can come to is the coil is the problem, as you stated a few days ago.
Tonight, I checked the ohms on the crank trigger sender....78.2 (MSD said between 65-85)...OK
Tried to start....fired right up.
Repeated 2 more times and fired up.
4th. try....no start
Grounded coil wire (dist. end) to block in two different locations approx. 1/16 gap......no spark
Tried again about 15 minutes later....spark like 4th of July.
Replaced coil wire.....fired right up.

Gotta be the Friggin coil.....
Going to get one tomorrow.

John Nechiporchik · 09-20-2013, 09:31 AM

Went through test process again this morning.
I believe when I tested the coil last night (metal screw in dist end of not) I did not have a proper connection.When I use a spark tester, it gives me a signal.
Throw out last nights test.
Tried to start car this AM....fires right up
Second try ...no start.
put spark tester on coil AND noid tester on injector simultaneously...Result...no start, spark at coil, NO light at noid tester.
Repeated several times same result.
HELP AGAIN!!

Rich Biebel · 09-20-2013, 11:29 AM

John....It sounds to me as I said before.....You have an intermittent wire connection problem between the ECU and your MSD or possibly your battery connections to your ECU.

It has been to long for me to recall the exact wiring connections needed between the MSD and the Accel ECU.....

Accel still shows the wiring diagrams and tons of info on their website.

The ignition connector on the Accel unit and all the connections related to it are where I believe your trouble may be. Your ECU needs to be switched on and also gets a tach signal from the MSD....

Without actually seeing your car and wiring it's impossible to tell you how to fix it.

You have isolated the problem and now know it IS the injectors are not turning on and supplying fuel to the engine......so the ignition system is not the problem.....

Kirk Morgan · 09-20-2013, 11:33 AM

Check for battery voltage in the injector harness when you have a no start condition.

Kirk

Rich Biebel · 09-20-2013, 11:58 AM

This is for a Gen VII Accel ECU and may be helpfull

The connector labeled IGNITION is what powers up the ECU....

http://data.prestoliteperformance.co...ng_diagram.pdf

A lot of info available here..

http://info.accel-ignition.com/dfi/a...-download.html

John Boland · 09-20-2013, 08:05 PM

The battery is something to consider before you spend real money. It could be failing in a way that it is generating electrical noise.

09-19-2013, 09:33 AM	#41
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Intermittent no start condition The sensor outputs a very low voltage and it would be millivolts...... A Fluke can read this accurately.... I just had some trouble with the ABS sensors in my GMC.... They do the same thing.......and can easily lose low speed output from rust building up under them. I found the info readily available online as to what they should read just by turning the wheels by hand......and a little work with a file and a wire brush.....and Viola....all better... That was after I had already replaced both sensors and they were probably good..... __________________ Rich Biebel S/C 1479 Stock 147R

09-19-2013, 09:44 AM	#42
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 316 Likes: 84 Liked 13 Times in 7 Posts	Re: Intermittent no start condition Mike/Joe/Kirk, I did the test of the crank trigger as Joe stated. Simple and effective. Next, I spoke to MSD and the tech rep indicated the ohms reading of the MSD pickup (test leads on purple and green wires) should be between 65 and 85 ohms. This is for the non magnetic pick-up.....magnets are in the wheel, not the sensor. Will test mine tonight along with using my newly acquired noit light to test injectors. Also got a few other areas to check (connections, grounds etc) tonight.

09-19-2013, 12:50 PM	#43
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 984 Likes: 0 Liked 11 Times in 8 Posts	Re: Intermittent no start condition Rich , I believe there is a special coverage for the wheel speed sensors you can check with your local GM dealer as it varies year to year. We clean and apply a compound to the knuckle so rust doesn't redevelope. John, good deal testing this stuff is not hard at all, but does require a few items, sounds like you're on top of it. Joe Oh and sorry bout that wrong resistance spec, I was shooting from the hip on that, which is the spec GM uses withtheir sensors must have got stuck in my head. __________________ Joe Buchanan SS/BX 3117 Last edited by buzzinhalfdozen; 09-19-2013 at 01:22 PM.

09-19-2013, 08:54 PM	#45
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 316 Likes: 84 Liked 13 Times in 7 Posts	Re: Intermittent no start condition FED 387....after testing every circuit I could test....it appears that the only logical conclusion I can come to is the coil is the problem, as you stated a few days ago. Tonight, I checked the ohms on the crank trigger sender....78.2 (MSD said between 65-85)...OK Tried to start....fired right up. Repeated 2 more times and fired up. 4th. try....no start Grounded coil wire (dist. end) to block in two different locations approx. 1/16 gap......no spark Tried again about 15 minutes later....spark like 4th of July. Replaced coil wire.....fired right up. Gotta be the Friggin coil..... Going to get one tomorrow.

09-20-2013, 09:31 AM	#46
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 316 Likes: 84 Liked 13 Times in 7 Posts	Re: Intermittent no start condition Went through test process again this morning. I believe when I tested the coil last night (metal screw in dist end of not) I did not have a proper connection.When I use a spark tester, it gives me a signal. Throw out last nights test. Tried to start car this AM....fires right up Second try ...no start. put spark tester on coil AND noid tester on injector simultaneously...Result...no start, spark at coil, NO light at noid tester. Repeated several times same result. HELP AGAIN!!

09-20-2013, 11:29 AM	#47
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Intermittent no start condition John....It sounds to me as I said before.....You have an intermittent wire connection problem between the ECU and your MSD or possibly your battery connections to your ECU. It has been to long for me to recall the exact wiring connections needed between the MSD and the Accel ECU..... Accel still shows the wiring diagrams and tons of info on their website. The ignition connector on the Accel unit and all the connections related to it are where I believe your trouble may be. Your ECU needs to be switched on and also gets a tach signal from the MSD.... Without actually seeing your car and wiring it's impossible to tell you how to fix it. You have isolated the problem and now know it IS the injectors are not turning on and supplying fuel to the engine......so the ignition system is not the problem..... __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 09-20-2013 at 11:32 AM.

09-20-2013, 11:33 AM	#48
Kirk Morgan Member Join Date: Jan 2009 Posts: 230 Likes: 1 Liked 80 Times in 44 Posts	Re: Intermittent no start condition Check for battery voltage in the injector harness when you have a no start condition. Kirk

09-20-2013, 11:58 AM	#49
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Intermittent no start condition This is for a Gen VII Accel ECU and may be helpfull The connector labeled IGNITION is what powers up the ECU.... http://data.prestoliteperformance.co...ng_diagram.pdf A lot of info available here.. http://info.accel-ignition.com/dfi/a...-download.html __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 09-20-2013 at 12:27 PM.

09-20-2013, 08:05 PM	#50
John Boland Junior Member Join Date: Apr 2008 Location: Baltimore, MD Posts: 46 Likes: 0 Liked 2 Times in 2 Posts	Re: Intermittent no start condition The battery is something to consider before you spend real money. It could be failing in a way that it is generating electrical noise.