97 regal gs

[nextplay]

Runs good but will not start sometimes and does not seem to get a spark when it happens. Is getting fuel. Battery and alternator check out fine. Is very intermittent and usually happens after driving it and trying to restart when still hot. Are the coils or module bad. Car has 140,000 miles. Always starts right off when not hot.

[HotZ28]

Are you showing RPM when it don't start?

[nextplay]

I do not recall if the rpm is moving when cranking. Most of the time when it does this no start thing, I have just driven it and go in a store, come out and it won't start. Cranks freely but acts like no fire. I have had times where the battery ran down trying to start it and when I would jump it, it would start right up. Other times, I just let is sit for awhile and it starts right up. It used to do the no start thing every couple of months, now it is happening all the time. Is it possible that the battery, even though it checks out good, is not pushing enough juice to fire the engine enough. It is an old delco battery and the looking glass is black. I want to suspect the ignition control module.

[HotZ28]

Originally Posted by nextplay

I want to suspect the ignition control module.

You might also want to suspect the crank sensor (CKPS) especially if you have no RPM when trying to start. Have you had the battery checked under load? I do not think this is the problem since the starter seems to be turning the engine over for some time. First, you need to check for spark when you have a "no start".

[BNaylor]

Are you sure that is a valid test Bo (HotZ28)? By looking at the tach while cranking?

I don't get jack on my tachs on my Regal GS or LS during cranking until the engine fires up. Tried it with all plug wires disconnected too. Nothing.

To the OP what was your fuel pressure readings or how did you determine it was in specs?

[HotZ28]

Originally Posted by BNaylor

Are you sure that is a valid test Bo (HotZ28)? By looking at the tach while cranking?

Yes Bob, this is absolutely a valid test and I have been using this method for years with excellent results. All of my Ultra & LeSabre tachs respond as soon as I turn on the ignition (the needle moves) and as soon as the engine starts to turn over, (300 RPM) shows clearly on the scale.

I don't get jack on my tachs on my Regal GS or LS during cranking until the engine fires up. Tried it with all plug wires disconnected too. Nothing.

If your tachs are not responding, I don’t know what to say, except that you must have some LAZY tachs! It could be that your tachs operate so often the high side of the scale (5-6K), that they don't like to respond less than 300 rpm.

In my case, rpm's are very easy to see. If the CKPS is working correctly, it will send a crank signal to the ICM from terminal B (Yellow wire) to terminal G of the ICM. In addition, CKPS terminal A (light blue-white wire) provides the sync signal to the ICM terminal H. When all sensors and the ICM are working as intended, the ICM will send the tach signal from terminal “E” (white wire) to the IC tach.

If you have a slow to respond tach, look at engine RPM on a scanner with all ignition wires disconnected. If a crank signal is present, the scanner will show 250-275 rpm when the starter is turning engine over. Of course, No (0) RPM, would indicate – no crank signal from the CKPS.

[BNaylor]

I'm aware of how the circuit works and have GM FSMs. It may work on your model GM cars but sure as hell doesn't work that way on any of mine which are Regals by the way. IMO the tachs are working just fine and not slow.

Maybe the '97 and up Regal PCM modules must be programmed different for tach display or maybe something in the IP. All I can say is none of my tachs read anything with a good battery and all ignition wires disconnected at the coil packs no matter how long I crank. Plus add my GTP.

Best way to check a CKPS is with an oscilloscope if you happen to have one.

[HotZ28]

Originally Posted by BNaylor

Best way to check a CKPS is with an oscilloscope if you happen to have one.

Have you tried looking at rpm on a scanner? It could be that the Regal & GTP just has a cheap tach; No offense intended. BTW, very few people have an oscilloscope at their disposal! I do, but never have a need to use it!

[BNaylor]

Originally Posted by HotZ28

Have you tried a scanner as suggested? It could be that the Regal & GTP just has a cheap tach; No offense intended.

Cheap tach? I doubt it.

Was the issue using an odb-ii scanner or having the member read off the tach on the IP? I don't recall your first post mentioning a scanner.

Originally Posted by HotZ28

Are you showing RPM when it don't start?

[HotZ28]

Originally Posted by BNaylor

Cheap tach? I doubt it.

Was the issue using an odb-ii scanner or having the member read off the tach on the IP? I don't recall your first post mentioning a scanner.

Well, if you read my first post:

Are you showing RPM when it don't start?

I did not specify whether the OP should be looking at the IP tach or a scanner. Obviously, the scanner is the best choice!

[BNaylor]

Originally Posted by HotZ28

Well, if you read my first post: I did not specify whether the OP should be looking at the IP tach or a scanner. Obviously, the scanner is the best choice!

Obviously. Yeah every forum member has a full function odb-ii scanner in their back pocket.

But it is a dead issue on the IP tach.

[HotZ28]

Originally Posted by BNaylor

But it is a dead issue on the IP tach.

May be for you, but not me! BTW, I have never had the need to, but I just hooked up my scanner to my 2006 Z71 Silverado and it reads starting RPM, so this is not a year or model issue! The IP display tach was also showing start rpm!

[BNaylor]

Originally Posted by HotZ28

May be for you, but not me! BTW, I have never had the need to, but I just hooked up my scanner to my 2006 Z71 Silverado and it reads starting RPM, so this is not a year or model issue! The IP display tach was also showing start rpm!

Double

Again obviously scanner tach readouts are more accurate or have a better scale so I can see getting the start rpms. But I still don't get anything on my IP tachs so I am assuming there is no problem. And add an '02 Alero GL2 with the 3400 SFI engine which has the same DIS system. With ignition wires removed at coil packs and long cranking - 0 rpms. Me thinks it has something to do with how the IP powers up after ignition. Either the 12 volts (IGN) or grounding.

BTW - Test it out on a '97-'04 Regal and let me know what you find.

[HotZ28]

Originally Posted by BNaylor

Double
Me thinks it has something to do with how the IP powers up after ignition. Either the 12 volts (IGN) or grounding.
BTW - Test it out on a '97-'03 Regal and let me know what you find.

Thanks Bob, for your detailed description on how the Regal/Alero GL2 tachs work, (or don’t) As you say, it could very well be something missing in the IP power-up. I will be looking for someone with a 97-03 Regal for testing and let you know what I find, either here, or by PM. This may take awhile, since I don’t know anyone handy who owns one!

[BNaylor]

Originally Posted by HotZ28

Thanks Bob, for your detailed description on how the Regal/Alero GL2 tachs work, (or don’t) As you say, it could very well be something missing in the IP power-up. I will be looking for someone with a 97-03 Regal for testing and let you know what I find, either here, or by PM. This may take awhile, since I don’t know anyone handy who owns one!

I'm handy. If you want to waste your time and effort like I did then go right ahead. I won't hold my breath either.