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Stutter


Ranger

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Plug wires can be faulty in two ways.

1/ When measuring Resistance, like you have done, and if the wire has a very high Resistance, (much higher than yours), then the "spark" does not have enough energy to complete the journey to the plug, due to the high resistance.

2/ The wire can measure the correct resistance, however it can have a crack or break in the insulation and the "spark" could jump to ground. (path of least resistance).

This is the reason for the water spray test. However it is not always conclusive as the break may be under a wire laying on a ground location and not be visible.

By "disturbing" the wires, you may have moved the crack/break from it's path to ground, then after a short period of time, the wire may have vibrated back to it's original location.

Of course this is all theory and may not be your problem. Just passing along some more things to try.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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This leads me to beleive that the 2.99 measured on #6 is actually 29,900 or 29.9K, well over the 15K max. I think the decemal just moves with the setting you use on the DVM but like I said this is not my strong point and want to be sure. I'm hoping someone will varify this tonight so I can get a new set of wires somewhere tomorrow morning before I have to go to work. Obviously I probably won't be able to get Delco's (don't want to pay dealer prices) unless I call Rock Auto and have them shipped in a day or two.

Larry, consider going to Radio Shack and buying a few resistors with a known value as a benchmark to better help you understand your meter, Mike

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Larry, consider going to Radio Shack and buying a few resistors with a known value as a benchmark to better help you understand your meter, Mike

Good idea, Mike. But Larry be careful, do not rely on help from sales people. I could not find a resistor at Radio Shack which would match the one on my key and had to buy two resistors to put them in parallel. When I said the guy what I was going to do he looked at me like :blink::blink::blink:

The saddest thing in life is wasted talent

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Larry, consider going to Radio Shack and buying a few resistors with a known value as a benchmark to better help you understand your meter, Mike

Good idea, Mike. But Larry be careful, do not rely on help from sales people. I could not find a resistor at Radio Shack which would match the one on my key and had to buy two resistors to put them in parallel. When I said the guy what I was going to do he looked at me like :blink::blink::blink:

I was not implying that it had anything to do with his key, I was suggesting he buy say a 5,000 ohm resistor, 10,000 ohm resistor, a 1 MEG resistor, and a 4.7 ohm resistor and do a direct read with is digital meter to see what 5,000, 10,000, 1 MEG and 4.7 ohm looks like on his meter. That will help him interpret his ignition wire readings and get to know his meter better with a known value.. They sell packs of resistors cheap. Just a thought.

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It seems that no one knows whether those readings indicate at bad wire or not so I think at this point I have no choice but to throw a set of wires at it and see if it helps.

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Just called Rock Auto. $116 for a set of Delco wires. WOW! I did not order them. I have to be sure before I throw $116 at this thing. I have eliminated plugs and coils so I guess it's gotta be wires or ICM. Wires seem most logical to me. Am I missing anything? Does this seem logical to everyone else?

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Just called Rock Auto. $116 for a set of Delco wires. WOW! I did not order them. I have to be sure before I throw $116 at this thing. I have eliminated plugs and coils so I guess it's gotta be wires or ICM. Wires seem most logical to me. Am I missing anything? Does this seem logical to everyone else?

I think I bought them cheaper at caddy, did you check, also check www.gmotors.com

Mike

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Ranger,

I just saw a pocket spark plug/wire tester at Wal-Mart for $3.00. It's kind of gas dischurge tube. You can judge on the condition of wires by the brightness of the tube. I thought it might be of interest to you.

The saddest thing in life is wasted talent

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Thanks Adallac. I have an old one from years ago that is a screw driver with a light in the handle. I had ground the tip to a point in my younger (dumber) days to pierce the cable. I was just thinking about putting it on the lathe and turning the tip down and threading it to take an old spark plug tip. Should work pretty good. If not I'll check Wal-Mart. I have to do something soon though and I am about ready to just bite the bullet and order a set from Rock Auto and hope that is the problem.

Mike, I checked Brasington (gmotors.com) and after shipping they are the same price as Rock Auto.

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Where is Jason? I was just searching the archives and I ran across his post with the exact same symptoms as mine. He was leaning towards wires also but the post got sidetracked and there was never a conclusion. I also noticed that he never piped in on my problem. JASON, WHERE FORTH ART THOU?

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JASON, WHERE FORTH ART THOU?

:lol:

Right, Jason ordered wires from gmpartsdirect.com and cancelled the order. Hate that .com. BTW, his symptoms showed up after fuel rail replacement. Gosh, you better never touch those wires. :angry:

The saddest thing in life is wasted talent

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Do not feel bad Ranger I have been following your post and all the other posts on this subject. I too have a stutter on gentle acceleration on my 94 Concours. I have changed the fuel filter, air filter, new OEM plugs, $90 for OEM wires, I misted the new wires, I have cleaned my phenolic plates 4 times, cleared the mouse holes and EGR passages, checked the EGR, I have done all the tests in the manual and I still can not cure mine. I read a post from BBobynski a while back and I am leaning toward the Fuel Pressure Regulator and/or the crank sensor. I did put some dielectric grease in the plug wires and I think it helped a little. I do get a P071 occasionally which is the MAP sensor, but I do not think that is the problem. I am going to check my FPR this weekend if the rain lets up. I will let you know what I find. Mine will cruise down the interstate just fine, but pull a hill and it starts. It is really frustrating.

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This is way off topic but a friend of mind had a stumble off idle from a light in a Chevy years ago and I pulled my hair out with it and NEVER figured it out. I rebuilt the carb as the accelerator pump in the carb used to cause that. Did everything and never nailed it. Very Frustrating

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Paul, it's somewhat (though not much) comforting to know I am not alone. I guess misery loves company. I just pulled the plug wires one at a time and plugged a spark plug tester (screwdriver with a light in the handle into each wire. They all fire normally (at idle loads). The engine idles smooth as glass even on 7 cylinders while testing. The problem seems to be at heavier engine loads ie: 45+ MPH, TCC engaged and light throttle. I am trying follow Guru's advise and diagnose it properly rather than throw parts at it. There are several variables, ICM, camshaft sensor and crankshaft sensors but I am not sure if they will cause the symptoms I am experiencing. Sure wish Guru, Logan or one of the techs would chime in here. This is frustrating.

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The ideal method would be to hook up a Tech-2 and run the misfire graph....that would pinpoint the problem in short order.

Awhile back, Logan mentioned a rental program for a Tech-2 but I don't recall if it became reality.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The ideal method would be to hook up a Tech-2 and run the misfire graph....that would pinpoint the problem in short order.

Awhile back, Logan mentioned a rental program for a Tech-2 but I don't recall if it became reality.

Yeah, I have thought about the tech II. I'm not sure I'd know how to use that thing anyway. If I cannot figure this out I will only have two choices. Pay for a diagnostic or start throwing parts at it. I am stubborn enough to throw parts but I'd sure like to win this battle on my own. Pride I guess, you know, never surrender, death before dishonor, go down fighting, etc.

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The ideal method would be to hook up a Tech-2 and run the misfire graph....that would pinpoint the problem in short order.

Awhile back, Logan mentioned a rental program for a Tech-2 but I don't recall if it became reality.

Yeah, I have thought about the tech II. I'm not sure I'd know how to use that thing anyway. If I cannot figure this out I will only have two choices. Pay for a diagnostic or start throwing parts at it. I am stubborn enough to throw parts but I'd sure like to win this battle on my own. Pride I guess, you know, never surrender, death before dishonor, go down fighting, etc.

Larry,

There is a way to monitor the misfire counts per cylinder in the onboard diagnostics. The instructions are in the service manual.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I was looking through the service manual today and there was a mention that all cars may not be able to use the inputs, outputs and peramiters. I suspect mine is one of them because after the DTC's are listed I get PCM? or CLEAR CODES?. I cannot get beyond that. I never get a prompt for INPUTS, OUTPUTS or PERAMETERS. I could do that on my '92 (OBD I) but it seems OBD II is not so user friendly.

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I think it is under the PCM section. I recall stumbling across it awhile back by accident.....my Seville is a '96 and is OBD-2.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I'll check again tomorrow as I am at work now but in the meantime I'm gonna order a set of wires. Probably from Rock Auto since Paul hasn't got back yet. This is getting crazy and I think everything points to wires.

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Paul T., where did you find OEM wires for $90? Best I can find is $116 + shipping at Rock Auto.

I got them from a local GM dealer. I am on good terms with the parts guy and he gives me the same break that they give local mechanics. I usually check gmpartsdirect.com for prices then go to the dealer and see if I can get a similar deal, most of the time I have to pay a little more but it is still cheaper than paying for shipping.

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