loosing 1 plug, will you notice

[lwmuddy]

Will the computer increase the injector flow on the remaining 7 plugs if 1 fails.
Will you feel a Radical difference when this happens.
Will you hear a big difference at the exhaust pipelike Putt-Putt-Putt?
Spent most of my years in Diesels [DDA Series 60's].
I'm new to the V8.1

[lwmuddy]

Will the computer increase the injector flow on the remaining 7 plugs if 1 fails.
Will you feel a Radical difference when this happens.
Will you hear a big difference at the exhaust pipelike Putt-Putt-Putt?
Spent most of my years in Diesels [DDA Series 60's].
I'm new to the V8.1

[Full-Timers]

For some reason all 3 of my failures felt different. The first one wasn't even noticeable except for a slight rough idle and if you went back by the tail pipe you could hear it. The second one was more sever. You could feel it driving and there was a definite lack of power. The third one only was apparent under heavy load in 4th gear at high rpms. Idle was fine and cruising was fine.

[golferdhm]

I lost one plug a few times because the plug wire came loose. I didn't notice anything on the flat or when idling, but there was a noticeable lack of power on hills, and the gas mileage plummeted at least a mile per gallon.

[Steady Eddie]

What I want to know is:
When you lost a plug, a misfire, did
the PCM throw a code and light up the
MIL light, or Service Engine Soon light?

[troth]

Good question Steady Eddie!!! I want to know too.
I would presume if the plug was constantly not firing it might cause a light (Service Engine soon) on the Actia dash; -or a message across the LCD...
But what if the misfire was intermittent? My gas mileage sucks, ranging from 6.0 to 7.5 mpg. How do I know whether or not I've got a spark plug acting up ? Is the intermittent stuff stored on the OBDII?

[Full-Timers]

All 3 of my failures, I never had a light come on.

[golferdhm]

Ditto with Full-Timers, when my plug wire came loose, there was not warning except for the loss of engine performance and lowered gas mileage.

[Steady Eddie]

Ohhhh--that's what I was afraid of,
gives me a headache. I've got the same
"stuff" in the L21 Vortec--it should throw
a code and light up the SES/MIL light, I'd
think (?) The Vortec has so much power most
of us would never know if it dropped a cylinder.
Or, had one bad plug wire. It should throw a
P0300 for an intermittent miss or a P0301 for
cyl. #1 thru P0308 for cyl. #8.....

[troth]

Hmmm.... This is bugging me now. Back in April we went to Florida pulling the toad. Running from NE Ohio down thru the WVa mountains to Wytheville, not using genny and traveling at 60 -62 mph, we had 6.7 mpg. That gas mileage was not per the Actia dash, but rather the actual caluation based on gallons filled up. On the return trip from Florida to back home just one week later, we calculated 7.5 mpg. This was basically under the same conditions and same leg of the trip through the mountains. So I wonder why the difference in gas mileage, and must admit there are some times going up hills when I'd expect more performance from the 8.1....
Is there an aftermarket scanner that could plug into the OBDII under my dash and give real time info which would prove that a spark plug was missing?

[Steady Eddie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by troth:
Hmmm.... This is bugging me now......
Is there an aftermarket scanner that could plug into the OBDII under my dash and give real time info which would prove that a spark plug was missing? </div></BLOCKQUOTE>

troth---
There are a bunch of OBDII scanner programs out there, that will interface with
a lap-top PC. All I have is a $199 Code Reader hand-held unit. It has bailed me out
several times. Personally, I have a couple of issues going on here. My GM-printed
Chassis Service Manual shows the codes that our P12 Chassis will throw. The random
mis-fire code and individual cylinder codes ain't on the list (?) The Manuals also
show which sensors will throw a code and set the SES or MIL light. Again, a missing
spark indication is not on the list (?) So, I was mulling this over a bit, and thought: "I'll just go yank a plug wire off and see if it'll throw a code..."
But, forcing a code requires a healing period of time whereby the OBDII brain-box
has to re-learn the parameters monkeyed with. You can "clear the codes" with a
code reader. That'll put out the SES/MIL light. But, as per the Chassis Manuals, it takes 40 warm-up and run cycles to re-learn everything. And a GM warm-up cycle is a monster, it requires among other things, sustained travel at road speeds and coasting with no brakes, etc. I'm sure that DriVer will jump in here and say that
the dealer-used Tech II scanner will re-set the brain-box back to square one, which
it will--for a fee--locally it is 89 bucks for the hook-up and 15 bucks for each
"operation" performed. The *system* is not set up for the DIY guy.

How many times, around the campfire, have we heard something like: "I changed the
spark plugs and it just keeps running better and better..." (?) The OBDII is re-learning the new plugs.....

[rvr2352]

Last month, northbound out of Destin, Fla I dropped a cyl immediately from cold start-up. We pulled into a WH service facility in Prattville, AL after talking to WH and "Prattville Auto and RV Repair" on the cell and assuring them I didn't need a tow. It was the #5 plug wire which came off BECAUSE IT HAD BEEN BENT/CRUSHED apparently during manufacturing. It was the 32nd WH chasis they encountered with either the #4 or #5 wire end in failure mode. In my mind, this likely was a body builder issue but the more I considered it, the more I wondered why so many different body builders could damage the same wires. BTW the 2 cyls are opposite each other. Things that make you go "hmmmmmm?"
These folks at Prattville are not only top notch but dedicated to getting their customers back on the road in short order at a fair price.
The answer to the originally posed question is, in my opinion, if you are somewhat experienced with gas engines, you will most certainly feel a dropped cyl.

Steve
2005 W22/Monarch/37'/06Vue

[lwmuddy]

What I want to know is:
When you lost a plug, a misfire, did
the PCM throw a code and light up the
MIL light, or Service Engine Soon light?

This is a question I forgot to ask also.

Above, someone said, "The 8.1 is so powerfull that you wouldn't notice a missing plug".

Hard to beleive.

How do we know when we need a tune up?

DriVer, we need your wisdom or at least a really good and beleivable made up answer. Take your choice.

[rvr2352]

You should notice. But then you should remember your spouse's birthday too. No my incident did not throw a code.