interesting!

UPDATE
my vehicle is back and runs smoother and idles better, but it still has a slightly ruff idle. when i asked them for the compression #'s they could not provide them but said they were "fine." they could be telling the truth but just the way this situation has been handled makes me suspicious. not to mention i had a blinking check engine light, then got it to them in less than 17 key cycles and they said their are no codes stored?

so to make a long story short i am going to take the vehicle to an independant next week to hook up to a drb3 and verify if what they are telling me is the truth? the tsb states it should have 10 misfires per minute for the tsb to apply. the dealer claims their ar no mifires per minute. i think it will be well worth the hour of labor?

advice from anybody? thanks mike

 

Well Mike can you tell if its missing? You can usually tell quite easily.

 

the tsb isn't talking about a hard miss felt when the power is applied. it is talking about a slight miss at idle. the motor still rocks (in the motor mounts) at idle when the stumble or roughness occurs, and it can be heard in the exhaust.

i think i may price the extended warranty since we love the vehicle and plan on keeping it.

 

just curious? what type of driving style do you have? hard, easy? short trips,longtrips? hgwy, city?

i am told buy a ase certified tech that driving style plays a factor and most will never need the tsb done? mike

 

update **** went back to the dealer monday, for a rough idle (2nd time). took them three days, but they found another tsb for a re-flash of the pcm (why didn't they find it on the first trip?). they re-flashed it (under warranty)
i asked what the re-flash did and they said they don't know, all they know is there is a update to the software?

so on the drive home last night i noticed the hot idle is now idling at 600rpm. before it was idling real low at 500rpm. i guess the re-flash rasied the idle and smoothed it out? i will drive it for a while and post back. hopefull the idle stays at 600rpm and smoother! they also told me that the 4.7/3.7 is normally
a rough idling motor, but couldn't provide the reason why.

i also asked for my money back on the original missed diagnosis. that went over like a terd in the punch bowl, but they said the would run the request up the dealership chain and call me today?

also they threw the vehicle on the drb3 again and siad it had no missfires at idle.

i will update later this week with the update! mike

 

Wow they didn't try the reflash first? The first time I had my truck into the dealer for something completely unrelated (thought my shocks were blown, turned out they're just lousy shocks, although I did blow them later on ) they noticed there was an updated version of the firmware and flashed it for me. Never thought to ask if that fixed anything specific, they just said there was an update available and they flashed it in for me.

 

yeah thats what amazed me. seems like that would be the first course of action? but the dealer i am dealing with is not a 5 star dealer. but still i would think the flash first is common sense? my wife brings the truck home from work tonight and i am going to drive it alot and see how she is idling (my wife couldn't tell a rough idle from a tire iron). mike

 

well i have been doing some research and found this from wikapedia. sounds like if your plugs are good, throttle body is clean and you have good compression the rough idle is normal. and the cut and paste below explains why. the 3.7 is even mentioned in the article. mike
well according to wikapedia the 3.7 is an odd fire v-6 with a three pin crank shaft making it a odd fire v-6. the lack of a split pin crank makes the rough idle. you can read about it in the cut and paste below!

Link in full:
http://en.wikipedia.org/wiki/V6_engine

90 degrees
90-degree V6 engines are also produced, usually so they can use the same production-line tooling set up to produce V8 engines (which normally have a 90-degree V angle). Although it is relatively easy to derive a 90-degree V6 from an existing V8 design by simply cutting two cylinders off the engine, this tends to make it wider and more vibration-prone than a 60-degree V6. The design was first used by Buick when it introduced its 198 CID Fireball V6 as the standard engine in the 1962 Special. Other examples include the Maserati V6 used in the Citroėn SM, the PRV V6, Chevrolet's 4.3 L Vortec 4300 and Chrysler's 3.9 L (238 CID) Magnum V6 and 3.7 L (226 CID) PowerTech V6. The Buick V6 was notable because it introduced the concept of uneven firing, as a result of using the 90 degree V8 cylinder angle without adjusting the crankshaft design for the V6 configuration. These engines were often referred to by mechanics as "shakers," due to the tendency of the engine to bounce around at idle speed. More modern 90-degree V6 engine designs avoid these vibration problems by using crankshafts with offset split crankpins to make the firing intervals even, and often add balancing shafts to eliminate the other vibration problems. An example is the 90-degree Mercedes-Benz V6 which, although designed to be built on the same assembly lines as the V8, uses split crankpins, a counter-rotating balancing shaft, and careful acoustic design to make it as smooth and quiet as the inline-6 it replaced.

[edit] Other angles
Narrower angle V6 engines are very compact but can suffer from severe vibration problems unless very carefully designed. Notable V6 bank angles include:

[edit] Odd and even firing
Many older V6 engines were based on V8 engine designs, without altering the V angle or using a more sophisticated crankshaft to even out the firing interval. One characteristic of these engines was a notorious odd-firing behavior.

Purpose-built V6 engines use one crankpin per cylinder for an even 120° ignition pattern. In contrast, most V8 engines share a common crankpin between opposite cylinders in each bank. That is, the crankshaft has just four pins for eight cylinders, and a cylinder fires every 90° for smooth operation.

V6 engines derived from V8 engines often have three shared crankpins arranged at 120° from each other, similar to an inline 3-cylinder, with two pistons per crankpin. If the cylinder banks are arranged at 90° (as they commonly are in V8-derived V6s), this leads to a firing pattern with groups of two cylinders separated by 90° of rotation, and groups separated by 150° of rotation.

An example is the Buick 231 odd-fire, which has a firing order 1-6-5-4-3-2. As the crankshaft is rotated through the 720° required for all cylinders to fire, the following events occur on 30° boundaries:

Angle 0° 90° 180° 270° 360° 450° 540° 630°
Odd firing 1 6 5 4 3 2
Even firing 1 6 5 4 3 2

Nissan uses the firing order 1-2-3-4-5-6 in some of the V6 engines they make.

In 1977, Buick introduced a new "split-pin crankshaft" in the 231. Using a crankpin that is 'split' and offset by 30° of rotation resulted in smooth, even firing every 120°. However, in 1978 Chevrolet introduced a 90° 200/229 V6, which had a compromise 'semi-even firing' design using a crankpin that was offset by only 18°. This resulted in cylinders firing at 108° and 132°, which had the advantage of reducing vibrations to a more acceptable level and did not require strengthening the crankshaft. In 1985 Chevrolet's 4.3 (later the Vortec 4300) changed it to a true even-firing V6 with a 30° offset, requiring larger crank journals to make them adequately strong.