Misfire CEL Coils ISSUES 07 Aero V6 2.8L

[Stephanie]

I used to love my 2007 Saab Aero V6 2.8L. Bought it in 2010 with 29K on it when I lived in FL. Fast forward to today, I am in NH and the car only has 55K on it. About a year ago the car began to misfire (or buck, jerk, stutter, chug) when accelerating at times on highway. Car would also do this at times when idle. It does it intermittently; therefore, whenever I had it tested out my shop could not diagnose it and there were no codes. And being a female in my 30's I was looked at like I was an idiot and the repair shop would try to get me to repair other things that were not an issue (windshield wipers, brakes etc). So I began to search myself and found this wonderful forum which gave me insight into the possible issue. I put down my findings on paper and brought it to a specialty shop that specifically works on Saabs, Volvos etc. Please note that I have an extended warranty until Sept 2016 Mercury Insurance Group Mechanical Breakdown Coverage (the Platinum package that covers EVERYTHING but normal wear and tear.)
Based on my findings this is what I told the shop:

POSSIBLE PROBLEMS: (in order of suspected issue - based on heavy research)
I DEFINITELY WANT PROBLEM 1 ADDRESSED AND FIXED.

1. REPLACE ALL IGNITION COILS/COIL PACKS and SPARK PLUGS - (and for a 2007 2.8 V6 – ALL should be replaced – 6 coils and 6 Iridium plugs - once one starts to fail they all start to fail – front 3 are easy but back 3 are a little harder to get to) Also 2.8s eat coil packs. Recommended place to order: RockAuto Parts Catalog

OTHER POSSIBILITIES BUT UNLIKELY:
DISTRIBUTOR CAP & ROTOR
VACCUM / BOOST LEAKS
IGNITION CABLES
FUEL INJECTOR
FUEL GAUGE / FAULTY VALVES / INTAKE VALVE SEALS
DIC

So I dropped it off for the day for diagnostic - required if I am going though the extended warranty. They were having trouble pulling any codes until late afternoon. Finally they got a code on cylinder 5. They called me and told me that the insurance company would only pay for ONE coil and ONE spark plug because the code was necessary for them to cover it. I told the shop that the codes will not always show or register and that I am just going to continue having problems with coils and plugs if they replace just one. They said probably but if they told the insurance that all needed to be replaced and he did not have codes that they would probably send an adjuster there to verify. UGH. So they fixed one cool and one spark plug on cyl 5. Two days later CEL is back - coming on then going off in a day or so coming on then off. My RPM has gone bezerk. When I start the car it revs super high (around 3) then calms back down in a minute. And NOW - every time I get on the highway and accelerate for the first time the RPMs go super-high and there is a burning smell initially. BURNING SMELL. I just got a new job and the commute is long. This is becoming a MAJOR headache for me. Can anyone offer advice on what the issue is and best way to proceed. I sincerely appreciate all feedback. Thank you - Stephanie

[SatchSportSedan]

Hi, Stephanie,

Quite a long story, around the initial topic: engine stumbles, bucks, jerks,or how do you call it ;-?
Keeping it shorter to the point, can help

What is the codes number? 0171? Does it clear itself after a while running OK?
Did it showed up suddenly, or after some particular handlings/maintenance/repair?

There are lists of TDC-codes, and what they mean.
Can also be the throttle pedal position sender.
It are variabel resistances, that track eachother for correct position (= throttle, power demand).

When it only happens more at spirited driving, high RPMs, I'd think about full pressure?
Maybe enough for idling, and slow driving; but inadequate at higher speeds? Clogged filter?
On the fuel line, should be a Pressure regulator.
Try fueling at other places, because can be bad fuel aswell.

Did you until now only replace 1coil and 1sparkplug?
Are you running on gasoline of autogas?

I have a 1.8t B207E, on LPG (with valve-saver additive automatically injected)
But it's injection rate was set way too high, by the installer.
And my plugs fouled, with a creamy dry deposite between Sparks electrodes.
Cleaning them, and setting that FlashLube rate from 6 -> 3 the correct rate for my 150BHP did it all.

Another erratic thing can be manifold and/or throttle house gasket (vacuum) leaks.

Can't you track that burning smell, when opening the hood?

Burning smells are never good, and won't go away from themselfs ;-?

Happy fidling with your Aero-V6.

PS, don't rely or trust on Insurrances, they're the same like banks.
The moment they need to give money, they'll do anything to not having to spend