Odd Situation -- Friend's Saab

[CJFusco]

Good morning, Pelican brain-trust. I was wondering if I could solicit your feedback about an issue revolving around my friend's Saab 9-3 (I think it's a 2010). I apologize in advance for the ambiguity of some of the details here, as I'm getting most of the information second-hand. I'm giving you as much info as I have.

About a year ago, my friend wanted to do an oil change and tune-up on his Saab. He knows that I do most of my own work on my cars, so he asked me for assistance. We changed the oil, air filters, and plugs. We got the plugs from an auto parts store, where you give them the make, model, and year of the car, and they give you spark plug options. We chose the Bosch plugs because that's... well, that's the quality brand, as far as I am aware.

Late last week, his car developed a series of symptoms that caused it to be brought in to the shop. It was bucking and stumbling under acceleration. The shop told my friend that the head needs to come off, as there are a couple of bad valves; one of the cylinders has a bad compression reading. When he removed the spark plugs, the mechanic noted that the plugs were 1) not torqued tightly enough, and 2) were the "wrong plugs". The mechanic told my friend that this particular Saab engine has a rarely-occurring issue (similar in rarity notoriety to the IMS bearing issue in M96 and M97 Porsche engines) that causes gasket/valve issues on one certain cylinder at around 60-80K miles, but also theorized that using the "wrong plug" and not torquing them tight enough caused a lean-running issue that exacerbated and hastened the rarely-occurring (but known) issue.

Now, I have never heard of plugs made specifically for an application causing a car to run lean and lead to an engine failure a year (and over 10,000 miles) down the line; I certainly have never heard of plugs causing a similar condition because they weren't torqued tightly enough. My friend is not blaming me -- he acknowledges that he came to me for help and had a hand in every decision we made -- but as his repair bill will be fairly large, I can't help but feel partially responsible if this failure was in some way caused by this maintenance session that occurred nearly a year ago. What are your thoughts about this? Can the spark plugs be at least partially to blame for this situation? Thanks in advance.

[wdfifteen]

A lean mixture is a prime cause high cylinder temperatures, which can affect the head/head gasket, but spark plugs don't have anything to do with fuel mixture.
They are a part of the cooling system though. Heat is transferred through the spark plug to the head. A loose plug can interrupt the flow of heat out of the cylinder. But I would expect the plug to overheat and get toasted long before any head or head gasket problem developed.
After 10,000 miles I wouldn't feel bad about the supposed plug torque issue. I'd say if the plugs were tight enough to cool themselves and last 10000 miles they wouldn't have an effect on the head.

[beepbeep]

Hi,

This is rather complicated when it comes to SAAB engines due to following reasons:
SAAB ECU (Trionic) uses ion knock sensing, which uses plugs to measures current in each cylinder after each combustion event. Thus, plugs in a SAAB turbo engine using Trionic (all turbo engines from 1994 onwards) are not just plugs that ignite the mixture. They double as "knock sensors" as well. Because of that, you *must* use prescribed plugs only as knock sensing is calibrated for that exact plug/resistance. It is like connecting wrong microphone to a sound analyser...you will get the signal but readings will be wrong.

Which engine is it? If it is 2010 model, engine is probably a variant of alloy block GM Ecotec 2.0L four, with turbo and Trionic 8 from SAAB. Correct plugs for 2010 SAAB 9-3 using B207R engine (210hk Aero) is NGK PFR6D10G and nothing else.

Is it a SAAB shop or just a generic "garage"? For what it's worth, I think shop is pulling your leg. It is very unlikely that plugs ruined the engine, it should be enough to change to correct NGK items, do the adaptation with Tech2 and try again.
Worst case scenario is that Trionic never "hears" the knock and knocks the hole in the pistons...

[CJFusco]

Hi -- thanks for your replies. Beepbeep, if the "wrong plugs" were used, and misfires occurred, wouldn't symptoms pop up sooner than a year after the plugs were changed?

It is a private garage that specializes in Saab and Volvo, and occasionally does German cars.

[beepbeep]

Originally Posted by CJFusco

Hi -- thanks for your replies. Beepbeep, if the "wrong plugs" were used, and misfires occurred, wouldn't symptoms pop up sooner than a year after the plugs were changed?

Hard to say. It would all depend on how plugs age, the charge air temperature, the octane rating of fuel etc.

But I see it as highly unlikely that valves would suffer. The worst case scenario is that knock sensing was somehow totally disabled, so ECU dialed in lots of boost and pre-ignition, which might have created pinging and affected the engine in long term (blown head gasket, pock marks on the pistons, blown pistons etc).
To my knowledge, those engines just "run bad" on wrong plugs and then run fine once you install correct ones.

If shop has Tech2-tool, they can check the ECU logs for number of misfires on per-cylinder basis.

[asphaltgambler]

So has his mechanic actually performed a cranking compression test? I know that all of this is reported 3rd hand but in order to help we all need to know the specifics. It sounds like his consultation is very general in terms and phrasing.

What, exactly are the issues currently? Has it been confirmed there is a mechanical failure? If so what were the test procedures, how did they come to those conclusions?

What were the events leading up to? I cannot imagine anything as serious as this and not having indicators along the way like CE light on and or flashing while he drives with other noticeable latency in performance.

Finally, based on what is reported, what is the reported fix / estimate?

[Jay Auskin]

Originally Posted by beepbeep

Hi,

...Correct plugs for 2010 SAAB 9-3 using B207R engine (210hk Aero) is NGK PFR6D10G and nothing else...

^^This. Saabs need to use the proper NGK plugs for their model/engine, or all hell breaks loose. If things are just acting weird, or intermittent, then the battery is probably bad, or going bad (for 2003+ models).

[hardflex]

If it was drawing in enough air to lean the mixture on intake cycle wouldn't you hear it spitting on compression ?

[CJFusco]

I'll try to get more information from my friend. It might be a 2009 car; I'm not positive. As I've said, replacing the plugs occurred over a year ago. I can't imagine that an auto parts store gave us the wrong plugs if we gave them correct make/model/year information...

[CJFusco]

Originally Posted by asphaltgambler

So has his mechanic actually performed a cranking compression test? I know that all of this is reported 3rd hand but in order to help we all need to know the specifics. It sounds like his consultation is very general in terms and phrasing.

What, exactly are the issues currently? Has it been confirmed there is a mechanical failure? If so what were the test procedures, how did they come to those conclusions?

What were the events leading up to? I cannot imagine anything as serious as this and not having indicators along the way like CE light on and or flashing while he drives with other noticeable latency in performance.

Finally, based on what is reported, what is the reported fix / estimate?

I think the consultation itself has been very thorough. My friend has been on the phone with the mechanic numerous times and for great lengths of time. Although he is an automotive enthusiast, he is not incredibly mechanically versed (and would be the first to admit so), so a lot of the information from the mechanic has been run through this filter.

I do believe they performed a compression test, and one cylinder was lower than it should be. There was no CE light; one day, the car was just stumbling under acceleration, so he brought it into the shop.

The reported fix (through the second-hand filter) is two new valves, machining of the head, and related gaskets. I don't remember the exact estimate, but it's something like $2800.

My friend was having difficulty trying to parse whether the mechanic was BLAMING the failure on the spark plug issue or if he was mentioning it offhand (e.g., "by the way, you had the wrong plugs on there and they weren't tight enough; this might have made things worse" -- that kind of thing).

[CJFusco]

BTW, Pelican sells a Bosch spark plug for the 2010 Saab 9-3... at least the "Aero" version...

[asphaltgambler]

OK - so that makes things clearer. So then this is a common issue with these engines?

[CJFusco]

Originally Posted by asphaltgambler

OK - so that makes things clearer. So then this is a common issue with these engines?

A known issue, if not a common one.

[CJFusco]

Correction: it's a 2011 Saab 9-3 Turbo 4-cylinder car. When I do a search for parts on Pelican, a Bosch plug DOES come up as specific to this model.

It looks like these plugs have an NGK parts number, though...?

[Jay Auskin]

There is also only one coil that works properly with the T8 2.0T motors. They need to be OEM, and have "Saab" and "Mitsubishi" stamped on them. But, it doesn't look like from your OP that any coils were changed.

There is a big thread here on intake valve wear which plagued some 2007-2001 9-3 2.0T's.

The Official (unofficial) 07-09 Intake Valve Tracking Thread - SaabCentral Forums

[CJFusco]

Thank you for the link. That forum thread is describing pretty much what is happening with my friend's car. Apparently the issue is common enough to 9-3 turbo engines to be marked as "Sticky" on that forum.

[sammyg2]

Note to self: don't ever buy a ****ing Saab.

[sugarwood]

That's just a **** position to be put into

[fastfredracing]

Originally Posted by sammyg2

Note to self: don't ever buy a ****ing Saab.

Yep, just another saab story

[CJFusco]

Originally Posted by sugarwood

That's just a **** position to be put into

HAH! Yeah, I pretty much told him that I don't like working on other peoples' cars unless they are as mechanically-inclined as I am, for this very reason. One time, years ago, I agreed to help a different friend change the brake pads on his Corolla at my house. It was right around lunch time, so I said something like "okay, jack the car up and I'll go inside and order pizza." Even though I had my floor jack out and ready to go, he decided to use his crappy scissor jack in my uneven driveway. Sure enough, the car started leaning forward and came crashing down right onto the rotor. I was pretty relieved that at least he wasn't crushed underneath the car. Lesson learned.