[EJM]

Just so you guys know she takes her car to the dealer for repairs. She has spent thousands over the years. I have seen some of the service sheets. Big $$$$. This is NOT something I am trying to make money on. I simply asked her to share what she has on this recent issue. The info is off of the paperwork. I am trying to send her back in with a little more info so she doesn't get gouged. She read the info to me over the phone, off of the paperwork.

Customer Complaint: Shaking when stopped
Actual issue is a rough idle as I explained to her what that is, and verified that is what she is actually experiencing.

Misfires on bank 1, cylinders 1 3 and 7. No miss on bank 2. Fuel trim up to 17% on bank 1, bank 2 ok. Compression test ok and even on both banks. Smoke test intake system and no vacuum leaks at this time. No exhaust leaks. O2 sensors both good. PCM Test Good and its telling the coil to fire. Switched coil cassettes and miss DID NOT FOLLOW. Misfires remained on 1 3 and 7. Further diagnosis required at additional charge.

What do you guys think. I said I would let them proceed. From what I see on the paperwork im guessing fuel injectors maybe? Lash adjusters?

One thing I did NOT like is how it said " no vacuum leaks AT THIS TIME" LOL.

Is there a way she may need a coil cassette even though it did NOT follow? If it was a cassette or ICM I would think it would follow. But im not sure if that is always the case.

Whatever. If theres any questions you have I can ask her its no big deal. Anything at all. Thanks!!

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Also the compression said 140 on both banks. What's good for an 00? I said that sounded good.

 

[Ranger]

If the ignition cassette was swapped and the misfire did not follow, the cassette & coils can be ruled out.

Being diagnosed at a dealer I am sure that the DTC's where check and there where none.

Seems like everything except the injectors where checked leading me to think injectors as well, BUT it is hard to imagine 3 failing at the same time. Maybe a wiring problem?

I don't see any options other than allowing them to continue.

EDIT:
Has the TB ever been cleaned? If it has been service by the dealer I'm sure they would not have missed that bit of income at some point, but it's worth mentioning as it CAN cause a misfire.

 

[EJM]

Hey Ranger!! Thanks. Yea I told her the report was fairly detailed and it seems like they did what I would do. I said to let them continue, but keep up on their progress.

This is what I was thinking.... With fuel trim a little high on the bank with the misses, could it be possible to still rule IN maybe intake gaskets??? Ever heard of a vacuum leak while running, but no smoke leaking on a smoke test?? Like a set of manifold gaskets sucking in while under vacuum, but have enough seal to keep the smoke in when not running. Im just thinking what if. Anyone ever heard of that?

Maybe not bad injectors, but clogged injectors...hmmmm

She said the SES light was on. So the codes were most likely a PO30X or something like that. I doubt 17% positive STFT would set a code but im not sure. But the SES light was on she said.

The way I put it together in a nut shell was ok, multiple cylinder misfire on one bank only. Does NOT seem to be ignition related. PCM adding fuel on same bank as miss so it seems lean. It says performed smoke test but did not NOTICE any leaks. Thats why I was tossing around manifold gaskets or injectors. But its an idle issue so Im not sure about the injectors. Something besides the 02 is telling the pcm to add fuel, and then it misses.

140 good compression for an 00 right????? I saw someone put 170 in another thread, but that was an older 10.3:1 motor. I told her 140 across both banks is good for a 15 year old motor with 150K. Head gaskets were done already by the dealer. It cost her like 7 grand.

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Im sure the TB is clean and the plenum boot was checked and all that. Like I said I would have done what they did. After ruling out the obvious stuff. Im really stuck on that "not so sure sounding" vacuum leak check. Like the rubber backfire plug having a slit, and working like a one way check valve or something letting vacuum in. I dunno just saying lol The way it was written sounded like the Technician himself was leeeaning towards a vacuum leak himself and wasn't sure about that

 

[Ranger]

Head gaskets were done already by the dealer. It cost her like 7 grand.

WOW! hope that included dinner and a goodnight kiss.

Maybe not bad injectors, but clogged injectors...hmmmm

Hard to imagine. The fuel is filtered so many times before it reaches the injectors, but I suppose anything is possible. Then again, if that where the case, why only those three?

 

[EJM]

There were many add-ons on that 7K bill. New Starter, alt, TB stuff like that. Lot of parts. Lot of labor. And that didn't sound too off to me cus I called the dealer about my gaskets and I got a 6K quote. They said they did not want to do it. So for them to take the job it was way overpriced.

Is 140 good compression or not in your opinion? I said good.(for 15 yr 150K miles). I never tested mine so I wouldn't know.

Thanks. I told her what you said.

 

[Submariner409]

From the 2002 GM/Helm service manuals: Compression pressure - 140 to 170 psi, all cylinders within 10% of average - throttle wide open at cranking speed. 2000 - 2004 Northstar = 10.0:1 ratio. Compression ratio is not the sole factor in compression pressures; cylinder volume and combustion chamber size at TDC also factor in, assuming sea level barometric pressure.

Granny's friend's STS probably needs to have the living snot run out of it. My compression pressures (2002.5 STS) are all within 5 psi of 154. Slow Northstars develop stuck compression rings.

 

[EJM]

Thanks sub. So at 140 thats pretty good. I thought so but I just wanted to check that with you guys though.Yea...It most likely isn't anything serious. You know very well diagnosis on these cars are not for the beginner, and can take time. And at the dealer time is $$$. I told her shes not being screwed. She has a car that is expensive to repair and hourly shop rate is astronomical. Up until recently I went through my N* my engine has been so babied. The old man I bought the car from told me he babied it(and it was obvious), so I babied it. Then I pulled the heads and saw first hand what babying a N* does. More carbon then I have ever seen no joke. Learned a million times more about this car in the past 6 months then I ever knew and i have had the car for a couple years. Its happy to be stretched out and back cracked with some 6K rpm WOT upshifts

She says thanks.

 

[Ranger]

Is 140 good compression or not in your opinion? I said good.(for 15 yr 150K miles). I never tested mine so I wouldn't know.

I've never checked mine either (never had reason to), but I believe that is a good reading.

 

[EJM]

Thanks guys. Im curious what it turns out to be. Ill let you guys know when I know. Im going to follow up on this one because I want to see if it turns out to be a vacuum leak.

 

[carnut]

You can unplug each injector much like pulling a plug wire out of a distributor cap. as you unplug each one the car should idle worse until you get to those affected cylinders. If the idle gets no rougher then you have either a failed injector or a poor connection. I've seen the connector at the injector come loose. A vacuum leak on a fuel injected car will raise the curb idle, not make it rough.