Number 3 Cylinder Missing And Fouling Plugs

[LEGACY_GN]

87 GN
motor has 11k miles on it.
has 7th injector plugged into factory harness. Been on there 12 years.
replaced plugs, wires, coil, ignition module and injector
ran seafoam through intake
put half a quart of rizone in it.
compression was 160 in that cylinder
all of this was done since it started missing so none of it is responsible



still missing under load (not when your rev it up in park) and fouling plug after plug in #3 cylinder (middle on driver side)

plug is wet with fuel when you pull it

sometimes it misses real bad and sometimes not at all

Any ideas are greatly appreciated. I personally think it's got to be the injector harness but noid light lit up when pluged into that injector and turned over. so I don't know and greatly appreciate any insight.

 

[TURBOTWIN2]

You need Fire, at the right Time, Fuel and Compression to not have a miss. Sounds like you're missing the Fire (spark). You've got compression and fuel (wet spark plug). Maybe try switching that #3 plug wire with another and see if the miss moves. If so, you've found the problem. HTH.

 

[LEGACY_GN]

You need Fire, at the right Time, Fuel and Compression to not have a miss. Sounds like you're missing the Fire (spark). You've got compression and fuel (wet spark plug). Maybe try switching that #3 plug wire with another and see if the miss moves. If so, you've found the problem. HTH.

Already did that. Thanks though.

 

[TexasT]

What about the coil or the coil pack? Have these been swapped with known good pieces?

 

[LEGACY_GN]

Brand new pieces.

 

[turbocody]

i was gunna say the injector, but you said you already tried that. so my next guess would be changing out the ecm with a KNOWN good one. HTH

 

[BAGN]

Also check you injector harness. #3 runs over the EGR. I've seen them get burnt and short.

 

[LEGACY_GN]

i was gunna say the injector, but you said you already tried that. so my next guess would be changing out the ecm with a KNOWN good one. HTH

Tried that too. No difference.

 

[JDSfastGN]

Brook, Ill call again tomorrow. I called earlier but i got a strange voicemail and wasn't sure it was yours. I would like to come by and take off the drivers side valve cover since its easy enough. Im wondering if it might have a partially broken valve spring (inside damper keeping it from fully collapsing) preventing the valve from fully opening and closing. That would explain the popping under load, and it may have enough to keep it from missing too bad at idle. It could also be a bent valve. I just keep coming back to valve train after you mentioned the lifter noise it had a while ago. If you don't hear from me by 2 give me a call on my cell.

 

[LEGACY_GN]

Brook, Ill call again tomorrow. I called earlier but i got a strange voicemail and wasn't sure it was yours. I would like to come by and take off the drivers side valve cover since its easy enough. Im wondering if it might have a partially broken valve spring (inside damper keeping it from fully collapsing) preventing the valve from fully opening and closing. That would explain the popping under load, and it may have enough to keep it from missing too bad at idle. It could also be a bent valve. I just keep coming back to valve train after you mentioned the lifter noise it had a while ago. If you don't hear from me by 2 give me a call on my cell.

Oh, I knew that number looked familier but couldn't place it. I have two different answering services depending on what lines are going to my cell and if I'm on another call. Anyway, sorry. Shouldn't be bent valve because their stainless steel. I've had my money on bad lifter or valve spring ever since it started because of the way it was hammering before the rizone and the coincidental timing of both. But everyone tells me no because of the load factor. Would do it all the time if it was mechanical and theres the 7th injector that I had unplugged around the same time. And I don't hear any miss when you rev it up in park. I don't know.

You know it's ironic, I spend tons of time in a Mortgage Broker forum talking to other brokers about how to get tough loans approved, yet if I just spent that time in here learning how to get tough car problems fixed, I might have a car that runs right. Wouldn't have no money for gas though. LOL

 

[LEGACY_GN]

Also check you injector harness. #3 runs over the EGR. I've seen them get burnt and short.

Check the wires and none are burnt from what I could see. Thanks for the tip though. I still wonder if it has something to do with the 7th that's tied into it.

 

[turbocody]

that might be it. doesn't hurt to check it out!

 

[DR BOOST]

flat cam?

 

[LEGACY_GN]

I posted this on the main page as well and just had a guy that said he had a broken rocker on the same cylinder doing the same thing. Said it ideled an reved fine but was fouling plugs and missing just like mine. We may have a winner.

 

[LEGACY_GN]

We pulled the valve cover, and the it's a wiped 3E cam lobe. Now who wants to tell me what my chances are if I just replace the cam clean out the motor without rebuilding it?

Oh, and if anyone could tell me it this is a result of something I did, I'd greatly appreciate it.

 

[SVORay]

That sucks.

The last time I replaced a whiped out cam, the motor lasted a week afterwards. I wish you the very best with it. My motor has about the same miles as you and it's got a bad miss as well. This weekend I'm going to start checking the simple stuff. I wonder if I can save time by doing an oil change...see if there is any metal in the pan.


As for something you did, it's probaly the whole EPA crak down on additives in the oil. It makes life VERY hard on flat tappet cams. Just do a search on it. I think there is a lot of people who's cams go south around 10,000 or less.


Again, best of luck
Ray

 

[Jerryl]

Grab yourself few cold beers, and, happy reading!
http://www.turbobuick.com/forums/ge...h/128304-what-cams-will-live-our-engines.html

 

[SVORay]

Grab yourself few cold beers, and, happy reading!
http://www.turbobuick.com/forums/ge...h/128304-what-cams-will-live-our-engines.html

To late, I read most of that stuff just right after I bought the car. There is so many threads and theories like lifter bore geometery to additives in the oil. Anyhow, I found some unwated material in my oil Atleast I found a good lead on a Roller short block. Just need to start saving some money.

Ray