still misfiring cont.... What to do now??
09-29-2005, 07:11 PM
#1
TECH Addict
Thread Starter
iTrader: (8)
Join Date: Apr 2003
Location: Honolulu HI
Posts: 2,513
Likes: 0
Received 0 Likes
on
0 Posts
still misfiring cont.... What to do now?? ok, im at a cross roads and am not sure what to do first.
should i
A. install just a new set of heads and my old cam (f10) and see if that corrects the issue or
B. Get a new block along with the head, install and be done with it?
Its a tough decision to make which is why im asking for eveyone's thoughts on it. One head is off so id need to pull the other, on the other hand, i could just wait till the new motor comes (used of course) install the new heads and be done with it and know ive got a great engine and heads (ls6).
heres the first thread: https://ls1tech.com/forums/generation-iii-internal-engine/384649-still-misfiring-suggestions.html
should i
A. install just a new set of heads and my old cam (f10) and see if that corrects the issue or
B. Get a new block along with the head, install and be done with it?
Its a tough decision to make which is why im asking for eveyone's thoughts on it. One head is off so id need to pull the other, on the other hand, i could just wait till the new motor comes (used of course) install the new heads and be done with it and know ive got a great engine and heads (ls6).
heres the first thread: https://ls1tech.com/forums/generation-iii-internal-engine/384649-still-misfiring-suggestions.html
09-30-2005, 12:50 AM
#2
Launching!
iTrader: (3)
Join Date: Nov 2004
Location: Fairmont, WV
Posts: 299
Likes: 0
Received 0 Likes
on
0 Posts
Have you had the head that's off checked? I would not call the block junk just yet. We never really had a definative idea of what was the problem. We did know for sure that #7 was losing compression. If the exh. valve touched the piston, I would say that is the problem with that cylinder. But #5 is another story.
It all comes down to your committment to getting it fixed and finances. If you do not mind wrenching on the car and possibly having to do work twice then I would try the heads. If you want to do it once and be done then I would get the spare block and go through it or if finances allow just rebuilt what you got. I think stock rebuilds are fairly economical considering how LS1 parts pricing is.
Hope you get this figured out soon.
Dave
It all comes down to your committment to getting it fixed and finances. If you do not mind wrenching on the car and possibly having to do work twice then I would try the heads. If you want to do it once and be done then I would get the spare block and go through it or if finances allow just rebuilt what you got. I think stock rebuilds are fairly economical considering how LS1 parts pricing is.
Hope you get this figured out soon.
Dave
09-30-2005, 08:13 AM
#4
TECH Addict
Thread Starter
iTrader: (8)
Join Date: Apr 2003
Location: Honolulu HI
Posts: 2,513
Likes: 0
Received 0 Likes
on
0 Posts
ill try that today. finances are gonig to allow to buy the used block, its a ls6 block with arp rod bolts and flycut pistons. I would also be getting a set of 243 casting heads. so basically, ill have a ls6. It only has 10k and id like to know that im not going to have this issue anymore with the new block. on the other hand, it is far cheaper to get the heads only and replace them.(still the 243 casting 
im not sure if i really want to pull the heads off again if it turns out to be the rings. just seeing what the rest of the board would do in this situation.
Thanks for all your help Dave!
Nino
im not sure if i really want to pull the heads off again if it turns out to be the rings. just seeing what the rest of the board would do in this situation.Thanks for all your help Dave!
Nino
09-30-2005, 05:45 PM
#5
Launching!
iTrader: (3)
Join Date: Nov 2004
Location: Fairmont, WV
Posts: 299
Likes: 0
Received 0 Likes
on
0 Posts
Well as far as ring issues, these LSx blocks are known to be setup loose from the factory. This is evident with all the piston slap and oil consumption we have seen over the years. So in that instances I would say it is a crap shoot.
Before we go any further lets back track and revisit what you have done.
1. Eliminated any potential ignition or fueling issue.
2. Checked valvetrain components. Did you ever dismount the valvesprings & take a close look?
3. Did Case Relearn. Not real clear on what this is.
4. Compression Test. #5-127, #7-0, #3-175, #1-175 May check Bank 2 to verify.
5. Removed Head/Lifters. Lifters checked out OK.
6. See visible ring gap on #5 & visible scuff mark on #7 piston. Possible exh. valve contact.
Problem is occurring under load and at idle. Valvetrain/Engine noise.
These are the things you have tried. What do you know for sure is OK and not causing the problem & also what is yet to be verified as OK?
Can you crank the motor and get #5 down in the hole more? I wonder what the cylinder wall looks like in that hole. If it is rings in #5 there should be some scuffing of the wall.
Is there any connection that it would be adjoining cylinders? Or is this just pure coincidence?
Dave
Before we go any further lets back track and revisit what you have done.
1. Eliminated any potential ignition or fueling issue.
2. Checked valvetrain components. Did you ever dismount the valvesprings & take a close look?
3. Did Case Relearn. Not real clear on what this is.
4. Compression Test. #5-127, #7-0, #3-175, #1-175 May check Bank 2 to verify.
5. Removed Head/Lifters. Lifters checked out OK.
6. See visible ring gap on #5 & visible scuff mark on #7 piston. Possible exh. valve contact.
Problem is occurring under load and at idle. Valvetrain/Engine noise.
These are the things you have tried. What do you know for sure is OK and not causing the problem & also what is yet to be verified as OK?
Can you crank the motor and get #5 down in the hole more? I wonder what the cylinder wall looks like in that hole. If it is rings in #5 there should be some scuffing of the wall.
Is there any connection that it would be adjoining cylinders? Or is this just pure coincidence?
Dave
09-30-2005, 06:32 PM
#6
TECH Addict
Thread Starter
iTrader: (8)
Join Date: Apr 2003
Location: Honolulu HI
Posts: 2,513
Likes: 0
Received 0 Likes
on
0 Posts
the cylinder walls look good. just the scuffs on the pistons. it looks like #7 exhaust valve is bent and the rest look ok. lifters look ok. thats why im stumped 
09-30-2005, 07:01 PM
#7
Launching!
iTrader: (3)
Join Date: Nov 2004
Location: Fairmont, WV
Posts: 299
Likes: 0
Received 0 Likes
on
0 Posts
Ok so what we know as being good:
Ignition - OK
Fuel - OK
Pushrods - OK
Lifters - OK
Things we need to look closely at and test:
Valvesprings
Valves
#5 hole
I think #7's problem is a bent valve. I could be wrong but it points strongly at that.
Now, #5's problem is still up in the air. If you haven't I would check the valvesprings on the head thats off. Check the valves on #5 & #7. I think the ring gap could be a possible wild goose chase, but need to get the unverified points OK'd first.
Ignition - OK
Fuel - OK
Pushrods - OK
Lifters - OK
Things we need to look closely at and test:
Valvesprings
Valves
#5 hole
I think #7's problem is a bent valve. I could be wrong but it points strongly at that.
Now, #5's problem is still up in the air. If you haven't I would check the valvesprings on the head thats off. Check the valves on #5 & #7. I think the ring gap could be a possible wild goose chase, but need to get the unverified points OK'd first.
Trending Topics
10-03-2005, 07:28 AM
#8
TECH Addict
Thread Starter
iTrader: (8)
Join Date: Apr 2003
Location: Honolulu HI
Posts: 2,513
Likes: 0
Received 0 Likes
on
0 Posts
well im gonna get a set of ls6 heads and get new valve seals when i reinstall my prc duals on them. the old cam is going back in. i pulled the other head yesterday and it looks fine. im gonna clean off the pistons to see if there are any issues with them. also getting new lifters and studs. #7 i think is figured out, but 5 is still got me confused 