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Old 09-22-2018, 05:12 PM   #1
JooktheSnooke
 
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Angry HELP! Engine misfire after cam install

Hello all!
Ive been reading these forms for a while now...and just became a member. Therefore, this is my first post and i can really use some guidance with my 2010 camaro ss.
I just finished doing the cam install in my ls3. I need some help The cam is texas speed & performance, stage 2, 229/244 .629"/.615" . included with the cam I also installed a new oil pump, timing chain and sprocket, lifters, push rods, valve springs, rockerarm trunion upgrade, got the heads cnc ported, spark plugs, and long tube headers.
When i went to start the motor for the first time, it was misfiring a lot through the exhaust. it sounds like gun shots. The check engine light came on with code P0300 (multiple cylinder misfire) after this happened, i removed all the spark plugs and found them to all be soiled except for cylinder # 1 & 5. I checked compression on all of the cylinders, they were all at 190 psi except for 1 &5, they were at 170 psi. after doing that i checked for spark on all coils, spark plugs, and spark plug wires. All was good there. Fuel injectors were also good, because i made sure they all sprayed doing the cam install. I am not sure if this is happening because of push rod length, or if the valves are not seating correctly. Or if the car just needs a tune to fix the problem. I read some forums on here about the misfire issue, but most of them talked about the check engine code.
Any advice or guidance would be greatly appreciated
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Old 09-22-2018, 08:06 PM   #2
craigd853
 
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Quote:
Originally Posted by JooktheSnooke View Post
Hello all!
Ive been reading these forms for a while now...and just became a member. Therefore, this is my first post and i can really use some guidance with my 2010 camaro ss.
I just finished doing the cam install in my ls3. I need some help The cam is texas speed & performance, stage 2, 229/244 .629"/.615" . included with the cam I also installed a new oil pump, timing chain and sprocket, lifters, push rods, valve springs, rockerarm trunion upgrade, got the heads cnc ported, spark plugs, and long tube headers.
When i went to start the motor for the first time, it was misfiring a lot through the exhaust. it sounds like gun shots. The check engine light came on with code P0300 (multiple cylinder misfire) after this happened, i removed all the spark plugs and found them to all be soiled except for cylinder # 1 & 5. I checked compression on all of the cylinders, they were all at 190 psi except for 1 &5, they were at 170 psi. after doing that i checked for spark on all coils, spark plugs, and spark plug wires. All was good there. Fuel injectors were also good, because i made sure they all sprayed doing the cam install. I am not sure if this is happening because of push rod length, or if the valves are not seating correctly. Or if the car just needs a tune to fix the problem. I read some forums on here about the misfire issue, but most of them talked about the check engine code.
Any advice or guidance would be greatly appreciated
The car needs to be tuned. Please talk to Ted Janetty as he is a guru with tunes. He tuneed my 2010 camaro with FI and it is a beast. Don't drive the car until it is tuned. Hope this helps and good luck
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Old 09-23-2018, 11:06 AM   #3
christianchevell
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Your DIY is not such a good idea now …….let alone if you had the perfect right information or skipped some critical stuff to keep you from majorly screwing the pooch.

Hopefully you knew the thread pitch for setting your preload is around.048 so one turn too much to get to around .045-.060 ls3/7 lifter preload tightening it down from zero lash..... and should be thought of as .048 x 1.7 ratio of rocker ( a Fulcrum) = .81 distance moved adjusting preload with one complete turn...overly tight even for a ls7 that takes .070 the max preload.

Hopefully your pushrods were measured/ heavily recommended; and with smaller most likely base circle on a aftermarket cam your pushrods are slightly longer than stock as .050 difference in the circumference of the base circle means on one side of the cam a .025 difference in the length the pushrod needs for the same top end architecture/ angle of the dangle etc...… hopefully you presoaked your lifters, installed your cam right at the right timing....and a whole bunch of other things ….and have plans to immediately tune it while breaking it in...yes I break mine in with Driven racing BR30 something people may scoff at as its a roller...but hey its gone to 8620 cores for a friggin reason etc..... stupid is not a thing a old hot rodder wants to say about their own lack of prep...…


You sound like you need help desperately before your trashing something...… back firing can destroy a engine BTW, with the age of your car you most likely should have done new head gaskets, new lifter baskets, new TTY head bolts new lifters if your mileage was more than say 20k and maybe even then its all in lifter condition old cam condition/tracking etc....

If you changed out your oil pump you had to change the dangerous to replace o ring and get the height perfect for the pick up tube something you can sneak in by loosening the pan for a DIY but my tuner does with a cradle drop....

This is not your old daddies Chevy the distributor could be 180 degrees out on as you know..... I would myself have to go back through things.....to find what's wrong even if I did it perfectly with every reference manual sometimes they miss a step or take for granted knowledge a person not a mechanic does not know...… of have just a timing wheel around or understand a cam with +4 comes with four degrees advance already ground in etc etc

So you may need help professionally in your area from a real good corvette type mechanic......IMO as you should not even with no tune be backfiring...…...your engine is with its ECU trying to adjust air/fuel , timing ;etc to avoid any detonation which is backfiring and it comes in two varieties....one with internal engine backfiring which is very harmful, and one in the exhaust which can be harmful also especially if its happening right out of the combustion chamber. Its totally different also from exhaust Burble or Decel Popping which occurs at the fuel cut off in a tune and the excess gas is then ignited making mild popping further down the exhaust than a back fire. Fuel cut off is of course from not stepping on it anymore or downshifting to higher revs not accelerating particularly.


Good Luck to you, so much to check ...every ground, every preload, every thing..... a canned tune in a handheld may stop some problems but its not going to most likely be perfectly good for your engine as that specific cam and your individual mods ; it makes saved tunes by tuners ,( that can be preloaded in handhelds), that much more important ;in a library of tunes even for tuners with dynos....to even be able to start with dyno tuning with HP tuners etc...…and lots of people then go on to data log, dyno Steve is a good remote tuner also used frequently on here; Frankly it would be hard not to keep tinkering with it yet even as a old experienced build many SBC?BBC engine guy I did not mess with the install myself.

I went to the best I could find for my install around here Thomas Wong after reading a ton and then buying parts over a long time and reading more constantly on here over the years and consulting with him over and over and I am on my second engine and understand springs have limited life, a over rev can trash a engine if not caught soon enough, push rods can bend and the engine is strong enough to be sounding just fine, etc etc etc.

And yes I know the faults to the DIY on here by Robert Way; and his short coming with being able to measure his Pushrods and set his preload....and most likely it came back to bite him as it was a work in progress for the DIY...I have not heard of him in years and years...…… IMO I would be for towing it to someone good and letting them take it over and spare yourself grief with just some cash. Specialty tools a timing wheel etc are not things I have just laying around for other than SBC BBC and then I have ….a timing gun, a pre oiler I made from a old distributor, hell I even have topless valve covers to adjust flat tappets running, do a break in /fluid drains etc etc etc lots of tricks just for much less complex builds. Good Luck again. Your new LSA is vastly different than the stock huge LSA and timing.
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Last edited by christianchevell; 09-23-2018 at 11:36 AM.
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Old 09-23-2018, 01:43 PM   #4
JooktheSnooke
 
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Quote:
Originally Posted by christianchevell View Post
Your DIY is not such a good idea now …….let alone if you had the perfect right information or skipped some critical stuff to keep you from majorly screwing the pooch.

Hopefully you knew the thread pitch for setting your preload is around.048 so one turn too much to get to around .045-.060 ls3/7 lifter preload tightening it down from zero lash..... and should be thought of as .048 x 1.7 ratio of rocker ( a Fulcrum) = .81 distance moved adjusting preload with one complete turn...overly tight even for a ls7 that takes .070 the max preload.

Hopefully your pushrods were measured/ heavily recommended; and with smaller most likely base circle on a aftermarket cam your pushrods are slightly longer than stock as .050 difference in the circumference of the base circle means on one side of the cam a .025 difference in the length the pushrod needs for the same top end architecture/ angle of the dangle etc...… hopefully you presoaked your lifters, installed your cam right at the right timing....and a whole bunch of other things ….and have plans to immediately tune it while breaking it in...yes I break mine in with Driven racing BR30 something people may scoff at as its a roller...but hey its gone to 8620 cores for a friggin reason etc..... stupid is not a thing a old hot rodder wants to say about their own lack of prep...…


You sound like you need help desperately before your trashing something...… back firing can destroy a engine BTW, with the age of your car you most likely should have done new head gaskets, new lifter baskets, new TTY head bolts new lifters if your mileage was more than say 20k and maybe even then its all in lifter condition old cam condition/tracking etc....

If you changed out your oil pump you had to change the dangerous to replace o ring and get the height perfect for the pick up tube something you can sneak in by loosening the pan for a DIY but my tuner does with a cradle drop....

This is not your old daddies Chevy the distributor could be 180 degrees out on as you know..... I would myself have to go back through things.....to find what's wrong even if I did it perfectly with every reference manual sometimes they miss a step or take for granted knowledge a person not a mechanic does not know...… of have just a timing wheel around or understand a cam with +4 comes with four degrees advance already ground in etc etc

So you may need help professionally in your area from a real good corvette type mechanic......IMO as you should not even with no tune be backfiring...…...your engine is with its ECU trying to adjust air/fuel , timing ;etc to avoid any detonation which is backfiring and it comes in two varieties....one with internal engine backfiring which is very harmful, and one in the exhaust which can be harmful also especially if its happening right out of the combustion chamber. Its totally different also from exhaust Burble or Decel Popping which occurs at the fuel cut off in a tune and the excess gas is then ignited making mild popping further down the exhaust than a back fire. Fuel cut off is of course from not stepping on it anymore or downshifting to higher revs not accelerating particularly.


Good Luck to you, so much to check ...every ground, every preload, every thing..... a canned tune in a handheld may stop some problems but its not going to most likely be perfectly good for your engine as that specific cam and your individual mods ; it makes saved tunes by tuners ,( that can be preloaded in handhelds), that much more important ;in a library of tunes even for tuners with dynos....to even be able to start with dyno tuning with HP tuners etc...…and lots of people then go on to data log, dyno Steve is a good remote tuner also used frequently on here; Frankly it would be hard not to keep tinkering with it yet even as a old experienced build many SBC?BBC engine guy I did not mess with the install myself.

I went to the best I could find for my install around here Thomas Wong after reading a ton and then buying parts over a long time and reading more constantly on here over the years and consulting with him over and over and I am on my second engine and understand springs have limited life, a over rev can trash a engine if not caught soon enough, push rods can bend and the engine is strong enough to be sounding just fine, etc etc etc.

And yes I know the faults to the DIY on here by Robert Way; and his short coming with being able to measure his Pushrods and set his preload....and most likely it came back to bite him as it was a work in progress for the DIY...I have not heard of him in years and years...…… IMO I would be for towing it to someone good and letting them take it over and spare yourself grief with just some cash. Specialty tools a timing wheel etc are not things I have just laying around for other than SBC BBC and then I have ….a timing gun, a pre oiler I made from a old distributor, hell I even have topless valve covers to adjust flat tappets running, do a break in /fluid drains etc etc etc lots of tricks just for much less complex builds. Good Luck again. Your new LSA is vastly different than the stock huge LSA and timing.
Thank you for taking the time to reply. i did put new lifters(presoaked), new head gasket, new lifter trays,and new lifter bolts. i had a few manuals and done alot of research before do this work. my uncle is a mechanic and was there as i was doing the work. i pulled the motor out of the car so the oil pump problem wasnt a problem. i checked pushrod length many times of different cylinders. I was coming up with 6.8+10turns x.05 to zero lash =7.3+.07 preload = 7.37 a rechecked using the other method and am coming up woth 1-1/2 turns. the marker technique shows a wear pattern more towards the intake side of the valve stem. texas speed said to install the cam at standard time so thats what i did
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Old 09-25-2018, 11:01 AM   #5
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I went stage 3, but otherwise sounds like your build is pretty similar to what I did. It will need tuned, but most definitely shouldn't be backfiring. Will need a tune before getting on it too hard, but ought to start trying to learn to idle and run relatively smooth.

You're sure you got the timing marks lined up right on the crank and cam sprocket? Being off a tooth could certainly cause a multiple misfire/backfire situation. And have you turned it over with valve covers off to make sure all valves are opening/closing as they should?
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Old 09-25-2018, 12:16 PM   #6
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Closely look at the spark plugs for any cracks in the porcelain, inside and out.

Get an infrared temp gun (very cheap at Harbor Freight), while idling and about 1500 rpm, aim it at each header tube. The temps will be very obvious to which cyls are misfiring.

If the plugs are good, and the timing gear was installed correctly with the dots lined up...I'd suspect wrong push rod length is holding a valve or two open.

Call the cam company... does it use anything other than stock base circle?

Were the heads decked? (if not, why not?) (always do at least a clean up pass on alum heads while off)

If either of those questions are a Yes answer, the PR length will not be stock. But...just a guide, still need to measure for every build. I've seen cams that they swear are stock base circle...are not.

What did your rocker nut turns end up at? lobe on base circle, turn rocker nut down to zero lash... then how many turns to TQ spec? You mentioned 1 1/2.... that sounds like too much if that is what actually ended up with. 3/4 to almost 1 complete turn is usually close to ideal. Or more accurate is to use a Comp Cams PR length checker.

The other thing you can do is take your compression gauge hose and put a compressor fitting on it to pressurize the cyl that is misfiring. With the cam on base circle for both lobes pressurize the cyl... anything blowing out the exh or intake? Yes...too long a PR if that blowby stops when loosening up the rocker. The blowby continues after loosening the rocker...bent valve.
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Old 09-26-2018, 08:34 AM   #7
christianchevell
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Yes what he said and I tried to say 3/4 turn from zero lash is more than enough .048 thread pitch x 1.7 = .081 for one complete turn and that's too much most go .045 ish for less typewriter sound to .060 stockish for ls3 not more for .070 ls7 with different rockers...….. and the engine is strong enough to overcome over lash/preload and will just mess up.... just a thought...gotta go. And most companies base circle is smaller by .050 that means a pushrod length should most likely be .025 longer as it only rides on half the circle...…….
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Old 09-27-2018, 05:05 PM   #8
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You cracked a spark plug. I did the same exact thing. Change them out and you’ll be good.
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Old 09-28-2018, 12:00 PM   #9
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more than likley

Quote:
Originally Posted by Superdonkey23 View Post
You cracked a spark plug. I did the same exact thing. Change them out and you’ll be good.
At least check the plugs first. You will need it tuned in the end .
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Old 09-28-2018, 05:02 PM   #10
christianchevell
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Yup cracked one or two myself over time.... that's always something to check a hair line fracture is enough to make a cylinder mis, and check the electrical connections and injectors connectors they are not so friendly either, even a loose ground can cause problems...
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