New injectors new build = Misfire#8

[stibuilder]

So we got the truck running over the weekend but now have a code for misfire on #8, looking at the balance rates #8 is way out of line. My concern is my tune didn't have any of the injector flow rates or codes in it.

Would this possibly contribute to the flow rates being out of wack?

What I am most afraid of is damaging the piston as this all started once I got on the road with the trailer and pulled a few hills and it sounds like its got a fuel knock at low rpms from that corner of the motor. I had to drive it 20 miles to get everything put away safe.

On the Kodiak #8 is the worst injector to get to its right up against the firewall, we are hoping this might be an injector harness issue and wont have to drop the engine or lift the cab to get a new injector installed.

 

[Tothemax]

I would try ice pick (bend the terminals tighter) at #8 injector plug. its a pain on a Kodiak but I have had 2 Kodiaks with that issue that I fixed like that on # 8. I pull the dog house off and disconnect the connector and pull it up towards the cab and work on it. you'll have to remove 1 bolt that holds the harness down and even then the connector will just make it to the metal flange of the floor.

 

[ikeG]

Possibly switch that injector to another hole where it's easier to access, that way you can narrow it down to a bad inj or not. Plus it's easier to change if it is bad

 

[stibuilder]

Possibly switch that injector to another hole where it's easier to access, that way you can narrow it down to a bad inj or not. Plus it's easier to change if it is bad

Yeah thats a great idea, I am waiting on call from LDS to discuss this as they are new injectors. Dropping the motor combined with moving the Cab is going be a challenging job to get at #8 ill look more at the connector today.

 

[zakkb787]

When I did my injectors and heads I had a dead misfire too. Ended up being a stuck valve so no compression

 

[stibuilder]

When I did my injectors and heads I had a dead misfire too. Ended up being a stuck valve so no compression

Wow how did you end up finding that, I did the valve job on the engine, my first time following MA Auto's guide.

 

[stibuilder]

Replaced the pigtail today still #8 is out of wack.

 

[zakkb787]

Wow how did you end up finding that, I did the valve job on the engine, my first time following MA Auto's guide.

Tried every trick in the book then did a compression test and no compression in cylinder 2. Had a push rod lodged sideways under the rocker holding the valves open so now I've got 2 nice little valve stamps in mybliston lol luckily nothing was bent or cracked

 

[stibuilder]

My truck seems to run but smokes then when you come to a stop it smokes like its pissing oil into the exhaust or something. The misfire went away it seems early on and its pulled the trailer pretty well temps stayed low on a 90 degree day and oil pressure was good so it seems like its in good shape. I guess i could have done the valve adjust too tight, but i think the push rods are in right. Ill have to go look at pictures. LDS was pretty sure the injectors being new are not the issue but I hope to hell it is for the fact of amount of work to be done to test it.

 

[stibuilder]

Misfire #8
Fuel knock when at low rpm solo (Going up inclines)

Engine
2006 LBZ
ARP Headstuds
Thickness C Head Gaskets
New LDS 30% Over Injectors
PPE Race Valve
PPE Fuel Rail Fitting Supply and Return
Fass 150 Lift pump
EGR Delete
3" Y Bridge
Efi Live by Kory Willis
Heads decked .04
Grid Heater Delete
Fass Fuel Filter Delete
Engine and CP3 have 73,000 miles


Remediation Steps

1.New injector Pigtail #8
2.Swapped #8 and #3 injector
3.Verified Valve lash on #8 intake and exhaust
4.Replaced Crank Position Sensor
5.Compression test on #8 and #2 both yielded 300PSI
6.Ohm resistance test of harness at injector
7.Cleaned MAF Sensor
8.Swapped Stock ECU (Ran like shit)

 

[big block]

Misfire #8
Fuel knock when at low rpm solo (Going up inclines)

Engine
2006 LBZ
ARP Headstuds
Thickness C Head Gaskets
New LDS 30% Over Injectors
PPE Race Valve
PPE Fuel Rail Fitting Supply and Return
Fass 150 Lift pump
EGR Delete
3" Y Bridge
Efi Live by Kory Willis
Heads decked .04
Grid Heater Delete
Fass Fuel Filter Delete
Engine and CP3 have 73,000 miles


Remediation Steps

1.New injector Pigtail #8
2.Swapped #8 and #3 injector
3.Verified Valve lash on #8 intake and exhaust
4.Replaced Crank Position Sensor
5.Compression test on #8 and #2 both yielded 300PSI
6.Ohm resistance test of harness at injector
7.Cleaned MAF Sensor
8.Swapped Stock ECU (Ran like shit)

So am I reading this right you swapped #8 and #3 and the problem stayed in #8?

 

[stibuilder]

So am I reading this right you swapped #8 and #3 and the problem stayed in #8?

Correct, and we did all that.

 

[big block]

Correct, and we did all that.

Just to confirm the #8 is the back drivers side? Duramax are opposite of standard gm v8's I forget sometimes.

 

[Chevy1925]

Just to confirm the #8 is the back drivers side? Duramax are opposite of standard gm v8's I forget sometimes.

yes, #8 is driver rear

 

[stibuilder]

Attached some log files

 

[big block]

yes, #8 is driver rear

Yes I know this, just was confirming with the op since the problem didn't move, maybe he swap the wrong injector.

So it just sounds like missing or is there a code?

 

[stibuilder]

It only throws the misfire code after its done it for a while you have to drive it for 10miles or so then it will. Its so obvious from the knock that its happening the code is like an after thought.

 

[big block]

Should put a video up on you tube or something, sometimes these hard to find problems are right in front of you.

 

[stibuilder]

If you download efi live you can play the log files back and see the data, but ill get a video also maybe tomorrow.

 

[stibuilder]

No video yet just wondering if anyone has any ideas? Cam Position Sensor?