lmm fuel knock misfire
- Thread starter mamu
- Start date
I've basically pushed truck outside at this point. trying to keep my sanity. but I'm dying inside everyday not being able to figure it out. so I plan to start over on it. start at the beginning. trace wires. load test circuits. pull grounds and clean. has anyone ever developed or used a noid (I think that's the term) light? to watch the power to the injector?
I'm grasping at straws but I'm too deep to quit. and I also don't give up that easy.
I'm grasping at straws but I'm too deep to quit. and I also don't give up that easy.
bringing this thread back up. put new engine harness on truck. still shows #1 misfire. can unplug #1 and it doesn't seem to run as bad but still not good. swapped injector with another from running engine. stays misfire on #1.
changed ecm again. ran good just low power because engine power reduced from not being programed for delete. made it about 2 miles down the road and started again.
load tested wires from injector to ecm to check continuity. wires are good.
could this rig have a broke crank and idle smooth? and still show good compression on the gauge?
changed ecm again. ran good just low power because engine power reduced from not being programed for delete. made it about 2 miles down the road and started again.
load tested wires from injector to ecm to check continuity. wires are good.
could this rig have a broke crank and idle smooth? and still show good compression on the gauge?
from what i just checked i don't think the crank is broke as i can put the flywheel holding tool in the trans and turn the crank back and forth. it moves just a little then stops when the tool takes up the slack on the teeth. unless someone thinks of another way to check it.
You may have checked everything here, but maybe something you missed:
Fuel Injector Flow Rate Programming
Circuit/System Description
The control functions for the fuel injection system are integrated in the engine control module (ECM). Each injector's flow rate information and cylinder position are stored in the memory of both the glow plug control module (GPCM) and the ECM. The fuel injector flow rate programming must be done when any of the following procedures are performed:
The ECM is replaced
The GPCM is replaced
Any fuel injectors are replaced
If the ECM does not communicate, the flow rate information can be retrieved from the GPCM. If both control modules fail to communicate, the fuel injector flow rate information, or injection quantity adjustment (IQA) flow rate numbers, will need to be retrieved from each individual injector.
Before Programming A Control Module
Important: DO NOT program a control module unless you are directed by a service procedure or you are directed by a General Motors Corporation service bulletin. Programming a control module at any other time will not permanently correct a customers concern.
Ensure the following conditions are met before programming a control module:
Vehicle system voltage
There is no charging system concern. All charging system concerns must be repaired before programming a control module.
Battery voltage is between 12-16 volts. The battery must be charged before programming the control module if the battery voltage is low.
A battery charger is NOT connected to the vehicle battery. Incorrect system voltage or voltage fluctuations from a battery charger may cause programming failure or control module damage.
Turn OFF or disable any of the following systems that may put a load on the vehicle battery:
Twilight sentinel
Interior lights
Daytime running lights (DRL)-Applying the parking brake, on most vehicles, disables the DRL system. Refer to the Owner's Manual.
HVAC systems
Engine cooling fans, etc.
The ignition switch is in the proper position-The scan tool prompts you to turn ON the ignition, with the engine OFF. DO NOT change the position of the ignition switch during the programming procedure, unless instructed to do so.
All of the following tool connections are secure:
The connection at the data link connector (DLC)
The voltage supply circuits
DO NOT disturb the tool harnesses while programming. If an interruption occurs during the programming procedure, programming failure or control module damage may occur.
Circuit/System Verification
Review the Display ECM & GPCM Inj. Flow Rates parameter with a scan tool. All cylinders should be programmed with a flow rate number. Both the GPCM and the ECM should be programmed with the same flow rate numbers for the corresponding cylinders.
Circuit/System Testing
Important: If the flow rate number is not available in either control module, the numbers will need to be retrieved from each individual injector.
Fuel Injector Identification Numbers
1 - Manufacturing Plant
2 - IQA Number
3 - Manufacturing Date
4 - Injector Number
5 - Serial Number
With a scan tool installed, enter the vehicle information and select the following options:
Engine Control Module
Module Setup
Injector Flow Rate Programming
Display ECM & GPCM Inj. Flow Rates
Record all flow rate numbers with the corresponding cylinders from the control modules.
Important: When installing a new fuel injector, ensure that the IQA data number from the yellow IQA Data Tag, shipped with the new injector, is programmed to the correct cylinder
If any injectors are replaced, go to Reprogram Injector Flow Rates parameter and enter the flow rate number of the new injector to the corresponding cylinder. The flow rate numbers will automatically update both control modules.
If the ECM was replaced, go to Copy GPCM Inj. Flow Rates to ECM parameter and reprogram the ECM. This will update the ECM with the GPCM flow rate numbers.
If the GPCM was replaced or the flow rate numbers are not the same for both modules, go to Copy ECM Inj. Flow Rates to GPCM parameter and reprogram the GPCM. This will update the GPCM with the ECM flow rate numbers.
If both control modules were replaced, go to Reprogram Injector Flow Rates parameter and enter the previously recorded flow rate numbers or the numbers retrieved from each individual injector, to the corresponding cylinders.
Repair Instructions
Install any components or connectors that have been removed or replaced during diagnosis.
Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
Turn OFF the ignition for 60 seconds.
Turn ON the ignition, with the engine OFF.
Clear the DTCs.
If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure. OR
If the repair was symptom related, duplicate the conditions under which the customer concern occurred to verify the repair. If the customer concern reoccurs, return to Symptoms - Vehicle and perform the appropriate symptom diagnostic.
Fuel Injector Flow Rate Programming
Circuit/System Description
The control functions for the fuel injection system are integrated in the engine control module (ECM). Each injector's flow rate information and cylinder position are stored in the memory of both the glow plug control module (GPCM) and the ECM. The fuel injector flow rate programming must be done when any of the following procedures are performed:
The ECM is replaced
The GPCM is replaced
Any fuel injectors are replaced
If the ECM does not communicate, the flow rate information can be retrieved from the GPCM. If both control modules fail to communicate, the fuel injector flow rate information, or injection quantity adjustment (IQA) flow rate numbers, will need to be retrieved from each individual injector.
Before Programming A Control Module
Important: DO NOT program a control module unless you are directed by a service procedure or you are directed by a General Motors Corporation service bulletin. Programming a control module at any other time will not permanently correct a customers concern.
Ensure the following conditions are met before programming a control module:
Vehicle system voltage
There is no charging system concern. All charging system concerns must be repaired before programming a control module.
Battery voltage is between 12-16 volts. The battery must be charged before programming the control module if the battery voltage is low.
A battery charger is NOT connected to the vehicle battery. Incorrect system voltage or voltage fluctuations from a battery charger may cause programming failure or control module damage.
Turn OFF or disable any of the following systems that may put a load on the vehicle battery:
Twilight sentinel
Interior lights
Daytime running lights (DRL)-Applying the parking brake, on most vehicles, disables the DRL system. Refer to the Owner's Manual.
HVAC systems
Engine cooling fans, etc.
The ignition switch is in the proper position-The scan tool prompts you to turn ON the ignition, with the engine OFF. DO NOT change the position of the ignition switch during the programming procedure, unless instructed to do so.
All of the following tool connections are secure:
The connection at the data link connector (DLC)
The voltage supply circuits
DO NOT disturb the tool harnesses while programming. If an interruption occurs during the programming procedure, programming failure or control module damage may occur.
Circuit/System Verification
Review the Display ECM & GPCM Inj. Flow Rates parameter with a scan tool. All cylinders should be programmed with a flow rate number. Both the GPCM and the ECM should be programmed with the same flow rate numbers for the corresponding cylinders.
Circuit/System Testing
Important: If the flow rate number is not available in either control module, the numbers will need to be retrieved from each individual injector.
Fuel Injector Identification Numbers
1 - Manufacturing Plant
2 - IQA Number
3 - Manufacturing Date
4 - Injector Number
5 - Serial Number
With a scan tool installed, enter the vehicle information and select the following options:
Engine Control Module
Module Setup
Injector Flow Rate Programming
Display ECM & GPCM Inj. Flow Rates
Record all flow rate numbers with the corresponding cylinders from the control modules.
Important: When installing a new fuel injector, ensure that the IQA data number from the yellow IQA Data Tag, shipped with the new injector, is programmed to the correct cylinder
If any injectors are replaced, go to Reprogram Injector Flow Rates parameter and enter the flow rate number of the new injector to the corresponding cylinder. The flow rate numbers will automatically update both control modules.
If the ECM was replaced, go to Copy GPCM Inj. Flow Rates to ECM parameter and reprogram the ECM. This will update the ECM with the GPCM flow rate numbers.
If the GPCM was replaced or the flow rate numbers are not the same for both modules, go to Copy ECM Inj. Flow Rates to GPCM parameter and reprogram the GPCM. This will update the GPCM with the ECM flow rate numbers.
If both control modules were replaced, go to Reprogram Injector Flow Rates parameter and enter the previously recorded flow rate numbers or the numbers retrieved from each individual injector, to the corresponding cylinders.
Repair Instructions
Install any components or connectors that have been removed or replaced during diagnosis.
Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
Turn OFF the ignition for 60 seconds.
Turn ON the ignition, with the engine OFF.
Clear the DTCs.
If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure. OR
If the repair was symptom related, duplicate the conditions under which the customer concern occurred to verify the repair. If the customer concern reoccurs, return to Symptoms - Vehicle and perform the appropriate symptom diagnostic.
Attachments
Mamu, any update to this thread? I had a customer with a similar problem until it wouldn't even fire at all. Tore into it and found a plethora of different contributors. For the sake of keeping the data together in one thread, an update from you as well may help many others in the future.
An update on this would be phenomenal. I have an LMM that the guy himself did a turbo swap and headgaskets. It has had a misfire since then on CYL 1 and has been to 2 different shops before it made it to me. The harness tests fine. Swapped injectors 1 and 3, problem stayed at CYL 1. Last shop did a compression test and leakdown which passed, I have yet to get that far. It has a light fuel haze at and dead miss at idle, unplug injector 1 and the haze goes away.
Couple of things that I found with the motor I referenced above was: customer had gotten terrible fuel with lots of water contamination, that's what started the downward spiral. Started with fuel rail pressure low code and gray smoke and rough running below 1500rpms, then got to throwing a cyl #5 misfire code randomly, then cyl #1, 3, 7, and 8 misfire codes in that order, then stopped being able to fire up. Would make great rail pressure and stumble like it wanted to fire, but no dice. Checked the circuitry, wires, plugs, and solenoids all checked out. Ckp and CMP sensors graphed well and no pulses missed. Tried unplugging up to 2 of the suspected bad injectors at a time, no change. Compression tested and scoped cyl # 5, was a tad lower than expected at 270psi and scope showed a bright shiny spot in the top center of the dome. Decided to pull the motor. While pulling the head, found a stainless washer down in the injector bore for cyl #5 that I certainly didn't put there:cool2: piston ended up being fine other than the shiny spot, which was interesting to me.... No damage to the tip of the injector or anything. Reluctor wheel ended up being fine too, but when I pulled the reluctor hub off after noticing it had excessive radial clearance, the alignment pin was pretty smashed up. Nothing wrong with the cam pin or balancer pin. Also found the piston protrusion on cyl 5 to be . 005" less than the average of the other 7. Quite a Frankenstein for being a super clean 08 with 123k and 2 owners.
Ended up swapping a whole other engine into it. I am waiting on test results for the injectors and pump. Fuel sample results weren't pretty.
Ended up swapping a whole other engine into it. I am waiting on test results for the injectors and pump. Fuel sample results weren't pretty.
Sorry guys just seen this.
I havent had any break through. Just talked to customer the other day (yes 3 years of sitting here while hes been in and out of jail/hospital/etc...) he threw a fit and said he wouldnt pay any bills towards the truck since it's not fixed. Pushed it back in the shop and starting again.
Sent from my SM-G892A using Tapatalk
Send him a bill for storage and when he doesn’t pay. Take the truck as collateral and either sell it or part it out.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk