misfiring on driver side cylinders

[irarb01]

hey everyone so i got my engine swapped in my 04 tahoe it’s a 5.3 was running great for a couple weeks then all of a sudden im getting multiple cylinder miss fires on all of my my odd cylinders this engine i swapped in was a market place find. was told it had 140k on it supposedly car runs great beside mis no coolant loss or anything. only thing is when i’m accelerating you can here it popping and back firing then all of a sudden it clears up and takes off like a bat out of hell. replaced all plugs and coils and ignition wires on driver side already. still no luck.

 

[Marky Dissod]

Try swapping injectors from left to right and vice versa. If problem moves to the right side,
you need new injectors.
If problem stays on the same side, serious diagnosis required.

 

[Donal]

hey everyone so i got my engine swapped in my 04 tahoe it’s a 5.3 was running great for a couple weeks then all of a sudden im getting multiple cylinder miss fires on all of my my odd cylinders this engine i swapped in was a market place find. was told it had 140k on it supposedly car runs great beside mis no coolant loss or anything. only thing is when i’m accelerating you can here it popping and back firing then all of a sudden it clears up and takes off like a bat out of hell. replaced all plugs and coils and ignition wires on driver side already. still no luck.

Check the ground cable for that side.

 

[Scottydoggs]

can also look over the harness and plugs to the coils and the injectors.

 

[irarb01]

Check the ground cable for that side.

which ground cable is that ?? and i haven’t swapped the injectors but i can give thet a shot tomorrow

 

[Fless]

Before swapping the injectors why not put a noid light on them to make sure they're getting their commands?

Could also measure the voltage drop between the rail ground and the engine block, also from the rail to the battery negative. Compare driver's side to passenger side.

 

[irarb01]

so one thing i noticed is if i let the car warm up it will stop missing if it’s cold it will miss slightly at idle and will miss heavy under load. once its a little bit warm it will run fine under load.

 

[afpj]

Oooh, what's your fuel trims? If the driver's side bank is high positive when cold, and is better than warm, suspect intake manifold leak for a item to explore.

 

[nonickatall]

so one thing i noticed is if i let the car warm up it will stop missing if it’s cold it will miss slightly at idle and will miss heavy under load. once its a little bit warm it will run fine under load.

That clearly sounds like an electric problem. Did you read out the car with a scanner? You can see on which cylinders you have missfire.

If they are on all cylinders on one bank, can be the ground as already mentioned, or a clogged cat which is not very likely, when you swapped the engine. Except the old Engine had the same problems.

It can also be a lose connector on the injectors or ignition harness, or a lose or damaged ignition cable.

Did you check the ground cable as mentioned already?

 

[irarb01]

That clearly sounds like an electric problem. Did you read out the car with a scanner? You can see on which cylinders you have missfire.

If they are on all cylinders on one bank, can be the ground as already mentioned, or a clogged cat which is not very likely, when you swapped the engine. Except the old Engine had the same problems.

It can also be a lose connector on the injectors or ignition harness, or a lose or damaged ignition cable.

Did you check the ground cable as mentioned already?

That clearly sounds like an electric problem. Did you read out the car with a scanner? You can see on which cylinders you have missfire.

If they are on all cylinders on one bank, can be the ground as already mentioned, or a clogged cat which is not very likely, when you swapped the engine. Except the old Engine had the same problems.

It can also be a lose connector on the injectors or ignition harness, or a lose or damaged ignition cable.

Did you check the ground cable as mentioned already?

where is the ground located?? i’ll check it today

 

[Hobert]

 

[DRLexpress]

View attachment 449089

Thanks for posting this. Don't need it now but downloaded and saved for future use.

 

[irarb01]

hey yall quick update grounds seem ok only thing i have found is my short term fuel bank is through the roof looking at it with a scan tool it’s around 80/90

 

[justirv]

so one thing i noticed is if i let the car warm up it will stop missing if it’s cold it will miss slightly at idle and will miss heavy under load. once its a little bit warm it will run fine under load.

Intake manifold gasket shrinkage could be the problem. When the engine warms, expansion helps "re-seal" it... possibly getting un-metered air when cold.

 

[irarb01]

Intake manifold gasket shrinkage could be the problem. When the engine warms, expansion helps "re-seal" it... possibly getting un-metered air when cold.

i tightened my intake found one loose still didn’t change noticed black
soot on my tail pipe and w sulfur smell from my exhaust some times i’m wondering if my cat failed when my previous motor blew the head gasket

 

[justirv]

i tightened my intake found one loose still didn’t change noticed black
soot on my tail pipe and w sulfur smell from my exhaust some times i’m wondering if my cat failed when my previous motor blew the head gasket

Not so much bolt tightening, but actual gasket shrinkage. Smoke check (when stone cold) or use your choice of (safe) aerosol spray to see if your idle speed changes when you spray the area with engine running.

 

[KerryBoehm]

On my 07 there is a common ground for the coils on each side. Mine corroded bad and lost all spark on the passenger bank. Really have to hunt for it but it's a round eyelet on the side of the block.