98 Tahoe - Cylinder 6 misfire - fuel or ignition problem?

[HoeLV]

I think I've come to the conclusion the new spyder injection unit is faulty. After trying to find the cause of this misfire and nothing seemingly fixing it and reading the reviews regarding the unit, it's not a far stretch that the unit was bad from day one or failed early on.

I'm going to remove it and exchange it under warranty. If that doesn't fix it, I'll be surprised.

 

[Tanner Peterson]

I think I've come to the conclusion the new spyder injection unit is faulty. After trying to find the cause of this misfire and nothing seemingly fixing it and reading the reviews regarding the unit, it's not a far stretch that the unit was bad from day one or failed early on.

I'm going to remove it and exchange it under warranty. If that doesn't fix it, I'll be surprised.

Sure hope that fixes it for you. I’m on my second one with the same results.

 

[exp500]

These injector systems are really picky about fuel pressure. Put a long hose on your gauge and stick it to windshield. Watch fuel trims. steady state cruise. My experience is when it's missing it is at 60 or below.
If I am removing injectors and theres more than 30-50k miles on lower intake gaskets, they get changed. Only adds 45 minutes and prevents coolant or air leaks you can't find.
Good luck and keep posting results.

 

[HoeLV]

These injector systems are really picky about fuel pressure. Put a long hose on your gauge and stick it to windshield. Watch fuel trims. steady state cruise. My experience is when it's missing it is at 60 or below.
If I am removing injectors and theres more than 30-50k miles on lower intake gaskets, they get changed. Only adds 45 minutes and prevents coolant or air leaks you can't find.
Good luck and keep posting results.

When I do the warranty swap and have the upper intake off, I plan to also do the lower intake gaskets. I should have done that the first time, but didn't think about it.

I am replacing the fuel pump regardless this afternoon If that does fix the misfire and I don't end up needing to warranty out the new spyder injection, I will post it. I just gotta think other cylinders would have some misfire action as well.

After doing the fuel pump, I will check the fuel trims as noted above and post the results.

Thanks again

 

[HoeLV]

Update: So after replacing the fuel pump, intermittently I am getting P0174 (System too lean - Bank 2) and P0302 (Cylinder 2 misfire). I haven't seen a pattern to it yet. But, I have randomly scanned for codes a couple times while driving and either both codes show up or no codes show up.

I will try to get a log of fuel trims, I have to refresh myself on how to set up the app to log the data.

 

[east302]

A couple of documents from alldata and the service manual…

 

[east302]

 

[east302]

 

[east302]

And last is alldata’s P0174, apparently revised for use with a Tech2 (fuel trim percentages)

 

[exp500]

Not really necessary to log fuel trims, just a look at them when steady state. Verify fuel pressure when missing or setting codes. Trying to narrow this down. Could still be leaking lower intake. I like to watch misfire counts per cylinder and front O2 sensors voltage also.