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

[Fless]

Thank you for the responses.

To the question asked, I did regap the plugs when I put them back in as they were no longer proper.

@YukonGTmaster, I did notice a few times the RPM jump when going into "Park," but I only recall it happening 2-3 times. I have not seen a drop in coolant.

It looks like I will be ordering some new plugs, wires, cap and rotor. Is there a consensus on brands to stick with or avoid? Just sticking with AC Delco? I've always heard good things about MSD when it comes to ignition, distributors, wires, etc.

Is there any benefit in making the switch from the CFI to the MPFI? Is the new system that much better?

@exp500 you usually have some recommendations. Any now?

 

[Eman85]

As far as ignition components go I've had the best luck with Standard Motor Products.

 

[exp500]

AC Delco/Delphi or United DCR 820X cap /rotor , Packard or GM wires, NGK or AC plugs Bare minimum.
Coil, ICM, CPS only delco/delphi/GM.
There is a substantial improvement to upgraded injectors in driveability and engine life.
You guys covered it well! He should still do a driving fuel pressure check when missing on #6, If you change injectors do lower intake gaskets also.

Eman- Which grade of Standard Motor Parts? And how do you determine which is which?

 

[YukonGTmaster]

Thank you for the responses.

To the question asked, I did regap the plugs when I put them back in as they were no longer proper.

@YukonGTmaster, I did notice a few times the RPM jump when going into "Park," but I only recall it happening 2-3 times. I have not seen a drop in coolant.

It looks like I will be ordering some new plugs, wires, cap and rotor. Is there a consensus on brands to stick with or avoid? Just sticking with AC Delco? I've always heard good things about MSD when it comes to ignition, distributors, wires, etc.

Is there any benefit in making the switch from the CFI to the MPFI? Is the new system that much better?

MSD makes good stuff. I used to run their fat 10mm plug wires. I went back to the factory 8mm AC Delco wires and plugs. I’ve never had a problem with AC Delco cap and rotors.

The MPFI is a real upgrade in fuel delivery. The CFI is a weak link, as are the original lower intake gaskets. The upgrade is a long weekend project, IF you don’t find other stuff wrong. Here are some of my adventures below.

5.7L Vortec Problems

I was having a rough idle, and the Amber engine light would flash (Random misfire) when I started up in the morning. I would cycle the key off for ten seconds, the light would go out and I would drive to work. It was not latching any codes. I had a bad coolant leak as well. Then I started to...

www.tahoeyukonforum.com

 

[HoeLV]

AC Delco/Delphi or United DCR 820X cap /rotor , Packard or GM wires, NGK or AC plugs Bare minimum.
Coil, ICM, CPS only delco/delphi/GM.
There is a substantial improvement to upgraded injectors in driveability and engine life.
You guys covered it well! He should still do a driving fuel pressure check when missing on #6, If you change injectors do lower intake gaskets also.

Eman- Which grade of Standard Motor Parts? And how do you determine which is which?

Thanks. I placed an order prior to suing you reply.
Here is what I ordered:

AC Delco D465 rotor
AC Delco D329A cap
AC Delco 9718Q wires
AC Delco 41-993 plugs
Standard FJ504 injectors w/ gaskets and bracket

 

[BG1988]

How is the fuel trims?

 

[HoeLV]

MSD makes good stuff. I used to run their fat 10mm plug wires. I went back to the factory 8mm AC Delco wires and plugs. I’ve never had a problem with AC Delco cap and rotors.

The MPFI is a real upgrade in fuel delivery. The CFI is a weak link, as are the original lower intake gaskets. The upgrade is a long weekend project, IF you don’t find other stuff wrong. Here are some of my adventures below.

https://www.tahoeyukonforum.com/threads/5-7l-vortec-problems.125550/[/URL

http://

MSD makes good stuff. I used to run their fat 10mm plug wires. I went back to the factory 8mm AC Delco wires and plugs. I’ve never had a problem with AC Delco cap and rotors.

The MPFI is a real upgrade in fuel delivery. The CFI is a weak link, as are the original lower intake gaskets. The upgrade is a long weekend project, IF you don’t find other stuff wrong. Here are some of my adventures below.

5.7L Vortec Problems

I was having a rough idle, and the Amber engine light would flash (Random misfire) when I started up in the morning. I would cycle the key off for ten seconds, the light would go out and I would drive to work. It was not latching any codes. I had a bad coolant leak as well. Then I started to...

www.tahoeyukonforum.com

Well shit, I don't have time to deal with all that. Hopefully what I have goes somewhat smoothly. While I do enjoy riding the motorcycle, there is a reason its not my only mode of transportation any longer.

 

[HoeLV]

How is the fuel trims?

Let me see if I can find the logs on my phone. I believe i set it up to log those along with the O2 sensors.

 

[HoeLV]

UPDATE:

I went ahead and replaced the following:

AC Delco D465 rotor
AC Delco D329A cap
AC Delco 9718Q wires
AC Delco 41-993 plugs
Standard Motor Products FJ504 injectors w/ gaskets and bracket
Fuel Filter

While at it, I put in a new AC Delco A1301C air filter and did an oil change.

Everything ran great, drove about 400 miles with everything smooth as silk, no misfires, etc.

Then out of nowhere, I started getting pretty consistent misfires on cylinder 2 once it warms up. Any suggestions to look for? I checked the plug wire and it's not loose. I am going to try and pull the plug this evening (work hours have been crazy the last few days).



And since you asked, here are the 8 plugs when I pulled them out.

What has been said. Replace plugs, cap, rotor and wires, especially since you think the wires may be OE. Deposits on those plugs and would love to see all 8 plugs when compared.

 

[exp500]

What is your plug gap? I don't see any anti-sieze on the threads either.