Hi everyone, I’m having some trouble with my engine. It keeps misfiring and I think my catalytic converters are bad. I’ve already swapped out the cats, put in new upstream and downstream sensors, replaced the spark plugs, and changed out the coil packs. The only thing I haven’t touched yet are the fuel injectors. I’m a diesel mechanic, so I’m not really sure about gas engines. How many injectors does this engine actually have? Some say it’s 6, while others mention 12. If it is 12, where would the other 6 be located?
The injectors are under the intake manifold. This setup uses a dual injector system with 6 port injectors and 6 direct injectors. If you have a good scan tool, you can look at freeze frame data when the misfiring occurs. The truck starts off with the direct injectors and runs off the port injectors at idle. There’s a point where it switches and runs on both, and under heavy loads, it uses the direct injectors only. If you can, try to command it to run on port injectors and do a full throttle sweep, then do the same with the direct injectors to find out which ones might be causing misfires. But you’ll need access to a reliable scan tool for that.
@Juno
I’m seeing these values:
0% on FUELSYSA_B1
100% on FUELSYSB_B1
0% on FUELSYSA_B2
100% on FUELSYSB_B2
Shane said:
@Juno
I’m seeing these values:
0% on FUELSYSA_B1
100% on FUELSYSB_B1
0% on FUELSYSA_B2
100% on FUELSYSB_B2
Are those readings at idle? If they are, it looks like fuel system B is your port injectors.
@Juno
I couldn’t make those values change at all, whether I’m idling or revving up the RPMs.
Shane said:
@Juno
I couldn’t make those values change at all, whether I’m idling or revving up the RPMs.
Sounds like you might need someone else to drive the truck while you monitor the scan tool.
@Juno
Lol, I thought about putting the scanner in my phone mount during my drive home. I’m still new to OBD2 scan tools. I mostly use TEXA software at my job and we don’t have an auto license. Are there any other values I should keep an eye on for fuel problems?
@Shane
I’m not sure what all you can view, but I usually check the low side fuel pressure actual vs what the PCM wants and do the same with the high-pressure fuel rail. With dual fuel injection systems, I always try to get it to run on either direct or port to narrow down which one might be causing the misfire.
Could it be the MAF sensor? Any check engine light on?
Charlie said:
Could it be the MAF sensor? Any check engine light on?
Yeah, I’m getting misfires on cylinder 2 and 5.