Supercharged111
Truly Awesome
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I'm thinking cold start fueling?
L29 411 Swap P0300 code
- Thread starter Beeffajitas
- Start date
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Christian Steffen
I'm Awesome
I didn't think to look at the fueling tables, good idea. At least for cranking there looks to be some useful information there.
Beeffajitas
OBS Enthusiast
What's the name of the black box tune?
Christian Steffen
I'm Awesome
Just go in to the tune repository and look for a 1998 7.4, it'll say stock tune.
Beeffajitas
OBS Enthusiast
Are some of the tables unavailable? There seems to be some missing information.
OutlawDrifter
Long Roof K2500 Driver
I chased the same code on my LS swapped Z28. Took a noid light to find the issue. I had an injector plug that had about 1 strand left attached on the ground pin causing issues. Took me a year to find it. You might start there.
Christian Steffen
I'm Awesome
Which tables are you referring to? The black box is missing a lot when compared to the 0411, that is one of the big benefits to the 0411.
Beeffajitas
OBS Enthusiast
I wanted to make an update and see if you guys have any ideas. I've isolated the misfire to Cyl 4. I swapped the plug to Cyl 2 and the wire to Cyl 6, no change. I replaced the crank sensor, no change. I've done a few crank relearns, no change. I've replaced the cap and rotor (which were pretty crusty), no change. I haven't touched anything fuel-related yet. I've hosed down the intake with starting fluid with no observed rpm change (i.e. no vacuum leaks).
Now, I've observed that the misfire is occurring at light throttle (between 35 - 65 kPA), but NOT at idle. If I get on it, there's no logged misfires. If I have it in neutral and hold the rpms over 3000 rpm, there's no logged misfires. When I am in that band of 35-65 kPA, cruising along, it logs a lot of misfires.
This morning, over a 50 min commute, it logged 29,635 misfires on Cyl 4. If I average 2000 rpm (just a guess), it ends up being 60% of the ignition events were misfires. Here's the thing, I can't tell that it's misfiring. If the SES never went off, I wouldn't even be looking at this.
The truck did sit for a few months while I changed out the rear axle, so maybe the injector is gummed up?
So what does the hivemind think? Do I pull the injectors and clean them (there is a place near me), or do I just ignore it at this point?
Now, I've observed that the misfire is occurring at light throttle (between 35 - 65 kPA), but NOT at idle. If I get on it, there's no logged misfires. If I have it in neutral and hold the rpms over 3000 rpm, there's no logged misfires. When I am in that band of 35-65 kPA, cruising along, it logs a lot of misfires.
This morning, over a 50 min commute, it logged 29,635 misfires on Cyl 4. If I average 2000 rpm (just a guess), it ends up being 60% of the ignition events were misfires. Here's the thing, I can't tell that it's misfiring. If the SES never went off, I wouldn't even be looking at this.
The truck did sit for a few months while I changed out the rear axle, so maybe the injector is gummed up?
So what does the hivemind think? Do I pull the injectors and clean them (there is a place near me), or do I just ignore it at this point?
Christian Steffen
I'm Awesome
I would try cleaning them, it isn't that hard to get to them. I would also check the wiring and all connections for the injectors.
Beeffajitas
OBS Enthusiast
The more I think about it, the more I agree. I need to do the lower intake to head gasket anyway. I've had a slight coolant leak at the crossover.
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