2002 5.7 conversion van misfire helppppp

[2002conversionblue]

Hey guys I have a 2002 5.7 express conversion van I keep getting a misfire code
I changed the cap and rotor
plugs are new
coil is 3 years old

after I changed the cap and rotor code went away for about a week maybe 60 miles driven and now it’s back

car shows no rough idle
no starting hesitation
I’m at a loss trying to chase this code down

any help will be appreciated thank you

[2002conversionblue]

Code is P0351 forgot to add that

[MountainManJoe]

try the troubleshooting steps here:


https://charm.li/Chevy%20Truck/2002/Exp ... rts/P0351/

[bman86]

try the troubleshooting steps here:


https://charm.li/Chevy%20Truck/2002/Exp ... rts/P0351/

WOW, this link is a FANTASTIC resource!!!! Thanks a million @mountainmanjoe

@2002conversionblue , I also have a 2002 GMC Savana 1500 with a 5.7L Vortec with 175K miles and am in the middle of trying to figure out a bunch of ignition related codes, as well as some others. The above link provides A TON more info than just a random internet search of the codes. I'm surprised I never came across it. Again, thanks @MountainManJoe !!


P0300 is the main code I've been dealing with, though I got a P0304 last night which is a bit more specific. I've got a lot of reading up to do on this. The thought of having to dig into the valves and heads is terrifying!!! The engine runs smooth as silk. The stumble that seems to cause the P0300 code is only noticeable under heavy load and high RPM, like going up a hill. That sometimes triggers it.

P0335 has also reared it's ugly head, but I found that the 3-wire harness had been partially burnt / melted by the exhaust manifold after I replaced the battery, battery cables and alternator. I replaced all of those parts because I had A LOT of trouble starting the engine, almost like a hard electrical cutout, with the engine jumping all over the place. I thought for sure it was a bad cable, and the battery was 7 years old and didnt load-test well. I eventually killed the starter with the flywheel jumping all over. I had great spark coming out of the coil and inevitably ended up checking the distributor cap and rotor - the cap looked like it had barnacles in it, it was SO corroded!! So the distributor cap ended up being the issue and a new cap / rotor resolved that problem. I had bought a new cam sensor and crank sensor, but had all sorts of codes related to installing them (likely caused by the melted crank sensor harness), so I put the old ones back in - they are still in now.

P0441 and P0455 have shown up, and right now I'm having trouble getting fuel into the filler neck without the gas station pump handle clicking off. So maybe the purge or vent valves are blocked or something. I have some forensics work there. I think the evap purge valve is up near the coil where I was working on the ignition troubleshooting, so maybe I knocked something loose or whatever.

P0430 has been a continuing issue over time. Even though I just replaced all four of the O2 sensors. Perhaps the catalytic converter has truly gone bad. or it's a result of an ignition of evap issue. Other than checking the wiring I'm not sure what else to do here.

Anyway, that's my long story on my 2002!! I love the van!!

[bman86]

An update on my post above ...

The melted crankshaft sensor harness seems to have been the culprit for all of the ignition codes. They haven't come back after a few days. I suppose time will confirm though. I feel confident in that one.

I looked down into the fuel filler neck and saw that the little metal flapper had become dislodged and was jammed down into the neck. This was clearly causing a fuel 'backup' as I was filling. I used a looooonnnng pair of straight pliers (from my long set of 3 from Harbor Freight) to pull the flapper out and then an extension magnet thing to get a little shard of metal that I could see. So that problem should be solved. Though I have no idea if the flapper plays a part in the EVAP checks that the ECM does. We shall see

P0430 is still hanging in there. I tried putting a thick washer under the head of the sensor to try and pull the sensor out of the exhaust stream a bit. That didn't work. The DTC light came on after about 20 minutes of driving. The engine runs smooth as silk so I just can't imagine it's a clogged fuel injector or something like that. I checked the wiring harness and it seems fine. I've got a bit more looking around to do but I think I'm going to pull the trigger on a new bolt-in set of catalytic converter from Rock Auto for $403 shipped. It's AP/Eastern P/N 645785 and listed as EPA Compliant vs CARB Compliant. I'm in CT and need to pass emissions for another couple of years. Fingers crossed this might work!!!

That's all for now. .ore later I'm sure

[MountainManJoe]

Nice work.

P0430 does not affect engine function at all. It's purely an emissions code.

Driving for too long with a misfiring engine will kill a catalytic converter from all the fuel being dumped into it.
When the engine light is flashing, it's saying "you need to stop driving and fix this right away"

[bman86]

Yeah, the misfire codes were recent. And again, likely caused by the burnt harness. But that series of events could have been the last straw for the cat (175k miles), sending me into P0430 land. I did have that code popping up every now and then when going up a hill or a bridge. But the CEL would go off after a while.

I just bought Qty 2 of the O₂ Sensor Spacer Adapter 90 Degree Connector Adapter M18x1.5 Universal from the Walmart web site (link below) for $14 each (both downstream bungs). I tried ordering something similar off Amazon yesterday but they are no longer available - maybe got pulled. I'm going to see if those do the trick from an OBD standpoint. If they do, then I will go see if I can get it through CT emissions - hopefully they don't see them and ping me!

Last resort option is to spend about $400 on Rock Auto for a whole new Y-pipe assembly that includes 2 new cats. They are listed as EPA compliant. The CARB compliant assembly is like $1300. Maybe EPA compliant equals good enough to pass CT emissions. I would have to drop the transmission cross member to get the old Y-pipe and out and the new one in. The rusted bolts holding the cross member in DO NOT look like they would be too willing to participate in that exercise. So that could be another can of worms.

Well, more later.

https://www.walmart.com/ip/O-Sensor-Spa ... om=/search