Muldible

Howdy all,

2002 Chevy Express 1500 Van, 5.7L v8 - Misfire Codes (p0300, p0307, p0128)

1) Initially had crank but no start condition
2) Replaced Dist. Cap
3) Replaced Rotor Button
4) Replaced Wires
5) Replaced Plugs
6) Confirmed Spark from Coil and to all Plugs with tester - Crank But Still No Start
7) Replaced Starter and Fuel Pump Relays (just to rule them out) - Crank But Still No Start
8) Finally Found ECT (Coolant Temp Sensor) was bad
9) Replaced ECT - Started Right Up w/ Misfire Code p0300 (Random Misfire) and a p0128 (thermostat code)

*sigh

The van is idling slightly rough on start and at low rpms, and has a lot of steam/white smoke coming out of the tail pipe. However, this all burnt off after car got up to temp so not sure if it is passing any coolant.

10) Tested Fuel Pressure - With ignition On, it was 53-55PSI. With Engine On it was 53-55PSI. This is below Spec of 60-66 PSI. The engine needs a minimum of 50 PSI to start, so hopefully meaning that the pump is good. (90%, not 100% sure of this)
11) Performed Leak Down - Pressure only loses a few PSI in 5 minutes, hopefully meaning that Fuel Pressure Regulator & Spider aren't leaking.
12) Replaced Fuel Filter - Now, with ignition On, it jumps to 60PSI. However with Engine On it drops back down to 55PSI. Not sure why at this point. Help.
13) Replaced Air Filter - It needed it badly, and couldn't hurt.
14) Cleaned MAF - It needed it badly, and couldn't hurt.

After doing steps 10-14, I cleared the codes and started it up. After a few minutes I got a p0307 code, which seemed like progress. I then:

15) Checked and confirmed spark on Cylinder #7 - Spark was all good
16) Reset DTC's and ran engine again - Received general p0300 again (p0307 and p0128 were gone).

Any help furthering my progress on solving this misfire would be VERY welcomed. I have not replaced the thermostat signaled by the p0128 code, but I figured the wouldn't be causing the misfire so I admit to ignoring it for the moment.

===

The only other variable is this odd spot I noticed on the block, right near cylinder #7. I am not sure if it is a break or normal for this engine, so please speak up if this is normal and you see this spot on your Van. I have attached an image. The image is shot as if you are looking at the rear of the engine from within the cab on the drivers side. The red lines are to help identify the gasket boundaries and help show where on the engine this spot is. Some things to note:

17) There is what appears to be rust and moisture inside and around the hole, and generally in that area
18) There seems to be no suction or puffs of air coming out of this hole, I would imagine it would be running VERY rough if this caused a compression/fuel leak. It has a slightly rough idle, but thats about it.
19) There seems to be no fluid coming from the area on start or during running

The acceleration is strong, and overall the engine is sounding much better than where it was, but I am at a loss for how to proceed with diagnosing the misfire at this point. I have spark, and my initial tests generally point to me having the fuel I need. I am thinking I should:

20) Perform a cylinder balance test
21) Perform a cylinder compression test
22) Pull the plenum and check for bad pressure regulator, or grounded injector (meaning possible problem with PCM, causing it to run all the time and not pulse)

I haven't spent that much $$$ on these fixes up to now, I am just going a little crazy trying to narrow down my options for moving forward. Any thoughts would help tremendously.

-Muldible

Muldible

Howdy all once again...

Just checking in to see if anyone could respond to any aspect of my post. Sorta at a stand still. I am leaning toward a intake manifold gasket being the culprit due to the white smoke from the tailpipe on start up, but haven't done a coolant pressure test yet. Gonna have wait out this snow storm before I can work on it again....

....thoughts?!

canucklehead

Yes could be intake gasket. Did you use iridium plugs?
Have you tried a shop with a bog tester instead of the small handheld ones? Sometimes the big ones find more codes.

purodude

I work as an owner operator for a large courier company. There are 30 trucks in the fleet about half of them are express/ savana cube vans. All the newer ones had the same problems as you describe. One of the guys spent thousands of dollars trying to fix the lean cods and check engine light problems. He did everything from fuel pump to intake gasket none of which did anything. Until he found a little corner garage with an old mechanic with 50'years of experience under his belt. Here's the kicker all you have to do is get a injector service. Now not the crap you buy at your local car parts store. A professional service. Where they hook up directly to your fuel system and flush all the crap out of the system. Apparently there is no fuel return line on the 6L so all the junk just piles up in the injectors.
Now since we came across this information every Chevy gmc truck in the fleet has had the codes and misfire problem and EVERYTIME this fix has worked.
I hope this helps.

canucklehead

I forgot about that. Here is a link describing the returnless system.

Engines: Returnless Fuel Injection Systems - EFI

jr32560

so since your vehicle in in the years of the returnless fuel system you might be on the right track --good luck post back and let everyone know what ya found--might be a common issue