Timing is at 0 on these trucks the computer sets the timing. I originally had it at 8 and it ran like crap. I'm at the point where I don't really care I got 14.4 under the hood. Engine has 165,000 so wouldn't doubt its trashed it runs good besides the little missfiring you barely notice so I'm content

 

yes i know its supposed to be at 0 degrees but with some wear and tear they like to be set at around 6 degrees or the good ol' 8 degrees. ive had a 85 full size and currently have a 91 fullsize also i use for a spare truck, but through my experience through friends and my own trucks the valves being corroded and PITTED from head gasket failure, causing a missing usually in several cylinders, its almost like electrolosis on diesel engine liners cause from overheating and/or too much water mixed with coolant.

 

The truck seems to run fine at 0 just that little bit of missing. Like I said I had it at 8 thinking of the old school engines and it would idle fine but any kinda gas and it felt like I was pulling a trailer.

 

ok so after a couple of months after fixing my p0300 code the missing and bucking came back, BUT this time it was doing it constantly at 2000 rpms regardless of what gear i was in and pulling off from stoplights and while cruising at 65mph highway speeds, and through my new snap-on solus scanner i bought i noticed the intake air temps were at 167 degrees and my fuel gauge had been jumping around for awhile and i also had some questionable egr flowing issues, well after some lengthy research and studying wiring schematics i found out that the EGR,FUEL LEVEL SENDING UNIT, AND THE INTAKE AIR TEMPERATURE SENSOR all share splice pack sp423!!!! which is located at the rear crossmember under on top of it, well i removed it and boy was it rusted and it was a B**CH to get to and remove but i relocated it to a more accessible spot on the back of the crossmember and cleaned the new grounding spot down to the bare metal and installed the sp423 with a new terminal end on it also since the wiring inside the old one were corroded too. now my truck has no more bucking or missing at 2000rpms anymore AT ALL!!!!! it actually drives like a brand new truck!! it has never ran this good and shifts smooth a pulls very hard in every gear with no letting up!!!! so to all people that has replaced and tested just about EVERYTHING on your trucks like i did, you might want to check splice pack sp423 cause it just might be the little electronic demon that was haunting mine, thanks!!!!

 

Wow! Glad you found your problem!

For those finding this later, you can ohm out the ground to those items to see if that is your issue.

 

what does this splice pack sp423 look like exactly? and does it have 1 pulg with 4 wires going to it? i found a black black with a yellow 4 wire plug mounted on the torsion bar crossmember near the drivers side. could this be it?

 

It is a connector that just has wires coming into one side. Typically, all of the wires are the same color.

 

i will take a couple of pictures of it and post them for you tommorrow, and you will see the actual bolt that the wires are mounted to and ill show you where i relocated the egr and fuel tank level sending unit grounds, also it should be located at the very rear crossmember on top of it on the drivers side right where the crossmember contacts the frame on the drivers side, it is kinda hard to pinpoint its exact location but if you look around right where i said its at you will find the wires there sharing the 1 bolt, i had to use a mirror to find it but once i found it i could easily see the bottom of the grounding bolt sticking down through the top part of the crossmember that we are talking about.

 

BUMP- Im bringing this back up to see if anybody ever took any pictures or tried this. Would like to know the location of this and try and see if it helps.

 

BUMP- Blazer started running even worse today. Its now missing at a low idle and when u try and rev it up quickly it misses pretty bad. I was going to check this and then change the fuel filter and check the fuel pressure to see if its the pump starting to go out.

If anybody can tell me a better description of where these wires are I can try an locate them to see if thats my problem.