UPDATE:
here is the info i was able to pull with my scan tool.

P0300 (freeze frame data)

Fuel System 1
closed loop

Fuel System 2
closed loop

Calculated LOAD
20 %

Engine Coolant Temp
188 degrees F

STFT Bank 1
0.0 %

LTFT Bank 1
6.2 %

STFT Bank 2
-0.7 %

LTFT Bank 2
8.5 %

Intake Manifol Pressure
17.7 in.hg.

Engine RPM
2011 RPM

Vehicle Speed
54 MPH

Mass Air Flow Sensor
004.38 lb/min.

Throttle Postion
20.3 %

*no enhanced DTC's present.

**fail since clear;
P0147, O2 heater cicuit (Bank 1, sensor 3)
-this was changed in the second week of January. still under warrenty.

P0300 Random Misfire Detected (twice)
-one in Freeze Frame data, one in "Pending"

P1380 ABS/EBCM/ED(T)CM DTC Detected/Rough Road Data unuseable.

 

I had the exact same symptoms on my '97 Jimmy, started at around 180k. FINALLY Pulled the distributor at 200k, teeth had less than 50% metal left on them. Replaced gear, no more problems. I highly recommend checking it. It took me less than an hour, and I had never had a disributor out before.

Steve

 

I dont know if this is relavent, but i blew the upper intake manifold gasket on my 01 blazer. I had coolant in my oil. The oil was "foamy" i guess. Pressure testing of the radiator failed too.

 

well, this goes back a few days-and i've posted some work i've completed elsewhere, just thought i'd let everone know what the out come of these issues was..............

on Saturday morning i did cap & rotor,thermostat and checked the cat-had a sudden loss of power on the top end (no passing ability), and kinda more sluggish than not on the bottom end.

cat temp was ok-colder @ the front-and it did seem to run better after the mini tune up (plugs were checked, they're fine). finally bought a new 1000 CA battery that afternoon-i knew i needed it since June, but was ok 'til the cold weather reminded me about it!

Saturday night coming back from Toronto, it was even worse than before! barely able to do 100 on the highway (60 for you boys down there ), a gutless wonder trying to make it up any hill.

Monday morning, i checked the fuel pressure-70 psi key on, 59 psi running, w/instant pressure response when the throttle was pressed, so the pump is good. guess it's the injectors then..............HOLY S**T! they're out to lunch on the cost of these things!!

even my parts supplier was too much for my taste (cheap bastard @ heart, plus no guarantee that was the problem) so i took the set up from another engine i had stripped for parts (broke the bottom end, had alot of new parts on it when i bought it the truck for parts).

ripped the top end off-why the hell is the main wiring harness run right over the top of the engine-IN THE WAY?!? changed the injector/nozzles, bolted her back together, went for a test drive, a little better but CEL flashing it's *** off & still a little slugish-now what!?!

threw my friends Snap ON scan tool on it (oh, such a nice tool!) cleared everything-and then found that the Cam timing is @ -15!!!

what the hell! i've never had it out, doesn't look like it ever has (only 158K/98M on it when i got it last Christmas) and with 194K on the clock i can't see the chain being a problem (i'm hoping), so what the hell do i do now?!?

"i'll tell ya what i'm gonna do, you piece of s**t!" i say to it...........i take off the distributor hold down tab, take the torch (my second favorite tool) and cut out a section so it'll line up with the bolt hole.

put it back on, re-set the timing, tightened the bolt, and so far so good.

we'll see just how well it goes tomorrow on the way to work.

question though, here are 2 pic's of the lower intake, the 1st one is my truck (kinda dirty), the 2nd one is from the other engine (loos pretty good for almost 280K on it). does my intake really look that bad (in your opinion)? the "scum" on my intake was barely enough to scrap off with your nail, so is it just a dirty wh*re, or what?





so that was on Monday, and Tuesday wan't much better, but........

i finally fixed the b**ch! (99.9999% sure)

sorry, but she's been driving me up the wall with her "issues".

as i mentioned earlier, i had checked the cat to see if it was running right (running correct, temperature wise), so i started looking elsewhere. but this morning (off work again) i said "chuck it!, it's got to be the cat".

swapped MAF with one i knew was good-no change. double checked the syncronization of the cam timing & cranck sensor-all good still. triple checked the plugs, again!-almost picture purfect.

so...........i drill a small hole right @ the weld for the cat's front flange, insert my vacuum gage, start the truck, rev 'er up to 3 grand, and.............HOLY S**T! just over 5 lbs of back pressure!! so now i'm getting a cat & gaskets, and i'm gonna do the back O2, since i had the code for that come up before. i know the O2 might have been a cause of the failing cat, but it's still actually driveable, just no ***** on the top end-especially when she warms up. but the fact that the truck still had the factory cat on after 194K, goes alot towards it finnaly giving up.

oh yeah, gotta remember to weld that hole up, don't want to be driving around, sounding like on of the locals, hahahahaha!

 

ok 3 things:

1) im not sure what you did with the torch? can you expain what you did with it?

2) i see some puddling in your intake, is it gas? or oil?

3) why not just temporalriy remove the cat and see how it runs with out it to see if its clogged?

 

1) you know how the hold down tab for the distributor has a bolt hole that just clears the bolt? i took the torch and removed almost all of the material to the back of the tab. so i made the hole into a slot-so i could play with the timing. understand what i did now now?

2) if you're refering to the little dark puddles along the sides, that's oil.

3) sorry, i don't f**k around with crap like that. used to in the past, but my time is stretched too short as it is.

besides, when i pulled off the cat-which i must say is soooo much easier with the flanged exhaust systems-the front elemant was all broken, and the second element was clogged & actually melting! never seen one melt before .

she's all better now, runs even better than when i first got her. no stuttering or hesitation (probably due to the timing being corrected), and now the power is back up to par-for an almost 200K 4.3 anyways.

 

1) oh so you elongated the hole so you could turn and modify and adjust the distributor timing. so how did it work out? did adjusting the timing put it from -15 to the advanced area +8 or +10 after the modification slot?

2) so no fuel leaking in your motor then, thats good!

3) i only ment removing the cat just for a test run, not prermantly...just to check if it runs better without it will tell you if its clogged or not....then you know to replace it or not....

 

1) it worked out great.

but now you've raised some new question................i thought these trucks (like the 1st gen's) needed the timing set @ 0 (that's be "zero")? you know how you'd disconnect the wire below the heater box on the 1st gen's, set timing to "0", then reconnect the wire for it to run properly. i thought these newer 4.3's needed to be set-up the same way (but of course no wire to disconnect)?

anyone care to clarify this question? the truck is running great right now, with it sat @ 0, but if it needs more, then it'll be amazing after that!

3) i kinda figured that's what you meant. plus after i posted, i digested your staement a little furthur, and realized i sounded like i was coming down on you & your commet. that was far from what i was trying to relay.

i just knew @ that point that the cat was toast. but if it wasn't, you guys would've been reading about all the new curse words i came up with, while trying to find a new engine. 'cause that would've been the only other problem. luckily my original diagnosis was on the money.

 

1) there is no wire to disconnect on your 98 model... that is true for the 94 and older only...just curious, how did you check your timing? with a timing light? or a diagnostic scanner read out hooked up under your dash? so your intial timing is set to zero now? also when you rev up the motor is the timing in the + range now? also what was the cure that fixed your truck? the timing or the cat? does your truck run excellent know without any misfire or sputters?

 

isn't that what i just said?

it was a combo of the two that fixed the truck. and i checked-and set-the timing using my friends Snap On scan tool. i was told (& under the impression) that you can't use a timing light on these engines.

1) the cat was clogged, so the exhaust wouldn't flow properly (chocking the engine). this of course was my "gut instinct" in the first place.

2) the timing was so far out, i know for certain that's what the cause of the stuttering was from-at least i know that now!

in the last month (since the temperature has been dropping) i'd need to warm up the truck for a solid 5 minutes before being able to "forcefully" drive away. it seemed like the engine needed to be totally saturated with heat before it got better, but not completely cleared up.

now, 30 seconds of warm up, and it drives away like there was nothing wrong in the first place.

all in all, i must say i've learned alot-which i do enjoy-about these newer engines, but i wish i could've gone without the headaches, but then we wouldn' remember the solutions next time, or have so much fun doing it.

i'm also really glad that i never cracked the top of the engine off for the typical LI gasket leak, that seems to be so common for these 4.3's, or the fact that i never dropped cash on the injector body & poppets to find out it wasn't the problem.

i do seem to remember saying in the begining, that i was 99% sure it was an electrical issue, not a leaky gasket problem. but i will freely admit that i was lucky as well-it could've been that too!

soooo............since i'm chewing the fat with ya Kane, i remember you mentioning something about using a 2L bottle of Coke to flush the coolant system out, was that correct? i'm asking, since the previous owner (original owner) never changed the Death Cool in it-ever! there's a dark brown sticky sludge inside the rad & overflow tank, so i'll pit money on it, that the inside of the engine/heater core/????? probably has the same throughout it.

thanks again to all that have helped throw ideas & suggestions/solutions out here for this. greatly appreciated

thank God for and finding this site!