WTF..IM GOING CRAZY...SOLVED!

[KORNBREAD]

I bought a 93 chevy suburban (350tbi) 2wd for my daily driver a week ago. Its was abused bad by old owner and has sat for almost a year. the oil and filter were the worst ive ever seen, 3 of the 8 spark plugs just crumbled when i changed them. the plug wires (not even going there), the pcv valve and hose were SHOT!, and the thermastat was beyond dead. anyways fixed everything new plugs,wires,cap,rotor, oil changed (twice to get it cleaner), new air filter, all new vacuum hoses, new muffler, and fuel filter. Anyways the truck ran really ruff but did get alot better after the work./ It still has a miss once in a while when sitting still and when i take off she bogs down and sounds like its missing untill i hit about 30mph then takes off like a rocket. while going down the e-way runs strong still but if i give it harder gas it starts to bog some and you hear a slight miss. I did notice the vacuum port on the throttle body for the pcv is very weak. i cleaned it out but i think there in it. Im starting to run out of ideas. Theres no check engine code either. has very strong oil pressure also. once im past 30mph it runs like a new truck all day long, but when i idle under 30mph or take off she boggs again and misses. any ideas?

[dhartman]

Maybe dirty injectors? We had one doing similar things, ran a can of Seafoam through gas tank and cleared right up. Been running strong for 2 years now. I am not a mechanic but a cheap idea.

[old school truck dude]

I would probably look into the vacuum situation a little further, maybe put a guage on it in a couple different places.. Can you spray some stuff around at it and see if your rpm changes I always spray in the carb/throttle body 1st to get an idea of what it might do if I got a vacuum leak I used to use a propane torch with the orifice drilled out a bit and a long skinny vaccum hose. This dont work too good outside especially if the wind is blowin even just a little bit. Does it have a cat conv on it..?

[old school truck dude]

Maybe dirty injectors? We had one doing similar things, ran a can of Seafoam through gas tank and cleared right up. Been running strong for 2 years now. I am not a mechanic but a cheap idea.

x2   And as an afterthought, any time youve had bad plugs and plug wires for quite a while, its very possible that the pickup, module, coil, rotor (pinhole in it??), any of that could be goin bad. It puts a strain on the ignition system because of the added resistance.

[Jjay78]

x2 on the cat and vacume lines, also have you gotten all teh old fuel out for sure? some of the old sludge could be mixing in...

[4x4xdodgeman]

dose it have a mass  air flow senorse ?

[old school truck dude]

dose it have a mass  air flow senorse ?

Hes sayin it has no codes.. Could it be bad and not throw a code?

[RIP_K52007]

93 burban dont have a mass air flow sensor. has a manifold absolute pressure (MAP) sensor and a intake air temp sensor (IAP) that does the same job.

[RIP_K52007]

are you loosing any collant? are you sure the timing is set correctly?

[J.C.]

fuel pump. hard to check the pressure tho. i dont get why gm didnt put them schrader valves in for fuel pressure testing purposes tho

[old school truck dude]

fuel pump. hard to check the pressure tho. i dont get why gm didnt put them schrader valves in for fuel pressure testing purposes tho

Use an a/c guage it fits, I used to use an old one for the high side

[J.C.]

the tbi fuel systems dont have a valve to be able to put the gauge on. thats what i was bitchin bout

[KORNBREAD]

Well I stuck to the road I was heading down and finally got my rebuild kit for the tbi and HOLY COW talk about a HUGE difference! That tbi was soooo pluged up and the screen was wasted. also teh tbi gasket had a super small crack threw it. She woke up big time. Still has a slight miss here and there but no where near what it was doing. Putting in a new coil and fuel filter tomorrow. Thanks for some of the ideas guys!

[KORNBREAD]

also checked it for codes and it flashed the check engine light properly telling me theres no problems being detected.

[old school truck dude]

the tbi fuel systems dont have a valve to be able to put the gauge on. thats what i was bitchin bout

Oh! I never have had any a/c workin in any of mine, all that aluminum goes to the scrap

[old school truck dude]

also checked it for codes and it flashed the check engine light properly telling me theres no problems being detected.

Then theres nothin wrong with it and its all your imagination

[Disturban]

With all the ignition components that you described that was in such bad shape I would replace all the internals in the distributor as well, something in there is probably causing your miss. Another thing to check is what kind of plug wires did you get, AC Delcos all the way buddy...used dielectric grease in the boots to prevent spark jumping out of boot and grounding on the block, it does happen. 

[old school truck dude]

X 2

[KORNBREAD]

yeah all i buy is ac lol. plugs also.   well it still has a slight miss but i noticed when i had the tbi off the egr looks really bad. its pretty much a toasted looking flying saucer lol.

[Disturban]

yeah all i buy is ac lol. plugs also.   well it still has a slight miss but i noticed when i had the tbi off the egr looks really bad. its pretty much a toasted looking flying saucer lol.

Delete that ...use an egr block off plate!