stalls and boggs down under acceleration

[satdog75]

my 89 astro 4.3 is bogging down under any acceleration and will not idle very long before dying. I have:

new plug wires
new plugs
new rotor
new distibutor cap
new egr valve
seafoamed the engine
replaced vaccum lines that were damaged
corrected timing (was about 10 degrees off)
tested TPS sensor
compression test (all within 140-145 psi)
changed fuel filter
checked flow of injectors


while testing we pulled plug wires to see if we lost power and had a drastic change on all except the ones for cylinders 2 and 4. If you floor the engine, it will hesitate and then backfire and then occasionally pick up just fine. I just bought this thing for 300 bucks and it is super clean just giving me a hell of a fit on this issue. Ive checked and tested everything i could think of. Even had it checked for codes and none showed. PLEASE HELP!!!!

[CD Smalley]

And your fuel pressure is ??? If you haven't checked that you should.

Also could be a plugged convertor. But I'd start with checking the fuel pressure.

[Kings-x59]

Might check the torque on the throttle body bolts as well. Better yet, rebuild the TBI. The gasket set is about 13 bucks. It's a fair bet that the TBI to manifold gasket is mush and probably sucking air.

[satdog75]

the tbi rebuild and catalytic converter dont scare me all that much, but the problem with no change on cylinders 2 and 4 have me a bit concerned. I know its not a piston issue since compression is good but still when i pull those wires, i get no change whatsoever while the vehicle is idling. i can actually pull both of them with no change to performance whatsoever. i have given up and decided to leave it to professionals. while taking it to the shop tonight the check engine light came on so that gives hope in diagnostics somewhat. I am just going to stop throwing money at it and let my mechanic diagnose it for me so i can get onto actually repairing it and driving it. I have thrown over 150 at it so far with no success so 60 to know for sure is sounding pretty good to me. right now i am installing satellites out of a 05 saturn vue and dont want to put the miles and wear and tear on a brand new vehicle since i will be paying for it for 6 yrs and only got a 100k mile warranty (we drive about 50k per year). thats why i bought the 300 dollar van. just hope i can get out for less than another 200 bucks in repairs. give me prayers and crossed fingers and will let you all know what my mechanic says

[CD Smalley]

Let's know. Hopefully it's something cheap and simple.

[azradrods99]

Did ya ever get your truck running right? I'm having similar issues. Boggs and backfires ever now and then. New plugs,wires,rotor and cap. Runs ok but felt better with the older stuff. Seems like its idiling a bit slower and you can smell a rich burning smell in the cab. Any help?
Thx,

89CargoVan

Originally Posted by satdog75

my 89 astro 4.3 is bogging down under any acceleration and will not idle very long before dying. I have:

new plug wires
new plugs
new rotor
new distibutor cap
new egr valve
seafoamed the engine
replaced vaccum lines that were damaged
corrected timing (was about 10 degrees off)
tested TPS sensor
compression test (all within 140-145 psi)
changed fuel filter
checked flow of injectors


while testing we pulled plug wires to see if we lost power and had a drastic change on all except the ones for cylinders 2 and 4. If you floor the engine, it will hesitate and then backfire and then occasionally pick up just fine. I just bought this thing for 300 bucks and it is super clean just giving me a hell of a fit on this issue. Ive checked and tested everything i could think of. Even had it checked for codes and none showed. PLEASE HELP!!!!

[satdog75]

yes it did. found out that the throttle body diaphram was bad and there were large amounts of carbon deposits in the vaccum guides in the bottom of the throttle body. i ended up paying a mechanic about 60 bucks to remove the tbi and clean out all the carbon and replace the gasket. runs like a wet dream now. the bottom of the tbi has vaccum chases that lead to each cylinder. they were completely plugged up on the ones leading to cylinders 2 and 4.

[azradrods99]

Satdog75
Thanks for the update. I will check with my mechanic and advise him of what you did to your rig. Thanks again
Sy




QUOTE=satdog75]yes it did. found out that the throttle body diaphram was bad and there were large amounts of carbon deposits in the vaccum guides in the bottom of the throttle body. i ended up paying a mechanic about 60 bucks to remove the tbi and clean out all the carbon and replace the gasket. runs like a wet dream now. the bottom of the tbi has vaccum chases that lead to each cylinder. they were completely plugged up on the ones leading to cylinders 2 and 4.[/quote]