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TBI spray pattern 94 K1500 w 350


mr.fixit

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new to this forum as poster...but do read threads for info.

 

my chevy '94 K1500 (350 cu. in.) stumbles a little on acceleration from slow idle and it recently failed emissions for high (slightly) HC at idle (but ok at 2000 rpm). the spray pattern from the injectors looks even and both look the same. the spray is not a fine mist as is often seen with a multiport. the fuel spray is like a cone-shaped sheet. is this normal or are these injectors worn? i've already run standard gas-tank fuel system cleaners without change. can they be cleaned in another way or repaired/rebuilt?

 

regarding the emissions test, the oxygen sensor is a few years old (not the original) but no codes are set. do they go bad without sending DTC?

 

and is this the right forum for this question or does it belong in one of the others? which?

thanks in advance. mr.fixit

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thanks for the help. i will try the cleaner. the base timing (pcm wire disconnected) is 0 deg BTDC. this is what my service manual specifies. with the pcm connected it looks like 20 deg or more; hard to tell because the timing mark is past the scale. my cat converter is not too old; it's from random technologies and i installed it when i put in headers and exhaust system from banks power. still wonder about my 02 sensor, though. probably cheap enough to just get a new one...

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I had my timing at 4* advance to clear out the hicups.I would consider taking off the whole thorttle body cleaning it out especially the IAC port,and be sure to replace that tb gasket they pretty know on these trucks good luck.BTW i had my truck up to 730hcs and got it down to 200 with the new cat,cleaned tb,new tb gasket,cleaned egr valve,and timing turned up.

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Yes the cone shaped spray is normal.Check the timing,Run some GM upper clyinder cleaner threw or seafoam,Replace the cat,i used this one for my 90 tbi350 and passed with flying colors that thing burnt oil like no tommorow.http://www.summitracing.com/parts/MPE-94109/

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