chevyguy1523

after moving the distributor as a unit counterclockwise ,of course after loosening the hold down bolt, clearing the codes, and drove around a few miles

the only codes showing in the ""codes since last erase"" are p0161 and p0141
but in the ""current code""" is the p0161

so, the p1345 has not came back, maybe the distributor is right now


while idling after moving the dizzy
small fluctuation between 650 rpm and 700 rpm
also the oil gauge fluctuates between 60-65
there feels as though a misfire exists through the steering wheel at idle
but when opening throttle it revs up instantly without a miss



have not performed a leak down test yet, still researching a decent one for under 80 bucks
have not tried a compression test yet either



before moving the dizzy,
at idle the truck would try to stall (about 300 rpm) then it would rev up to about 1500 rpm. 30 seconds later it would repeat
when opening the throttle at idle it would stumble and eventually rev

GM_tech92

if the idle is fluctuating so will your oil pressure. it sounds like its more like a 650-800 rpm fluctuation... stock gauges are only so accurate.. idle on a vortec is supposed to be 600 rpm +/- 25.... do you have a timing light? set the timing with that, not just turning it. because we dont know if you still have a problem or just advanced it to point that you no longer feel the
effects of said problem.. now as far as your codes...

p0161 is bank 2 sensor 2 (heated oxygen sensor or H02S) it is post catalytic converter. p0141 is bank 1 sensor 2 (heated HO2S) which is post cat. you need to check all your wiring to the post cat sensor. ill through a wiring diagram up here for you..
now, system voltage for the HO2S is 9–17 volts anything out side that is a bad thing. check for a broken wire with a multimeter.... tell us what you find

chevyguy1523

so with the truck running connect the pink wire in connector with positive and find a ground on the truck for black?


eng1 20 amp fuse was blown (maybe two hots are touching somewhere?)
erased the codes, drove it a few minutes has not come back on yet, but a slight miss is still there at idle
also the oil gauge actaully fluctuates between 25 and 35 at idle, Intermittenly

where the exhaust connects to the 2nd converter there seems to be a leak, I can hear it , and the gasket looks deteriorated

wish I had a timing light, combustion tester, and leak down tester

chevyguy1523

cam advance ranges from 22-28 at idle...this is bad correct? shouldnt it read +-2

GM_tech92

after rethinking... i gave you some bad information. on your 98 (i have no idea why i didnt catch this) the ignition timing is set by the pcm, and can only be changed with a tech 2. now.. heres what i want you to do. your going to need to properly reset your distributor. have you had it out before? the p1345 you were experiencing before, is an indicator to an improperly installed distributor, lose shaft, or distributor, or cam sensor or loose timing chain. someone wrote up an article that does an amazing job at telling you how to do this having already moved the distributor. GM Truck Central setting a Vortec distributor it saves me alot of typing and having a book for a post...

now... in regards to the HO2S... if the codes have not come back, then the fuse was your problem. find out why it blew. check your wiring.

and as far as the oil pressure fluctuating... two things are coming to mind... the oil pump is driven by a shaft in the bottom of the distributor... and with a 10 psi fluctuation at idle, make sure its not happening any higher in the rpm range. if it is, you could be getting ready for a pump failure.. in the mean time reset the distributor. and make sure that it is set correctly. when you pull the dist. let us know what the gears look like... if their burred or significantly worn...