need help with knock sensor issues

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Re: need help with knock sensor issues

Postby 91' pro street s/10 » Thu Jul 27, 2017 6:13 pm

already got a new set of heads being built , those where used i got off C.l so i could keep with the install schedule since my Buddy was nice enough to allow me to do it in his garage, plqan on doing leak down test on sat , incidently did a presure test on the cooling system and within 5 min . presure dropped from 17 lbs down to 5 did the test twice to confirm that in conjunction with the compression test producing 60 psi on cylinder 8 makes me question if its not a broken or seized ring possibly but will lmow on sat , ill get back to you on sat
thanks again for all the help
91' pro street s/10
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Re: need help with knock sensor issues

Postby Rickracer » Fri Jul 28, 2017 8:03 am

Any coolant in the cylinders after the cooling system pressure test?? :?: 8)
Rickracer
ASE Certified Master Automotive Technician (well over 3 decades of experience, :thumbup: )
'93 S10 SB,RC, Comp XR276 Hydraulic Roller, Vortec head 363, 400 + hp, built 700R4, JW 2800 stall lockup converter, 3.73 posi, disc brake, narrowed 8.8 Exploder rear, LS Camaro front discs, Cal-Trac clone traction bars, Best N/A passes to date: 7.76 in the 1/8th, 12.24@109.27 mph in the 1/4, gonna spray it one of these days... :mrgreen:
76 Chevy Vega Drag Car, TWIN TURBO 355, P/G trans w/ brake and JW 4000 stall vert, 4 link back half, narrowed 9", 3.50 gears, 29.5x10.5W ET Drags. Best time9.669 @ 139.79, Latest video: https://www.youtube.com/watch?v=S59riYn ... ata_player
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Re: need help with knock sensor issues

Postby 91' pro street s/10 » Fri Jul 28, 2017 4:38 pm

actually don't think i checked , ill do it again tomm. before the leakdown test and get back to you when i pulled the plugs after doing the compression test i didnt see any trace or smell any on the plug of any cylinders including suspect cyl 8 witch was only 60 psi , but ill double check and let you know ,I'm hoping its just a burnt exh. valve or cracked or warped head , don't want to open it up til i have the new heads back probably next fri or so any thing else i might be overlooking here ?
91' pro street s/10
I found rocker arm monkey's on ebay!
 
Posts: 12
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Re: need help with knock sensor issues

Postby Rickracer » Sat Jul 29, 2017 7:18 am

Did you try squirting any oil in the low cylinder? Generally if it's rings, oil will make the compression rise, if it's a valve, seat, or head gasket, oil will make virtually no difference. Also, I'd say you only need to leakdown the one low cylinder, and maybe one adjacent to it for a reference. 8)
Rickracer
ASE Certified Master Automotive Technician (well over 3 decades of experience, :thumbup: )
'93 S10 SB,RC, Comp XR276 Hydraulic Roller, Vortec head 363, 400 + hp, built 700R4, JW 2800 stall lockup converter, 3.73 posi, disc brake, narrowed 8.8 Exploder rear, LS Camaro front discs, Cal-Trac clone traction bars, Best N/A passes to date: 7.76 in the 1/8th, 12.24@109.27 mph in the 1/4, gonna spray it one of these days... :mrgreen:
76 Chevy Vega Drag Car, TWIN TURBO 355, P/G trans w/ brake and JW 4000 stall vert, 4 link back half, narrowed 9", 3.50 gears, 29.5x10.5W ET Drags. Best time9.669 @ 139.79, Latest video: https://www.youtube.com/watch?v=S59riYn ... ata_player
Rickracer
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Posts: 28857
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Re: need help with knock sensor issues

Postby 91' pro street s/10 » Sat Aug 05, 2017 11:28 am

sorry about the delay in responding work alot of ot and time is very limited right now , I'm driving my other 4.3 s/10 blazer right now and having drama with that too just drove it to PA 230 mi. flawless operation except notice the volt meter going down , well i was getting nervous and had no tools with me and made it about 1.5 mi . from home and it stalled on me , and restarted but once in gear would sputter and bunny hop and stall again well long story short babied it home feathering the gas to keep it running and the starter wouldnt even click so figured the battery or alt. died .threw a charge on it and it took five min. to charge and started right up ran perfectly took it down the street ran great so parked it and went to work following day , went and got aanother battery and about 8 mi from work so total of about 20 mi. and the truck stalled again on me about a block from where i bought the battery , truck wouldnt restrt after installing new battery had to tow it back to my job checked the battery it was only 57 % charged 4 hrs later it showed a 100% charge and 680 cca of the rated 700 on my battery tester so started the truck ran great for about as long as it takes to get to temp and then put it in gear and it stalled , well ive got it narrowed down to as soon as it goes closed loop it wont idle at all adn have to work the gas feathering it to barely keep it running , I'm baffled nothing was touched prior to this happening plugged my scanner in and started checking lve stream data , got code 33 and 24 map sensor is reading like 3. volts when it goes into closed loop and prelude to stalling , i unhooked my iac and unscrewd it and looked at the bore in the t,b looked fairly clean no build up on the pintle so put it back in swapped map sensor with a spare known good one and same reading so i am guessing fuel presure is adaquate cause if low it would do the sasme thing in cold start mode no? i have a f,p gauge I'm gonna tap into the fuel line and leave on it didnt get around to that yet though, any sugestions I'm stumped on this one i seem to have really bad luck with s/10s latley lol
thanks again for the help
91' pro street s/10
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