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Slight misfire, hesitation at moderate speed.


TheRoger

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Yes I know that but cant trust it a long time ago when i had a torn wire my car was missing all over the place but took over a week for the P0300 to show up.  Havent had time to throw a fuel pressure tester on it yet will update when i do.

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While you are working with the car, if it has silicone heater hoses behind the block, you might think about a way to make sure that they never get too close to the exhaust.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I could be wrong but they look like standard rubber heater hoses.  They won't withstand heat as well and you need to inspect them often for drying out and becoming brittle.

The 95 I am working on had its heater pipes "fixed" by using hoses.

Plan on replacing the pipes for better reliability 

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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hey my car has the solid factory heater pipes behind the block.  Whats seen in the photos is the 2-3 inch green piece of rubber hose that attaches the solid pipe to the water pump.  Havent worked on it today after the seized wiper transmission surprise from my truck i need a few days free of vehicle trouble

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  • 3 weeks later...

UPDATE - Ok i thought i had the problem licked with new wires but it came back in about a week. after a bunch of headscratching and frustration and swapping EGR, and TPS from my parts car to no avail.  Got a proper scan tool and checked, had 200+ misfire #3 codes.  Pulled #3 plug and it had bad carbon track on it.  This explains why it would get better when i put new wires, but re emerge later.  changed plugs and wires for all brand new and shes mint.  Did not really think plugs before because they were only 5-6 months old but the cheap wires i originally used must have allowed carbon tracks to start.  Once this happens any wires used are garbage unfortunately. brand new ac delco plugs and wires problem solved. 2 of the other plugs had some light tracking starting. Car did not show any PCM codes at all using the dash computer to pull codes.  

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Congratulations on solving your no-code problem.  Those can be very difficult to diagnose.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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it was 2 months of pure agony.  I knew it was someting stupid as the motor ran well when it didnt miss intermittently, and ive had trans rppblems before and i knew this was different.  It seems that any number of common problems with these devilles, sticky EGR, Torque converter shudder, Plug/wire caused misfire, clogged catalytic conveter, all have very similar symptoms so with no codes it is a nightmare.  Luckily now i have a decent scanner which obviously catches alot more than the in dash obd computer.

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Being able to see the misfire counts helps to direct you to the source.

Believe it or not, if you went into the PCM data? category on your DIC, you would have been able to see the misfire count.  That is where a TECH2 gets the data from.  The misfire must have been below the threshold for the PCM to report it but you felt it.  A carbon track does not STOP the PLUG from firing, it only shunts away some of the spark to ground, so the plug fires weakly, but still fires.   That makes it difficult for the PCM to look definitively at it and say, HEY we have a misfire, because its just "a partial misfire"

There is another thread right now with a misfire that is also NOT setting a code, Logan posted it yesterday, here is a link

I use a program on my laptop that provides misfire counts called AutoTap, it is discontinued but still works for me, having real time data is very helpful.  Good luck with your new scanner, it will become a favorite tool :hatsoff:By the way, look at all you learned!, so don't be frustrated

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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