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Y'know, based on your images in the oxygen sensor thread, and despite changing 2 and 5 w/o change, if the injectors are OK and CPS/CKS turns out OK, while you got the o-scope out why not check to make sure all the coil drivers are working:
i will do all the time consuming checks on my off days..tried several things since quick and "easy". Changed out the crank sensor with a new mopar..good for 1 1/2 days then back to nbr 2 misfire. As determined by CEL code. Only at idle. Still constant nbr 2 misfire count with snap on scanner. Nbr 2 misfire count no matter what rpm on scanner but only throws cel at idle Removed nbr 1 injector plug...nbr 1 plug misfire and nbr 1 plug injector fault. Installed nbr 2 injector plug on nbr 1 injector....nbr 1 misfire count goes to 0 with nbr 1 injector driver fault. No nbr 2 injector driver fault....therefore no issues with nbr 2 injector plug...nbr 1 injector plug on nbr 2 injector gives constant nbr 2 misfire count.. with no injector driver failures. vacuum gauge on one of the manifold hoses...absolutely no fluctuations..I can only assume that means no issues with intake/ exhaust gasket or valves...the scanner reads 18 inch of vacuum constant at idle. Cleaned t/b and iac. No change. I have swapped nbr 2 and 5 spark plug wires a few days ago...I run a coil rail eliminator...nbr 2 misfire remains... Nbr 2 spark plug visually fires continuous and strong at idle. nbr 2 compression at 160. All other plugs 155-165. Nbr 2 injector new...will try the old stock coil pack tomorrow and then swap nbr 2 and 4 injectors ...see what happens.
So i was pretty sure it was not an ignition issue so I figured I would check fuel pressure, even though it effects only #2 cyl. With key on after the quick fuel pump precharge I read 45 psi and running it reads 47 psi. Turned everything off and it takes 20 min to drop 10 psi, down to 37 psi Im assuming thats ok for a 20 year old system. My plan was to then swap #2 injector with #4 just to see what happens. I pulled off the rail and I thought let me take a look in there to see whats happening with my boroscope...What the hell is that stuck under the #2 intake valve..It looks like a tywrap.I cant do anything through the injector hole so I am pulling the intake, I should be able to attempt a removal with that out of the way..I really don't want to pull the head off.
So wild goose chase..when I got the manifold off I found out I was looking at the spark plug tip. I did find the nbr 2 exh runner cracked where it goes into the pipe..will have to get a new one. Have to hunt down a decent one and get some o2 bungs welded in so its going to be a while. Im replacing the manifold gasket and swapping nbr 2 and 4 injectors just for the hell of it to rule out a bad injector. At least its not winter yet
So what an incredible time consuming process for mostly nothing. I replaced the intake/exhaust manifold gasket and swapped nbr 2 and 4 injectors...never even had a blink on nbr 4... put it all back together and it ran like super ****. Very rough, stalled every time i took my foot off the gas...I had done a temporary repair to the cracked exh pipe. I ran many layers of a high temp alluminum tape over the cracked area and locked it down with a hose clamp. I am sure its not leaking for the time being. Scanner showes misfire counts on nbr 2 and 4 cyl...logged misfire codes on 2 and 4 and a transmission fault. So as a last resort ,I installed the "stock" wrangler coil pack. Before i started it up i was looking through the scanner tool menu and saw a memory erase function. I said. Whats that, so i hit the button. It erases the learned memory of the pcm. I erased it....when i started it up it was baby smooth with not a single misfire on any plug. Its possible the cracked exh pipe was screwing with the 1/1 O2 sensor and the computer was leaning me to death...even when i disconnected it because it "remembered" The exh pipe repair Will not last forever so i will have to get a new manifold but who would have guessed a computer erase would fix everything...WOWS
So had to wait for the remnants of the hurricane to dissipate, had to get my new Dorman manifold welded to accept 2 O2 bungs and paint it with POR 15 manifold grey paint. ..finally had time to put the whole thing together. In the interim I had taped up the crack in the old manifold pretty well. I only threw the #2 misfire every 3 or 4 days. Ive taken that damn motor apart so many times, Ive gotten it down to less than 2 hours to get both manifolds off...and a little bit longer to put it all back together. I screwed myself a little, when I put the intake back on...I missed the alignment dowell on the back side of the head. It all went together easy, except I spent an hour trying to get the rear most upper bolt in...couldn't do it and didn't know why. Finally after much frustration I found the back half of the intake was 1/4 inch higher than the top end of the gasket...I had to pull all of the bolts out...repo and do it again. Luckily I didn't have anything more than finger tight so nothing got damaged. All put back together and 0 misfire codes on any cylinder.
So hopefully this endless saga will finally come to an end.....new exh manifold did not fix my issue...3 days into it with no CEL, drove the truck to the inspection site...and 1 block away...CEL multiple misfire cyl 2 and 4. never had a 4 misfire until I swapped 2 and 4 fuel injectors earlier in my repair attempts. Pulled all the "original", since the stroker rebuild. They were reportedly 27 lb 4 hole injectors. They are the grey ones in photo. Always ran lean.. I replaced all of them with new 28 lb 4 hole injectors. The injector head seems to stick further into the airflow than the old. I also did the rocker arm shimming, since I have been running a bigger cam than stock. I needed to add 0.030 shims to all the rockers and now my preloads seem to be around .040 to .050 seems to run with a quieter valve train noise as compared to before. Now 4 days into it and have checked my codes every day...no codes and no pending codes. Will try again for an inspection on Monday...I am finally hopeful
09-16-2022, 08:08 PM
