Help Request: P0300 on fresh rebuild 99 Sub K1500 5.7
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CF Beginner
Joined: Jun 2020
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Ok...Im back.finally got the new fuel pump in. Basically, the pressures were identical to the above....
I also put the Foxwell on the ECU finally..and basically confirmed the readings from what i was getting with the Torque App (Contrary to what ive seen in other posts, and confirmed by Foxwell Tech, I was not able to read the CMP Retard using the scanner..it just showed 0 degrees (meaning it was just showing some default value and not actually reading the actual value) , but from the Torque App, I was at 1 degree.
I did confirm cyl 5and 7 as the only misfires (and alot of them, about same magnitude with 5 slightly higher than 7).
I did scan through some of the live data...as far as I could tell, everything seems fine with the following possible exceptions discussed below.
But some of the sensor values at idle are as follows:
Loop Status : Open, Barometric Pressure 93 kPa, IAT 66C, ECT 90 C
Spark 18-27 deg, MAP 37 kPa, MAF 7.67 g/s, MAF Freq 2550 Hz,
Injector PWM B1/B2 : 4.2ms/4.2 ms
A few thoughts:
a) The scanner was showing loop status as open, but I would have thought this should have switched to close loop. I also noticed that I was not able to monitor the O2 sensor responses, but then saw that STFT B1S1, B2S1 were both at 0% and STFT B1S2 and B2S2 were at 99.2% - continuous, The LTFT were both at 0% so any feedback on what this means would be help. (Keep in mind this is a fresh rebuild with maybe all of 2 miles on the engine.)
b) I have not swapped out the fuel filter or the plug wires on 5 and 7 yet. I can do the plug wires tomorrow morning easily enough, but I dont think that's the issue. The cap and rotor were already replaced, as were the plugs. And I have a new distributor on order, but dont think that's the issue either as I didnt see any issues with the old one when it was transferred over. I guess I will also try compression and maybe leak down tests tomorrow on Bank 1. And then think about valve adjustment or spider and/or fuel filter based on what I find out from those test.
c) Ok, so here is another thing I am wondering. Both heads were used ones provided by the machine shop as my old ones both had cracks...when I was rebuilding, and adjusting the valves, I thought I heard what sounded like a spring breaking. I didnt see anything wrong with the exposed valve springs and offhand I dont recall whether it was from 5 or 7 or some other but my vague recollection is that maybe it was from when i was adjusting 7. Is it possible one spring (and one only) of either cyl 5 or 7 may have broke and I didnt notice it and that is subsequently causing misfires on both 5 an 7? Or maybe I did the adjustment just fine and they provided a head with crap springs in it?
d) similarly, is it possible that it was a spring inside one of the lifters?? (I assume they have a spring in them?) The hydraulic lifters are new.
I also put the Foxwell on the ECU finally..and basically confirmed the readings from what i was getting with the Torque App (Contrary to what ive seen in other posts, and confirmed by Foxwell Tech, I was not able to read the CMP Retard using the scanner..it just showed 0 degrees (meaning it was just showing some default value and not actually reading the actual value) , but from the Torque App, I was at 1 degree.
I did confirm cyl 5and 7 as the only misfires (and alot of them, about same magnitude with 5 slightly higher than 7).
I did scan through some of the live data...as far as I could tell, everything seems fine with the following possible exceptions discussed below.
But some of the sensor values at idle are as follows:
Loop Status : Open, Barometric Pressure 93 kPa, IAT 66C, ECT 90 C
Spark 18-27 deg, MAP 37 kPa, MAF 7.67 g/s, MAF Freq 2550 Hz,
Injector PWM B1/B2 : 4.2ms/4.2 ms
A few thoughts:
a) The scanner was showing loop status as open, but I would have thought this should have switched to close loop. I also noticed that I was not able to monitor the O2 sensor responses, but then saw that STFT B1S1, B2S1 were both at 0% and STFT B1S2 and B2S2 were at 99.2% - continuous, The LTFT were both at 0% so any feedback on what this means would be help. (Keep in mind this is a fresh rebuild with maybe all of 2 miles on the engine.)
b) I have not swapped out the fuel filter or the plug wires on 5 and 7 yet. I can do the plug wires tomorrow morning easily enough, but I dont think that's the issue. The cap and rotor were already replaced, as were the plugs. And I have a new distributor on order, but dont think that's the issue either as I didnt see any issues with the old one when it was transferred over. I guess I will also try compression and maybe leak down tests tomorrow on Bank 1. And then think about valve adjustment or spider and/or fuel filter based on what I find out from those test.
c) Ok, so here is another thing I am wondering. Both heads were used ones provided by the machine shop as my old ones both had cracks...when I was rebuilding, and adjusting the valves, I thought I heard what sounded like a spring breaking. I didnt see anything wrong with the exposed valve springs and offhand I dont recall whether it was from 5 or 7 or some other but my vague recollection is that maybe it was from when i was adjusting 7. Is it possible one spring (and one only) of either cyl 5 or 7 may have broke and I didnt notice it and that is subsequently causing misfires on both 5 an 7? Or maybe I did the adjustment just fine and they provided a head with crap springs in it?
d) similarly, is it possible that it was a spring inside one of the lifters?? (I assume they have a spring in them?) The hydraulic lifters are new.
Last edited by oldandintheway; Jul 1, 2020 at 5:25 PM.
CF Monarch
Joined: Jul 2011
Posts: 5,920
Likes: 140
From: kevinkpk
Injector PWM B1/B2 : 4.2ms/4.2 ms
Ok, so here is another thing I am wondering. Both heads were used ones provided by the machine shop as my old ones both had cracks...when I was rebuilding, and adjusting the valves, I thought I heard what sounded like a spring breaking. I didnt see anything wrong with the exposed valve springs and offhand I dont recall whether it was from 5 or 7 or some other but my vague recollection is that maybe it was from when i was adjusting 7. Is it possible one spring (and one only) of either cyl 5 or 7 may have broke and I didnt notice it and that is subsequently causing misfires on both 5 an 7? Or maybe I did the adjustment just fine and they provided a head with crap springs in it?
d) similarly, is it possible that it was a spring inside one of the lifters?? (I assume they have a spring in them?) The hydraulic lifters are new.
Ok, so here is another thing I am wondering. Both heads were used ones provided by the machine shop as my old ones both had cracks...when I was rebuilding, and adjusting the valves, I thought I heard what sounded like a spring breaking. I didnt see anything wrong with the exposed valve springs and offhand I dont recall whether it was from 5 or 7 or some other but my vague recollection is that maybe it was from when i was adjusting 7. Is it possible one spring (and one only) of either cyl 5 or 7 may have broke and I didnt notice it and that is subsequently causing misfires on both 5 an 7? Or maybe I did the adjustment just fine and they provided a head with crap springs in it?
d) similarly, is it possible that it was a spring inside one of the lifters?? (I assume they have a spring in them?) The hydraulic lifters are new.
Thread Starter
CF Beginner
Joined: Jun 2020
Posts: 25
Likes: 2
OK.. so......are you ready??? I decided to brave the heat and start on the compression. I started dry with Cyl5, after about 5 cycles on the starter..it was125...and then another 5 and it went up to about 145... Im thinking...hmm..for fresh rebuild..that seems a little low.... so Im ready to move over to cyl 3 because frankly..access to cyl 7 is rather a bitch...and I wanted to get a comparison......but ....not so fast.....since I already had the plug wire off the plug..I might as well swap it out as I had a few extra wires.......however..it then turns out that the extra set had a different termination and wouldnt fit the cap. OK..no big deal... I continue on...so I go and try to put the plug wire back on the plug and what do you think I found??? drum roll here....
I had the frickin wires for 5 and 7 crossed!!! I told you..Im old.. son of a B..... I swap the wires....break out the scanner...and NO MISFIRES... can you frickin believe it..
Moral the the story.. when you got P0300 with two cylinders on the same bank only giving misfires...and even next to each other...and the misfire counts are pretty much the same....umm...maybe you crossed the frickin wires....
Im still in open loop which I dont understand...but I guess i have to say....SOLVED...
Oh..and I forgot the CMP retard only shows when you are up above some rpm threshold...so the Foxwell is showing 1-2 degrees now. I may get off my **** and try to tweek that down a bit at some point...but at least I got some wheel back....
thanks for the help..you gave me the motivation to finish off my first rebuild to completion..
Now Im off to redo the body work on my porsche which someone decided to back into a few days ago, take off, and leave me with about $3000 in damage....oh joy..
I had the frickin wires for 5 and 7 crossed!!! I told you..Im old.. son of a B..... I swap the wires....break out the scanner...and NO MISFIRES... can you frickin believe it..
Moral the the story.. when you got P0300 with two cylinders on the same bank only giving misfires...and even next to each other...and the misfire counts are pretty much the same....umm...maybe you crossed the frickin wires....
Im still in open loop which I dont understand...but I guess i have to say....SOLVED...
Oh..and I forgot the CMP retard only shows when you are up above some rpm threshold...so the Foxwell is showing 1-2 degrees now. I may get off my **** and try to tweek that down a bit at some point...but at least I got some wheel back....
thanks for the help..you gave me the motivation to finish off my first rebuild to completion..
Now Im off to redo the body work on my porsche which someone decided to back into a few days ago, take off, and leave me with about $3000 in damage....oh joy..
Last edited by oldandintheway; Jul 1, 2020 at 7:10 PM.
Thread Starter
CF Beginner
Joined: Jun 2020
Posts: 25
Likes: 2
Yup...I still have an issue with the O2 sensors and not going into closed loop... the ECT is showing 190-192 and I believe it should be making it to at least 195 F. I actually think I may have another thermostat and maybe even a temp sensor if Im lucky..but i need to search the forums and see how to debug this one.. I will open a new thread once I do a little reading and testing if I cant figure that out...no codes..but clearly still an issue there... closing this one out..
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