Howdy folks, I recently joined this forum and would like to share my story of the distributor from hell.
I have a 1999 Chevy 2500 with a 5.7 Vortec.
Story Time: As I was heading home two days ago, I started up my truck, and noticed that it had a really bad shimmy, the idle was very rough and when i pulled out of my parking spot, acceleration was bucking like a wild horse. Okay not a big deal, I probably have a misfire. I pulled out the trusty Haynes manual and the book pointed me to a misfire, but I wasn't throwing a code nor could I find anything wrong using my scan tool. I decided it was time to get a whole new set of spark plugs, wires. Being as I bought this truck 3 weeks ago, Lord knows the last time these things were checked. Plugs and wires were changed out without difficulty, I started it back up and the result was the same bad idle.
Fast forward through hours of troubleshooting, I believed the issue to be the distributor cap. I popped the cap off and sure enough it was rusted and gunky to all hell, so i found my "culprit". However, during my adventure of using the T series screwdriver, the screw housing on the dizzy shaft snapped right in half.... and it was time for a whole new distributor! Following the instructions that came with the dizzy, and numerous online videos, I lined up the dimple with the white dash, and dropped it in all while being at #1 TDC compression stroke. Tightened everything up and started her up... kinda.
This first start after the new distributor was met by a violent jerking of the whole truck as the engine was cranking, eventually it barely started and immediately died. Through some troubleshooting I eventually got it to hold at 1,000 rpm. A P1345 fault popped up on the dash, and now my cam/crankshaft timing was off enough to throw a code.
Throughout the next 24 hours of multiple YouTube videos, this forum, and then eventually Mr. Road Trip and THIS YouTube video, I finally resolved it. Issue was the timing teeth on the distributor was two teeth too far clockwise. After some trial and error, I finally got her to start up without any shakes, rough idle, or a code being thrown.
In conclusion, this was a very hard task due to me being brand new on classic trucks like this, but it was a very good learning experience overall.
TL/DR: Dizzy makes my head dizzy. I will paste the conversation I had with Mr. Road Trip below
Me:
Hey Sir, I saw your with a similar issue I've been having.
Quick question: what specific field service manual are you using?
Anyways, I'm replacing a distributor in a 99 c2500 5.7. I have aligned the rotor dimple with the white mark on the shaft, and set it down. I'm pretty sure I'm TDC, I don't have a good way of testing other than the mark on the balancer and my thumb over the spark plug hole. I also might be having issues with the oil pump female end connecting to my male end on the distributor, since the rotor goes past #1 a little, but I can't get it fine tuned without getting TDC for sure.
With it like this, it barely starts, runs rough, and gives me the P1345 code. Do you have any tips? Feel free to text me at 7178505872 since I'm new to this website and probably will forget to check in the morning.
Road Trip:
Hello M_Gumby,
I'm actually using the '99 GM C/K Factory Service Manuals. It's a 4-volume set,
available both in paper (ebay) and online (.pdf) format. There is a thread in the
forum with free links to the .pdf files for most of the years in the first reply over HERE.
However, in order to find the links for the '99 model year, you need to navigate down
to reply #77. (These are the ones I use.)
As a matter of fact not too long ago we had a P1345 thread in the forum, and I was able to
walk the other person through the steps it took to fix his P1345 issue. The short story is
that if the distributor was manufactured correctly it's pretty straightforward to clear up the
P1345 by getting the CKP (Crank position sensor) and the CMP (Cam position sensor)
synchronized to 0° of each other.
However, if the distributor's drive gear is installed 180° out, this will give you the problem
where the distributor is lined up to the marks and the timing is off too far in one direction,
but when you move it tooth it's now off too far in the opposite direction? And no matter
how you try to adjust it, you can't get the crank <> distributor cam sensor sync'd up to 0°?
The answer to this weird behavior is that the distributor's drive gear has an odd number of teeth,
so if this gear is installed 180° out at the factory then you end up not being able to adjust it
properly within the tight confines where it lives?
Anyway, to cure this P1345 you will need a scan tool that can show you this value, loosen
the distributor, and see if you can twist the distributor to obtain a 0° reading. (+/- 2 degrees)
With any luck you will be able to get this to a zero reading with a quick adjustment. And if
that doesn't work, then try moving the distributor 1 tooth and see if that doesn't fix the
issue. And in the worst-case scenario you have a distributor where you have to remove
the drive gear, rotate it 180°, and reinstall it in order to get the good sync (0° difference)
and get the P1345 to go away.
For more detail/specifics, here's the thread where someone was having a P1345 issue,
and we talked him through the fix: (P1345 thread)
The good news is that so far every P1345 issue has been solved. Most pretty easy, but
every once in awhile the GMT400 owner has to reclock an incorrectly assembled distributor
drive gear.
Hope this helps. Best of luck...and Welcome to the GMT400 forum.
Cheers --
Me:
Thanks for the reply, I did flip it 180 and it would crank but not start. I'm starting to think fuel is a possible issue, will get a fuel pressure gauge today. I'll keep you updated with what I'm trying to fiddle with today.
Me:
I fixed it!! This morning I out the distributor in, got it running rough, took the distributor out, rotated it 2 teeth counter clockwise, then got it to engage the cam gear, cranked on the harmonic balancer until the male end of the distributors oil pump notch engaged the female end for the oil pump, cranked it back over to TDC, hooked everything back up and she fired right up. No check engine light, no rough start or rough run. Took her for a test drive, no jumping of acceleration. So I'm pretty positive it's good now and within the tolerance of the cam offset. Thank you so much for your help.
Road Trip:
Fantastic! These old GMT400s are so much fun when they are running right!
By the same token, the Vortec ignition system is just different enough (with
the base timing set by the CKP sensor, the total timing set by the computer,
so now we have to sync the dizzy to the CKP sensor, etc) ...that there is a
lot of misinformation out there to wade through.
As for the help, you are most welcome. Maybe pay it forward it you get the
opportunity. :0)
Safe travels --
I have a 1999 Chevy 2500 with a 5.7 Vortec.
Story Time: As I was heading home two days ago, I started up my truck, and noticed that it had a really bad shimmy, the idle was very rough and when i pulled out of my parking spot, acceleration was bucking like a wild horse. Okay not a big deal, I probably have a misfire. I pulled out the trusty Haynes manual and the book pointed me to a misfire, but I wasn't throwing a code nor could I find anything wrong using my scan tool. I decided it was time to get a whole new set of spark plugs, wires. Being as I bought this truck 3 weeks ago, Lord knows the last time these things were checked. Plugs and wires were changed out without difficulty, I started it back up and the result was the same bad idle.
Fast forward through hours of troubleshooting, I believed the issue to be the distributor cap. I popped the cap off and sure enough it was rusted and gunky to all hell, so i found my "culprit". However, during my adventure of using the T series screwdriver, the screw housing on the dizzy shaft snapped right in half.... and it was time for a whole new distributor! Following the instructions that came with the dizzy, and numerous online videos, I lined up the dimple with the white dash, and dropped it in all while being at #1 TDC compression stroke. Tightened everything up and started her up... kinda.
This first start after the new distributor was met by a violent jerking of the whole truck as the engine was cranking, eventually it barely started and immediately died. Through some troubleshooting I eventually got it to hold at 1,000 rpm. A P1345 fault popped up on the dash, and now my cam/crankshaft timing was off enough to throw a code.
Throughout the next 24 hours of multiple YouTube videos, this forum, and then eventually Mr. Road Trip and THIS YouTube video, I finally resolved it. Issue was the timing teeth on the distributor was two teeth too far clockwise. After some trial and error, I finally got her to start up without any shakes, rough idle, or a code being thrown.
In conclusion, this was a very hard task due to me being brand new on classic trucks like this, but it was a very good learning experience overall.
TL/DR: Dizzy makes my head dizzy. I will paste the conversation I had with Mr. Road Trip below
Me:
Hey Sir, I saw your with a similar issue I've been having.
Quick question: what specific field service manual are you using?
Anyways, I'm replacing a distributor in a 99 c2500 5.7. I have aligned the rotor dimple with the white mark on the shaft, and set it down. I'm pretty sure I'm TDC, I don't have a good way of testing other than the mark on the balancer and my thumb over the spark plug hole. I also might be having issues with the oil pump female end connecting to my male end on the distributor, since the rotor goes past #1 a little, but I can't get it fine tuned without getting TDC for sure.
With it like this, it barely starts, runs rough, and gives me the P1345 code. Do you have any tips? Feel free to text me at 7178505872 since I'm new to this website and probably will forget to check in the morning.
Road Trip:
Hello M_Gumby,
I'm actually using the '99 GM C/K Factory Service Manuals. It's a 4-volume set,
available both in paper (ebay) and online (.pdf) format. There is a thread in the
forum with free links to the .pdf files for most of the years in the first reply over HERE.
However, in order to find the links for the '99 model year, you need to navigate down
to reply #77. (These are the ones I use.)
As a matter of fact not too long ago we had a P1345 thread in the forum, and I was able to
walk the other person through the steps it took to fix his P1345 issue. The short story is
that if the distributor was manufactured correctly it's pretty straightforward to clear up the
P1345 by getting the CKP (Crank position sensor) and the CMP (Cam position sensor)
synchronized to 0° of each other.
However, if the distributor's drive gear is installed 180° out, this will give you the problem
where the distributor is lined up to the marks and the timing is off too far in one direction,
but when you move it tooth it's now off too far in the opposite direction? And no matter
how you try to adjust it, you can't get the crank <> distributor cam sensor sync'd up to 0°?
The answer to this weird behavior is that the distributor's drive gear has an odd number of teeth,
so if this gear is installed 180° out at the factory then you end up not being able to adjust it
properly within the tight confines where it lives?
Anyway, to cure this P1345 you will need a scan tool that can show you this value, loosen
the distributor, and see if you can twist the distributor to obtain a 0° reading. (+/- 2 degrees)
With any luck you will be able to get this to a zero reading with a quick adjustment. And if
that doesn't work, then try moving the distributor 1 tooth and see if that doesn't fix the
issue. And in the worst-case scenario you have a distributor where you have to remove
the drive gear, rotate it 180°, and reinstall it in order to get the good sync (0° difference)
and get the P1345 to go away.
For more detail/specifics, here's the thread where someone was having a P1345 issue,
and we talked him through the fix: (P1345 thread)
The good news is that so far every P1345 issue has been solved. Most pretty easy, but
every once in awhile the GMT400 owner has to reclock an incorrectly assembled distributor
drive gear.
Hope this helps. Best of luck...and Welcome to the GMT400 forum.
Cheers --
Me:
Thanks for the reply, I did flip it 180 and it would crank but not start. I'm starting to think fuel is a possible issue, will get a fuel pressure gauge today. I'll keep you updated with what I'm trying to fiddle with today.
Me:
I fixed it!! This morning I out the distributor in, got it running rough, took the distributor out, rotated it 2 teeth counter clockwise, then got it to engage the cam gear, cranked on the harmonic balancer until the male end of the distributors oil pump notch engaged the female end for the oil pump, cranked it back over to TDC, hooked everything back up and she fired right up. No check engine light, no rough start or rough run. Took her for a test drive, no jumping of acceleration. So I'm pretty positive it's good now and within the tolerance of the cam offset. Thank you so much for your help.
Road Trip:
Fantastic! These old GMT400s are so much fun when they are running right!
By the same token, the Vortec ignition system is just different enough (with
the base timing set by the CKP sensor, the total timing set by the computer,
so now we have to sync the dizzy to the CKP sensor, etc) ...that there is a
lot of misinformation out there to wade through.
As for the help, you are most welcome. Maybe pay it forward it you get the
opportunity. :0)
Safe travels --
