Timing, sensors, what the?? I'm stuck
FishinGuide
03-20-2006, 12:34 AM
Hi guys I'm new here. I have to say I have learned alot by reading the archived posts over the last few day while trying to sort out the problem I'm having with my truck.
My problem started with a loss of power and also a major hesitation when I put the pedal down trying to pass, etc. There was also a slight miss at idle. I tow my boat with this truck so something had to be done. I changed cap, rotor, plugs, and egr valve (it stuck open once before). Nothing changed.
I started looking on the net for help and found these forums. After reading them for hours I have discovered a few things about my problem. When I first start it up in the morning it runs like a champ. Snappy throttle, smooth running, no miss. When it comes up to temp is when the problems start. According to what I have read here that would suggest a sensor problem. It runs fine in open loop, but has problems in closed loop.
The other thing I noticed is the timing. When I pull the wire under the dash and put a light on it it reads just a tad past 0 (to the right). When I plug the wire back in it is off the scale, way off and seems to jump around. I don't know if it's moving around because the rpm's are changing with the miss or it's actually moving around which is causing the miss. Also I want to describe the timing scale and get some input there. It has notches and numbers to zero. Starting from left they go 10, 8, 6, 4, 2, 0 then nothing. I'm assuming those numbers are BTDC? If that is the case then like I said the timing with the wire pulled is sitting at about 2 ATDC. With the wire it is at about 30 BTDC because it is a good inch or more off the end of the scale.
So, there is my book about what I know so far. I'm hoping for suggestions on what to try next. Also if someone could speak to wheather my timing observations are normal or not would be helpful. Thanks in advance and thanks for all I have learned so far.
*Edit* I guess a little info on my truck might help. It is a 95 k1500 5.7L TBI
My problem started with a loss of power and also a major hesitation when I put the pedal down trying to pass, etc. There was also a slight miss at idle. I tow my boat with this truck so something had to be done. I changed cap, rotor, plugs, and egr valve (it stuck open once before). Nothing changed.
I started looking on the net for help and found these forums. After reading them for hours I have discovered a few things about my problem. When I first start it up in the morning it runs like a champ. Snappy throttle, smooth running, no miss. When it comes up to temp is when the problems start. According to what I have read here that would suggest a sensor problem. It runs fine in open loop, but has problems in closed loop.
The other thing I noticed is the timing. When I pull the wire under the dash and put a light on it it reads just a tad past 0 (to the right). When I plug the wire back in it is off the scale, way off and seems to jump around. I don't know if it's moving around because the rpm's are changing with the miss or it's actually moving around which is causing the miss. Also I want to describe the timing scale and get some input there. It has notches and numbers to zero. Starting from left they go 10, 8, 6, 4, 2, 0 then nothing. I'm assuming those numbers are BTDC? If that is the case then like I said the timing with the wire pulled is sitting at about 2 ATDC. With the wire it is at about 30 BTDC because it is a good inch or more off the end of the scale.
So, there is my book about what I know so far. I'm hoping for suggestions on what to try next. Also if someone could speak to wheather my timing observations are normal or not would be helpful. Thanks in advance and thanks for all I have learned so far.
*Edit* I guess a little info on my truck might help. It is a 95 k1500 5.7L TBI
horse482
03-20-2006, 02:48 PM
The timing will look that way when you plug the timing connector back in and reset the codes. I had the same problem and it was my distributor causing the idle and miss problems. Pull the distributor cap and see if there is side to side play in the distributor, if so then the shaft or bushings are bad.
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