1999 4.3l start problem after new dist !!!!!
#1
12-15-2014, 03:25 PM
1999 4.3l start problem after new dist !!!!!
ok this mess started with replacing steer column -- that has all been repaired-- before column replace I noticed it starting a little hard from cold start - to no start -- pulled cap only to find tab on center of rotor missing --china sheet !!!!! could not find tab -- went out and purchased NEW dist was installed properly !!!! but on cold start it wants to fire just before compression (only cold) runs strong idles a lil rough for ten minutes than smoothes out and is fine -- starter drive is now out because of this -- going to gat NEW starter -- would a crank sensor possibly do this -- I an getting a P1345 code --also there is no timing adjustment on this dist or o/e there is a fork ( hold down ) that firmly holds this in place has anyone cut part of these fingers to tweek timing a hair ?
#2
12-15-2014, 04:29 PM
P1345 means the distributor was not installed properly. It's off at least one tooth. If you have access to a high end scanner, it will tell you if it's advanced or retarded. You will need the scanner to make the final adjustment to the distributor after it is installed properly. More than likely this is what's causing the performance problems. As for the hold down bracket: Yes, you can trim the tabs if necessary, AFTER the distributor is installed properly. When P1345 sets, there isn't enough clearance to rotate the distributor to "tweek" it. This link will help you time the distributor: https://blazerforum.com/forum/tech-a...-timing-24373/
Last edited by Captain Hook; 12-15-2014 at 04:34 PM.
#3
12-15-2014, 04:52 PM
thank you again -- I do not have a high end scanner -- I am 56 y/o been wrenching most of my life !! have built many engines ect.ect. I really do not want to shell out for a solus or so -- I will re-pull dist and re check my position it is poss I am 1/2 tooth off (lol) but even when I do as long as it is out I am going to cut hold down clamp -- I do have enough movement room but I will re position dist after I go get new starter -- thanks again
#4
12-16-2014, 07:52 AM
Another way to look at it .... If you cut your clamp, without the scan tool displaing CMP retard, how will you know in what position to put the housing in order to have (at least close to) the correct value? With the fixed clamping orientation you only have to worry about getting distributor on the right tooth, so not to set the code.
I'm 58 and it took me some time to wrap my mind around this system! So don't feel bad. Good luck!
Les
Last edited by LesMyer; 12-16-2014 at 08:26 AM.
#5
12-16-2014, 12:42 PM
Turning the distributor does not change ignition timing at all. Ignition timing is based entirely off the crank sensor. The only thing you can change by turning the distributor housing is the relationship of the distributor mounted cam sensor to the crank sensor (this is called CMP Retard) and what terminal on the cap the rotor is pointing to. Your P1345 code indicates that the CMP retard is in excess of ~23° (if I remember correctly). This points the rotor in-between cap terminals and cross firing to the wrong cylinder can occur (hence your performance problem). Either you are at least one tooth off, or you have major problems with wear in timing gears/distributor gear in your new engine. I would fix that obvious at least one tooth off problem and forget trying to turn the distributor. If the code goes away and performance is restored, you will know you have succeeded in getting the distributor back in the correct orientation. Personally I would change the cap/rotor afterwards to prevent future electrical tracking down same old (wrong) path in the cap.
Another way to look at it .... If you cut your clamp, without the scan tool displaing CMP retard, how will you know in what position to put the housing in order to have (at least close to) the correct value? With the fixed clamping orientation you only have to worry about getting distributor on the right tooth, so not to set the code.
I'm 58 and it took me some time to wrap my mind around this system! So don't feel bad. Good luck!
Les
Another way to look at it .... If you cut your clamp, without the scan tool displaing CMP retard, how will you know in what position to put the housing in order to have (at least close to) the correct value? With the fixed clamping orientation you only have to worry about getting distributor on the right tooth, so not to set the code.
I'm 58 and it took me some time to wrap my mind around this system! So don't feel bad. Good luck!
Les
Whenever a distributor is removed you will have to check the cam retard to get it as close to zero as possible. This is accomplished by rotating the distributor. This is of course done after you get the distributor installed correctly by having the #1 cylinder at TDC on the compression stroke and the rotor pointing at the #6 on the distributor base.
#6
12-16-2014, 06:15 PM
good news -- moved dist 1 tooth-- it started -(at first I thought it was crank sensor but when those fail it is for good no spark at all) .
- a little hard but it did - cut 3/4 of ears off on hold down and tweeked it enough to now just tap key and it is running great -this is a new replacement dist with cap/rotor mexico made ,that's where I assume a little tweek made all the diff in the world !!!- pedal to floor with load on nice and smooth up past 60mph !!!! now all I have left to do is trace vacuum lines to find leaks -- heater control and 4x4 have issues at times
thank you guys for all the help
- a little hard but it did - cut 3/4 of ears off on hold down and tweeked it enough to now just tap key and it is running great -this is a new replacement dist with cap/rotor mexico made ,that's where I assume a little tweek made all the diff in the world !!!- pedal to floor with load on nice and smooth up past 60mph !!!! now all I have left to do is trace vacuum lines to find leaks -- heater control and 4x4 have issues at times
thank you guys for all the help
Last edited by trapperdog; 12-16-2014 at 06:19 PM.
#7
12-16-2014, 07:09 PM
If the P1345 is gone, it means it is within ~26 degrees of being correct... spec is zero degrees plus or minus 2. Ain't no way to check it without a scanner capable of accessing CMP streaming data.
If you think it runs good now, have a shop adjust camshaft retard for you
If you think it runs good now, have a shop adjust camshaft retard for you
#8
12-17-2014, 12:07 PM
As I understand the operation, the cam sensor is used to time the fuel injection pulses. Disconnect it and the mode of fuel injection goes from sequential injection to simple pulsing of 2 banks of injectors. Yes, the CMP retard should be close to zero, but not for ignition timing purposes. However, the CMP retard can be used to diagnose a distributor in 1 or more teeth off and the importance of this is where the rotor is pointing.
So I think everyone here is right!
Les
Last edited by LesMyer; 12-17-2014 at 12:19 PM.
#9
12-17-2014, 09:17 PM
My signature holds true on this one too
Short story:
Crankshaft position sensor relearn data and camshaft retard BOTH need to be correct if you want the engine to perform correctly, and accurately detect & identify misfires.
Long story:
The PCM uses crankshaft position sensor data for ignition timing and injector timing. It tells the PCM exactly where the crankshaft is in its rotation. Pretty much how it got its name of crankshaft position sensor The sensor is "focused" in a very small area, and each sensor is unique. The crankshaft position sensor relearn procedure "teaches" the PCM precisely where the sensor is focused on the tone ring. The relearn data is burned to a file in the PCM, and it remains there until the next relearn. The procedure is initiated with a capable scan tool. Once initiated, it takes roughly 1 to 2 seconds to complete. If the sensor and or timing cover is moved, removed, replaced, or disturbed in any way, the focus area changes. When the focus area changes, the sensor does not provide accurate data to the PCM. The engine will still start and run using the original relearn data, but the PCM will be using the old relearn data, which is now incorrect, which causes ignition timing & injector timing to be incorrect.
The PCM uses camshaft position sensor data, along with crankshaft position sensor data, to detect misfires and accurately identify which cylinder or cylinders are misfiring. That's basically all the camshaft position sensor does. As mentioned, you can totally disconnect the camshaft position sensor and the engine will start and run the same as when it's connected. There will be no misfire data though. The sensor is adjusted by rotating the distributor while watching the camshaft retard data stream on a capable scan tool. Spec is zero degrees plus or minus 2 degrees. When camshaft retard is within spec, the distributor cap is also aligned so the air gap between the rotor segment and the cap terminal is at a minimum distance when the ignition coil fires. As camshaft retard increases, so does the physical distance between the rotor segment and the cap terminal. This will cause crossfire inside the cap. Spark travels at roughly the speed of light, (186,000 miles per second) so ignition timing is not affected.
Some of you may remember the old distributors with points, or pick up coils mounted inside. Some of them also had centrifugal and vacuum advance. Rotating the distributor changed the rotational position of the points, or pick up coil, which changed when the spark was generated. Centrifugal and vacuum advance also changed when the spark was generated. That was how ignition timing was adjusted on them. To adjust ignition timing on an engine with a crankshaft position sensor, you would need to move the crank sensor, or reprogram the PCM.
Short story:
Crankshaft position sensor relearn data and camshaft retard BOTH need to be correct if you want the engine to perform correctly, and accurately detect & identify misfires.
Long story:
The PCM uses crankshaft position sensor data for ignition timing and injector timing. It tells the PCM exactly where the crankshaft is in its rotation. Pretty much how it got its name of crankshaft position sensor
The sensor is "focused" in a very small area, and each sensor is unique. The crankshaft position sensor relearn procedure "teaches" the PCM precisely where the sensor is focused on the tone ring. The relearn data is burned to a file in the PCM, and it remains there until the next relearn. The procedure is initiated with a capable scan tool. Once initiated, it takes roughly 1 to 2 seconds to complete. If the sensor and or timing cover is moved, removed, replaced, or disturbed in any way, the focus area changes. When the focus area changes, the sensor does not provide accurate data to the PCM. The engine will still start and run using the original relearn data, but the PCM will be using the old relearn data, which is now incorrect, which causes ignition timing & injector timing to be incorrect.The PCM uses camshaft position sensor data, along with crankshaft position sensor data, to detect misfires and accurately identify which cylinder or cylinders are misfiring. That's basically all the camshaft position sensor does. As mentioned, you can totally disconnect the camshaft position sensor and the engine will start and run the same as when it's connected. There will be no misfire data though. The sensor is adjusted by rotating the distributor while watching the camshaft retard data stream on a capable scan tool. Spec is zero degrees plus or minus 2 degrees. When camshaft retard is within spec, the distributor cap is also aligned so the air gap between the rotor segment and the cap terminal is at a minimum distance when the ignition coil fires. As camshaft retard increases, so does the physical distance between the rotor segment and the cap terminal. This will cause crossfire inside the cap. Spark travels at roughly the speed of light, (186,000 miles per second) so ignition timing is not affected.
Some of you may remember the old distributors with points, or pick up coils mounted inside. Some of them also had centrifugal and vacuum advance. Rotating the distributor changed the rotational position of the points, or pick up coil, which changed when the spark was generated. Centrifugal and vacuum advance also changed when the spark was generated. That was how ignition timing was adjusted on them. To adjust ignition timing on an engine with a crankshaft position sensor, you would need to move the crank sensor, or reprogram the PCM.
#10
12-18-2014, 05:59 AM
My signature holds true on this one too
Short story:
Crankshaft position sensor relearn data and camshaft retard BOTH need to be correct if you want the engine to perform correctly, and accurately detect & identify misfires.
Long story:
The PCM uses crankshaft position sensor data for ignition timing and injector timing. It tells the PCM exactly where the crankshaft is in its rotation. Pretty much how it got its name of crankshaft position sensor The sensor is "focused" in a very small area, and each sensor is unique. The crankshaft position sensor relearn procedure "teaches" the PCM precisely where the sensor is focused on the tone ring. The relearn data is burned to a file in the PCM, and it remains there until the next relearn. The procedure is initiated with a capable scan tool. Once initiated, it takes roughly 1 to 2 seconds to complete. If the sensor and or timing cover is moved, removed, replaced, or disturbed in any way, the focus area changes. When the focus area changes, the sensor does not provide accurate data to the PCM. The engine will still start and run using the original relearn data, but the PCM will be using the old relearn data, which is now incorrect, which causes ignition timing & injector timing to be incorrect.
The PCM uses camshaft position sensor data, along with crankshaft position sensor data, to detect misfires and accurately identify which cylinder or cylinders are misfiring. That's basically all the camshaft position sensor does. As mentioned, you can totally disconnect the camshaft position sensor and the engine will start and run the same as when it's connected. There will be no misfire data though. The sensor is adjusted by rotating the distributor while watching the camshaft retard data stream on a capable scan tool. Spec is zero degrees plus or minus 2 degrees. When camshaft retard is within spec, the distributor cap is also aligned so the air gap between the rotor segment and the cap terminal is at a minimum distance when the ignition coil fires. As camshaft retard increases, so does the physical distance between the rotor segment and the cap terminal. This will cause crossfire inside the cap. Spark travels at roughly the speed of light, (186,000 miles per second) so ignition timing is not affected.
Some of you may remember the old distributors with points, or pick up coils mounted inside. Some of them also had centrifugal and vacuum advance. Rotating the distributor changed the rotational position of the points, or pick up coil, which changed when the spark was generated. Centrifugal and vacuum advance also changed when the spark was generated. That was how ignition timing was adjusted on them. To adjust ignition timing on an engine with a crankshaft position sensor, you would need to move the crank sensor, or reprogram the PCM.
Short story:
Crankshaft position sensor relearn data and camshaft retard BOTH need to be correct if you want the engine to perform correctly, and accurately detect & identify misfires.
Long story:
The PCM uses crankshaft position sensor data for ignition timing and injector timing. It tells the PCM exactly where the crankshaft is in its rotation. Pretty much how it got its name of crankshaft position sensor
The sensor is "focused" in a very small area, and each sensor is unique. The crankshaft position sensor relearn procedure "teaches" the PCM precisely where the sensor is focused on the tone ring. The relearn data is burned to a file in the PCM, and it remains there until the next relearn. The procedure is initiated with a capable scan tool. Once initiated, it takes roughly 1 to 2 seconds to complete. If the sensor and or timing cover is moved, removed, replaced, or disturbed in any way, the focus area changes. When the focus area changes, the sensor does not provide accurate data to the PCM. The engine will still start and run using the original relearn data, but the PCM will be using the old relearn data, which is now incorrect, which causes ignition timing & injector timing to be incorrect.The PCM uses camshaft position sensor data, along with crankshaft position sensor data, to detect misfires and accurately identify which cylinder or cylinders are misfiring. That's basically all the camshaft position sensor does. As mentioned, you can totally disconnect the camshaft position sensor and the engine will start and run the same as when it's connected. There will be no misfire data though. The sensor is adjusted by rotating the distributor while watching the camshaft retard data stream on a capable scan tool. Spec is zero degrees plus or minus 2 degrees. When camshaft retard is within spec, the distributor cap is also aligned so the air gap between the rotor segment and the cap terminal is at a minimum distance when the ignition coil fires. As camshaft retard increases, so does the physical distance between the rotor segment and the cap terminal. This will cause crossfire inside the cap. Spark travels at roughly the speed of light, (186,000 miles per second) so ignition timing is not affected.
Some of you may remember the old distributors with points, or pick up coils mounted inside. Some of them also had centrifugal and vacuum advance. Rotating the distributor changed the rotational position of the points, or pick up coil, which changed when the spark was generated. Centrifugal and vacuum advance also changed when the spark was generated. That was how ignition timing was adjusted on them. To adjust ignition timing on an engine with a crankshaft position sensor, you would need to move the crank sensor, or reprogram the PCM.