99 Blazer 4.3 Ignition Problem
July 13th, 2015, 5:37 PM
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99 Blazer 4.3 Ignition Problem
I have a 99 4x4 Blazer with the 4.3 vortec engine (plastic intake plenum). Recently one of the pistons went on a rampage ruining the engine. I replaced the engine with a remand 4.3 purchased from the parts store. I have no codes currently.
New:
Engine
CKP Exciter Ring OEM
Timing Cover
Distributor Cap BWD
Distributor Rotor BWD
Spark Plugs
The Problem At Hand:
I currently have a nice blue spark coming from the Coil. I used my spark tester and it's sparking an inch distance with no problem and again the spark is nice and blue. I am also using the Coil Wire during this test. So the coil and coil wire seems to be working very well.
I originally replaced the cap with the engine because I was not that careful with the original distributor cap and ended up breaking one of the ears off of it and loosing a screw. I have checked with my spark tester and I am not getting any spark from the wires or directly from the output terminals of the distributor. Therefore i replaced the rotor on the distributor. The condition did not change.
The distributor timing has been checked and re-timed too many times to be wrong. If you must know how i do it. I popped off #1 plug, put my finger in the hole, slowly cranked the engine over until i got pressure, brought it to TDC using a screwdriver in the plug hole and watching the markings on the Harmonic Balancer (lined up to the tab), dropped the distributor in so the metal tab on the rotor was facing the #1 cylinder marker that has a 6 stamped on it.
I have no clue what to do next. I imagine I am going to put the old cap back on tomorrow and see if that changes anything. I am getting good vacuum on the intake tube because i put my hand up to it while cranking the engine and it was a good pull of air.
When I am trying to start the engine with everything hooked up it immediately stumbles a tiny bit maybe twice then goes back to cranking. It sounds like one cylinder fires then another follows. I have never had a backfire and my oil pressure at the top of the engine is good while cranking to say the least.
I have looked all over the forums and cant find one resolved relate able issue.
UPDATE
I just put the old cap back on and found that two of my cylinders are in fact sparking. The number 3 and 6 cylinders are firing which explains my stumble when it tries to start. The cylinders only share the fact that they are adjacent to one another on the distributor cap.
I took it a step further and pulled the cap and put a spark tester on the coil. Every time the coil sparks the distributor rotor is pointing at #3 or #6. I still do not have any codes. Would this odd firing point me at the cam sensor or the coil module?
New:
Engine
CKP Exciter Ring OEM
Timing Cover
Distributor Cap BWD
Distributor Rotor BWD
Spark Plugs
The Problem At Hand:
I currently have a nice blue spark coming from the Coil. I used my spark tester and it's sparking an inch distance with no problem and again the spark is nice and blue. I am also using the Coil Wire during this test. So the coil and coil wire seems to be working very well.
I originally replaced the cap with the engine because I was not that careful with the original distributor cap and ended up breaking one of the ears off of it and loosing a screw. I have checked with my spark tester and I am not getting any spark from the wires or directly from the output terminals of the distributor. Therefore i replaced the rotor on the distributor. The condition did not change.
The distributor timing has been checked and re-timed too many times to be wrong. If you must know how i do it. I popped off #1 plug, put my finger in the hole, slowly cranked the engine over until i got pressure, brought it to TDC using a screwdriver in the plug hole and watching the markings on the Harmonic Balancer (lined up to the tab), dropped the distributor in so the metal tab on the rotor was facing the #1 cylinder marker that has a 6 stamped on it.
I have no clue what to do next. I imagine I am going to put the old cap back on tomorrow and see if that changes anything. I am getting good vacuum on the intake tube because i put my hand up to it while cranking the engine and it was a good pull of air.
When I am trying to start the engine with everything hooked up it immediately stumbles a tiny bit maybe twice then goes back to cranking. It sounds like one cylinder fires then another follows. I have never had a backfire and my oil pressure at the top of the engine is good while cranking to say the least.
I have looked all over the forums and cant find one resolved relate able issue.
UPDATE
I just put the old cap back on and found that two of my cylinders are in fact sparking. The number 3 and 6 cylinders are firing which explains my stumble when it tries to start. The cylinders only share the fact that they are adjacent to one another on the distributor cap.
I took it a step further and pulled the cap and put a spark tester on the coil. Every time the coil sparks the distributor rotor is pointing at #3 or #6. I still do not have any codes. Would this odd firing point me at the cam sensor or the coil module?
Last edited by bat681987; July 14th, 2015 at 8:50 AM. Reason: Update in diagnosis
July 14th, 2015, 10:14 AM
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Solution reached
Using Part 1 -How to Test the GM Ignition Control Module (1995-2005) I was able to test the trigger from the ECM and found it was only triggering on 3&6 cylinders. Assuming that the ECM is fine considering it's rare for them to go bad. I replaced the CKP sensor and rechecked my spark. The coil was rattling sparks off like crazy.
Hopefully this thread helps others with my problem.
Using Part 1 -How to Test the GM Ignition Control Module (1995-2005) I was able to test the trigger from the ECM and found it was only triggering on 3&6 cylinders. Assuming that the ECM is fine considering it's rare for them to go bad. I replaced the CKP sensor and rechecked my spark. The coil was rattling sparks off like crazy.
Hopefully this thread helps others with my problem.
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