Timing 96 5.0
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Senior User
Joined: Dec 2003
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From: Groton, CT
Timing 96 5.0
OK, here is a new one.
While troubleshooting another problem, I decided to check my base timing. I have not done this before on this Bronco, although I have done it many times before on my previous and other folks Broncs.
I have a MSD 6A, so I disconnected the MSD box and hooked up my stock ignition to get a more true reading. Started the Bronc to make sure everything was working properly. Started up and ran just fine.
Hooked up the timing light to make sure all was well on that end, light working fine but timing mark no where in sight. Shut it down and pulled the spout. Started up and Bronc running like a couple of cylinders were not firing. She started and ran, but definately a serious problem. Re-installed spout, truck runs fine. Pulled spout, same symptoms. It would appear that #1 cylinder is one of the cylinders not firing, as the timing light will not work with the spout pulled and the rig is misfiring.
I have never seen this one before, and cannot figure out why she would stop firing on all cylinders with the spout pulled. Pulling the spout should only disable computer controlled advance, not cause what I am seeing.
Any ideas?
While troubleshooting another problem, I decided to check my base timing. I have not done this before on this Bronco, although I have done it many times before on my previous and other folks Broncs.
I have a MSD 6A, so I disconnected the MSD box and hooked up my stock ignition to get a more true reading. Started the Bronc to make sure everything was working properly. Started up and ran just fine.
Hooked up the timing light to make sure all was well on that end, light working fine but timing mark no where in sight. Shut it down and pulled the spout. Started up and Bronc running like a couple of cylinders were not firing. She started and ran, but definately a serious problem. Re-installed spout, truck runs fine. Pulled spout, same symptoms. It would appear that #1 cylinder is one of the cylinders not firing, as the timing light will not work with the spout pulled and the rig is misfiring.
I have never seen this one before, and cannot figure out why she would stop firing on all cylinders with the spout pulled. Pulling the spout should only disable computer controlled advance, not cause what I am seeing.
Any ideas?
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
OK, I am assuming the timing light will trigger when the SPOUT connector is installed? I mean otherwise, the computer could be compensating for the dead cylinder and you just aren't seeing it during normal operation because of the compensation.
I agree, thats really strange. Your assesment of the SPOUT connector is right to the best of my knowledge. It should only remove the control of spark timing, not the spark itself. Gonna ponder this a bit more but I have nothing logical to add beyond what I have at this point.
Here is an odd thought (and it may not be a viable point because I am not as well versed in the OBD-II as I am the EEC-IV)... does the OBD-II have the capacity to reduce or remove spark to a given cylinder if it detects a misfire in an injector? So, in short can the computer kill the spark to one plug if the injector quits (sparing the dead cylinder the agony of being "dry fired" because no fuel is getting through)? I don't know the answer but if the OBD-II has this capability, it may be the start of an answer.
I agree, thats really strange. Your assesment of the SPOUT connector is right to the best of my knowledge. It should only remove the control of spark timing, not the spark itself. Gonna ponder this a bit more but I have nothing logical to add beyond what I have at this point.
Here is an odd thought (and it may not be a viable point because I am not as well versed in the OBD-II as I am the EEC-IV)... does the OBD-II have the capacity to reduce or remove spark to a given cylinder if it detects a misfire in an injector? So, in short can the computer kill the spark to one plug if the injector quits (sparing the dead cylinder the agony of being "dry fired" because no fuel is getting through)? I don't know the answer but if the OBD-II has this capability, it may be the start of an answer.
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Senior User
Joined: Dec 2003
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From: Groton, CT
Grey, you assume correctly that the timing light triggers on #1 with the spout connected. OBD II not smart enough to remove spark from a cylinder then compensate. They just came out with the technology to shut down a couple of cylinders and remain stable this year.
I am thinking of an experiment to at least determine which cylinders are or are not firing. Here is my thought:
1. Using the inductive timing light check each wire with spout connected to prove or disprove that all eight cylinders are firing.
2. Using the timing light again check each wire with spout disconnected to determine which cylinders are not firing.
Although this test will not really resolve anything, at least it will give me a clearer picture of the scope of the problem.
If there are any FOMO computer gurus out there, I could sure use your help on this one.
I am thinking of an experiment to at least determine which cylinders are or are not firing. Here is my thought:
1. Using the inductive timing light check each wire with spout connected to prove or disprove that all eight cylinders are firing.
2. Using the timing light again check each wire with spout disconnected to determine which cylinders are not firing.
Although this test will not really resolve anything, at least it will give me a clearer picture of the scope of the problem.
If there are any FOMO computer gurus out there, I could sure use your help on this one.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
A good test procedure to be certain. PIP was my next thought but it would affect all eight cylinders unless the excitor ring in the dizzy is damaged. Someone has got the answer. Hopefully. Its still a confusing situation and I would be very interested in getting some insight to the cause.
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Senior User
Joined: Dec 2003
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From: Groton, CT
Well, since there doesn't seem to be any takers on this one, I came up with one idea and thought I would throw it out there. I figure either my idea is a possibility, or it would demonstrate the depths of my ignorance and provide you some cheap entertainment.
Here goes...
I wonder if it is possible that my timing chain has jumped a tooth and the computer is compensating? No idea if OBD II has enough brains to pull this off, but I am grasping at straws here.
My thought is based simply on the fact that cylinders are not firing with the SPOUT pulled, but everything works fine with the spout in.
I figure by now you are either going "hmmm...I wonder" or you just fell out of your chair holding your sides laughing. Either way, at least your thinking about it...
Here goes...
I wonder if it is possible that my timing chain has jumped a tooth and the computer is compensating? No idea if OBD II has enough brains to pull this off, but I am grasping at straws here.
My thought is based simply on the fact that cylinders are not firing with the SPOUT pulled, but everything works fine with the spout in.
I figure by now you are either going "hmmm...I wonder" or you just fell out of your chair holding your sides laughing. Either way, at least your thinking about it...
Thread Starter
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Senior User
Joined: Dec 2003
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From: Groton, CT
Hey Grey, found the problem...It was my Ignition Control Module. Been tracing wiring diagrams and logic diagrams and troubleshooting diagrams till I was going crosseyed (I love ALLDATA). The only component that made any sense was the ICM, so I sprung for the $45, and voila!
Now that I have fixed this gremlin, we will see if it also solved my 171, 174 code problem (ignition timing fault is a possible cause according to Alldata). I hope so, because I have ruled out just about any other possibility.
Anyway, this one was a head-scratcher, so I thought you would like to know.
Now that I have fixed this gremlin, we will see if it also solved my 171, 174 code problem (ignition timing fault is a possible cause according to Alldata). I hope so, because I have ruled out just about any other possibility.
Anyway, this one was a head-scratcher, so I thought you would like to know.
