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General Forums => The Mess Hall => Topic started by: Lu on February 22, 2010, 03:49:46 PM
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a month ago my jeep (95) started idling and running rough and had a noticeable loss in power. I popped the dist cap off and saw that the contacts were all black and gross. I replaced the cap, rotor, and wires. the plugs were already new. It ran great, smooth and more powerful. so the last few days it has been running a little rougher and not so great. I popped the cap off again and saw the same black crap building up. the guy at the auto parts store said just clean it. He didn't know what it could be. So, anyone? what is it?
i've also read that if the distributor shaft wobbles it could cause arching which would cause this i think. I don't know how much it should or shouldn't wobble. i pull the rotor off and it shakes slightly when I move it.
any help would be appreciated
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a month ago my jeep (95) started idling and running rough and had a noticeable loss in power. I popped the dist cap off and saw that the contacts were all black and gross. I replaced the cap, rotor, and wires. the plugs were already new. It ran great, smooth and more powerful. so the last few days it has been running a little rougher and not so great. I popped the cap off again and saw the same black crap building up. the guy at the auto parts store said just clean it. He didn't know what it could be. So, anyone? what is it?
i've also read that if the distributor shaft wobbles it could cause arching which would cause this i think. I don't know how much it should or shouldn't wobble. i pull the rotor off and it shakes slightly when I move it.
any help would be appreciated
just a guess but what coil do you have and what did you set the gap at on the plugs?
EDIT: there is always arching there, but the shaft wobbling can cause issues (like the rotor actually touching the prongs inside the cap which is not supposed to happen.
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I have whatever the stock coil is and I am running Bosch Platinum+4 plugs which are pre-gapped and can't be gapped I don't think. I tested the shaft more and it doesnt move back and forth but only a little up and down and slightly when turned
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I have whatever the stock coil is and I am running Bosch Platinum+4 plugs which are pre-gapped and can't be gapped I don't think. I tested the shaft more and it doesnt move back and forth but only a little up and down and slightly when turned
dunno what to say - i would try different plugs, just buy whatever cheapest recommended plugs are (they go for about $2.50 a piece), no fancy stuff and see how that goes. Did you find these platinums in the catalog to be the ones recommended for your engine?
the movement of the shaft sounds normal to me
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I got the plugs from napa and the guy said they were the right ones. So you think it could be the plugs being wrong for my engine and are fouling up my cap and rotor?
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I got the plugs from napa and the guy said they were the right ones. So you think it could be the plugs being wrong for my engine and are fouling up my cap and rotor?
i would at least double check to make sure they're the right ones.
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I tried the Platinum +4's and my 2.5 did not like them. Never idled right. Ran ok at high revs though.
Went back to Copper Core std NGKs
Dave
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I have the plus four and the e3. Both have helped in my mileage war. Much better than standard plugs. I run the accel coil for big spark.
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I'm going to have to redo the coil test so I can document the
performance or lack of it from a lot of the "special" after market coils.
:stick:
Dave
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I'm having to clean the contacts off the rotor and cap every few days
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Is the rotor getting a burnt spot or black edge as well?
Sounds like the sparc current is going too high maybe,
My YJ never has gotten great mileage out of the cap and rotor.
About 15K is the best I've done.
Dave
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Yeah, rotor and cap contacts. I have to clean it off every few days. What does it mean the current is going too high?
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If you gap the plug too big, (Usually above .045) and the coil cant quite handle it,
the current becomes unstable then you get secondary arcing which burns the
contacts. I've also seen mild oil leaks at the distributor shaft bearings cause blackening
when the oil deposits on the contacts and burns.
Also if the coil is old and has some internal leaking the sparc is unstable and it can burn
contacts as well.
Dave
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When I replaced the spark plugs, I found the gap to be anywhere between .055 and .062, far above stock .035. Could this incorrect gap have caused the cap to get black by wearing out the coil or something? I really have no idea and I'm just throwing something out there. So now could the coil be old and worn out and causing an unstable spark?
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if you have the correct plugs gapped properly and good cap rotor and wires should all be fine - all is left is the coil so if you suspect that to be the prob give it a shot with a different (new/old) one. Also, make sure the distributor is locked in place by the fork, but if you didn't take it out or try to turn it there's no reason for which would be clocked.
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In general, its not 100%, but if you widen the gap it increases the current in the sparc and causes
more burning of the contacts in the distributor. I usually try and find a cap with Brass not
aluminum contacts when running a hotter ignition setup. I also find if your running stock wires
and bump the gap they seem to break down and wear out faster, not scientific just seems like they do...
It likely did not ruin the coil, the coil is just getting old and the windings insulation breaks down with age.
Some last forever some last a few years./// Kinda luck of the draw there.
I'f the coil is over say 7 years old, it might be worth replacing with a quality
replacement and keep the one you have as a spare.
One thing to note, if you didn't know, the distributor in that motor distributes sparc and provides
the cam position sensor feed, which triggers the fuel injection, the spark is controlled by the crank position sensor.
On mine there is no adjustment for timing on the distributor unless you pull the distributor and clock it a tooth.
Dave
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So I threw in a new accel ignition coil. Within a day, the contacts were burned again. So I guess it's not the coil. Back to the distributor leaking oil, there would be residue inside the cap, right? I don't have any residue.
What else can I try? I appreciate all the advice
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I'd check plug wires(resistance) and put in standard plugs with the stock gap. See if that helps?
Yes you'd find some residue in the cap if it had the oil leak issue.
Other than that I'm stumped, HMM. If you have a meter with peak reading memory,
you could check the voltage at the coil on the low voltage side, maybe your getting
too many volts in the system? (Totall wild guess here!) At least check the alternator
charge voltage across the battery terminal.
Dave
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I'd check plug wires(resistance) and put in standard plugs with the stock gap. See if that helps?
Yes you'd find some residue in the cap if it had the oil leak issue.
Other than that I'm stumped, HMM. If you have a meter with peak reading memory,
you could check the voltage at the coil on the low voltage side, maybe your getting
too many volts in the system? (Totall wild guess here!) At least check the alternator
charge voltage across the battery terminal.
Dave
x2 on all that
I was thinking the same thing as far as the charging voltage but it's a long shot so i didn't mention it - now that you did maybe is not that wild of an idea.
other than that it sound pretty misterious ???
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Aha, wait a second, have you checked the polarity of the coil connections? If the coil is backwards it will do odd things...
Dave
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Well, it seems that there is only one way the connection can go on. I'll run a check on the charging system soon and the meantime I'll just deal with it. Thanks for all the help. By the way, what should the normal voltage coming from the alternator be? What should the gauge in my dash read?
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The dash gauge is usually not very accurate, you should be somewhere between 13.9 and 15.5 as I recall, but I'd check a manual....
Dave
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Aha, wait a second, have you checked the polarity of the coil connections? If the coil is backwards it will do odd things...
Dave
i don't know if it would matter that much at the distributor cap and rotor, more at the spark plugs i would think (polarity at the electrode) - interesting point though
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Here's an update. I picked up a set of Autolites and made sure they were gapped properly at .035 and ran them for about a week including a 4 hour round trip on one day. The same burning effect on the cap and rotor contacts happened with the Autolites as well as E3's and +4's. I re-gapped the Autolites to .055 because I have a hotter coil now and I got a little more boost out of them but still with the burning effect.
The Platinum +4's are by far the best plugs I've run. They give a noticeable increase in pep and on hills I can maintain 60mph no problem, given that it isn't too steep of a hill. I also get 1-2mpg better with the +4's.
Since the +4's make me happier, I'm sticking with those for now.
So what now? I've had a Firepower ignition kit on my fantasy list for a while...would it help to install one?
Thoughts?
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try the stock coil with and gap back at .035
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if you have ignition problems on most modern cars,
going more powerful will usually just aggravate the root cause.
One thing I have done in the past is taken an old cap and cut a hole in
the top so I could see the #1 contact, then run the motor to see where
the rotor is in relation to the contact when it fires.(A timing light will help see the rotor....)
If your off a tooth, its possible to have the arc jumping way too far....
Which would raise the current way up in the arc the distributor.
Usually the engine does not run very well but its possible the computer is
dragging the timing just far enough fix it... Would a thought the cam position
sensor in the distributor would have forced a code but the mopar computer
ain't the sharpest knife in the drawer....
Dave
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if you have ignition problems on most modern cars,
going more powerful will usually just aggravate the root cause.
One thing I have done in the past is taken an old cap and cut a hole in
the top so I could see the #1 contact, then run the motor to see where
the rotor is in relation to the contact when it fires.(A timing light will help see the rotor....)
If your off a tooth, its possible to have the arc jumping way too far....
Which would raise the current way up in the arc the distributor.
Usually the engine does not run very well but its possible the computer is
dragging the timing just far enough fix it... Would a thought the cam position
sensor in the distributor would have forced a code but the mopar computer
ain't the sharpest knife in the drawer....
Dave
wouldn't hurt to align up your timing marks and pull the distributor and check the teeth I have seen vehicles wear the teeth off and cause problems
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The PCM should be able to compensate for a tooth or two though.
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The PCM should be able to compensate for a tooth or two though.
the spark would occur at the same advance point relative to tdc regardless of the dist or rotor position based on the flywheel to crank sensor signal
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There is a max number of degrees the PCM can pull, I think its < 40...
For instance if you have all the wires 1 connector off on the distributor
the PCM can't deal with it...
I'm just kind of brainstorming, only excess current could burn the cap,
SO something is causing that... Hmmm
Dave
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the pcm has no way to "know" what wire go to which cylinder.
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Let me re write that, what I was trying to say was that if you are a
tooth off the PCM can pull enough timing to get things synched up, if
for instance you were a post off in putting on the plug wires, the PCM
cant correct 90 degrees of timing, so it would pop bang and backfire....
It would be the equivalent of having the distributor 4 teeth off or so...
Does that make better sense? :biggrin:
Later
Dave
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Let me re write that, what I was trying to say was that if you are a
tooth off the PCM can pull enough timing to get things synched up, if
for instance you were a post off in putting on the plug wires, the PCM
cant correct 90 degrees of timing, so it would pop bang and backfire....
It would be the equivalent of having the distributor 4 teeth off or so...
Does that make better sense? :biggrin:
Later
Dave
it makes more sense but this is my thinking: the advance has to occur at the same angular point bfore TDC for some given engine running params (rpm, temps, etc)
now if you move the dist 1 tooth ahead or behind the PCM will still give the spark at the same point for the same engine running params - the spark would occur at a different position inside the dist cap but the ignition advance is the same relative to the TDC for a cylinder (and that is given by the flywheel teeth and the crank sensor and these have not moved).
the cam sensor is only used for injector sequence, has no input/influence in the ignition timing.
I don't see what/how would the PCM do with the timing to correct that (the spark would still occur at the same point, so you still have the same ignition advance)
i don't even think the engine would run with the cam/crank out of sync (i read an article for a 4.0 where the dist was not set properly and the engine would run for 2 seconds and then cut out, once they fixed the dist position started to run fine) - have not tested this so it's only from what i read.
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When I rebuilt my engine I got the distributor in a tooth off,
It ran, but when I used my cap with the hole in it the spark was jumping
from the leading edge of the rotor not from the face of the rotor to the contacts.
It was also wicked rich and fouling plugs at idle, which I attributed to
the injection firing way out of sync and puddling fuel in the manifold?
It would run ok if ya revved it enough to get it up to firing more continuously...
At least this is what I observed and kinda guessed was happening,
I corrected the distributor and it went away. Now I don't know for sure what
was happening with the injection but that's what it looked like it was doing...
My understanding is the cam position sensor in the MPI distributor only fires
the injection, and the ignition is all off the crank sensor. A mopar mechanic
told me once the ECU is really like multipe small computers in one box, the
Ignition is one the injection is one and there is one that runs some accessory
stuff like the alternator. Thats why they act sort of phsychotic because they just
talk on a local buss to sync their activities.
The Renix uses a continuous pulse system that is related to RPM and sensor feeds. So its not timed right?
And I'd assume it has a regular distributor that fires the ignition?
Dave
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The Renix uses a continuous pulse system that is related to RPM and sensor feeds. So its not timed right?
And I'd assume it has a regular distributor that fires the ignition?
Dave
tbi distributor has no electronics, just the rotor and cap. just uses cps and other sensors like you said. i know the timing is computed in a box that the coil connects to which receives a signal from the computer and 12v.. so maybe its just a dumby but a similar system (renix / bendix) was used by Volvo and computed timing with cps and map outputs.
what do you mean by timed? (im guessing you are talking about timing for injector pulse on / off... but not sure)
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When I rebuilt my engine I got the distributor in a tooth off,
It ran, but when I used my cap with the hole in it the spark was jumping
from the leading edge of the rotor not from the face of the rotor to the contacts.
It was also wicked rich and fouling plugs at idle, which I attributed to
the injection firing way out of sync and puddling fuel in the manifold?
It would run ok if ya revved it enough to get it up to firing more continuously...
At least this is what I observed and kinda guessed was happening,
I corrected the distributor and it went away. Now I don't know for sure what
was happening with the injection but that's what it looked like it was doing...
My understanding is the cam position sensor in the MPI distributor only fires
the injection, and the ignition is all off the crank sensor. A mopar mechanic
told me once the ECU is really like multipe small computers in one box, the
Ignition is one the injection is one and there is one that runs some accessory
stuff like the alternator. Thats why they act sort of phsychotic because they just
talk on a local buss to sync their activities.
The Renix uses a continuous pulse system that is related to RPM and sensor feeds. So its not timed right?
And I'd assume it has a regular distributor that fires the ignition?
Dave
yeah, that's what i'm saying - the timing has nothing to do with the dist position - sounds about right from what you describe (spark being offset off the rotor).