J
Jack Klarich
Guest
HMMMMMM, may be a problem with the control module or coil?
Missing at constant speed?
- Thread starter Bodeen
- Start date
HMMMMMM, may be a problem with the control module or coil?
dolt
Well-Known Member
Compression would be right for stock bore; should hit 165psi (sea level) with good ring seal and a .030" head gasket. However, that cam would like more.
Sounds like something is going on with the rear cylinder. Because there is better compression in the rear cylinder doesn't mean it's heathier. Could be a leaky valve seal that has allowed carbon build up in the rear cylinder.:s The rear cylinder plug should read leaner than front as it runs hotter than the front. If compression is good, next check would be a leak down test.
Up to this point, we have been talking about a "miss" but now you make reference to a "noise", that's different chase.
Refresh my memory. Did the miss show up coincidental with the motor upgrades?
Any pictures of the plugs? Not the new ones but the ones you replaced.
Still leaning toward the ignition module or the ECM; however, ECMs rarely fail incrementally. When they decide to go, the go and the bike will become unrideable.
The original project was a camplate, oil pump, inner bearings, PR's, Axtell oil bypass, and cam update only. This update immediately caused an unknown noise in the front rocker box. Upon inspection, the exhaust valve guide seal had dislodged and was beating up and down. Enter a new to me set of heads that have been completely redone with new valves, springs, seals, street port etc. Installed those and that leads us to now. To answer when the miss showed up is hard to say with the original head having a seal dislodged upon completion of the original project.
As for the noise now, I know its a different issue but just trying to link them together. I did tear into the front rocker box and could not find anything amiss. Rockers are tight with only small lateral movement. Seals still in place etc. Turning the motor over by hand did not produce anything out of the ordinary. I am not really too worried about the noise at this point. The miss is an issue.
When I removed the older stock plugs to put the NGK's in it didnt raise any eyebrows but when I removed the NGK's to re-check compression, they raised eyebrows. Didnt photo them but I will.
Been thinking about the MAP sensor and CKP sensor but as far as I know these cause un-rideable issues when they go bad. The MAP sensor would mess with the advance curve though. Just not sure if it will go a little bad. Seems it would work or not.
Hard to believe that this cam and lack of compression would make the ignition timing map that far out of whack. Could be the coil too I guess but I am just not sure
I hate replacing parts just to replace them! Where is Jim (Hoople) when I need him?
As for the noise now, I know its a different issue but just trying to link them together. I did tear into the front rocker box and could not find anything amiss. Rockers are tight with only small lateral movement. Seals still in place etc. Turning the motor over by hand did not produce anything out of the ordinary. I am not really too worried about the noise at this point. The miss is an issue.
When I removed the older stock plugs to put the NGK's in it didnt raise any eyebrows but when I removed the NGK's to re-check compression, they raised eyebrows. Didnt photo them but I will.
Been thinking about the MAP sensor and CKP sensor but as far as I know these cause un-rideable issues when they go bad. The MAP sensor would mess with the advance curve though. Just not sure if it will go a little bad. Seems it would work or not.
Hard to believe that this cam and lack of compression would make the ignition timing map that far out of whack. Could be the coil too I guess but I am just not sure
I hate replacing parts just to replace them! Where is Jim (Hoople) when I need him?
dolt
Well-Known Member
The original project was a camplate, oil pump, inner bearings, PR's, Axtell oil bypass, and cam update only. This update immediately caused an unknown noise in the front rocker box. Upon inspection, the exhaust valve guide seal had dislodged and was beating up and down. Enter a new to me set of heads that have been completely redone with new valves, springs, seals, street port etc. Installed those and that leads us to now. To answer when the miss showed up is hard to say with the original head having a seal dislodged upon completion of the original project.
As for the noise now, I know its a different issue but just trying to link them together. I did tear into the front rocker box and could not find anything amiss. Rockers are tight with only small lateral movement. Seals still in place etc. Turning the motor over by hand did not produce anything out of the ordinary. I am not really too worried about the noise at this point. The miss is an issue.
When I removed the older stock plugs to put the NGK's in it didnt raise any eyebrows but when I removed the NGK's to re-check compression, they raised eyebrows. Didnt photo them but I will.
Been thinking about the MAP sensor and CKP sensor but as far as I know these cause un-rideable issues when they go bad. The MAP sensor would mess with the advance curve though. Just not sure if it will go a little bad. Seems it would work or not.
Hard to believe that this cam and lack of compression would make the ignition timing map that far out of whack. Could be the coil too I guess but I am just not sure
I hate replacing parts just to replace them! Where is Jim (Hoople) when I need him?
The noise could easily be related to concentricity of the valve in the guide. If it is off just the slightest bit, the valve will "hit" the face of the pocket and make noise. The valve will usually seal OK but not without some noise. You would be surprised how many head porters do not check concentricity of the valve in the pocket when porting heads.
As a general rule, you are right about the results of a bad CPS or TPS but there are exceptions to every rule. I have learned over the years not to sule out anything. I don't recall if you have checked to see if the ECM has thrown any codes? If no codes, you can eliminate the TPS and CPS as a source of the problem. If it was the MAP sensor, you should be experiencing some detonation; I doubt that is the problem.
The coil is an easy test; all you need is an ohm meter to check resistance.
We haven't considered the VOES but a dirty VOES could cause the problem you are experiencing. When the contacts are dirty or corroded they can make intermittent contact when they are supposed to be closed.
When this happens, the bike will start and run okay under acceleration (low vacuum), but during steady running (high vacuum) the switch makes intermittent contact, and thus, will be constantly switching at random between the two advance curves. This will cause very rough running, and can easily be mistaken for a large vacuum leak. The "rough running" part is inconsistent with your issue but perhaps the VOES contacts are just starting to act up or the wired connections could be loose? You can also check the VOES for resistance.
Just throwing options out there for your consideration. It's very hard to diagnose any sort of fuel or electrical issues without the bike.
I'll check codes again but last I checked I had none.
I don't have a VOES so that is easy to check! Its a 2003.
We're going to swap with a known good coil this week and see what happens. I can ohm it out too but Hoople use to say that ohm'ing it out was not the end all for coil diagnosis.
The noise is for another day and time. I guess if I need to change the ignition module I will look at the DTT 1008 and the coil. I just dont want to sink $300 on it to add it to the parts collection pile.
Thanks Dolt!
I don't have a VOES so that is easy to check!
Its a 2003.We're going to swap with a known good coil this week and see what happens. I can ohm it out too but Hoople use to say that ohm'ing it out was not the end all for coil diagnosis.
The noise is for another day and time. I guess if I need to change the ignition module I will look at the DTT 1008 and the coil. I just dont want to sink $300 on it to add it to the parts collection pile.
Thanks Dolt!
I think Dolt needs a real pat on the back for all the thought he has put into diagnosing your problem Bodeen. He just doesn't give up and has given a lot of excellent advice.
I know you would like to see this thread end Bodeen,and I don't blame you, but it has been a great read.
Tried to give Dolt some rep points but it says I have to spread them around before I can give anymore to him. He's a great asset to this forum.
I know you would like to see this thread end Bodeen,and I don't blame you, but it has been a great read.
Tried to give Dolt some rep points but it says I have to spread them around before I can give anymore to him. He's a great asset to this forum.
dolt
Well-Known Member
I don't have a VOES so that is easy to check!
Thanks Dolt!
Brain fart.
I think '98 was the last year for the VOES and the TCs went to the MAP sensor.
dolt
Well-Known Member
Brain fart.
Forgot to add that I doubt the coil is the offender. IIRC, the miss occurs at cruise, light throttle conditions? A bad coil would tend to miss under load but certainly worth checking. I am real curious what could be causing your issue, please post the cure.
J
Jack Klarich
Guest
If you can isolate the noise( front or back cylinder) you may find your answer faster. If it is in the valve train look at valve springs closely and check valve guides