I posted 6 months ago about a glowing red exhaust manifold on a Duke. This forum is the reason it was resolved! But this is a head scratcher....
Car: 1986 stock Iron Duke (distributor), 5 speed Izuzu
Symptoms: Ran very very well for the 6 months I have had it running. I was driving it in the garage a week ago and rpms lowered and it sputtered a few times and stalled. I tried to start it again but it turns over as if it has too much compression....weird. If I floor it when I turn it over I can get it to spin like normal, it will pop once, backfire a huge fireball out of the throttle body and then turn over slowly like it has too much compression again. (You know: rr....rrr....rrr...rrrr). This is not a battery/starter issue! I have jumped it, and fully charged it.
What I have replaced or checked in the past month: Cylinder compression - 150-157 across all cylinders (abnormally high?) All fuel components including new pump (works well) and overhaul throttle body Checked Ignition module, replaced dist cap, rotor, plugs, wires. Has good hot blue spark. Checked rockers, all are moving I have recently cleaned and greased all grounds New sensors - oxygen, oil pressure, temperature, and tested TPS and MAP=Good
If it was extremely flooded, it would at least try to do something more with the throttle wide open. I have even unplugged the injector and turned it over to clear it out and nothing. There is a nice spray coming from the injector as well. What would you suggest I try next? I have run out of ideas. Suggestions welcome and I will let you know if I have already done that (hard to keep track from a year long project). I have seen a couple threads about similar issues, but the one turned out to be the crankshaft position sensor, which the 86's do not have (correct?). Thanks!!
My guess would be cam timing, the cam gears are bad actors on these engines, so it may have broke a couple of teeth and the cam is badly out of time. Larry
Unplug the coil to ICM 2 conductor wire and crank it. Does it crank normally? If so your timing is way too advanced.
I suspect the timing is too advanced. When you floor it the injectors are not pulsed. No gas in the cylinder means the cylinders don't fire and it cranks normally.
To retard your timing - loosen the hold down bolt and turn the distributor body in the same direction the rotor spins (clockwise). After you get it to start you then need to time the engine with a light and jumpering A-B.
When the timing is too advanced and you try to start it, when a cylinder fires the piston is before TDC. The firing of the cylinder stops the cranking of the engine for a second and then when the starter can overcome the compression it starts going forward again.
When the teeth on your cam gear fails, your cam will stop turning. Cam not turning also means the distributor doesn't turn. It won't jump a tooth. When it gets that bad the gear just fails.
[This message has been edited by phonedawgz (edited 06-15-2013).]
I would normally think that too about the timing gear, but the way it failed is what makes me think that. I don't know any way the timing would all of a sudden advance it's self like 20 degrees. Larry
Phonedawgz: Thanks, I have been messing with the distributor placement for a bit, but I have not tried just unplugging something to stop the fire to see if that is the issue. I am assuming unplugging the coil wire will have the same effect. I will try that later. I'm not sure how the timing would change enough to kill the engine when it was running perfectly and then sputtered and stopped. Thanks!
Larry: There is an ongoing debate as to whether these gears can slip a tooth, but now that you mention it, it is at that age (162,xxx) and was recently revived from sitting in the mud for 12 years.... Do you know if there is any way to check this? (valve timing or timing gear) without having to take off the timing cover? I understand that requires at least partially dropping the engine to get a puller on the crank's pulley. Thanks!
I think it will be hard to check. I would pull the plugs and the valve cover, then rotate the engine by hand with a wrench on the crank pulley. You can then see if the valves open at about the right place, like the exhaust valve open about bottom dead center or the intake opening at about TDC. If ti is way off then you may have to look further. It is sort of a longer shot, but the way it failed is sort of a clue. Also, the gear could have sheared a pin or key? Never know. Larry
Turn the engine clockwise using the balancer bolt. Then the timing mark is getting close to TDC have someone put something in the spark plug hole to verify the timing mark is still correct. The 2.8s have a rubber mounted ring on the balancer that sometimes moves. Assuming the timing marks look like TDC = TDC then have your assistant put his finger over the #1 hole. Continue to turn the engine clockwise until he states air is pushing past his finger. Then continue turning the crank clockwise till you get to 10deg before TDC per the timing marks. Stop there. Don't go past and then reverse into position.
Now open the distributor. Look at the rotor. The rotor needs to be pointing to the #1 spark plug wire tower. If so then fine tune align the prongs and points under it (by rotating the dist body). Then snug the dist down. Make sure again the rotor is still pointed at the #1 plug wire. If not, you can rearrange so the #1 is the wire it is pointing at. Remember the firing order is 1 - 3 - 4 - 2. The dist turns clockwise.
With the timing set per this procedure the engine will be close enough to start. Again set the timing with a light after you get the engine running.
I will follow this procedure tomorrow! If anything it will clear up the timing gear question.
Are compression readings of 157 normal for a 2.5? Seemed high to me. When I first tested them 6 months ago, they were all around 125 (that was before it was running well) so I am assuming the rings have seated a bit better since then?
Yes, if the cam is not timed rigth the intake valve may close early so there is more air trapped in the cylinder which will show up as higher compression. Larry
Phonedawgz: Just a clarification, when I take the cap off of the distributor, how can I then tell if the rotor is pointing at the #1 post? Is it just a close estimate?
So when you have the crank stopped at 10 deg before tdc, then open the dist. Hopefully the rotor is pointing at #1 but maybe not. Align the prongs and points of the pick up below the rotor exactly by rotating the distributor body. Once they are aligned exactly you will notice the rotor is also now exactly pointing at one of the spark plug wire towers. Now assuming you did what I said before and the crankshaft/camshaft of the engine is on the COMPRESSION stroke of the #1 cylinder and at 10 deg before tdc that will be your #1 spark plug tower. Connect the wire from the #1 spark plug to that tower. When using this procedure disregard the pictures in the book of where the wires should be. This is the new correct picture.
I could give you a longer post that would make the dist look like the picture in the book but that is not needed. Just that at this time that the crank/cam is at compression on #1 that the rotor also needs to be pointing to a spark plug tower, and that will be your #1 spark plug tower. Makes sense right? (If your engine IS at 10 deg BTDC on it's compression stroke you had better be sending the spark to the #1 spark plug)
Snug down the dist so it doesn't turn. Put the remaining wires on the dist cap in a clockwise manner following the firing order of 1, 3, 4, 2. Put it together and the timing will be close enough to start. It will be withing a few degrees of the setting with a light.
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The reason you will never skip a tooth on the geared Duke - There is nothing to flex and allow a tooth to skip. No long metal timing chain. No rubber belt. No Tensioner. Just a steel crankshaft gear and a micarta camshaft gear. They don't flex to jump a tooth. The crank doesn't flex out of the way and the cam doesn't flex out of the way. When something goes bad the camshaft tooth breaks. Once the camshaft tooth has broken there is nothing to propel the shaft to the next tooth. It just stops.
[This message has been edited by phonedawgz (edited 06-16-2013).]
Okay, thank for clearing that up. I think the only thing that confused me was that the prongs were not aligned over the points on the pickup. So I turned the body so they were aligned (right over top of eachother). Putting it together now...
Align the prongs and points of the pick up below the rotor exactly by rotating the distributor body. Once they are aligned exactly you will notice the rotor is also now exactly pointing at one of the spark plug wire towers.
Okay, one more issue, as you said above, I aligned the prongs and the points by turning the body. However this alignment makes it so the rotor would no longer be pointing exactly at a spark plug wire tower if I was to put on the cap. Was what I did correct then? I have the rotor, the points below, and the prongs all aligned. They all point to about 11 o'clock which is now right between two spark plug towers if I was to put on the cap.
I think the way it failed is the clue here, it was running perfect, then a big ball of flame out the intake and it quit running and won't start and acts funny when it cranks. I am thinking something stranger than just somehow getting way out of time happened to it. Bet we will find out. Larry
V6 distributors have the slot in the top of the shaft line up right between two prongs in the rotor below. The spark plug towers then align to this pattern. A spark is made when the prongs line up. When your spark is made the rotor isn't pointing at a spark plug tower.
I have been looking at pics on line of distributors. The bottom piece of the prongs looks to be in the correct position. I don't have a 4 cylinder distributor to double check with what I am saying. Don't over do it but does the rotating part of the prongs seem like it is tight on the dist shaft?
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6 cylinder shaft - the notch on the shaft is in between the two rotating prongs.
[This message has been edited by phonedawgz (edited 06-16-2013).]
On mine, the way the notch on the shaft is pointing is the way the rotor is pointing - which is directly toward a prong, which is in between two spark plug wire posts.....
So prongs are not in the right spot? Are we thinking the prongs slipped or were moved in relation to the distributor body? Causing it to send spark when it was between posts? If I remember right from my spark plug test, it did seem as if it was sparking twice quickly. I will see if i can in any way turn the posts tomorrow evening.
Yeah I am really confused as to what might have happened. From the pics I see the static prong position is correct. So I am wondering if the rotating prongs could have slipped on the shaft? Barring that has anyone been messing with the distributor?
From the looks of it the 85-86 duke dist (I think) should have the notch right between the rotating prongs.
From the looks of it I think the 84 duke dist has the notch aligned with the prongs.
Can anyone out there with a 85 - 86 duke confirm this or otherwise prove it wrong?
Phonedawgz you were absolutely right. Upon further inspection of the distributor, the rotating points (the ones supposed to be attached to the shaft) were relatively loose. It was pretty obvious that it had slipped about a quarter turn on the shaft, thus causing the spark to come when the rotor was not pointing at a spark plug post.
So, I took out the distributor, cleaned up the shaft, tried to scuff it up a bit. Putting it in the vise and using the plain white wall next to my work bench, I used a long straight edge to mark on the wall where the spark plug post is located and then aligned the rotor to that same place. This showed me where the rotating points needed to be (and stay!). I then brazed the rotating points onto the shaft to hold them in place....hopefully for good!
I then put the distributor back in, following the procedures you told me with it pointing at 1 with everything lined up and the engine still at 10 bTDC.
It turns over now fine and starts, but misses very badly and cannot rev up. Well, at least we know the issue! Thanks for your help. I am looking into getting a new distributor, I am assuming my alignment for my brazing was off a bit, or the head destroyed something. I found a nice used distributor for $20 to be shipped to me.
Just an update.....finally got around to getting a re-manufactured distributor. Popped it in (took 10 minutes) and it fired right up as if the last 6 months never happened.
I just got back from driving a Fiero for the first time!! The shaft on the distributor rusted and the piece that is pressed on there rusted loose and rotated 45 degrees. I tried to solder and braze it back on in the right position, but it was still a bit off and was missing and backfiring. This new one (the picture you posted, acardone) looks a lot better. I appreciate the help on this. This Fiero just saw the street/highway for the first time in 12 years! Now on to the front suspension (ball joints). Thanks again!
