Timing mark moves

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Timing mark moves

Postby flatwater » Sun Jan 08, 2017 12:00 am

I am still struggling with this trooper. I have swapped out the I-Tec for a Weber carb. I started out with a junk yard distributor when I performed the swap but could not get it to run great. it would seem to idle fine but run terrible under load. While setting the timing, the mark would be steady at about 10 btdc and then would disappear. today I installed a brand new dizzy and got it running. It seemed to idle fine until I got it warmed up. then it would have an occasional very small stumble every 10 seconds or so. It was not anything major but as I was trying to set the ignition timing, the mark would do the same thing. I put the timing light on it and it would seem to hold steady and then disappear for a couple of seconds. I found it clear over at about 2 o'clock (pointed towards the exhaust manifold.} then it would return to 8-10 btdc.

what could be causing it to do this? I have never had so many weird things go on trying to get one vehicle running.

thanks in advance for the help.
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Re: Timing mark moves

Postby Ed Mc. » Sun Jan 08, 2017 1:30 am

The 2.6 has a known problem with the harmonic damper slipping. The outer ring is rubber-bushed to the middle, and when this bond breaks, the outer ring will "walk" all over. Thus making it difficult if impossible to get a good reading on spark advance.

So you might want to check that out. Otherwise a possibility the timing light is failing. You could check it on another vehicle.

New balancers are not cheap, $120 on Rockauto.com:

http://www.rockauto.com/en/catalog/isuz ... ancer,5512

Cheaper than eBay, they're running over $150!

MSRP of $147.47 at this Isuzu parts site:

https://www.isuzupartscenter.com/parts/ ... eid=216496

You could also check with Jerry Lemond, he may have a deal on a good used part and likely could source new OEM as well. " JLEMOND " on this forum.

HTH............ed
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Re: Timing mark moves

Postby flatwater » Sun Jan 08, 2017 1:33 am

thanks for the reply.

I dont think that it is the harmonic damper slipping, While I am checking the timing the mark will move for a couple seconds and then return to normal for several seconds before it does it again. The engine also seems to run a little rough when it does it.
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Re: Timing mark moves

Postby Ed Mc. » Sun Jan 08, 2017 2:34 am

Ok, so it sounds like maybe it's the ECM moving timing around. Spark advance on the ITEC engine is electronically controlled by the ECM, with inputs from various sensors & switches.

There are a few things to bypass/disable before checking timing. See the attached printout from the manual. Make sure the throttle switch is closed when the throttle is closed, that'll probably mess it up for sure.

For troubleshooting you could disconnect the sensors that the engine could run without, such as the coolant temp sensor. This may allow you to pinpoint the problem. Other sensors which affect the ECM timing advance are the vehicle speed sensor, and airflow sensor.

You may have to check wiring from these sensors to the ECM, as grounds and shorts can cause a lot of spurious issues. Or it could even be the ECM itself, but good to rule out all the external items first.

Also attached is an engine controls diagram for '88-89 Trooper, hope that helps.
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Re: Timing mark moves

Postby itsmehb » Sun Jan 08, 2017 6:25 am

When you did the conversion, what distributer did you use? The ecm on a conversion is out of the picture. The proper distributer is a vacuum advance one from a 2.3 engine. The ecm will no longer send any signals to either the injectors (carb.) or the distributer. When the vacuum line is hooked up properly to the distributer it should be hooked to the port on the carb, and should be disconnected for timing. With the vacuum advance disconnected, and not changing the engine speed, I don't see how the advance could be working. It almost sounds like there's some issue with the signal to the timing light intermittently coming from another source, like the cap on the distributer is cracked or messed up, or your plug wires are bad.
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Re: Timing mark moves

Postby DSUZU » Sun Jan 08, 2017 8:14 am

I agree with Harry. Are you using a vacuum advance distributor? If not, the ECM is looking for inputs and not finding them so it is not adjusting timing properly. Dennis
1991 LS Trooper 2.8 V6 5 speed conversion (Sold)
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Re: Timing mark moves

Postby flatwater » Sun Jan 08, 2017 10:56 am

I am using the Distributor for the 2.3 with vacuum advance. THe timing mark moves with the vacuum line disconnected or connected. It has to be something weird going on, I dont see how the engine could continue to rune if the timing actually moved as far as the light seems to indicate that it is moving. perhaps the clamp that goes around the #1 plug wire is picking up the signal from the #2 wire intermittently. :scratch:
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Re: Timing mark moves

Postby itsmehb » Sun Jan 08, 2017 11:26 am

I found it clear over at about 2 o'clock (pointed towards the exhaust manifold.} then it would return to 8-10 btdc.

Moving in that direction is hard to figure. That's not moving toward an advanced position typical of what a centrifical or vacuum advance would move it. It's moving toward a position past TDC.

Did you make 3 block off plates to seal your intake when you installed it. Just wondering if you have some kind of vacuum leak. Just saying, when your at idle with the timing light hooked up, the vacuum advance disconnected and plugged and not changing rpm, there should be no reason for the timing to move in either direction. The fact that it's running crappy would indicate somethings not right. I know with mine, there is a slight pause or hesitation when the carb is transitioning from single to both barrels.

itsmehb » Tue Sep 27, 2016 6:37 pm




itsmehb wrote:
Thanks guys, too early to crow about the conversion. I need to wait till I can get it dialed in better than it is. I haven't checked the timing yet. It idles finally below 1000 rpm. Something the itec would never do. And the installation eliminates lots of maint. headaches with hard to access parts on the itec. But it doesn't run any better than the itec did. Right now it's still out at the hanger where I can keep it inside. I have 1000 invested in new tires and restored wheels and have no room in the garage now. Too tempting for someone with low morals who wants to visit midnight auto parts for there needs.

Well today, got the timing dialed in. I hadn't checked it and since I had replaced the head and did the weber conversion and it was off quite a bit. It was actually on the right side of the TDC mark when I first checked it No wonder it didn't run very well. Got it set around 10 before tdc and it runs real well and starts easily. After putting up with idle problems ever since I got it, I now have a nice idle speed around 900 rpm. And I'm glad I got the manual choke version.as the more control I have over everything the better. I installed the fuel filter between the tank and the carter pump. That's the only way they'll provide a warranty for the pump. I'll be checking the plugs after I run it a bit to see how the jets are performing. I'm running it without a regulator as suggested by redline, when using the carter 4070 pump. We'll see how it does once I take it for a long ride.Attachments

Thought I'd throw in mine when I got it running. It at first was timed to after TDC, but when I set it to 10 it really fixed everything.
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Re: Timing mark moves

Postby flatwater » Sun Jan 08, 2017 12:36 pm

I did make the block off plates and I have capped every vacuum port that I know of. I will attempt to take a video this afternoon and post it.

thanks for the input guys.
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Re: Timing mark moves

Postby DSUZU » Sun Jan 08, 2017 1:05 pm

Absolutely sure your balancer isn't slipping? Dennis
EDIT: Just re-read post. WHOLE new dizzy? What about cap, rotor and wires? If cap is "tracking" or cracked, it may be feeding a different terminal occasionally. Same with the rotor or wires. I agree that a slipping balancer would most likely not return to the same place. (clip on cap or the 3 screw cap - which I hate?) D.
1991 LS Trooper 2.8 V6 5 speed conversion (Sold)
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Re: Timing mark moves

Postby flatwater » Sun Jan 08, 2017 1:14 pm

It is a clip on cap. I have tried two sets of wires two caps and two rotors. I am beginning to think that this trooper hates me.
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Re: Timing mark moves

Postby kg4miq » Sun Jan 08, 2017 7:33 pm

Where do you have the vacuum connected to the carburetor for the advance on the distributor? Can you post a picture?

Forget about the harmonic balancer for a bit. Your engine will run perfectly fine, even if it has slipped (unless it is wobbling or is constantly slipping, in which case, it needs to be replaced). Line up the timing marks on the cam gear and the crankshaft, then line up the rotor button to the hold-down nut on the distributor backing plate. That will get you to within five degrees either way of TDC. It should crank and run, but you'll have to adjust from there to get it dialed in. Doesn't really matter where the timing mark on the harmonic balancer is, if you don't have everything else lined up.

The vacuum advance should be connected to a ported vacuum, i.e. one which doesn't have vacuum on it all the time, only when the throttle is cracked open a bit. I'll have to look for a picture of where to connect it on the Weber base, but I believe it's the lower side port on the passenger side, as the carb is mounted.

EDIT: Found it:

DGV-connections-1.jpg
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How to rebuild a 2.6L 4ZE1 distributor

'89 S Trooper - "Kal-El" - 4ZE1
'88 LS Trooper - "Delta" - 4ZE1
'92 Pickup - "Blacktail" - 4ZE1
'89 S Trooper - "Red Leader" - 4ZE1
'89 SE Trooper - "Vader" - 4ZE1
'90 Trooper - "Leia" - 4JG2T swap on hold
'89 Pickup - "Wicket" - 4ZD1
'90 S Trooper - "Nan" - 4ZE1 (possible V8 swap - Ford 302 with 5 speed?)
'94 S Amigo - "Artoo" - 4ZE1, SOLD
'92 XS Rodeo - "Jabba", LH0, 3.1L V6
'89 S Trooper - "Chewie" - 4ZE1, TRADED
'89 XS Trooper - "Red" - 4ZE1, SOLD, bought it back
'89 LS Trooper - "Obi-Wan" - LH0, 3.1L V6
'88 S Trooper - "Stormtrooper" - 4ZE1, SOLD
'91 S Trooper - "Ghost" - L32, 3.4L V6, SOLD
'89 S Trooper - "Angry Bird" - 4ZE1, SOLD
'89 S Trooper - "Phantom" - 4ZE1, salvaged
'90 Pickup - "Uno" - 4ZD1, SOLD
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Re: Timing mark moves

Postby flatwater » Sun Jan 08, 2017 8:32 pm

I ended up in Olympia this afternoon with my wife. I haven't had a chance to do anything except look out the window at the trooper sitting in the driveway this morning.

When I put the motor back together I put #1 & #4 at tdc and then marked the harmonic balancer at 0° I lined up the mark on the cam when I put the new timing belt on that part has been checked and double checked. I am positive that the vacuum advance is hooked up to the ported vacuum port on the base of the carb. The dang thing will run great for a while and I will have it timed at 10° btdc and then it will have an occasional hiccup. And the timing mark will move. I don't understand how it can run fine for a few minutes and then all of a sudden it changes. I have replaced everything except the engine block and the head.
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Re: Timing mark moves

Postby flatwater » Sun Jan 08, 2017 8:34 pm

Itsmehb. I did make the block off plates.
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Re: Timing mark moves

Postby totten » Sun Jan 08, 2017 9:30 pm

I'm going to make a guess= Maybe the cam gear bolts are loose changing the timing.Does that make sense?
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Re: Timing mark moves

Postby DSUZU » Mon Jan 09, 2017 8:17 am

Just to be sure, you are setting the timing with the vacuum advance unplugged and hose capped right? Dennis
1991 LS Trooper 2.8 V6 5 speed conversion (Sold)
1989 LS Spacecab 2.6 5 speed 4x4 manual hubs, Rodeo torsion bars, extended shackles, 2" lift, K&N airfilter (drop in), dump bed conversion, burgundy interior change, warn brush bar.
Previously owned: 1987 Trooper II LS, 1989 Trooper (parts only), 1994 Trooper 3.2 Auto, 1997 Rodeo 2.6 5 speed, 1993 shortbed pickup 2.3 (project - sold) 1992 Rodeo 4x4 LS (parts car, devoured by Spacecab needs) plus some 70 plus other non Isuzu vehicles over the years.

http://forum.planetisuzoo.com/viewtopic.php?f=15&t=64060

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Re: Timing mark moves

Postby flatwater » Mon Jan 09, 2017 11:09 pm

OK. Here is a link to a video of the timing mark this afternoon. I swapped distributor caps right after making this video and it did the same thing.

If anyone has any good ideas feel free to give me a call.
931-809-0855

https://youtu.be/27gLgT-R_3A
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Re: Timing mark moves

Postby kg4miq » Mon Jan 09, 2017 11:29 pm

After watching the video, and seeing how steady it is on #4, but seeing the skipping on #1, I'm with itsmehb and think it's either a bad wire, or a bad plug. I've seen new ones bad, or have faulty conductors, straight from the box. I've quit using anything but NGK plugs and wire sets on four cylinder engines now. If you run it in the dark, with no lights on, and let your eyes adjust, can you see any stray sparking from the distributor or the wires?

From the video, it appears your coil wires have been spliced at some point. Are those connections good? I've not tried using the newer style coil with the carb conversion. I've only stuck with the older coil, but don't see any reason why it shouldn't work. I've watched with the sound off, and it's obvious you are losing sparks on the #1 cylinder. There aren't that many components in the spark chain, and you've replaced almost all of them (if not all). So, that leads me to believe one of the new components is having difficulty.

EDIT: One more question, are you using the standard NGK plugs, and not the platinum-tipped ones? Standard work better in these engines.
Last edited by kg4miq on Wed Jan 11, 2017 11:12 am, edited 1 time in total.
How to rebuild a 2.6L 4ZE1 distributor

'89 S Trooper - "Kal-El" - 4ZE1
'88 LS Trooper - "Delta" - 4ZE1
'92 Pickup - "Blacktail" - 4ZE1
'89 S Trooper - "Red Leader" - 4ZE1
'89 SE Trooper - "Vader" - 4ZE1
'90 Trooper - "Leia" - 4JG2T swap on hold
'89 Pickup - "Wicket" - 4ZD1
'90 S Trooper - "Nan" - 4ZE1 (possible V8 swap - Ford 302 with 5 speed?)
'94 S Amigo - "Artoo" - 4ZE1, SOLD
'92 XS Rodeo - "Jabba", LH0, 3.1L V6
'89 S Trooper - "Chewie" - 4ZE1, TRADED
'89 XS Trooper - "Red" - 4ZE1, SOLD, bought it back
'89 LS Trooper - "Obi-Wan" - LH0, 3.1L V6
'88 S Trooper - "Stormtrooper" - 4ZE1, SOLD
'91 S Trooper - "Ghost" - L32, 3.4L V6, SOLD
'89 S Trooper - "Angry Bird" - 4ZE1, SOLD
'89 S Trooper - "Phantom" - 4ZE1, salvaged
'90 Pickup - "Uno" - 4ZD1, SOLD
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Re: Timing mark moves

Postby DSUZU » Tue Jan 10, 2017 9:32 am

I'd start with swapping #1 and #4 plug wires and see if mark stays consistent on 1 with wire swapped = bad wire. If that didn't work, look at the plugs. I have seen "spark blowout", but that is usually at higher RPMs. Through my own experimenting, I got a stronger spark with standard plugs. Did the test using a weedeater engine (magneto) and different types of plugs. Resistor type plugs definitely had a weaker spark.
A "lean misfire" (if there were a vacuum leak @ #1 intake) wouldn't affect the spark plug firing, it would still be jumping a spark. Dennis
1991 LS Trooper 2.8 V6 5 speed conversion (Sold)
1989 LS Spacecab 2.6 5 speed 4x4 manual hubs, Rodeo torsion bars, extended shackles, 2" lift, K&N airfilter (drop in), dump bed conversion, burgundy interior change, warn brush bar.
Previously owned: 1987 Trooper II LS, 1989 Trooper (parts only), 1994 Trooper 3.2 Auto, 1997 Rodeo 2.6 5 speed, 1993 shortbed pickup 2.3 (project - sold) 1992 Rodeo 4x4 LS (parts car, devoured by Spacecab needs) plus some 70 plus other non Isuzu vehicles over the years.

http://forum.planetisuzoo.com/viewtopic.php?f=15&t=64060

The American dream is getting farther and farther away from the American.

If your wife has 5.00, and you have 20.00, your wife has...25.00

"Water is one of the greatest essentials of life. Without water, you can't make coffee."
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Re: Timing mark moves

Postby kg4miq » Tue Jan 10, 2017 10:13 am

Dennis,
I don't know about the set he's using, but with the NGK wires, #1 and #4 won't interchange because they're physically different enough in length to prevent #4 from being used on #1.
How to rebuild a 2.6L 4ZE1 distributor

'89 S Trooper - "Kal-El" - 4ZE1
'88 LS Trooper - "Delta" - 4ZE1
'92 Pickup - "Blacktail" - 4ZE1
'89 S Trooper - "Red Leader" - 4ZE1
'89 SE Trooper - "Vader" - 4ZE1
'90 Trooper - "Leia" - 4JG2T swap on hold
'89 Pickup - "Wicket" - 4ZD1
'90 S Trooper - "Nan" - 4ZE1 (possible V8 swap - Ford 302 with 5 speed?)
'94 S Amigo - "Artoo" - 4ZE1, SOLD
'92 XS Rodeo - "Jabba", LH0, 3.1L V6
'89 S Trooper - "Chewie" - 4ZE1, TRADED
'89 XS Trooper - "Red" - 4ZE1, SOLD, bought it back
'89 LS Trooper - "Obi-Wan" - LH0, 3.1L V6
'88 S Trooper - "Stormtrooper" - 4ZE1, SOLD
'91 S Trooper - "Ghost" - L32, 3.4L V6, SOLD
'89 S Trooper - "Angry Bird" - 4ZE1, SOLD
'89 S Trooper - "Phantom" - 4ZE1, salvaged
'90 Pickup - "Uno" - 4ZD1, SOLD
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Re: Timing mark moves

Postby flatwater » Tue Jan 10, 2017 4:39 pm

Yeah. With the set I am using the #4 wire won't reach the #1 plug.

At idle right now the timing mark does it's weirdness on #3 & #1. On #2 & #4 it is steady so when I get home I will try switching the wires on 1&2.

To add to all of this, I noticed by accident as I reached across the top of the carb and inadvertently closed the choke with my forearm and as the idle increased the timing mark stayed steady. Don't know if that tells you anything or not.
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Re: Timing mark moves

Postby Ed Mc. » Tue Jan 10, 2017 5:12 pm

On your vacuum-advance distributor, there's a mechanical advance as well. If it isn't operating smoothly, it's gonna cause erratic spark timing problems.

Sometimes the mechanical advance has issues; binding, shot springs, etc. So maybe check that out.
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Re: Timing mark moves

Postby flatwater » Tue Jan 10, 2017 8:01 pm

I thought the same thing Ed before I changed the distributor. The timing was doing the same thing with the old distributor that I picked up from the junk yard along with the intake. I thought perhaps there was something funky going on with the mechanical advance so I took it apart to clean it and there was rust and gunk in it so I just ordered a new distributor. I know that having a new distributor does not guarantee that it is perfect but I think the chances of it doing the same thing with both distributors is slim.
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Re: Timing mark moves

Postby itsmehb » Tue Jan 10, 2017 11:56 pm

flatwater wrote:Yeah. With the set I am using the #4 wire won't reach the #1 plug.

At idle right now the timing mark does it's weirdness on #3 & #1. On #2 & #4 it is steady so when I get home I will try switching the wires on 1&2.

To add to all of this, I noticed by accident as I reached across the top of the carb and inadvertently closed the choke with my forearm and as the idle increased the timing mark stayed steady. Don't know if that tells you anything or not.


Really is turning into an interesting , but perplexing problem. We want to try to help you solve this so you can enjoy your Isuzu. I thought of this today as I was out driving mine, (I have the weber conversion) and really enjoying it. Yes your right, assuming that it can't possibly be a distributer problem as you've tried 2 of them. We're racking our brains, trying to figure what's going on. It sure sounds like cross firing happening with the ignition system. Probably when you inadvertently changed the rpm by closing the choke slightly and noticing no change in the timing mark, it's probably because it wasn't enough to cause the centrifical (mechanical) advance to advance your timing. The early ignition systems relay on both vacuum and mechanical advance to change the timing so the full force of the explosions occurs at TDC. This is probably not always going to happen as lean and rich mixtures burn at different speeds and rpm also increases piston speed so TDC occurs quicker. All this being said, the timing mark should hold steady when timing the engine and not change unless engine speed (mechanical advance) is changed. As a side note, what fuel pump are you using with your conversion and are you using a fuel pressure regulator? Also another side note on ported vs not ported vacuum signal for the distributer. As I understand it, the reason ported vacuum is used is so no advance of the timing occurs at idle. This works in conjunction with emissions systems so there is a hotter exhaust (burning hydrocarbons) at idle. Once the throttle is opened it doesn't really matter where the signal comes from (ported or not ported) as the vacuum advance will operate as scheduled. Anyway, no matter where your vacuum source is, you must disconnect it for timing, as you already know. I know this is long, but really trying to think what could be going on as I'm typing, and can't come up with anything.
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Re: Timing mark moves

Postby kg4miq » Wed Jan 11, 2017 11:02 am

flatwater wrote:Yeah. With the set I am using the #4 wire won't reach the #1 plug.

At idle right now the timing mark does it's weirdness on #3 & #1. On #2 & #4 it is steady so when I get home I will try switching the wires on 1&2.

To add to all of this, I noticed by accident as I reached across the top of the carb and inadvertently closed the choke with my forearm and as the idle increased the timing mark stayed steady. Don't know if that tells you anything or not.


If you closed the choke far enough, the engine should have died, but if it's running lean, and the choke closed slightly, this may have provided enough fuel to smooth out the idle.

Two things come to mind:
A) The linkages of the choke have a slight cam action when closed which raises idle speed slightly, which could smooth out the spark in the distributor and overcome a slightly higher impedance in a plug wire or somewhere up the chain in the spark system (still symptomatic of a wire or spark plug which has higher resistance from the factory).
B) The behavior you described could indicate a lean fuel condition in the carburetor at idle. To fix this, the idle mixture screw on the carb needs to be adjusted slightly. Turn it counterclockwise to open it 1/4 turn and see if it changes things better or worse. This is not related to the spark condition, but fits the description of behavior you gave above.

You can get it dialed in by adjusting the idle screw either direction until the engine noticeably stumbles (either rich or lean), then re-centering the screw in-between the two extremes.

On another related note, have you put a vacuum gauge on the engine to visually diagnose what's going on? A good, steady needle around 20 inches of vacuum is what you want.

When switching the plug wires, if the problem stays where it is (#1, #3), the plugs need to be checked to verify the gap is correct. If the problem moves to #2 and #4, then the plug wires are suspect. Also, I don't recall seeing if you said you were using standard plugs or platinum, or something else altogether.

Keep feeding us information, and we'll keep trying to help.

/tim
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