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I would need to see a photo of your manual before I can help you decifer the numbers.

The volts being high at the distributor connection with the ecm connected would mean a bad ECM. Or should. Can you get a copy of YOUR manual up here?

One more test should include testing the ohms at the distributor terminals like you did AND also THRU the harness. That way you can rule out a faulty or dirty connection fouling up the signal.

Good job on the testing, sounds like your close to getting your baby purring like a kitten! :thumbright:
 

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Discussion Starter · #42 ·
I sure hope you're right. The values are the same, just the connector #s and pin #s are different. same diagrams too lol. what manual do you have?


So i should hook the distributor back up and test at the engine harness again but this time for resistance of the CKP sensor, right? Does 5.12k ohms seem ok? and i should get about the same through the harness.

also, i was testing the right spot for voltage that read too high? I read about some tests that tested while the motor was cranking. Impossible for one person. Of course, that was for a crank pos sensor that was not part of the distributor.

Thanks Ben
 

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My diagram came from an old chiltons manual. As for the cranking while testing, I don't think that would be nessisary, because we already know that there's a problem with the distributor or the ECM. Have you called the dealer to see if that model uses a hall effect generator? I don't think it does but you really need to know.

I wouldn't worry about the high voltage right now (so far anyway) I'm going to go with the hunch that the check engine light will come on for a ECM high voltage problem but I have been wrong before about that useless light.
The ohms are what concerns me right at the moment. They should be 0 and one pole should make your meter go crazy or display the infinent symbol. Give me a minute for my wife to get home and watch the kids so I can go out to the garage and test one of my spares that I know works right. I may not be able to tell you what poles did what but at least I can give you ACTUAL numbers off a working model.
 

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Discussion Starter · #44 ·
that would be so awesome. I hope there comes a time when i can repay you for your guidance. Jerry hasn't gotten back to me yet about the hall effect sensor. I'll call Isuzu tomorrow.
 

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Ben may be on to something. Your rpm description sound like sticky advance weights in an old school dizzy. I'm not real up on how these advance because I've never had to deal with it. The surging idle is pretty normal on these motors. Especially with your cam. That's a pretty hot cam and I would suspect probably doesn't kick into the power band until around 3-3.5k. The time I heard your engine running on the phone it sounded like a little cam lope at idle. Probably is with that cam.
 

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Alright, since your .5 ohm values are all consistant on three of the poles I'm assuming that your meter either didn't have a good enough ground or isn't calibrated right.

All your numbers match mine on two of my working spares. So I think yours is ok. Until we know for sure if your amigo uses a hall effect gen. lets get back to the mechanical parts on your engine. Starting with the timming,

Are you serious about getting through this no matter how many "free" dead end test you do?

If so start with the cam timming, verify its correct then set the distributor gear so that the raised mark on the dist. housing alignes with the hole on the gear. Then set the adjusting plate (where you tighten the set nut when you adjust the timming) so that the indented slot lines up with the raised arrow looking thing on the dist. housing. This technique sets the distributor to "top dead center" for the #4 cylinder. Set your engine to the TDC mark on the balancer (+3* because your balancer is off) with the #4 piston on the COMPRESSION stroke. Now very carefully install the distributor assembly without disturbing the marks. You can tighten the adjusting nut to hold that one BUT keep the rotor on that mark until it hits the cam gear. Now verify that the rotor is pointing to the 5 0'clock position. Better yet because your distributor is different then mine, look at the dist. cap to see where your #4 spark plug wire post is. Because you set your distributor to TDC using the marks, Make sure the rotor is pointing exactly to the #4 post no matter where it is.

This will give you a base line, since the 2.6 will run fairly well with the dist. set one tooth advanced or 1 tooth retarded, its very important to get the gear set at TDC for #4 cyl BEFORE you time the engine. Remember...the crank angle sensor is IN the distributor. So where ever you set the shaft, is where the ECM calls TDC even if you adjust the timming to 12*. You get what I'm saying?

Try the above and get back to me. Hey it's time consuming but very free. I'll keep my fingers crossed for an improvement.
 

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Discussion Starter · #47 ·
Ok. I am pretty serious. i have like twenty something hours into this problem most would just deal with. In a way, it's good i'm not working. Free is my cup of tea. Here are a couple pics of the motor right before i dropped it to verify cam timing.



When i pulled the distributor to take pics for this thread, I did most of what you are saying. The rotor pointed to the #4 post on the cap. I retarded the distributor one tooth to compensate for my 30* BTDC reading to restore factory specs.
Here is what i did when i prepped my motor to reinstall. I marked the distributor cap for the #4 post. transferred mark to distributor. removed cap. installed distributor into the motor so the rotor points exactly to the mark i transferred to the distributor. Pictured below is a pen pointing to the mark on the distributor and the rotor pointing to it. so you know what i'm saying.

Then I line up the raised line on the distributor housing with the mounting plate notch. this gives TDC for compression stroke #4 and timing set to 0* BTDC or TDC.

Tomorrow i'll pull the distributor again and follow all these steps. I sure hope this ends soon. When my truck ain't right, i ain't right.

Thanks
 

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Discussion Starter · #48 ·
Resistance throught the harness is the same-5.12k ohms. I set the meter for the next range and numbers 1 and 4 read out at 1.161M ohms. others still open.

I called isuzu and they have no part number for a hall effect sensor for my distributor. If it is a part that is sold separately, then i don't have one. Check out these isuzu prices:
Distributor assembly:$832.47
Ecm: $2175.97
E gad!

Pick n pull has the dizzy for 37.98, ecm for 33.98

update:The manual said that when installing the distributor, you should pull the valve cover and there is a mark on the head that is supposed to line up with the hole on the distributor at TDC cyl 4 comp stroke. That checked out good, so i left the distributor alone. I adjusted valves while i was in there. Still have valve tap for whatever reason. or at least that is what it sounds like. The junk yard didn't have a distributor or ecm, so i'm out of luck for swapping out. The truck drives a lot different since i have adjusted so much stuff. it's better at times and worse at other times. It has weak spots in the rev range. but i'm leaving everything as it is until i figure out what is wrong. I'm pretty close to losing hope. The wife is sick of me spend time and money on this truck. It sucks.
 

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I think we can rule out the distributer for now. Whats confusing me is the subtle differences in the ignition system between yours and mine. I'm trying to be careful not to lead you in any false directions.

Get me in the right direction here if you will. Is your #4 cylinder post in the 11 o'clock position? I think mine is in the 5 o'clock position. Is it possible that yours is 180*'s off or are our distributors really that different?

Don't give up, I really think I can help you find the ONE part that is faulty.
 

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Discussion Starter · #50 ·


that should clarify. Don't worry, i check what i can in my manual. It is pretty good, but no diagnostic direction. That's where you come in. It seems that without a trouble code, the troubleshooting in the manual is worthless. It doesn't give any check for the distributor. Basically, if you get the code, you check the wiring. if the wiring is ok you need to replace the distributor. That doesn't really work for me. Jeremy worden pm'd me saying he had a similar problem and he changed the distributor and all was good. you know, after 6 months and $1500. It is definitely good to go over the truck like i have. I think that when i do figure it out, it will be in top running condition.
The symptoms are changing a bit. Last time i started it, i opened the throttle a bit like i must do, and instead of bogging down and bouncing around all over the place, it smoothly bounced from 1000 to 2000 rpms with a sort of rhythm. Sometimes it recovers quickly. sometimes it takes a minute with the throttle cracked.

What if it was 180* off? what would that be like?
 

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Discussion Starter · #51 ·
What i've tried:

Replaced alternator
Tested MAP sensor
Cleaned throttle body
Adjusted valves
Checked cam/crank timing
Reset timing to spec
Reset idle to spec
Checked all vacuum lines
Cleaned EGR
No trouble codes stored
Tested wiring and connections to distributor
Tested crankshaft position sensor
Replaced dist. cap and rotor
Checked spark plugs
Replaced connectors at gas tank
It isn't a leaky injector
It isn't a faulty Fuel pressure regulator
Air regulator is new

Don't know how to eliminate the distributor or ECM as a possibility without swapping a known good one.

WTF
 

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ok, besides the condition of the dizzy, i doubt its that. you put in the new O2 sensor and just didnt swap screws to put out the light?

next, did you try spraying carb cleaner around the intake manifold?

anyone, is it possible the air regulator under the intake is sticking???

i got parts lined up for you to try....from running vehicles (94 and 95 model year).
 

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Discussion Starter · #53 ·
The air regulator is OEM and a year or so old. I konw that doesn't rule it out, though. I sprayed MAF cleaner all over every vacuum connection and intake manifold, throttle body, intake ducts. Only found one leak, but it didn't change anything.

Correct on the O2 sensor. It probably has about 30k on it. I didn't mess with the light because i didn't feel like taking the dash apart. that, and i changed the O2 sensor at like 175k and real quick afterward the light came on. I actually replaced it again, IIRC. then i found the forum...
 

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how about the coolant sensor? the truck is acting like a switch is thrown, as if the grounding connection is all of a sudden ON...and the ecm is getting proper parameters for air fuel mixture (why i suggested the air regulator).
im more then willing to send the parts out on consignment :p once you swap parts and get the proper results, just return what you dont need or keep it all for spares and pay me for what you keep....ill look for coolant switch and other parts....what about the thermal valve on the t stat housing? the light blue vacuum switch part????? maybe thats defective....i HATE guessing at others expense...
 

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Very nice of you to go that far to help another Zoo member, Ron.

+10 for Good Samaritan award. :thumbup:
 

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Discussion Starter · #56 ·


Coolant temp sensor is fairly new. i think it was only like $10 and i could replace it if you think i should.

....i HATE guessing at others expense...
i know how you feel. don't sweat it, i wont hold it against you :wink:
what does the thermal valve do? i thought it just controlled the coolant going into the heater core.

+10 for Good Samaritan award.
X2 :)
 

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No, that is a thermo valve that controls the fast idle when and only when the engine over heats. If it fails it WILL rev the engine up, or if it is only leaking it will rev the enigine. Try pinching the hose that comes off the right side of it (that goes to the black intake runner) If your idle or performance changes then look into corrective action.

Ron, you are a great example of an american! My hats off to you sir.

Try this next, Get out the timming light and shoot it at the balancer. While your looking at the timming mark flashing at 15* reach over and crack the throttle, don't rev it high just crack it little by little and watch the timming mark.

Here's why....You can check your throttle position sensor by the long complicated method or you can do it the easy way by following the above instructions....YOUR TIMMING MARK SHOULD JUMP TO THE ADVANCED POSITION AS SOON AS THE THROTTLE IS CRACKED. I MEAN AS SOON AS ITS CRACKED. IF IT DOESN'T THEN YOU WILL EXPERIENCE HESSITATION AND SHUTTERS WHEN YOU TRY TO TAKE OFF. If it doesn't advance then the tps will need a slight adjustment.

BEN
 

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Discussion Starter · #58 ·
TPS was a tiny tiny bit off. That is good now. timing advances with any action in the throttle position. No effect on motor when i pinch, disconnect and plug the vacuum to the thermal valve. Should i have it pinched while driving?

While i was in there with the timing light, i got to experimenting. I put the light on each one of the plug wires to monitor spark. They all seemed a little erratic. I kinda attributed this to the hot cam i have in there. Then i put the light on the high tension lead coming from the coil. It too was quite sporatic and definitely misses probably long enough for the spark to be missing for an entire revolution. Should i be looking at the coil?
 

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well that COULD be the ignitor or a weak coil....coils are easy to upgrade, the stock one is about 20k volts at best, you can get Accel aftermarket can type that put out 50k....or a realllllllllly cool set up is the Jacobs Ignition. i had one on a 2.3L and it was AMAZING....idled perfectly, had super low emissions and got 25mpg. the power was amazing too, it woke the truck up. eventually im going to do that to my 2.6L 4x4.....when money allows. let me know what you want to do, what parts i should include, it will be inexpensive overall for everything if you want spares for the vehicle. im using a flat rate USPS medium box 11.00 IF i can fit it, worst case large is 14.00 and i can put MORE in there :)
guys, ive been out of the loop abit on the Isuzus, about 6 months, so anyone give us ideas on parts i can send to change and fix this issue. one thing to check is the PLUG on the harness on the distributor. ive heard people had the harness damaged from rubbing the firewall causing intermediate miss fires and no run conditions spuratically....
Ron

if anyone has ideas or needs to call me, 201-983-3176

its my business cell but its MY personal phone as well :)
 

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Discussion Starter · #60 ·
I checked the distributor harness and connector for excessive resistance and short circuits, but everything checked out ok. I'm going to go get an accel or MSD ignition coil. I can use the can type?
 
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