need help from the isuzugurus 2.6L (where'd everybody go?)

[caveman]

That is NOT a leaking injector. An leaking injector will run fine but idle low, then spudder and fall on it's face when you gas it. But will quickly even out after a couple of rev ups.

Yours however isn't running even at all. the rpms are all over the place. If it were me I'd warn it up fully then adjust everything to factory specs no matter how bad it ran. Seriously, start with the basics....idle speed first then ignition timming, then idle speed again.

I'm not sure on the 94's but the older 2.6's have a problem with the crank pulley slipping, even the new ones are off 3* BUT ITS VERY VERY VERY IMPORTANT TO THIS PATICULAR ENGINE THAT THE TIMING, IDLE SPEED IS DEAD ON. Well maybee + or - , 2 degrees or so. You can check yours for accuracy by either removing it and the front timming cover and checking it to the mark on the crank, OR remove the upper timming belt cover and lining up the #4 cylinder to the compression stroke and lining up the cam marks. Then look at the mark on the crank to see what its pointing at. Then make that your 0* TDC mark from now on. Then you'll be able to set or check your timming properly.

Your engine runs good I can tell, but something is just off, its normal to have a idle rpm bounce but nothing that bad.

After everything is verified and re-set, then spray around for a vacuum leak. Be sure to spray brake cleaner around the throttle body too. And post another video to demonstrate what changed.

Hope this helps.

[SSM200]

perfect. thanks a lot rollintroopers.

[SSM200]

alright. i got the idle adjusted. It bounces around from like 880 to 920 rpms. I found that my balancer is only about 3* off. When i originally timed my motor, i did it by ear on recommendation because of my aftermarket and performance mods. The timing mark was off in outer space (i'm talking like 30-40* BTDC). I figured the balancer had slipped, but unless it went all the way around since then, it didn't. When i go to adjust the timing, the motor doesn't care where the distributor is. I can go from one extreme to the other and the only thing that changes about how the motor runs is the idle speed. any idea what this is this all about?

i had my motor rebuilt about a year ago. after i pulled the motor, i found that the distributor gasket was stretched out and not sealing at all. i replaced the gasket before reinstalling the motor. Today, i found the gasket stretched out again and oil in the distributor. it hadn't sprayed or anything, it was just sitting there. The other rubber plug thing in the dizzy was in pretty bad shape. i think this is where the oil came from. also, the points on the cap were worn a bit and looked like there was arcing in there. Is that normal? What brand should i replace it with?

Once i get all that back together, i can proceed with getting everything to factory specs.

[caveman]

All right first things first, The interior dist. seal is leaking and not worth fixing unless you have a real delicate touch and can get the trigger wheel off without bending it. I did it once but swear I'll never do it again. The trigger wheel is RAZER sharp.

The outer seal will deteriorate unless you use a nitrile or teflon o-ring. I used an airconditioner o-ring on mine.

If your engine runs fine with the distributor at one extreme or another I may be that the distributor isn't sending the 360* "reference" signal. At least that was the issue when the harness went bad on mine. I could do the same exact thing with the timming until I figured it out. Now I could stall the engine if I adjust it all the way retarded. The ECM didn't give a check engine light either so I'm thinking that it was sending a signal just not a very strong signal. However, it did run very flat on the performance side, and had no upper rpm power or rev performance before I fixed it.

Did you set the timming by the use of a timming light? Just set your timming mark at 15* or so to make up for the 3* that the balancer is off. And re-set the idle speed to factory specs.

I just found a couple different distributors listed for the 94 amigo, and the isuzu parts house is showing a hall effect sensor for one of the two. Your's could either be unplugged or be bad (if it has one). They are cheap too.

Any way you can get a picture up of yours? Or even better call the dealer and give them your VIN# and ask if your amigo has the hall effect sensor. That would seriously give you problems that you are experiencing.

Or send Jlemond a PM and ask him what yours has.

[SSM200]

I don't have a pic of the distributor head on. i have a side view w/cap off and front view with cap on. when it's light tomorrow i'll snap a picture head on w/cap off. what should i be taking a picture of?

i used a timing light to time it, but didn't do much good at the time. When i put the motor back together, i had to pull the distributor out and turn it one tooth. maybe i ought to turn it back and try to get it closer to spec. I didn't bother adjusting timing because i found the bad seals. when you say you used an a/c o-ring do you mean for the cap to distributor? or the seal to the block- the o-ring that is like 1 1/4" diameter. The seal from the cap to distributor is bad and so is the weird shaped rubber plug thing on the lower part of the distributor.

I am definitely feeling the "flat on the performance side" thing too. Well like you said,i'll start with the basics and go from there.

I really appreciate all the help.

[squatch]

If you can turn the dist all the way one way and back without making much difference something is not right. That may explain the performance issue you've had since you installed the cam. I've always found the 2.6 to be pretty finicky about timing both cam and dist. Too much advance and it will ping like crazy. I've never had probs with a dizzy on mine so I can't help you much with the stuff Ben mentioned. That may also be telling you that something else is off somewhere that's got it running far enough off peak that the dist ignition timing just doesn't matter much. That leads me back to cam timing. I know we've beat that horse pretty hard. As for the caps I've found that OEM caps and plug wires work fine and last longer than any aftermarket I've tried over the years and I've used several kinds. As for plugs the 2.6 doesn't really seem to care about brand ect as long as you change them every 20k. I used to run single electrode Bosh platinums for years along with denso's and a few champions. All drove about the same. My 1st trooper spit out an NGK on a road trip that I had installed and torqued with a torque wrench. Only time that has happened to me in 35 years of driving. I never ran them again in my truck. Probably just a fluke but it was a major inconvenience.

What did your old plugs look like when you pulled them? Were they all the same? Have you done a compression test on the engine? How about doing that and posting up the numbers for us.

[Apeiron]

Apeiron-the other day, you suggested a problem in open-loop after warm restart. Could you go into a little more detail about what you know about this?

I don't know a lot about how Isuzu ECMs deal with it, but when the engine first starts, it can't trust all the data from its sensors yet. The O2 sensors and MAF need time to warm up, for example. Even if the sensor data was good, a cold engine needs a richer mixture than one at operating temperature, so data from a narrowband sensor would be useless anyway. The ECM runs in "open loop", esentially making a guess about what it needs based on the sensors it trusts, like the temperature and throttle sensors. Then when i sees "good" data coming in, like the O2 sensor crossing the stoich voltage, it decides it can trust the sensor data and goes into "closed loop", where it uses the feedback data to adjust the inputs to the engine.

If there was a problem with the "trusted" sensors, then it could be making an incorrect guess about the running state of the engine. As an example, if the temperature sensor read -40, then the ECM would think that it was in frigid conditions and could excessively enrich the mixture and greatly advance the timing. On a cold start, this might be acceptable for the engine to run until it warms up even though not ideal, but on a warm restart they could cause poor performance. Because there's no feedback data in open loop, the ECM can't really evaluate the validity of the sensor data, so as long as the data isn't completely absurd (the sensor is open or shorted), it won't set a code.

As soon as the rest of the sensor data starts to look good, the ECM goes into closed loop and the feedback data makes enough sense for it to keep the engine running properly despite the other sensor problem, and your problem magically disappears and stays away for as long as the engine keeps running.

I don't know exactly what sensor data the ECM uses in open loop, and what triggers its decision to go closed, though. Usually it's coolant temperature and oxygen sensor voltage. Some ECMs have more sophisticated checks than others though, so it make realize things like "I've been running for 10 minutes but my coolant temperature hasn't risen", but I don't see anything like that in the book. The only codes that I can see for the CTS for example are for open and short circuits, nothing that would detect and potentially incorrect value.

[SSM200]

i think i'm going to just use rtv silicone to replace the busted rubber plug (very carefully) and repair the stretched gasket. they are quite expensive for the seals and i am not going to just keep replacing them.

Apeiron- i have the HELM service manual and i can get all the information on which sensors are being read at what time. if you think it would help.

Squatch- once i get it all put back together i'll try to do the comp test. Last time i had the plugs out, they all looked the same. I'll get pics of the plugs later when i post up about the compression.

[SSM200]

replaced dist. rotor and cap. got it timed properly with no apparent performance change. I went from WAY off to dead on with timing and no noticeable difference. idle bounces from 880 to 920. replaced alternator w/napa gold. still have to check plugs and compression. Can't find my F-ing compression tester. No info on hall effect sensor. I would post another video, but it is exactly the same. No luck whatsoever.

Willy Wonka to SSM200- "YOU LOSE! YOU GET NOTHING! GOOD DAY SIR!"


Diagnostic fail

[SSM200]

[caveman]

I can't see your photo's on the work computer, but I feel bad you spent money on a Alt. I tried to stop that purchase. The more I read into this and watch the video, the more I believe you have a distributor problem.

One more question for you....does your engine sound real loud and vibrate at certain highway RPM's and quieter and more comfortable running at a lesser or higher speed/RPM?

[SSM200]

Not sure exactly how to answer the question. But yes. It really likes 4k and 2k. around 3k rpms it shakes a little/surges. It is just like the feel of the slack in the driveline, but at steady throttle position. It is most noticeable in 2nd, 3rd and 4th gear if i hold it steady around 3k. it shakes noticeably. I think i would notice it in 1st and 5th, but in 1st, i don't really hold a steady rpm and in 5th i don't think the surge is powerful enough to notice in high gear. i haven't driven much at all since everything is set to factory spec.

where did you find the info on the hall effect sensor? did any of those pictures tell you if i have one? I haven't heard back from JLEMOND yet. he's out of town till tomorrow.

I think the alternator fixed another intermittent problem i was having. i'll find out some day. and it has a lifetime warranty, so it's not all bad.

[caveman]

I'll report back on your photo's and distributor type when I get home in a hour or so. My work computer automatically cuts out all video and pictures but allows me to read text.

I don't feel so bad now about the alternator, some times it's better to have a piece of mind. Napa sells good parts.

EDIT....

Ok saw the pictures of the distributor. It looks the same as the earlier models just with a different connection. Heres what you need to do to test it. Just follow the value chart in the upper right corner of the page. It tells you what pin connector is what and what your ohm meter should read when you test the said terminal. Don't pay attention to the rest of the page, its a diagnostic for a total failure of the crank angle system. You don't have a total failure just a bad connection....well possibly.



Test the distributor right on the connection to get your base line. If the values match the values in my above manual then re-test the distributor with the wire harness connected (testing thru the wire harness).

Either way you'll know if the distributor or harness is bad or not and you can move on to the next step in finding your issue. Holla! Ben

[SSM200]

Edit: I found the test in my helm manual. The numbers for the pins are a little different from yours. It looks like they want you to test from the distributor connector to the ECM connector. That is a bit of a stretch for one guy. Need more like 3 lol. I'll check it to the engine connector and check the CKP sensor. If i don't find anything, i'll call a brother over and check from engine harness to ECM (if my meter reaches).

[SSM200]

We might be on to something.
Key off engine off, distributor and engine harness disconnected:
Harness side distributor connection to Engine room harness connector resistances look fine. They all read 0.6 ohms, but my tester isn't exactly top quality. There is no short circuit between the 4 distributor wires. this may be relevent in a minute.

Key on engine off, distributor and ecm disconnected:
Values for harness side distributor connector-
#1 (B) -continuity to ground=0.8 ohms
#2 (G.B.) - terminal #2 to ground=12.15volts
#3 (G.Y.) - terminal #3 to ground=0volts
#4 (B.W.) - terminal #4 to ground=0volts

Key on engine off, distributor only disconnected (voltage):
#1 (ground terminal)
#2 (Bat voltage)
#3 - (position)5.10volts This should read 2~3volts?
#4 - (reference)5.10volts This should read 1~3volts?

Is there somewhere i'm supposed to be testing on the distributor itself? I checked for voltage there w/key on and dist. disconnected (i know didn't make sense to me either) and there was nothing at any terminal (expected). I don't understand why position and reference would be high, or why they would be exactly the same. Unless there is some way i'm supposed to be testing the distributor connected.

Checked Distributor for resistance between terminals.
1-2: open
1-3: open
1-4: open
2-3: open
2-4: open
3-4: 5.12k ohms

[caveman]

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!

[SSM200]

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

[caveman]

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.

[SSM200]

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.

[squatch]

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.

[caveman]

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.

[SSM200]

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

[SSM200]

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.

[caveman]

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.

[SSM200]

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?