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Unread 04-14-2013, 05:48 PM   #16
4Hamsters
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I'm thinking you're right, I may have some issues with carb settings around the fuel delivery. I'm pretty ignorant about the inner-workings of the carb specifically. When the new Jasper went in, my friend rebuilt the BBD as well. I cannot recall if that consisted of a thorough cleaning and new gaskets, o-rings, etc. or the whole work up with new bushing, accelerator pump, and all those pieces. I did recently put a new fuel line and filter on, the one coming the fuel pump, over the valve cover and to the BBD.

When I tightened the line going into the brass connector I probably messed with all of those measurements on the float.

Would that sort of thing be what you're referring to 86cj74.2L?

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Unread 04-14-2013, 06:11 PM   #17
86cj74.2L
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If you have a lot of up and down play on the throttle shaft it may be time for bushings. It seems that somewhere above 1/32 inch play.

Easy way to tell if the throttle shaft bushings are worn is to open the throttle slowly and watch that shaft going up to the top of the carb. Any throttle movement at all before the rod going to the top of carb is bad. That rod operates the accelerator pump and the needle assembly. They need to move together.
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Unread 04-14-2013, 06:17 PM   #18
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You need to drive it and observe the O2 readings at cruise mod, idle, wide open throttle.

If you are able to Velcro the volt meter beside the speedo and shoot a video of both............... And talk about what your doing. Like holding steady throttle. Getting on the gas etc.................

I have a video on my YouTube channel "EugeneKingify" that shows me watching the O2 feedback while its controling the stepper motor. Mine goes rich lean rich lean.......yours will be more steady. Unless your moving the throttle.
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Unread 04-19-2013, 05:18 PM   #19
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Eugene,

I watched your video and it was excellent. The gauge I have set up for my O2 sensor is terrible. I don't believe it has any filter/averaging to it and it jumps around like crazy, unlike your meter that has averaging.

For those who are curious as to what were referring to:

I think it would be ideal (no pun intended) to have a small LED strip read-out the voltage rather than these bar-chart type gauges.

I'm going to try and setup my meter for a ride along. I reset the screws again and tried to tune at idle. Currently they're set at about 4 to 3-7/8 turns out, somewhere in there. My gauge shows full rich but if I turn them in any more (lean out the mixture) it starts to stumble and have a rough idle.

Thanks again for working on this with me.
Shaun
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Unread 04-19-2013, 05:30 PM   #20
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If you don't have the stepper operating, your numbers shouldn't jump around too much.

Only reason I used average is because of the stepper pins going rich lean rich lean trying to maintain a .5 average.

If your all over the place you have a misfire or something. Your carb should be metering fuel at a steady rate with a steady foot on the throttle.

Like I said before idle should be rich. Like around .8v. To .85. Anything below that its not happy.

Edit make sure you have a good ground for your meter. The single wire O2 relies on the rusty manifold for its ground. Putting Anti-seeze on the threads is good.
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Unread 04-19-2013, 06:08 PM   #21
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Right now the idle is somewhere between 0.85-0.95V depending on how warm the engine is and what the ambient temperature is. (Or so it seems)

I've spliced into the wires going to my gauge and am going to try and have my lady assist me with making a ride-along of the meter. From what I saw so far, cruising at 35 in 4th was about 0.05-0.12V.

Am I experiencing a lack in performance from this Eugene? This is honestly best it's run since the rebuild. It can hold 75 on the highway (with only moderate throttle) with ease, and it will even chirp/spin the tires on dry/wet pavement in 2nd if I go WOT.
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Unread 04-19-2013, 06:29 PM   #22
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You are still using the stepper pins and the MCU?


If so, you need a high impedance meter like a Fluke so it won't effect the signal by dragging it low.

If you have a non stepper BBD or a stepper BBD with the nutter bypass preformed your readings should be more steady. But with a cheep low impedance meter its up in the air.

As a process engineer you should have fluke meters out the wazo available to you.

Edit. I don't know if your AF meter is able to be in parallel with the MCU if that's what your doing. I personally wouldn't trust its impedance being high enough to not effect the signal. Unlike a fluke or higher end DVM that's designed to read in circuit.
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Unread 04-19-2013, 06:38 PM   #23
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I just re read your post and you have the mcu bypasses. So I'd disconect the O2 wire from the harness and read it alone with no other wires connected to it but your meter or AF monitor.

Its been my experience that the only time your reading should change is when you move your foot.

And exhaust leak will pull wads of fresh air into the exhaust stream causing the O2 readout to show lean. A misfire will also cause a momentary lean condition.
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Unread 04-19-2013, 07:00 PM   #24
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P.S.

the mcu does a mighty fine job of controlling the fuel mixture of the carb. My video is proof. Heck half my YouTube channel is proof.

It does a crappy job of controlling the spark.

I paralleled my distributor pickup (Orange and Purple wires) to both the mcu and the MSD6a ignition box.

To me I have the best of both worlds.
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Unread 04-20-2013, 07:05 AM   #25
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this is a result of fixed position stepper motor

When I open up the throttle, the gauge jumps to full lean or off (<0.1V from the sensor) and when I let off the throttle the gauge would jump all the way to full rich. I thought this was weird. Shouldn't it be the other way around?

im pretty sure by setting the stepper pins at a fixed position this is exactly what should happen. the transition from idle circuit to main jets is going to have a lag time and your seeing that on your meter. your metering rod height imo is your only option at lean above idle. is the stepper motor inop?. hook it back up and let it attempt to control the mixture using the ecu and watch your meter.
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Unread 04-20-2013, 09:19 AM   #26
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Quote:
Originally Posted by thompsoj22
When I open up the throttle, the gauge jumps to full lean or off (<0.1V from the sensor) and when I let off the throttle the gauge would jump all the way to full rich. I thought this was weird. Shouldn't it be the other way around?

im pretty sure by setting the stepper pins at a fixed position this is exactly what should happen. the transition from idle circuit to main jets is going to have a lag time and your seeing that on your meter. your metering rod height imo is your only option at lean above idle. is the stepper motor inop?. hook it back up and let it attempt to control the mixture using the ecu and watch your meter.
When I did the nutter back around 2005 I saw the same thing you are seeing.

It's all fuzzy now but I had a incorrect accelerator pump arm adjustment and the manifold leaks. After that I started adjusting the Allen screw that holds the needles. The rebuild kits have instructions on which direction is rich and lean.

I couldn't get a linear curve where it was .4 to .5v at all conditions. If I got 35mph to read .5 then 55mph was down around .2 and if I got 55mph to read .5 then 35mph was .7.

That's when I gave up, blaming it on the crapy needle profile and hooked the mcu back up to just the carb.

Then it was all good.

If you could get the needles out of a non stepper BBD may solve that. Or slap on a non stepper BBD. Any AMC car, Wagoneer, truck, etc had them.
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Unread 04-20-2013, 09:45 AM   #27
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Quote:
Originally Posted by thompsoj22
When I open up the throttle, the gauge jumps to full lean or off (<0.1V from the sensor) and when I let off the throttle the gauge would jump all the way to full rich. I thought this was weird. Shouldn't it be the other way around?

im pretty sure by setting the stepper pins at a fixed position this is exactly what should happen. the transition from idle circuit to main jets is going to have a lag time and your seeing that on your meter. your metering rod height imo is your only option at lean above idle. is the stepper motor inop?. hook it back up and let it attempt to control the mixture using the ecu and watch your meter.
I'm also figuring that the 1/8 shoulder showing which is where the computer puts it during warmup may be to account for choke operation since during the same time of warmup the choke will be in operation and at 130 degrees the mcu starts looking at the O2 reading and takes action.

You could try moving the stepper pins in another 1/8 inch and see what happens. Farther in it more rich.

I made a manual stepper control to operate it with a rotary switch. It worked 90% of the time but gave it to John Strenk to incorporate in his gauges diagnostic box

What are your readings at steady throttle?
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Unread 04-20-2013, 12:15 PM   #28
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I agree with you, Eugene, the metering pins appear to do a very good job. However, I cannot hook my stepper motor back up because it won't have an MCU to receive orders from!

(I removed my 'puter all together after the nutter. I was originally just going to pull it to inspect but once I got it out, I could see all the contacts were corroded badly. )

At any rate, I have been able to get that video, but I can't get it to load. I'll keep trying to get it posted but below is a description of what happened during the ride-along.


You can see at idle that the read out is very very rich, near 0.95-0.99V. Then when I open the throttle, I drop to >0.1V. Each time I shift I get a rich reading, you can count them, I have the T5. But when I'm accelerating at constant throttle, the reading is almost constant. When I go WOT in 4th it enriches to the 0.8V range and then when I cruise in 5th at 55 mph, it is almost dead-nuts on 0.032, with maybe a thousandths here and there.

What do you guys think? (JeepHammer, MoC, Romain, McMud, I know you're lurking somewhere. Not that I don't trust your opinion Eugene, I'm just curious as to what others think I should be looking at.)

Thanks guys!
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Unread 04-20-2013, 12:22 PM   #29
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.32 is to me a tad lean. I'd lift the needles a hair and see if you can't get a .45 out of it.

Wide open looks good. That's around Grammys wot readings.
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Unread 04-20-2013, 12:51 PM   #30
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Bahaha Eugene, it shows 0.032 not 0.32 (I wish it was 0.32).

What are these needles you're referring to? I know you guys have mentioned the needles and accelerator pump but I don't have a clue.

Pictures? Vid's?
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