Lugging at speed/No power at WOT

[85lebaront2]

Installed the old computer. Drove it around (no obvious changes or issues), did a KOEO test. No faults.

Noticed that the "new" ECU is missing screws and was poorly spray painted... I'm beginning to think that the only refurbishing the ECU received is the rattle can treatment... Considering seeking a warranty refund due to all the issues (TPS and MAP faults). Seeing if this helps, since I didn't find/fix the EGR and loose carb issues until after the ECU swap.

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Besides a float adjustment issue, are there any carb adjustments that could cause it to run too rich? When I rebuild the carb, I didn't replace or adjust the float... I don't think I measured the metering rod either. I'd think if the float was hanging open too long, I'd have found it by now. Just lookign for things I might have previously overlooked

If the ECU is not controlling the mixture, I believe it may default to full rich. All the solenoid does is control the air bleeds, unfortunately I do not have one I can look at (sold my 4.9L feedback carburetor to a friend with an 86 4.9L bullnose). If you put your finger on the solenoid with the engine running you should be able to feel it "cycling". You can try first see if you have power at the red wire going to all the various emission solenoid valves with the engine running. The EEC relay is a time delay, which tells me it waits long enough to allow the engine to stabilize before closing to power the components. Go here for the pertinent EVTM section: http://www.garysgaragemahal.com/electronic-engine-control1.html that should help you with what is supposed to happen. If the relay never closes, then none of that system will work.

Another sanity check, there should be an idle speed motor, which also has a closed throttle switch to tell the ECU you are at idle, it is supposed to control the idle speed and open the throttle on deceleration. If it isn't working then I would bet none of the other stuff is working either.

[ratdude747]

If the ECU is not controlling the mixture, I believe it may default to full rich. All the solenoid does is control the air bleeds, unfortunately I do not have one I can look at (sold my 4.9L feedback carburetor to a friend with an 86 4.9L bullnose). If you put your finger on the solenoid with the engine running you should be able to feel it "cycling". You can try first see if you have power at the red wire going to all the various emission solenoid valves with the engine running. The EEC relay is a time delay, which tells me it waits long enough to allow the engine to stabilize before closing to power the components. Go here for the pertinent EVTM section: http://www.garysgaragemahal.com/electronic-engine-control1.html that should help you with what is supposed to happen. If the relay never closes, then none of that system will work.

Another sanity check, there should be an idle speed motor, which also has a closed throttle switch to tell the ECU you are at idle, it is supposed to control the idle speed and open the throttle on deceleration. If it isn't working then I would bet none of the other stuff is working either.

The mix solenoid is being controlled; when shut down once can hear it being pulsed for a couple seconds.

EEC relay already verified to be sending 12V to the ECU (proven when probing such for adding the heated O2). Throttle motor was replaced not long ago (later found the old one to still be good and is still on the shelf); it is controlling throttle based on turning the AC on and off (idle is maintained in both cases).

My questions about carb adjustments relate more to the fact that with the exception of the choke and idle fuel mix, I didn't adjust or measure anything (just did an R&R on all the carb parts in the kit). I also have a mostly compatible spare carb ready for rebuild (throttle shaft is wrong; it came from a manual trans truck and has no AOD TV cable provision), which I could rebuild and swap over/replace the incompatible throttle shaft/throttle body. Or I could open my existing carb and readjust/remeasure what I skipped.

One other thing: I adjusted the idle fuel mix by maximizing idle vacuum. On feedback carb trucks, is that the correct way to adjust such?

Edit- found the 1985-1986 fuel system book. Referring to such. Edit: no mention of the idle mix screw or choke adjustments... although the sample under hood sticker happens to be for my application, and mentions that neither is adjustable due to having a feedback carb. Did I mess up by adjusting them?

[Gary Lewis]

The mix solenoid is being controlled; when shut down once can hear it being pulsed for a couple seconds.

EEC relay already verified to be sending 12V to the ECU (proven when probing such for adding the heated O2). Throttle motor was replaced not long ago (later found the old one to still be good and is still on the shelf); it is controlling throttle based on turning the AC on and off (idle is maintained in both cases).

My questions about carb adjustments relate more to the fact that with the exception of the choke and idle fuel mix, I didn't adjust or measure anything (just did an R&R on all the carb parts in the kit). I also have a mostly compatible spare carb ready for rebuild (throttle shaft is wrong; it came from a manual trans truck and has no AOD TV cable provision), which I could rebuild and swap over/replace the incompatible throttle shaft/throttle body. Or I could open my existing carb and readjust/remeasure what I skipped.

One other thing: I adjusted the idle fuel mix by maximizing idle vacuum. On feedback carb trucks, is that the correct way to adjust such?

Edit- found the 1985-1986 fuel system book. Referring to such. Edit: no mention of the idle mix screw or choke adjustments... although the sample under hood sticker happens to be for my application, and mentions that neither is adjustable due to having a feedback carb. Did I mess up by adjusting them?

Hopefully Bill will be along to comment as he knows far more than I. But have you found the 1982 Emissions section on carburetion? https://onedrive.live.com/View.aspx?resid=80736256535317EF!31874&authkey=!AFiAlxbipPm387k

[85lebaront2]

Hopefully Bill will be along to comment as he knows far more than I. But have you found the 1982 Emissions section on carburetion? https://onedrive.live.com/View.aspx?resid=80736256535317EF!31874&authkey=!AFiAlxbipPm387k

Gary, that one is also hosed, I found the same sequence of pages several places and quit trying to find the idle setting procedure. First thing that needs to be done VERY IMPORTANT is the find out if the computer system is even functioning. I covered the quick sanity checks previously. Added to that is see if the spark advance is taking place with the SPOUT connected after setting it to 10° BTDC with the SPOUT disconnected.

I may have the correct emissions diagnostic manual for his truck, I will check shortly.

[85lebaront2]

The mix solenoid is being controlled; when shut down once can hear it being pulsed for a couple seconds.

EEC relay already verified to be sending 12V to the ECU (proven when probing such for adding the heated O2). Throttle motor was replaced not long ago (later found the old one to still be good and is still on the shelf); it is controlling throttle based on turning the AC on and off (idle is maintained in both cases).

My questions about carb adjustments relate more to the fact that with the exception of the choke and idle fuel mix, I didn't adjust or measure anything (just did an R&R on all the carb parts in the kit). I also have a mostly compatible spare carb ready for rebuild (throttle shaft is wrong; it came from a manual trans truck and has no AOD TV cable provision), which I could rebuild and swap over/replace the incompatible throttle shaft/throttle body. Or I could open my existing carb and readjust/remeasure what I skipped.

One other thing: I adjusted the idle fuel mix by maximizing idle vacuum. On feedback carb trucks, is that the correct way to adjust such?

Edit- found the 1985-1986 fuel system book. Referring to such. Edit: no mention of the idle mix screw or choke adjustments... although the sample under hood sticker happens to be for my application, and mentions that neither is adjustable due to having a feedback carb. Did I mess up by adjusting them?

On the choke adjustment, most of the feedback carbs have a tab or slot on the choke thermostat cover to "lock" it in place. There is a procedure for setting idle mixture, and if it is anything like what I had to deal with at the Dodge dealership I worked at, it will either require a propane enrichment or even a combustion analyzer.

Idle speed, there should be (somewhere, maybe in the emission manual) a base idle RPM, with either the idle speed control fully retracted or disabled. This is the setting to prevent dieseling. The noise you may be hearing when you shut it off could be the idle speed motor retracting to allow the throttle to close fully.

[ratdude747]

On the choke adjustment, most of the feedback carbs have a tab or slot on the choke thermostat cover to "lock" it in place. There is a procedure for setting idle mixture, and if it is anything like what I had to deal with at the Dodge dealership I worked at, it will either require a propane enrichment or even a combustion analyzer.

Idle speed, there should be (somewhere, maybe in the emission manual) a base idle RPM, with either the idle speed control fully retracted or disabled. This is the setting to prevent dieseling. The noise you may be hearing when you shut it off could be the idle speed motor retracting to allow the throttle to close fully.

The ECU is functional... I've verified that several times! If I wasn't getting SPOUT (or were in limp mode), trust me, I'd know. Very distinct difference in idle based on experiences with setting the base timing.

I did see that the idle mix procedure is in the book... at the very end. Requires a propane tool and a precision tachometer. I also found a procedure on another site that doesn't require propane but does require a Tach (translation: I need to pony up and upgrade my instrument cluster; I'm not keen on aftermarket tachometers for a "stock" build). The "maximize vacuum" method must only be for non-feedback carbs?

Nothing on the choke... so I'll leave my setting alone. The choke does open all the way when running warm, and I'm not having cold start issues, so I figure it's set correctly.

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Pulled the carb last night and readjusted everything. Found the following issues:

-Float was way off on both sides of the travel. Took a lot of digging to find the spec for this (as all the spec lists I found were for the YF, not the YFA); for 1977+, it's 29/32" for the high side, and 1 5/8" for the low side. The high side was low (float valve opening early); the low side was too high after adjusting the former.

-Metering rod was slightly off.

-I rediscovered that the check ball and weight for the accelerator pump didn't match the drawings (two balls instead)... and lost both by accident. Luckily, I had the spare carb (which is a corrosion filled basket case, and has a factory blocked off accelerator pump), and it had the correct ball and weight, which I moved over.

Reinstalled. Driving it today; so far, it isn't worse... better I can't say since I haven't driven it enough to see if it is any different at highway speeds.

[Gary Lewis]

The ECU is functional... I've verified that several times! If I wasn't getting SPOUT (or were in limp mode), trust me, I'd know. Very distinct difference in idle based on experiences with setting the base timing.

I did see that the idle mix procedure is in the book... at the very end. Requires a propane tool and a precision tachometer. I also found a procedure on another site that doesn't require propane but does require a Tach (translation: I need to pony up and upgrade my instrument cluster; I'm not keen on aftermarket tachometers for a "stock" build). The "maximize vacuum" method must only be for non-feedback carbs?

Nothing on the choke... so I'll leave my setting alone. The choke does open all the way when running warm, and I'm not having cold start issues, so I figure it's set correctly.

---

Pulled the carb last night and readjusted everything. Found the following issues:

-Float was way off on both sides of the travel. Took a lot of digging to find the spec for this (as all the spec lists I found were for the YF, not the YFA); for 1977+, it's 29/32" for the high side, and 1 5/8" for the low side. The high side was low (float valve opening early); the low side was too high after adjusting the former.

-Metering rod was slightly off.

-I rediscovered that the check ball and weight for the accelerator pump didn't match the drawings (two balls instead)... and lost both by accident. Luckily, I had the spare carb (which is a corrosion filled basket case, and has a factory blocked off accelerator pump), and it had the correct ball and weight, which I moved over.

Reinstalled. Driving it today; so far, it isn't worse... better I can't say since I haven't driven it enough to see if it is any different at highway speeds.

I think you may have made major progress. The two balls in the accelerator pump circuit could cause problems as w/o the weight the bottom ball probably wouldn't seal. And a leak there can really make the mix rich.

I'm anxious to see what you find at highway speeds.

[ratdude747]

I think you may have made major progress. The two balls in the accelerator pump circuit could cause problems as w/o the weight the bottom ball probably wouldn't seal. And a leak there can really make the mix rich.

I'm anxious to see what you find at highway speeds.

Hard to say... more of the "stuck in kickdown" issue.

Which prompted me to remember how I adjusted the TV cable last time... and dicked it up royally. What should happened was running a KOEO test beforehand to retract the throttle motor (which I did), and then adjust to no slack (which I didn't do, instead thinking letting the return spring tighten it all the way was right). As a result, it was WAY too tight... Duh!

Readjusted it, and now I have working OD again. It seemed to be too loose though, so I've made it a hair tighter and will retest tomorrow.

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Side note: I plan to do my first oil change at 1500 miles. Right now I'm at around 1000.

[Gary Lewis]

Hard to say... more of the "stuck in kickdown" issue.

Which prompted me to remember how I adjusted the TV cable last time... and dicked it up royally. What should happened was running a KOEO test beforehand to retract the throttle motor (which I did), and then adjust to no slack (which I didn't do, instead thinking letting the return spring tighten it all the way was right). As a result, it was WAY too tight... Duh!

Readjusted it, and now I have working OD again. It seemed to be too loose though, so I've made it a hair tighter and will retest tomorrow.

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Side note: I plan to do my first oil change at 1500 miles. Right now I'm at around 1000.

Glad you found and fixed that. If the AOD has a weakness it is in the way that is adjusted. Off very far can cause serious problems.

[85lebaront2]

Hard to say... more of the "stuck in kickdown" issue.

Which prompted me to remember how I adjusted the TV cable last time... and dicked it up royally. What should happened was running a KOEO test beforehand to retract the throttle motor (which I did), and then adjust to no slack (which I didn't do, instead thinking letting the return spring tighten it all the way was right). As a result, it was WAY too tight... Duh!

Readjusted it, and now I have working OD again. It seemed to be too loose though, so I've made it a hair tighter and will retest tomorrow.

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Side note: I plan to do my first oil change at 1500 miles. Right now I'm at around 1000.

AOD cable adjustment, I put a section in on it, but, the AOD is a lot like the old GM Hydra-Matics on throttle adjustment, too tight and it will either not get into OD or is hyper sensitive to throttle, kicking down at the least throttle. Too loose and it will shift (and slip) super early. There are special gauges for adjusting it, but, shift "feel" is a good test, shift 2-3 is your test point, if it is early and soft, tighten the cable (move the outer casing away from the carb) if it is late and hard, loosen the cable. 2-3 should be firm, but not slam. It is a purely mechanical gear, no torque converter, 3-4 should normally be around 45 mph under normal driving.