Lugging at speed/No power at WOT

[FuzzFace2]

Oh. Boy.

Other than replacing a poorly flared steel fuel line (pump to carb) and "stock" filter to rubber fuel line with a clear servicable filter, and the R12 AC being previously converted to R134A (which I resealed and recharged ), everything under the hood is pretty much stock or a stock replacement.

Been down a long list, which included the following repairs/fixes (some predate the thread as they were "obvious fixes"):

-Rebuilt carburator

-Fixed many vacuum leaks until none seen by smoke test. This includes a previous repair (made as soon as I bought the truck) which replaced a faulty brake booster and master cylinder

-Replaced all belts, including a previously missing A/C belt.

-Checked (and replaced if at all bad) all sensors. New O2, TPS, and idle solenoid (the latter was found to be OK)

-Confirmed via vacuum gauge and open header test drive that the exhaust is not restricted (including the two stock cats. Exhaust leaks do exist; my injection pipe has a big hole right before the bung between the cats, and everything past the cats is an aftermarket rotted out aluminumized mess.

-For a while ran with just the electric choke (choke stove tubes rotted off, and wasn't able to fix in place). Later fixed, see below

-Replaced the entire ignition system. PO ran it with the ECU (and many accessories) powered off (fusible link not connected to starter relay) and the timing over advanced. Fixed all of this, but damage was done to the engine (or was already done, see below).

-Replaced broken tie rod ends. Never got around to getting it aligned; in recent times (after the next several items) the front tires have worn to needing replacement. Shame on me. .

-Noted that cylinder 1 and sometimes 2 were running pig rich and/or burning oil. Turns out the latter was the case, as most cylinders had low compression (120-130PSI) and was leaking into the crankcase

-Replaced two bald rear tires while on a long trip with the truck (1500 miles! My Ranger blew a brake line the morning I was to leave, and my wife's escape pees tranny sauce when hot, so I had no choice to make the trip work)... Early christmas gift from parents when I visited them on the way. The fronts were in passable shape at the time; due to having a long trip ahead, I didn't have 3 hours to wait for the alignment rack to free up. Again, shame on me!

-Replaced my U joints. No issue found, but it was cheap insurance.

-Replaced the worn/blown out factory shocks.

-Rebuilt the bleeping engine! Found that everything but cylinder 4 had broken compression rings, and the bores were scored and glazed. Had the block bored 30 over, and rebuilt with new pistons/rings (both 30 oversized) and bearings. Valvetrain was reused and re-assembled in the exact locations they came from.

-Replaced the choke stove tubes while the manifold was off the engine. Also discovered the butterfly assembly in the exhaust manifold, and determined that while it is crusty, it does move. Move correctly? Don't know. It wasn't until the last few days of research I found out what that does; due to the EGR tube being rusted in place to both manifolds, I didn't split them apart since I didn't know if a new tube could be sourced (in my experience with my two 1995 rangers, rusted EGR tubes come off destructively).

-Did a compression test at 500 miles past rebuild; only got 125 PSI on all six cylinders. Still running break in oil, but have driven it somewhat more conventionally (no more rev and coast; is this a problem???).

-Did a 4 wheel brake job last weekend. Both calipers seized, both rotors worn, one wheel cylinder exploded. Front wheels were tight after new pads installed; I had to pull the factory shim off one pad in order to make it fit on the new rotors. My hope is that they'll break in and loosen up (had a special coating to break the pads in; they're centric PG Pro ceramic pads).

Today I replaced the voltage regulator... only to find the old stock regulator wasn't bad nor was it mechanical in the first place. At least I have a spare... DOH! I also changed my diff fluid... gears and fluid didn't look bad, so I think I can rule out a rear end issue is the cause. I also pulled codes with my scanner... no codes to be found (just gave the code 11 "all passed" code), so it's not in limp mode.

The truck has stock wheels/tire sizes (for an RWD), and 3.08 open gears. AOD transmission.

At this point, other than the alignment being so far off the tire scrub is braking the truck (which is possible, the wheel is far from center, indicating the toe is FUBAR, hence the chewed to heck tires), some issue with the tranny (haven't bothered the change the fluid; what's in there still looks and feels good, and I'm balking at $50 in fluid if I drain the T/C like I'm supposed to), or the low compression being a bigger issue than I think (and my rebuild being a fail ), I'm stumped. The first two are easy... I just have to pony up the $$$ (the former would include new tires since every alignment shop is also a tire place, and no way I'll be able to get in without replacing balding tires). The last one is probably the issue, and I'm fearing that all my time and effort was mostly a waste if the rebuild is junk and I have to start over. It doesn't shake and miss under torque at least and I have no more blow by... but if the rings aren't going to seal, what was the point? I did everything "right"; I offset my ring gaps 180 degrees, used the best break in oil I could get (other than the 1/2 qt of synthetic I used during assembly not knowing that synthetic and break in really don't mix), and followed the service manual and the like to the best of my ability. But I'm a noob at rebuilds, and I might have gotten owned. I'm 1100 miles past rebuild, and with no change in performance, I'm not feeling too good about it. I'll do another compression test when I have time (tomorrow/today I'll be booked with Church and Mowing my badly overgrown lawn ).

Edit: The odometer readings are good as far as I can measure. The speedometer reads a bit slow though (65 shown = 70 driven); at 70mph actual it usually could stay in gear without bogging down in cruise, but any faster and unless I was drafting or down hill, it would bog down 10mph before downshifting. Since it is bogging down at low RPM (not high), I'm still not thinking it's an intake/exhaust flow or fuel delivery issue.

Thanks for the run down on what was done.

Lets say the motor rebuild it good, 125 across all holes I say is ok for an 1984 motor in my book.

But sounds like you are still running the feedback carb & dist. and from what I have seen posted if just 1 thing is out of spec the system goes into limp home mode. This can / could hurt performance & MPG.

The speedo reading 65 MPH when doing 70 MPH will also throw off the mileage and throwing off the MPG.

Take it no tach so we don't know what RPM @ what MPH you have to see if in the sweet RPM range or not at a given speed / RPM.

Mine w/T18 (non-OD), 2.74 gear, 235/75/15 tire at 65 I have 2300 to 2500 RPM, 70 MPH is like 3000 RPM. I hope with OD to get the RPM down to 1800 that is the sweet spot of the 300 six from what I have found.

If you think the toe is off you can set that with a tape measure and get it close.

Dave ----

[ratdude747]

Thanks for the run down on what was done.

Lets say the motor rebuild it good, 125 across all holes I say is ok for an 1984 motor in my book.

But sounds like you are still running the feedback carb & dist. and from what I have seen posted if just 1 thing is out of spec the system goes into limp home mode. This can / could hurt performance & MPG.

The speedo reading 65 MPH when doing 70 MPH will also throw off the mileage and throwing off the MPG.

Take it no tach so we don't know what RPM @ what MPH you have to see if in the sweet RPM range or not at a given speed / RPM.

Mine w/T18 (non-OD), 2.74 gear, 235/75/15 tire at 65 I have 2300 to 2500 RPM, 70 MPH is like 3000 RPM. I hope with OD to get the RPM down to 1800 that is the sweet spot of the 300 six from what I have found.

If you think the toe is off you can set that with a tape measure and get it close.

Dave ----

Yep. Running the feedback carb and stock TFI ignition.

I thought that if it entered limp mode, there would have been a code set? Before the rebuild, I was getting stored lean codes all the time. Since then, I am getting no stored codes (see last post). It's idling like the timing is getting ECU advanced, so I highly doubt it's in limp mode.

Before the rebuild, cylinder 4 was running 145PSI compression... which is why 125 seems low to me.

I've done some testing on the odometer previously (using interstate milemarkers)... wasn't too far off. I'll retest. Seems like the error is in the speedometer itself, not the speedometer gearing in the tranny.

I don't have a tach, so I can't say what RPM's I'm getting. Been wanting to swap for a cluster with a tach and trip odometer, but I keep balking at the cost. I also haven't been keen on adding an aftermarket tach; Trying to keep a somewhat stock interior look (other than the CB).

[ratdude747]

Yep. Running the feedback carb and stock TFI ignition.

I thought that if it entered limp mode, there would have been a code set? Before the rebuild, I was getting stored lean codes all the time. Since then, I am getting no stored codes (see last post). It's idling like the timing is getting ECU advanced, so I highly doubt it's in limp mode.

Before the rebuild, cylinder 4 was running 145PSI compression... which is why 125 seems low to me.

I've done some testing on the odometer previously (using interstate milemarkers)... wasn't too far off. I'll retest. Seems like the error is in the speedometer itself, not the speedometer gearing in the tranny.

I don't have a tach, so I can't say what RPM's I'm getting. Been wanting to swap for a cluster with a tach and trip odometer, but I keep balking at the cost. I also haven't been keen on adding an aftermarket tach; Trying to keep a somewhat stock interior look (other than the CB).

Re-ran the KOEO test, this time letting it complete... still no stored codes, but I did get a 41 as always.

I've already replaced the O2 sensor once (which is a bit hacked due to most of the manifold threads being stripped; I had to cut off the copper washer to get the sensor to bite threads ). The wiring is good, so other than the "new" O2 sensor being faulty out of the box or a Bad ECU, I had no explination for the code and figured it was normal.

If it isn't normal... DUH. System thinks it's lean ->forces it pig rich -> crappy performance and fuel economy. But other than tossing another O2 at it or trying to do a torch test, I have nothing. I honestly forgot about this issue... figured that if it really was bad, that I'd get a stored code.

Edit- engine had been sitting... maybe too cold for the O2 to work. DOH!

[ratdude747]

Re-ran the KOEO test, this time letting it complete... still no stored codes, but I did get a 41 as always.

I've already replaced the O2 sensor once (which is a bit hacked due to most of the manifold threads being stripped; I had to cut off the copper washer to get the sensor to bite threads ). The wiring is good, so other than the "new" O2 sensor being faulty out of the box or a Bad ECU, I had no explination for the code and figured it was normal.

If it isn't normal... DUH. System thinks it's lean ->forces it pig rich -> crappy performance and fuel economy. But other than tossing another O2 at it or trying to do a torch test, I have nothing. I honestly forgot about this issue... figured that if it really was bad, that I'd get a stored code.

Edit- engine had been sitting... maybe too cold for the O2 to work. DOH!

Drove home... ran a KOER test. Got codes 23 (TPS) and 41 (Lean/O2 Voltage low). Same codes as always!

The 23 is probably because my wife was slow to yell at me to punch the gas during the test (I've previously replaced the TPS and verified that the correct signal is making it to the ECU). Or the ECU is fried. Given the unknown history I don't know.

The 41 probably means I have an O2 sensor wiring issue... or once again, a fried ECU. Need to test at the ECU and work my way towards the sensor. I could also be lean... but where would the air come from? I've been through this routine before... no leaks, so it *has* to be an electronic issue?

If I'm looking at a new ECU, what sort of interchange options are there? Obviously it would need to be for an EEC IV carbed 300... but was there a difference between the manual and auto

[ratdude747]

Drove home... ran a KOER test. Got codes 23 (TPS) and 41 (Lean/O2 Voltage low). Same codes as always!

The 23 is probably because my wife was slow to yell at me to punch the gas during the test (I've previously replaced the TPS and verified that the correct signal is making it to the ECU). Or the ECU is fried. Given the unknown history I don't know.

The 41 probably means I have an O2 sensor wiring issue... or once again, a fried ECU. Need to test at the ECU and work my way towards the sensor. I could also be lean... but where would the air come from? I've been through this routine before... no leaks, so it *has* to be an electronic issue?

If I'm looking at a new ECU, what sort of interchange options are there? Obviously it would need to be for an EEC IV carbed 300... but was there a difference between the manual and auto

Did a backprobe test at the ECU (engine running)... was getting no signal. Unplugged the 02 sensor and read it directly, there is signal... 0.8-0.9V. Noted how loose the connector was, and chopped the old harness plug and replaced it with a spade crimp... got more signal at the ECU, but still zilch. Did some debugging and found the ecu connection is good, and my backprobe was bad; redid the backprobe and I got signal at the ECU.

Made an inline test lead out of some wire I had sitting and ran it to the cab for a drive test. While driving, it's running at 0.9V. The O2 seems to be OK since when I coast, it drops to zilch (0.06V or so), and when I accelerate it peaks at 1.4-1.6V then comes down to 0.8-0.9.

She's running pig rich all right. I already replaced the feedback controller on the carb with a NOS OE unit (had a cheap looking aftermarket one), so, to me, it's looking like I have a fried ECU.

I'd like to find another ECU... as I wasn't planning on nuking the entire ECU system and turning it into farm truck ... Maybe with as many people have ripped the OE systems out, maybe finding a spare ECU won't be too hard?

FYI: I did pull the ECU apart last year... nothing visibly bad (shame, my other hobby is electronics/computer repair and soldering).

[FuzzFace2]

Did a backprobe test at the ECU (engine running)... was getting no signal. Unplugged the 02 sensor and read it directly, there is signal... 0.8-0.9V. Noted how loose the connector was, and chopped the old harness plug and replaced it with a spade crimp... got more signal at the ECU, but still zilch. Did some debugging and found the ecu connection is good, and my backprobe was bad; redid the backprobe and I got signal at the ECU.

Made an inline test lead out of some wire I had sitting and ran it to the cab for a drive test. While driving, it's running at 0.9V. The O2 seems to be OK since when I coast, it drops to zilch (0.06V or so), and when I accelerate it peaks at 1.4-1.6V then comes down to 0.8-0.9.

She's running pig rich all right. I already replaced the feedback controller on the carb with a NOS OE unit (had a cheap looking aftermarket one), so, to me, it's looking like I have a fried ECU.

I'd like to find another ECU... as I wasn't planning on nuking the entire ECU system and turning it into farm truck ... Maybe with as many people have ripped the OE systems out, maybe finding a spare ECU won't be too hard?

FYI: I did pull the ECU apart last year... nothing visibly bad (shame, my other hobby is electronics/computer repair and soldering).

So if it running pig rich how would that show on the O2 readings?

If they and not showing pig rich then I would think the O2 is bad or a connection back to the ECM.

Is there a way to see the signal from the ECM to the carb that should be leaning it out?

If there is and it is at full to make it lean then that part or carb is bad.

I would also pull a plug on something that the ECM would pick up to see if it throws a code for it for just a test.

Just my thinking

Dave ----

[ratdude747]

So if it running pig rich how would that show on the O2 readings?

If they and not showing pig rich then I would think the O2 is bad or a connection back to the ECM.

Is there a way to see the signal from the ECM to the carb that should be leaning it out?

If there is and it is at full to make it lean then that part or carb is bad.

I would also pull a plug on something that the ECM would pick up to see if it throws a code for it for just a test.

Just my thinking

Dave ----

Multimeter readings while driving (peak voltages?) are 0.8V-0.9V, indicating a rich condition. From what I read on these type of O2 sensors, the correct value for proper fuel/air mix should be 0.6-0.7V peak. I'm getting the correct value swings during acceleration (momentary peak at "high" levels) and deceleration (dropping below 0.1V very quickly), which tells me the O2 sensor is functioning.

I tested this by making an intermediate wire to plug between the O2 and the harness with a long side lead, which I ran in the cab (out the hood gap and through a window) to a meter to measure while driving. I previously had confirmed good connection to the ECU plugl, ruling out the wiring.

As for a carb issue, I rebuilt it already and replaced the feedback solenoid... so what could be the issue? I have no data on what the correct feedback values from the ECU are supposed to be; from looking at the diagram, it's ground side switched on the Tan/Light Green wire (referenced to the Red ECU power out wire); I'm told it's controlled via pulsed DC (duty cycle?)... but otherwise, unless there's a troubleshooting manual with such info (one of my meters can measure frequency and duty cycle), I don't know. Edit: If the Carb is the issue, then why did the ECU report a lean fault? I'll retest tomorrow, but if it's still giving such a fault, then I don't see how the ECU can't be the issue; it's reporting one thing but the signal at the pin says the opposite.

---

Pulled the ECU and did another inspection. After some filtering and resistor circuitry (which all mesured as well within spec), the signal goes to a proprietary chip that I can't find any data on... so electronically, I'm at a dead end on testing the ECU board itself.

[Gary Lewis]

Multimeter readings while driving (peak voltages?) are 0.8V-0.9V, indicating a rich condition. From what I read on these type of O2 sensors, the correct value for proper fuel/air mix should be 0.6-0.7V peak. I'm getting the correct value swings during acceleration (momentary peak at "high" levels) and deceleration (dropping below 0.1V very quickly), which tells me the O2 sensor is functioning.

I tested this by making an intermediate wire to plug between the O2 and the harness with a long side lead, which I ran in the cab (out the hood gap and through a window) to a meter to measure while driving. I previously had confirmed good connection to the ECU plugl, ruling out the wiring.

As for a carb issue, I rebuilt it already and replaced the feedback solenoid... so what could be the issue? I have no data on what the correct feedback values from the ECU are supposed to be; from looking at the diagram, it's ground side switched on the Tan/Light Green wire (referenced to the Red ECU power out wire); I'm told it's controlled via pulsed DC (duty cycle?)... but otherwise, unless there's a troubleshooting manual with such info (one of my meters can measure frequency and duty cycle), I don't know. Edit: If the Carb is the issue, then why did the ECU report a lean fault? I'll retest tomorrow, but if it's still giving such a fault, then I don't see how the ECU can't be the issue; it's reporting one thing but the signal at the pin says the opposite.

---

Pulled the ECU and did another inspection. After some filtering and resistor circuitry (which all mesured as well within spec), the signal goes to a proprietary chip that I can't find any data on... so electronically, I'm at a dead end on testing the ECU board itself.

Are you using the 1982 ENGINE EMISSIONS DIAGNOSIS book?

[FuzzFace2]

Are you using the 1982 ENGINE EMISSIONS DIAGNOSIS book?

I was thinking you know what the O2 is telling the ECU but not knowing what the output DC to the carb should be for a given condition you are kind of stuck at that point.

Could unplug the carb and see what that does with O2 readings but I don't see a safe way to send a signal (ma or mv) to it to see what that does to the O2 readings.

Do you get a lean reading from the O2 at any one time that you can repeat and if so maybe see what the carb is getting from the ECU at that time.

I kind of under stand how this should work but that ECU is a black box with no way to know what it is trying to do with out the information.

Think that is why most remove the feed back system and go old school as "WE" can make and see the changes and not rely on a black box to do it for us.

Do I remember the ECU needs a good ground?

Maybe run another just to make sure it is grounded and see what happens.

Dave ----

[ratdude747]

I was thinking you know what the O2 is telling the ECU but not knowing what the output DC to the carb should be for a given condition you are kind of stuck at that point.

Could unplug the carb and see what that does with O2 readings but I don't see a safe way to send a signal (ma or mv) to it to see what that does to the O2 readings.

Do you get a lean reading from the O2 at any one time that you can repeat and if so maybe see what the carb is getting from the ECU at that time.

I kind of under stand how this should work but that ECU is a black box with no way to know what it is trying to do with out the information.

Think that is why most remove the feed back system and go old school as "WE" can make and see the changes and not rely on a black box to do it for us.

Do I remember the ECU needs a good ground?

Maybe run another just to make sure it is grounded and see what happens.

Dave ----

Worked a very long day (15 hours ), so just now reading these. I did a KOEO and a KOER when I got home.

KOEO: Passed, no errors.

KOER: 23 and 41. and I slammed the gas as soon as 10 came up on my scan tool. Previously the 23 was found to be partially an out of spec TPS (which was fixed), and the rest, like the O2, a case where the fault doesn't match the signal measured at the ECU plug. Assumption was that it was something I was doing wrong, and that the 41 was something to do with a blasted engine. Obviously that wasn't the case...

Gary: I"ll look at the manual. I skipped it previously because EEC-IV didn't come out anywhere Ford until 1983, but in hindsight that's a dumb thing to do; taking such difference into account, the sensors are likely similar. Edit: No help on the O2... it says to look in the EEC manual and gives no other useful info. Ditto for the TPS. .

Edit2: Re-discovered the EEC schematic... due to the scan resolution I can't say for sure, but while the O2 pin is the same, the circuit looks to be different. Has a separate ground and the input passive circuitry isn't there... and with the part number being from 1987, my guess is this was designed to use a heated O2 which includes a stand-alone signal ground instead of using the manifold/block ground (hence why an O2-only ground would make sense and even work).