Lugging at speed/No power at WOT

[ratdude747]

I'm at wits end with my 1984 F150 (bought a month ago as a project). It has a 300 with an AOD transmission. RWD, 3.16 Gears (Limited Slip, but needs new clutches), and factory sized tires. The issues are:

1. At highway speeds (over 55) it lugs when I try to mildly accelerate. Once I get a downshift, it does better... but in OD it can't handle anything more than 55 on flat land or hills. It also does this around 25mph as well.

2. This morning at least, It stalled several times when given heavy throttle from a stop. Not the first time it's done this... but it's intermittent.

Information:

-Almost 100% stock. The only changes are rubber fuel between the pump and carb line with a clear filter (no OE steel lines or filter), and plugging off the choke stove lines at the carb (Rusted out, using the electric element by itself).

-EEC IV codes: Did a KOER test, got one for running lean, one for TPS. I did punch the gas when code 10 came up.

-Air/Fuel system: Found and fixed many vacuum leaks. Rebuilt the carb. Verified with a homemade smoke machine (party fogger) that there are no more leaks. Had a rough/bad idle, which I was able to fix by going richer on the idle screw. Replaced O2 sensor due to suspected issues (reported no switching). Vacuum is OK, mostly stable.

-Ignition: New plugs, wires, cap, rotor, and TFI module (PO had the wrong unit installed, which was also faulty). All were bad. Used Motorcraft copper plugs. Timing set to target, within 1 degree of 10 BTDC (Notched target on timing scale). Yes, I did unplug SPOUT when setting timing

-Mechanical: Haven't looked at mechanical timing yet. Engine has 102K on it. Uses some oil, but seems to be due to many oil leaks. Does have oil fog when vent tube unplugged... but not forceful blowby. Replaced a faulty PCV valve to correct oil flooding the air filter.

-Transmission: seems to be working. Fluid is old but not thick or gritty. Verified TV cable adjustment (0 slack/tension at idle) and correct TV cable travel/lever movement.

Otherwise, I'm out of ideas short of mechanical timing (AFAIK, it hasn't had a gear swap, so I'm doubting a gear timing issue?). No vacuum leaks (that I can find), and the carb is getting fuel it seems.

Suggestions on places to look next?

[Gary Lewis]

Wow! What a thorough post, and a thorough approach to fixing it. But, it didn't work.

I don't remember hearing of a 300 six getting out of time, but that is possible. Still, unless someone else has seen the problem, it seems remote.

But you a code for the TPS and didn't mention fixing it. Have you? I've heard bad things about how the engines run when the TPS isn't right.

And it would seem the engine is NOT running correctly. With those gears I would expect the 300 to handle 60 MPH and above quite well. So, if the AOD linkage is spot-on, then it must be the engine.

But how does it do out of OD? With those gears it should still do quite well on the highway w/the OD locked out. Does it?

[ratdude747]

Wow! What a thorough post, and a thorough approach to fixing it. But, it didn't work.

I don't remember hearing of a 300 six getting out of time, but that is possible. Still, unless someone else has seen the problem, it seems remote.

But you a code for the TPS and didn't mention fixing it. Have you? I've heard bad things about how the engines run when the TPS isn't right.

And it would seem the engine is NOT running correctly. With those gears I would expect the 300 to handle 60 MPH and above quite well. So, if the AOD linkage is spot-on, then it must be the engine.

But how does it do out of OD? With those gears it should still do quite well on the highway w/the OD locked out. Does it?

I haven't looked at the TPS since my (in hindsight, foolish) assumption is I'm doing the throttle stomp wrong... also because I'm having a heck of a time finding feedback carb info since 90% of "solutions" are to swap a DSII and 4 barrel. Is there a test procedure out there for such? The schematics I found here don't give resistor values for such (I don't think, will relook), so I'm flying blind (I feel dumb, I have an EET degree for crying out loud). And I really don't want to fire the parts cannon, especially on a $40 part. Suggestion?

Out of OD it does OK... I don't think it's OD related as much as it's RPM related. Seems like I have no bottom end. Which for a 300, makes no sense. Aren't these supposed to be torquey?

Timing: My fear/concern was it skipped a tooth due to a worn out timing gear (fiber fail). But as leaking and old as the timing gasket looks, I doubt anybody's been there... and I doubt helical gears "skip" like that without completely failing? I do know the base ignition timing was way off... too advanced. Like the PO timed it without disconnecting SPOUT.

Other note: this is a far cry from where it was when I bought it. When I bought it, it had no brakes and wouldn't idle or start consistently. With the exception of the O2 sensor (which was a hunch and a rockauto closeout), every move mentioned had positive impact. No idle was partialy carb tuning (I beefed the resetting of the idle screw during the carb rebuild), and a bunch of vacuum leaks. The intermittent no-start was all of the ignition issues. The brakes were a bad MC and booster... swapping those and bleeding the system took care of such. I've done other unrelated work (oil/coolant change, A/C seal replacement and recharge, etc.)... Not bad for a $750 truck with virtually no rust (other than the floor of the bed :( ).

 

[ArdWrknTrk]

I haven't looked at the TPS since my (in hindsight, foolish) assumption is I'm doing the throttle stomp wrong... also because I'm having a heck of a time finding feedback carb info since 90% of "solutions" are to swap a DSII and 4 barrel. Is there a test procedure out there for such? The schematics I found here don't give resistor values for such (I don't think, will relook), so I'm flying blind (I feel dumb, I have an EET degree for crying out loud). And I really don't want to fire the parts cannon, especially on a $40 part. Suggestion?

Out of OD it does OK... I don't think it's OD related as much as it's RPM related. Seems like I have no bottom end. Which for a 300, makes no sense. Aren't these supposed to be torquey?

Timing: My fear/concern was it skipped a tooth due to a worn out timing gear (fiber fail). But as leaking and old as the timing gasket looks, I doubt anybody's been there... and I doubt helical gears "skip" like that without completely failing? I do know the base ignition timing was way off... too advanced. Like the PO timed it without disconnecting SPOUT.

Other note: this is a far cry from where it was when I bought it. When I bought it, it had no brakes and wouldn't idle or start consistently. With the exception of the O2 sensor (which was a hunch and a rockauto closeout), every move mentioned had positive impact. No idle was partialy carb tuning (I beefed the resetting of the idle screw during the carb rebuild), and a bunch of vacuum leaks. The intermittent no-start was all of the ignition issues. The brakes were a bad MC and booster... swapping those and bleeding the system took care of such. I've done other unrelated work (oil/coolant change, A/C seal replacement and recharge, etc.)... Not bad for a $750 truck with virtually no rust (other than the floor of the bed :( ).

TPS values are around here (somewhere)

I know I looked them up.

When you first mentioned 'sluggish, won't pull' I thought of Ron's month long escapade (which included timing gears and a carb rebuild) when it was a clogged Cat that I suggested within an hour of his OP.

But the intermittent part seems different.

Anyway, subscribed, to see what happens.

[ratdude747]

TPS values are around here (somewhere)

I know I looked them up.

When you first mentioned 'sluggish, won't pull' I thought of Ron's month long escapade (which included timing gears and a carb rebuild) when it was a clogged Cat that I suggested within an hour of his OP.

But the intermittent part seems different.

Anyway, subscribed, to see what happens.

Forgot to mention: I did an exhaust backpressure test while I had the O2 out. Less than 1PSI at idle or at ~2K RPM. Doubt it's a clogged Cat. The exhaust past the cats is garbage though (rusted out aftermarket looking bullcrap).

I'll look for TPS values... So much info here I probably missed it (and I thought I was spoiled with tech info over at the RangerStation- My other truck is a 1995 Ranger).

Intermittent: as in sometimes I'll let off the gas, try again, and it will pull a bit better. Sometimes, no change. Does seem to be running lean (other than meh gas milage, mixed driving has been around 13-14mpg, I read these can do better???).

[ArdWrknTrk]

Forgot to mention: I did an exhaust backpressure test while I had the O2 out. Less than 1PSI at idle or at ~2K RPM. Doubt it's a clogged Cat. The exhaust past the cats is garbage though (rusted out aftermarket looking bullcrap).

I'll look for TPS values... So much info here I probably missed it (and I thought I was spoiled with tech info over at the RangerStation- My other truck is a 1995 Ranger).

Intermittent: as in sometimes I'll let off the gas, try again, and it will pull a bit better. Sometimes, no change. Does seem to be running lean (other than meh gas milage, mixed driving has been around 13-14mpg, I read these can do better???).

Sure! Now you tell me...

Rangers are cool.

Don't see many left up here, but when I was down in NC at my brother's, they were everywhere!

[ArdWrknTrk]

Forgot to mention: I did an exhaust backpressure test while I had the O2 out. Less than 1PSI at idle or at ~2K RPM. Doubt it's a clogged Cat. The exhaust past the cats is garbage though (rusted out aftermarket looking bullcrap).

I'll look for TPS values... So much info here I probably missed it (and I thought I was spoiled with tech info over at the RangerStation- My other truck is a 1995 Ranger).

Intermittent: as in sometimes I'll let off the gas, try again, and it will pull a bit better. Sometimes, no change. Does seem to be running lean (other than meh gas milage, mixed driving has been around 13-14mpg, I read these can do better???).

David gets over 20 mpg when he baby's his 300.

But it is DSII.

[ArdWrknTrk]

Forgot to mention: I did an exhaust backpressure test while I had the O2 out. Less than 1PSI at idle or at ~2K RPM. Doubt it's a clogged Cat. The exhaust past the cats is garbage though (rusted out aftermarket looking bullcrap).

I'll look for TPS values... So much info here I probably missed it (and I thought I was spoiled with tech info over at the RangerStation- My other truck is a 1995 Ranger).

Intermittent: as in sometimes I'll let off the gas, try again, and it will pull a bit better. Sometimes, no change. Does seem to be running lean (other than meh gas milage, mixed driving has been around 13-14mpg, I read these can do better???).

Cut the exhaust off after the cat and stick a turndown tip on it.

Those trucks don't really need anything more than the cat anyhow.

[ratdude747]

Sure! Now you tell me...

Rangers are cool.

Don't see many left up here, but when I was down in NC at my brother's, they were everywhere!

I've owned two 1995 Rangers... the first was my first Ford ever (I was raised a chevy guy, and traded a POS durango for it). But something clicked, and I built it up into my dream truck (or as close as I could get), only for my wife to wreck it a couple winters ago. Found a nearly identical one 5 hours way, and made a road trip up there to fetch it and moved my mods over. It doesn't look too modded, but looks are deceiving. It's not Farm Truck, but it's not a bare bones POS either.

Picture of both trucks from my facebook page:

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I'll look around for TPS info and follow up with what (if anything) I find.

[ArdWrknTrk]

I've owned two 1995 Rangers... the first was my first Ford ever (I was raised a chevy guy, and traded a POS durango for it). But something clicked, and I built it up into my dream truck (or as close as I could get), only for my wife to wreck it a couple winters ago. Found a nearly identical one 5 hours way, and made a road trip up there to fetch it and moved my mods over. It doesn't look too modded, but looks are deceiving. It's not Farm Truck, but it's not a bare bones POS either.

Picture of both trucks from my facebook page:

-----

I'll look around for TPS info and follow up with what (if anything) I find.

What river is that?

Where (about) do you live?