Lugging at speed/No power at WOT

[Gary Lewis]

Some quick updates:

-I replaced the TPS... idle got worse. Still lugging. But it did make a difference. I reset the base timing to 10 degrees (as per the indicator) and readjusted the idle fuel with no change either way.

-Yesterday, I power cycled the ECU... and things got way, way worse. Stalled on me several times... and lugged a lot worse than before. I didn't have time to readjust the idle fuel (had to go to Church). Something is very wrong here.

Right now she's out of commission due to a brake line blowing up on my way home. I've pulled the line (rubbed on a frame rivet on one spot, and locally rusted out) and will be bending/flaring it this evening after work.

That said, it seems that something is off. Either I'm not getting good fuel delivery (which makes no sense; no vacuum leaks, rebuilt carb, and adequate fuel supply), or I wonder if I have a mechanical problem (low compression, bad valve timing/adjustment, etc.). My next move will probably be to obtain a compression tester and see what I'm getting there.

Thoughts?

I'm not buying that you have a mechanical or a fuel problem if things got worse with a new TPS, and then got "way, way worse" with a power cycle of the ECU. That says "electrical" to me. Neither of those changes would alter either a mechanical or fuel problem, and yet they altered the symptoms.

I'd pull the codes now and see what you have. But my worry is that the ECU is bad and, if so, won't tell the truth about codes.

Wait - let me rethink this. You have what I think is an EEC-III system. Wikipedia describes the system this way, and while I don't buy everything else they say about the system, I think this is correct for your application:

EEC-III uses a Duraspark III module (brown grommet where wires emerge) and a Duraspark II ignition coil. A resistance wire is used in the primary circuit. The distributors in EEC-III (and later) systems eliminate conventional mechanical and vacuum advance mechanisms. All timing is controlled by the engine computer, which is capable of firing the spark plug at any point within a 50-degree range depending on calibration. This increased spark capability requires greater separation of adjacent distributor cap electrodes to prevent cross-fire, resulting in a large-diameter distributor cap.

So, I'm guessing that your ignition is "off". Maybe too early. Maybe all over the map. But, it is also very possible that your harmonic balancer has slipped and you are adjusting the timing completely wrong.

I'd start by verifying the balancer's mark to TDC. Get a cheap piston stop that goes in the spark plug hole and gently run #1 piston against it and adjust the stop so that you are stopping just a few degrees ahead and behind TDC. True TDC will be half way between the two stops.

If that is correct, then put a timing light on it and watch the timing as you rev the engine. Does it stay the same? Does it move smoothly? Is it erratic?

[Dorsai]

So, I'm guessing that your ignition is "off". Maybe too early. Maybe all over the map. But, it is also very possible that your harmonic balancer has slipped and you are adjusting the timing completely wrong.

Wouldn't this be a good time to try vacuum timing the engine instead? Regardless of whether his balancer is slipped or not, he could at least getting the engine running the best it can at idle, and proceed from there.

Gary, AKA "Gary fellow"

I just noticed this!

[Gary Lewis]

So, I'm guessing that your ignition is "off". Maybe too early. Maybe all over the map. But, it is also very possible that your harmonic balancer has slipped and you are adjusting the timing completely wrong.

Wouldn't this be a good time to try vacuum timing the engine instead? Regardless of whether his balancer is slipped or not, he could at least getting the engine running the best it can at idle, and proceed from there.

Gary, AKA "Gary fellow"

I just noticed this!

Matthew - Better late than never. Please show your grandmother. And tell your mother I'll catch her, age wise, next June - for a few months.

Anyway, yes it might be a good time to set the timing via a vacuum gauge.

[ratdude747]

I'm not buying that you have a mechanical or a fuel problem if things got worse with a new TPS, and then got "way, way worse" with a power cycle of the ECU. That says "electrical" to me. Neither of those changes would alter either a mechanical or fuel problem, and yet they altered the symptoms.

I'd pull the codes now and see what you have. But my worry is that the ECU is bad and, if so, won't tell the truth about codes.

Wait - let me rethink this. You have what I think is an EEC-III system. Wikipedia describes the system this way, and while I don't buy everything else they say about the system, I think this is correct for your application:

EEC-III uses a Duraspark III module (brown grommet where wires emerge) and a Duraspark II ignition coil. A resistance wire is used in the primary circuit. The distributors in EEC-III (and later) systems eliminate conventional mechanical and vacuum advance mechanisms. All timing is controlled by the engine computer, which is capable of firing the spark plug at any point within a 50-degree range depending on calibration. This increased spark capability requires greater separation of adjacent distributor cap electrodes to prevent cross-fire, resulting in a large-diameter distributor cap.

So, I'm guessing that your ignition is "off". Maybe too early. Maybe all over the map. But, it is also very possible that your harmonic balancer has slipped and you are adjusting the timing completely wrong.

I'd start by verifying the balancer's mark to TDC. Get a cheap piston stop that goes in the spark plug hole and gently run #1 piston against it and adjust the stop so that you are stopping just a few degrees ahead and behind TDC. True TDC will be half way between the two stops.

If that is correct, then put a timing light on it and watch the timing as you rev the engine. Does it stay the same? Does it move smoothly? Is it erratic?

It is not DSII or EEC III.

It is EEC IV with TFI. 1984 was the first year for it on the F series, some sedans got it for 1983. The ways to tell are (1) it has an EEC IV connector and (2) it has TFI ignition (ignition module on the side of the distributor, "narrow" distributor diameter).

The reason I suspect it's a mechanical/fuel issue is that various kludges and the like being removed, which bring the system closer to "stock operation", make it worse. The only sensors I haven't messed (found to be suspect and replaced) with are the MAP sensor (no code thrown, maybe I should test?) and the coolant temp sensor... which I don't suspect due to there not being a code set and my issues not going away with engine warmup/cooldown. I could look there (and probably will, come to think of it), but barring a fried ECU (which is possible but, honestly, remote), I'm running out of electrical control issues to find. The TFI module is new (old one burnt and incorrect module), and I verified that the SPOUT signal is making to said module (10 degree ignition advance from base timing at idle when SPOUT is connected).

Writing this reminded me of two sensors I didn't test... while they're not throwing faults, maybe something is up. Dunno. Will have to test.

 

[ratdude747]

Matthew - Better late than never. Please show your grandmother. And tell your mother I'll catch her, age wise, next June - for a few months.

Anyway, yes it might be a good time to set the timing via a vacuum gauge.

I tried vacuum timing it. Brought me to 30 degrees advanced base (stock is 10). Which caused an idle issue (light pinging) once I reconnected SPOUT. When backed off to 20 degrees it stopped pinging but the performance wasn't any better... leading me to believe such isn't the issue.

What I haven't tried (and maybe need to try) is having my wife rev it and see if my timing adjust actually advances. I know the signal is making it to the TFI module (and such is responding), but I don't know if it's actually changing dynamically. Edit- Gary already suggested it that. I need to learn to not read and reply when I just got out of a stressful meeting at work.

[Gary Lewis]

I tried vacuum timing it. Brought me to 30 degrees advanced base (stock is 10). Which caused an idle issue (light pinging) once I reconnected SPOUT. When backed off to 20 degrees it stopped pinging but the performance wasn't any better... leading me to believe such isn't the issue.

What I haven't tried (and maybe need to try) is having my wife rev it and see if my timing adjust actually advances. I know the signal is making it to the TFI module (and such is responding), but I don't know if it's actually changing dynamically. Edit- Gary already suggested it that. I need to learn to not read and reply when I just got out of a stressful meeting at work.

Yes, you've told me before that it is EEC-IV, but I forgot. Sorry. However, if you'd put that in your sig then I should see it before replying next time.

Anyway, I do think you should check the timing with the timing light when the computer is controlling it. And, since you have an auto you can put it in gear, chock the wheels, and put the e-brake on and do a load test.

[ratdude747]

Yes, you've told me before that it is EEC-IV, but I forgot. Sorry. However, if you'd put that in your sig then I should see it before replying next time.

Anyway, I do think you should check the timing with the timing light when the computer is controlling it. And, since you have an auto you can put it in gear, chock the wheels, and put the e-brake on and do a load test.

Fixed the brake line this evening. Took for a test drive, then did the idle/rev timing light check. No timing change at low throttle, but around 2000RPM or so it jumped to 30 degrees advanced.

It is advancing... but not immediatly.

I took some video of the test drive (of the lugging/stumbling condition)... I'll see if it turned out and if so, I'll post a link.

[ratdude747]

Fixed the brake line this evening. Took for a test drive, then did the idle/rev timing light check. No timing change at low throttle, but around 2000RPM or so it jumped to 30 degrees advanced.

It is advancing... but not immediatly.

I took some video of the test drive (of the lugging/stumbling condition)... I'll see if it turned out and if so, I'll post a link.

Yesterday I remembered that the ignition coil was iffy (very loose on core, cracked plastic)... so, as a matter of good practice, I replaced it, and... no change. It needed replaced anyway at least.

Pulled running codes, Codes 41 and 63 Set. The former is the "always lean" code, the latter is a "TPS below minimum threshold" fault.

My next move will be to verify that I'm getting good voltage readings from the TPS at the pin at the ECU connector in the dash... if so, something has gone wonky in the ECU and I'll be cracking it open (I do electronic repair as another hobby, maybe it's something simple blown). If not, I get to trace wires. Fun.

As for the "always lean"... I think that's a symptom, not the root issue. TPS too low -> ECU keeps the mix too lean -> O2 reads lean. Right???

[Gary Lewis]

Yesterday I remembered that the ignition coil was iffy (very loose on core, cracked plastic)... so, as a matter of good practice, I replaced it, and... no change. It needed replaced anyway at least.

Pulled running codes, Codes 41 and 63 Set. The former is the "always lean" code, the latter is a "TPS below minimum threshold" fault.

My next move will be to verify that I'm getting good voltage readings from the TPS at the pin at the ECU connector in the dash... if so, something has gone wonky in the ECU and I'll be cracking it open (I do electronic repair as another hobby, maybe it's something simple blown). If not, I get to trace wires. Fun.

As for the "always lean"... I think that's a symptom, not the root issue. TPS too low -> ECU keeps the mix too lean -> O2 reads lean. Right???

Yes, I think you are right in planning to test the TPS voltage at the ECU. But I'm not sure there's much to fix inside there. We may have to figure out the part number of that ECU and what other vehicles it was used on.

As for the codes, I don't know. But if you have a new TPS and it still has its knickers in a twist about TPS values then I'd focus on that and hope the lean problem goes away when the TPS issue is fixed.

[ratdude747]

Yes, I think you are right in planning to test the TPS voltage at the ECU. But I'm not sure there's much to fix inside there. We may have to figure out the part number of that ECU and what other vehicles it was used on.

As for the codes, I don't know. But if you have a new TPS and it still has its knickers in a twist about TPS values then I'd focus on that and hope the lean problem goes away when the TPS issue is fixed.

Finally had time to crack open the ECU.

No obvious internal issues. All electrolytic capacitors still read good (surprising, given the age of the vehicle). No cracked solder joints or blown components (aside from a diode that the original assembler scarred when hand soldering the ground plate- it measured OK)

I then plugged it back in with the cover off and traced the signal all the way to the microcontroller chip itself. No issues... the voltage was a bit off though (0.8V at idle, 3.8 full throttle). Maybe it is legitimately out of range, but not by much.

Back together... Sometimes connections also go flakey and cause issues, so there is a small chance that with a replug it will start working again. Dunno.

Side note: unlike EFI, these feedback carbs will run without an ECU... not run well, obviously. Maybe the only benefit over EFI?