Sputter

[randomguy]

Okay while the car is running better when I take off from it still seems to sputter still like its running lean. I floored it once from 50 mph and it seems fine when I floored it. I don't think there should be any issues with the fuel system since the mechanic test the system pressure and the results was 6lbs of fuel pressure. This is the second reman'd carburetor installed. It's an 84 meaning it has a Feedback Carter BBD 2bbl. I fueled up with 89 octane today and outside temperature when driving the car was 78-82 degrees today. This is because becoming slightly frustrating.

Oh well, at least the A/C is working now. The only thing I will add that I have changed yet is the timing chain and EGR valve. Do you all think it is the one of the two. The car has approximately 92k miles on it.

 

[Aspen500]

Throwing this out there for what it's worth.
Eon's ago I had a '78 Cordoba 360 with ESC (electronic spark control). Ran fine at higher speeds but taking off from a stop it would always kind of "sputter" and miss and even stall sometimes. I never dug into it too much other than going through the carb which made no difference at all, just converted to regular electronic ignition and it ran like a dream. I SUSPECT it was a problem in the ESC module (computer). Now, this car didn't have a feedback carb if I remember correctly, just the spark control. It was 30 years ago when I first bought the car and it's long gone now.

 

[randomguy]

Thanks Aspen 500. I bought a remanufactured computer for it just after buying it. It is a Standard Motor Products one IIRC. Anyways, I still have the factory computer and may give it a shot. One thing I will add is that car has the issue with a load on it. I can shift it into park and it runs fine even when revving it.

 

[Blackbirdsrt78]

timing chain

 

[Aspen500]

There is a way to sort of estimate how loose a timing chain is. Pull the distributor cap and then turn the engine counter clockwise until the rotor starts moving and then go clockwise until it moves again. See how many degrees of rotation is "slop". If it's not that much, probably OK but if you get like 10 degrees (at the crank) or something,,,,,,,,,,,,,,,,,,,,,,,,a chain and sprockets are in your future. If it's still the original timing set it's most likely got a cam gear with nylon teeth and is living on borrowed time (no pun intended) anyways.

 

[randomguy]

I'm going to try to the computer first. I'm still think its a reman'd carb issue though. We'll see.

 

[Blackbirdsrt78]

timing chain bro 92,000 miles....

 

[greymouser7]

timing chain

X2. Imagine the engine (or a bicycle) starting off with a loose chain, which kinda gets tight as the motor begins to wind up the rpm. Also, buy the timing chain tensioner-pushes this maintenance even further down the road.
-------------------

There is a way to sort of estimate how loose a timing chain is... If it's still the original timing set it's most likely got a cam gear with nylon teeth and is living on borrowed time (no pun intended) anyways.

Exactly.

 

[MBDale]

Chain, agreed. Skid that nylon sprocket set up.

 

[Jack Meoff]

Another vote for timing chain.
The computer almost always works fine or quits.
There's rarely a middle ground

 

[randomguy]

Thanks everyone. Well, I swapped the computer back to factory one and I also changed the EGR valve. The car is running much better. Perhaps part of my problem was the factory EGR valve. I guess if I keep the car I'll change the timing chain and add the tensioner.

 

[Aspen500]

Wonder if the reman aftermarket ECU maybe has incorrect programming. What I mean is, maybe it's doing what it's being told to do but that's not the right thing to do.

We have been running into problems on older vehicles that have a drivability problem but all the inputs are exactly what they should be but some outputs are implausible (don't make sense). It's like the computer loses parts of the programming as the years roll by and they just go "stupid", or some of the transistors have failed,,,,,,,,,,,,,,,who really knows. Same applies to body control modules, electrical control modules, etc, etc, etc, etc.............. That right there is why I can't see anyone restoring a 2015 (insert car make and model here) in 25 years. It's what one of the trade magazines calls "zombie cars". You know, they need a brain (and it's made of unobtanium), LOL. Sorry to stray off topic. I tend to do that more than I'd like.

 

[Jack Meoff]

I do know that a clogged or malfunctioning EGR will cause issues. Also......those computers are year specific. If it's not the right one it'll cause issues.

 

[Aspen500]

If the spring in the EGR valve was weak or broken, the exhaust pressure can actually blow it open and give recirculation when the exhaust pressure suddenly spikes, like on take off from a stop. Can also open too soon with too little vacuum pressure and cause a lean surge at cruise even if exhaust pressure can't push it open. Of course, stuck open and idle will be really bad or not at all. Pesky little things!

On the computers, don't forget were talking late 70's/early '80's computer technology and they can only do so much and only so fast. Difference between then and now for electronics is like the difference between "our" cars (F/M/J body) and a 1902 Oldsmobile.

 

[kkritsilas]

I don't know how much of a "computer" there is in the ESA/Lean Burn system. In the 1980s, real CPUs were not cheap, and programmers (now called "developers") weren"t common in the Big 3 automakers. I haven't taken a look at an ESA/Lean Burn controller board (I will when I take mine off) but I wouldn't be surprised to see some hard wired electronics and some GAL/PAL type devices (pre-programmed logic devices that can be used to make up things like "state machines"), which really is all of the logic required in the ESA/Lean Burn system. The model year specific modules sort of points to this, as a computer (what is actually a microcontroller) based ESA controller module would be easy to change over if it were computer based; just swap out the EPROM/PROM (the technology of the 1980s). A hard wired logic or GAL/PAL device would need different modules, as any year to year changes would require the programming of the GAL/PALs to change, which could only be done prior to them being soldered onto the controller PCB.

 

[Jack Meoff]

Just a note.
If it's an 84 Fifth wouldn't the carb be a Holley?
Non feedback was the 2280
Feedback was the 6280.

What these lads are saying sounds totally spot on about the "computers" too. That's why they're year specific and why not just any one will work.

 

[randomguy]

Thank you for the insight. Being an 84, it would have the Carter BBD. Also, the computer I ordered through Advance was a Cardone. I cross-referenced the computer numbers and order the one specified. Now, I looked at the computer and one thing I noticed on the computer is that it had extra pins compared to original one. The other thing I noticed is the reman'd one did not have the foil shield. I think that could attribute since heat and electronics do not mix well unless sealed properly. I think the EGR was a problem too since the factory cats were partially clogged.

 

[Jack Meoff]

You learn something new everyday.
I thought they dropped the BBD earlier.
I have one on my Caravelle and Volare.
Both Super Sixes and non feedback.

 

[Aspen500]

I don't know how much of a "computer" there is in the ESA/Lean Burn system. In the 1980s, real CPUs were not cheap, and programmers (now called "developers") weren"t common in the Big 3 automakers. I haven't taken a look at an ESA/Lean Burn controller board (I will when I take mine off) but I wouldn't be surprised to see some hard wired electronics and some GAL/PAL type devices (pre-programmed logic devices that can be used to make up things like "state machines"), which really is all of the logic required in the ESA/Lean Burn system. The model year specific modules sort of points to this, as a computer (what is actually a microcontroller) based ESA controller module would be easy to change over if it were computer based; just swap out the EPROM/PROM (the technology of the 1980s). A hard wired logic or GAL/PAL device would need different modules, as any year to year changes would require the programming of the GAL/PALs to change, which could only be done prior to them being soldered onto the controller PCB.

Yes, I used the word "computer" loosely! Maybe electronic control unit is more what they really were (are). Amazing how far electronics have come since then.

About the foil shield..........Just thinking out loud here. Is it possibly not a heat shield but more of an RFI shield or am I over thinking it all! lol

 

[Jack Meoff]

Yes, I used the word "computer" loosely! Maybe electronic control unit is more what they really were (are). Amazing how far electronics have come since then.

About the foil shield..........Just thinking out loud here. Is it possibly not a heat shield but more of an RFI shield or am I over thinking it all! lol

I tend to agree with the foil being more of an RFI shield.
I've had one of those computers apart and there's not really enough from what I can see to be an effective heat shield.