1985 4+3 hesitation under load
11-06-2017, 07:19 AM
#21
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hmmm. How would I know it had spun? I replaced the balancer on my other car (that was a crappy job) and would love to not do it again, although I suspect I’m going to have to do it...
11-09-2017, 10:06 AM
#22
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after more driving it is DEFINITELY worse in cold weather. Not at cold engine temps, but cold outside weather. I'm thinking an intake temp sensor or MAF? I have spares of both so might swap.
This is probably why it didn't show up in 90 degree heat when I test drove it, but shows up now in 40 degree weather.
This is probably why it didn't show up in 90 degree heat when I test drove it, but shows up now in 40 degree weather.
11-09-2017, 09:29 PM
#23
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Just thought of a possible issue..... have you very closely examined your spark plugs? I've had a situation like yours where the ceramic insulator was cracked and causing a cold condition miss.... Not saying thats the problem, but might be worth a look....
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Bfenty (11-10-2017)
11-10-2017, 09:07 AM
#26
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You’re right, I started to do that but I could not get the distributor cap off. It’s a bear to reach those two bolts on the back of the distributor cap. Any suggestions on how to get them off without dropping it all down into the engine?
11-10-2017, 09:54 AM
#27
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Yep, they're a bear to get to. Try a short, skinny screwdriver that can clear the firewall lip, or a slotted screwdriver bit (if not magnetic, tape it to the socket) with a 1/4" extension sized to clear the cap, and a rachet. You only need to turn the screws 90 degrees.
The reason I keep coming back to this is simple: Too many times a rough running (or no start, or idle issue, or etc., etc.) symptom is automatically assumed to be a computer or sensor problem. OBDII tends to reinforce this in a way because its diagnostic capabilities are far greater than previous generations. OBDI is not like this. The early generations of OBDI have very simplistic diagnostic capabilities, generally it can only report a sensor failure or system failure by an "out of limits" condition. The OBDI port and scanner will tell you exactly zero about a bad spark plug or wire, cracked dist cap or bad rotor, broken valve spring, vacuum leak, etc.
Simplistic explanation - the "EFI" for the L98 is literally fuel control only. The only control the EFI has over ignition is spark advance. And it can't diagnose anything beyond that. Your ignition system is essentially no different than a '70s or early '80s carbureted vehicle except there is no vacuum advance. So if there is a basic problem, say a cracked distributor cap, the diagnostics can't tell you that. If the cracked distributor cap causes a sensor "out of limit" condition it will throw that code, even though the sensor is only doing it's job. If you think about all you have tried to do so far, checking or replacing most every possible part of the electronics, you've validated that the electronics are doing their job but you've got a mechanical failure outside of the system that is the actual cause.
Just for grins, can you try the following before digging much further? Find a helper, wait til dark (the darker the better!), raise the hood and start the car. Look around the distributor cap, plug wires and plugs for arcing or a blue (bluish) glow. Kick the rpm up while looking. Since you have a manual putting the engine under a load is tougher, but maybe your helper can load the engine (parking brake on, in gear, revs up, slip the clutch enough to load the engine) while you look around the ignition components. If you see arcing or the blue glow that is a failing component and could be (all or) part of your issue. If it all looks good, dig further.
Way back in the age of dinosaurs, I was sent to one of the first factory classes for the Ford EEC IV system (around 1983, I think). They hammered into our brains some simple rules. Rule #1 was assume the computer and EFI system is NOT the problem, something else mechanical is triggering the fault. Rule #2 - refer back to rule #1. They were right!
The reason I keep coming back to this is simple: Too many times a rough running (or no start, or idle issue, or etc., etc.) symptom is automatically assumed to be a computer or sensor problem. OBDII tends to reinforce this in a way because its diagnostic capabilities are far greater than previous generations. OBDI is not like this. The early generations of OBDI have very simplistic diagnostic capabilities, generally it can only report a sensor failure or system failure by an "out of limits" condition. The OBDI port and scanner will tell you exactly zero about a bad spark plug or wire, cracked dist cap or bad rotor, broken valve spring, vacuum leak, etc.
Simplistic explanation - the "EFI" for the L98 is literally fuel control only. The only control the EFI has over ignition is spark advance. And it can't diagnose anything beyond that. Your ignition system is essentially no different than a '70s or early '80s carbureted vehicle except there is no vacuum advance. So if there is a basic problem, say a cracked distributor cap, the diagnostics can't tell you that. If the cracked distributor cap causes a sensor "out of limit" condition it will throw that code, even though the sensor is only doing it's job. If you think about all you have tried to do so far, checking or replacing most every possible part of the electronics, you've validated that the electronics are doing their job but you've got a mechanical failure outside of the system that is the actual cause.
Just for grins, can you try the following before digging much further? Find a helper, wait til dark (the darker the better!), raise the hood and start the car. Look around the distributor cap, plug wires and plugs for arcing or a blue (bluish) glow. Kick the rpm up while looking. Since you have a manual putting the engine under a load is tougher, but maybe your helper can load the engine (parking brake on, in gear, revs up, slip the clutch enough to load the engine) while you look around the ignition components. If you see arcing or the blue glow that is a failing component and could be (all or) part of your issue. If it all looks good, dig further.
Way back in the age of dinosaurs, I was sent to one of the first factory classes for the Ford EEC IV system (around 1983, I think). They hammered into our brains some simple rules. Rule #1 was assume the computer and EFI system is NOT the problem, something else mechanical is triggering the fault. Rule #2 - refer back to rule #1. They were right!
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Bfenty (11-10-2017)
11-10-2017, 10:58 AM
#28
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Yep, they're a bear to get to. Try a short, skinny screwdriver that can clear the firewall lip, or a slotted screwdriver bit (if not magnetic, tape it to the socket) with a 1/4" extension sized to clear the cap, and a rachet. You only need to turn the screws 90 degrees.
The reason I keep coming back to this is simple: Too many times a rough running (or no start, or idle issue, or etc., etc.) symptom is automatically assumed to be a computer or sensor problem. OBDII tends to reinforce this in a way because its diagnostic capabilities are far greater than previous generations. OBDI is not like this. The early generations of OBDI have very simplistic diagnostic capabilities, generally it can only report a sensor failure or system failure by an "out of limits" condition. The OBDI port and scanner will tell you exactly zero about a bad spark plug or wire, cracked dist cap or bad rotor, broken valve spring, vacuum leak, etc.
Simplistic explanation - the "EFI" for the L98 is literally fuel control only. The only control the EFI has over ignition is spark advance. And it can't diagnose anything beyond that. Your ignition system is essentially no different than a '70s or early '80s carbureted vehicle except there is no vacuum advance. So if there is a basic problem, say a cracked distributor cap, the diagnostics can't tell you that. If the cracked distributor cap causes a sensor "out of limit" condition it will throw that code, even though the sensor is only doing it's job. If you think about all you have tried to do so far, checking or replacing most every possible part of the electronics, you've validated that the electronics are doing their job but you've got a mechanical failure outside of the system that is the actual cause.
Just for grins, can you try the following before digging much further? Find a helper, wait til dark (the darker the better!), raise the hood and start the car. Look around the distributor cap, plug wires and plugs for arcing or a blue (bluish) glow. Kick the rpm up while looking. Since you have a manual putting the engine under a load is tougher, but maybe your helper can load the engine (parking brake on, in gear, revs up, slip the clutch enough to load the engine) while you look around the ignition components. If you see arcing or the blue glow that is a failing component and could be (all or) part of your issue. If it all looks good, dig further.
Way back in the age of dinosaurs, I was sent to one of the first factory classes for the Ford EEC IV system (around 1983, I think). They hammered into our brains some simple rules. Rule #1 was assume the computer and EFI system is NOT the problem, something else mechanical is triggering the fault. Rule #2 - refer back to rule #1. They were right!
The reason I keep coming back to this is simple: Too many times a rough running (or no start, or idle issue, or etc., etc.) symptom is automatically assumed to be a computer or sensor problem. OBDII tends to reinforce this in a way because its diagnostic capabilities are far greater than previous generations. OBDI is not like this. The early generations of OBDI have very simplistic diagnostic capabilities, generally it can only report a sensor failure or system failure by an "out of limits" condition. The OBDI port and scanner will tell you exactly zero about a bad spark plug or wire, cracked dist cap or bad rotor, broken valve spring, vacuum leak, etc.
Simplistic explanation - the "EFI" for the L98 is literally fuel control only. The only control the EFI has over ignition is spark advance. And it can't diagnose anything beyond that. Your ignition system is essentially no different than a '70s or early '80s carbureted vehicle except there is no vacuum advance. So if there is a basic problem, say a cracked distributor cap, the diagnostics can't tell you that. If the cracked distributor cap causes a sensor "out of limit" condition it will throw that code, even though the sensor is only doing it's job. If you think about all you have tried to do so far, checking or replacing most every possible part of the electronics, you've validated that the electronics are doing their job but you've got a mechanical failure outside of the system that is the actual cause.
Just for grins, can you try the following before digging much further? Find a helper, wait til dark (the darker the better!), raise the hood and start the car. Look around the distributor cap, plug wires and plugs for arcing or a blue (bluish) glow. Kick the rpm up while looking. Since you have a manual putting the engine under a load is tougher, but maybe your helper can load the engine (parking brake on, in gear, revs up, slip the clutch enough to load the engine) while you look around the ignition components. If you see arcing or the blue glow that is a failing component and could be (all or) part of your issue. If it all looks good, dig further.
Way back in the age of dinosaurs, I was sent to one of the first factory classes for the Ford EEC IV system (around 1983, I think). They hammered into our brains some simple rules. Rule #1 was assume the computer and EFI system is NOT the problem, something else mechanical is triggering the fault. Rule #2 - refer back to rule #1. They were right!
I agree the computer is most likely NOT the issue. If anything, it would be a bad sensor. I've also got a brand new set of AC Delco spark plugs that I'm planning on dropping in this morning as a process of elimination thing. The ones in there look original to the car, they may not be bad, but for $18 I'd like to KNOW that they're not the problem.
I am going to do my best to get into the distributor today. With a 2 month old child my time just gets very limited very quickly sometimes, thanks for all the patience with me on this issue.
The ONLY thing that makes me doubt it's the distributor (or the ignition system at all) is that it is VERY noticeably worse in cold weather. I doubt the ignition system cares what the outside temperature is? so that's what is making me think it might be a sensor issue that is causing the computer to not supply enough fuel to keep up with the more oxygen-dense cold air. I could be way off on that, but it makes sense to me...
Another thing that was floated to me today was a bad EGR valve. Looking up symptoms online, that can cause stuttering if it is stuck closed when it should be open. I thought that would throw a code, though? Quite possibly not, just a thought.
I'll definitely post back as I work through things today. I would really like to solve this, it's really getting on my nerves!
11-10-2017, 11:56 AM
#29
Intermediate
Actually temperature changes are MORE likely to affect non-computer related systems. The whole point of EFI is to provide stable fuel delivery despite changes to air temp, air density, etc.
I don't think the EGR is the culprit. I would look elsewhere way before that. The EGR gets a bad wrap but it's one of the more simple and foolproof gizmos on the engine.
I tried to discern from your previous posts whether you had done any work to the ignition system yet. Other than saying that you had a complete ignition from another car and you've not yet replaced the spark plugs it sounds like no. My .02c is start simple and keep it simple. New plugs, wires, cap, rotor. Check base timing (while cap is off, check distributor bushings!) These are wear items, sensors are not.
I don't think the EGR is the culprit. I would look elsewhere way before that. The EGR gets a bad wrap but it's one of the more simple and foolproof gizmos on the engine.
I tried to discern from your previous posts whether you had done any work to the ignition system yet. Other than saying that you had a complete ignition from another car and you've not yet replaced the spark plugs it sounds like no. My .02c is start simple and keep it simple. New plugs, wires, cap, rotor. Check base timing (while cap is off, check distributor bushings!) These are wear items, sensors are not.
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Bfenty (11-10-2017)
11-10-2017, 12:57 PM
#30
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Fuel pressure is definitely not it. Sat at 36 psi for the whole test drive no matter what I did.
Spark plugs look like garbage. I’m replacing them and then will test. I also replaced intake temp sensor, it looked really bad and covered in soot.
If if that doesn’t fix then new cap and rotor is next.
See below low for the spark plugs condition.
11-10-2017, 09:11 PM
#32
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Bfenty (11-10-2017)
11-10-2017, 09:35 PM
#33
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sigh...for now, I'm just going to enjoy driving the car. She is running very well. I'll check the plugs in a few hundred miles and see if they're getting that kind of build up. My bet is those plugs have been on there a VERY long time-the previous owner doesn't seem like he was much for maintenance beyond the occasional oil change.