Hey folks. Trying to help my friend with a 2000 Grand Marquis, but we're both kind of stumped, and neither of us are particularly "bad at cars"...so we're hoping there's someone out there who might have some thoughts.
History:
Approx 10L of old stale fuel was recovered from a running vehicle that was having some work done on it.
That old stale fuel was put in the 2000. The source vehicle ran without issues but the gas was old and smelled bad.
Later that day, but not immediately, the 2000 began showing mild misfire symptoms while driving. An intermittent flashing CEL began during this time, but it would not consistently flash even when the car was misfiring aggressively.
Decided to dilute the bad gas, filled tank with premium.
Drove car from gas station to shop (workplace) with no change in symptoms.
Car was parked for a few hours.
When leaving, car started, but had difficulty idling. It was revved a bit to try to warm it up quicker and clear the misfire. All 4 cats were glowing within a couple minutes of this (not surprising given running condition).
Drove car home, found it was misfiring in extreme ways causing significant reduction in power. Max speed the car would reach was about 60kmh. Violent misfires jerking whole car.
Car has mostly been parked for a few weeks since then. The battery has run flat and been disconnected multiple times, which has not appeared to cause any change in behaviour.
Problem has worsened to the point that the engine is very hesitant to start at all. When/if it does, it sounds to me like it has bad ignition AND cam timing (combustion is happening at totally wrong times), and it does not respond to throttle input, including WOT, at all.
If the MAF is unplugged, the car will start every time, but still hesitantly, and still runs like it is out of time, but will respond to throttle input and will hesitantly rev.
It usually does not show a CEL (flashing OR solid). It has to be running for a relatively long time before the CEL will give any sort of output, but it will be running terribly the whole time leading up to that.
Car showed codes for misfires on 2 cylinders, we don't recall which ones at this point, also a MAF code while MAF is unplugged, but no MAF code while MAF is connected.
Injector spray pattern was unscientifically studied by lifting the fuel rail and injectors with engine running. 2 injectors on right side bank had bad spray pattern but all were cycling open/closed and flowing fuel.
All coils changed - no change. Cheap Amazon parts used because we figured even if they are garbage parts, they should at least change the issue if we find the problem part.
Plugs changed - no change. Cheapest copper plug that the part store computer said would fit the car. The plugs that came out looked awful, but we believe that was an "effect", not a "cause" in this situation.
Drained all fuel and refilled with premium - no change.
Tested fuel pressure - it makes about 35PSI on first prime and sustains 35-40PSI while engine is running, so we know there is no fuel flow issue.
Changed all 4 injectors on right side bank which is where 2 of the misfires were - no change. Cheap Amazon parts again, for same reason as coils. Even crappy parts should have changed the symptoms.
Cleaned the MAF - no change.
Changed MAF with a technically incompatible one (mostly but not quite) from a different Ford vehicle - no change.
Pulled the PCM. Found water sealed inside the connector.
Used MAF cleaner to clean and dry out the connector.
Opened the PCM. Found these units contain only two electrolytic caps, the others are ceramics. One of the caps, the larger one closer to the connector, does have a bulged top but it is not split open and hasn't leaked.
No burn damage or any obvious faults besides the one cap.
We are at a loss at this point. I do not believe it's a fuel system issue anymore despite the fact the symptoms appeared the same day as giving the car questionable gas. It seems to just have been coincidence.
I have been trying to figure out if there is a way to make it run at "base timing" because I think that will tell us useful information, but it seems the EEC-V cars do not offer that - am I missing something?
PCM is very suspect and we are trying to borrow one to try (actually trying to pick up a whole second 2000 for parts-swapping adventures). We don't have shop manuals for this car unfortunately, and all of mine are of course for boxes.
Any thoughts, please?
History:
Approx 10L of old stale fuel was recovered from a running vehicle that was having some work done on it.
That old stale fuel was put in the 2000. The source vehicle ran without issues but the gas was old and smelled bad.
Later that day, but not immediately, the 2000 began showing mild misfire symptoms while driving. An intermittent flashing CEL began during this time, but it would not consistently flash even when the car was misfiring aggressively.
Decided to dilute the bad gas, filled tank with premium.
Drove car from gas station to shop (workplace) with no change in symptoms.
Car was parked for a few hours.
When leaving, car started, but had difficulty idling. It was revved a bit to try to warm it up quicker and clear the misfire. All 4 cats were glowing within a couple minutes of this (not surprising given running condition).
Drove car home, found it was misfiring in extreme ways causing significant reduction in power. Max speed the car would reach was about 60kmh. Violent misfires jerking whole car.
Car has mostly been parked for a few weeks since then. The battery has run flat and been disconnected multiple times, which has not appeared to cause any change in behaviour.
Problem has worsened to the point that the engine is very hesitant to start at all. When/if it does, it sounds to me like it has bad ignition AND cam timing (combustion is happening at totally wrong times), and it does not respond to throttle input, including WOT, at all.
If the MAF is unplugged, the car will start every time, but still hesitantly, and still runs like it is out of time, but will respond to throttle input and will hesitantly rev.
It usually does not show a CEL (flashing OR solid). It has to be running for a relatively long time before the CEL will give any sort of output, but it will be running terribly the whole time leading up to that.
Car showed codes for misfires on 2 cylinders, we don't recall which ones at this point, also a MAF code while MAF is unplugged, but no MAF code while MAF is connected.
Injector spray pattern was unscientifically studied by lifting the fuel rail and injectors with engine running. 2 injectors on right side bank had bad spray pattern but all were cycling open/closed and flowing fuel.
All coils changed - no change. Cheap Amazon parts used because we figured even if they are garbage parts, they should at least change the issue if we find the problem part.
Plugs changed - no change. Cheapest copper plug that the part store computer said would fit the car. The plugs that came out looked awful, but we believe that was an "effect", not a "cause" in this situation.
Drained all fuel and refilled with premium - no change.
Tested fuel pressure - it makes about 35PSI on first prime and sustains 35-40PSI while engine is running, so we know there is no fuel flow issue.
Changed all 4 injectors on right side bank which is where 2 of the misfires were - no change. Cheap Amazon parts again, for same reason as coils. Even crappy parts should have changed the symptoms.
Cleaned the MAF - no change.
Changed MAF with a technically incompatible one (mostly but not quite) from a different Ford vehicle - no change.
Pulled the PCM. Found water sealed inside the connector.
Used MAF cleaner to clean and dry out the connector.
Opened the PCM. Found these units contain only two electrolytic caps, the others are ceramics. One of the caps, the larger one closer to the connector, does have a bulged top but it is not split open and hasn't leaked.
No burn damage or any obvious faults besides the one cap.
We are at a loss at this point. I do not believe it's a fuel system issue anymore despite the fact the symptoms appeared the same day as giving the car questionable gas. It seems to just have been coincidence.
I have been trying to figure out if there is a way to make it run at "base timing" because I think that will tell us useful information, but it seems the EEC-V cars do not offer that - am I missing something?
PCM is very suspect and we are trying to borrow one to try (actually trying to pick up a whole second 2000 for parts-swapping adventures). We don't have shop manuals for this car unfortunately, and all of mine are of course for boxes.
Any thoughts, please?
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