99 Ford Ranger 2.5 auto with Pre-ignition and shifting problems unless i reset the computer


dissturbbed

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I have a 1999 Ford Ranger automatic that has pre-ignition problems and shifting problems "skips second gear completely" unless i reset the computer by removing the battery terminal for a few minutes. This clears up the problem for about two to three weeks then gradually the problems come back. I've had this problem for years and have done just about everything including bringing the truck to the dealer and two automotive shops. It doesn't matter if its cold or hot, the problem remains the same.

Things i have done;

Replaced the pcm
Brought truck to dealer "They couldn't find anything wrong and told me to use higher grade gasoline"
replaced o2 sensors
Vss
injectors
Brought the truck to two automotive shops, couldn't find anything cost $160
Scanned with two different obd II scanners
intake air temp sensor
checked timing several times
Mas air flow sensor "twice"
timing belt and tensioner
tps sensor
water pump
replaced the whole EGR system including the DPFE sensor and egr valve
replaced the tranny $$$$
air filter
checked compression all cylinders read 180 +-5
spark plugs, wires, and etc

STuff i haven't replaced

Camshaft position sensor, Reason i havent replaced is that the timing is normal
Engine coolant sensor
 
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RonD

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1999 4cyl will have a 4R44E 4-speed automatic

From 1st, does the RPM go very high before the shift to 3rd, or does it shift to 3rd and lug down?

What if you manually put it in 1st then manually shift to 2nd?


By pre-ignition you mean pinging/knock noise?
That can also be post ignition; after a cylinder ignites there will be a thin coating of fuel left on the surfaces, and this can ignite causing a pressure spike and the 'pinging' noise, called detonation

Does it only ping after its warmed up, or can you get it to ping cold going up a hill(high load)?

Did running 91 or 93 octane eliminate the pinging or just reduce it?
That can tell you if its a heat issue

You have dual spark plugs and dual coil packs
Unplug one coil pack(3 wire connector) and start the engine
Should run OK, no misfires
Now do the same with other coil pack

This will tell you that all 8 spark plugs are working as they should
This engine can run fine with just 4 working spark plug, and it did from 1974 to 1988, lol, it just runs better with dual spark plugs, like any engine would/does, i.e. the Dodge Hemi


You have gone through the usually suspects, EGR being the big one.
The 2.5l was less "pingy" than the 2.3l because it runs lower compression, 9.1:1, 2.3l was 9.4:1

Has any one tested the compression.
Should be about 160psi cold
If it is 170psi or higher then there is a carbon build up issue, which is the cause of the pinging, carbon is a double whammy in that it keeps cylinder hotter and raises compression.
 

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1999 4cyl will have a 4R44E 4-speed automatic

From 1st, does the RPM go very high before the shift to 3rd, or does it shift to 3rd and lug down?

What if you manually put it in 1st then manually shift to 2nd?


By pre-ignition you mean pinging/knock noise?
That can also be post ignition; after a cylinder ignites there will be a thin coating of fuel left on the surfaces, and this can ignite causing a pressure spike and the 'pinging' noise, called detonation

Does it only ping after its warmed up, or can you get it to ping cold going up a hill(high load)?

Did running 91 or 93 octane eliminate the pinging or just reduce it?
That can tell you if its a heat issue

You have dual spark plugs and dual coil packs
Unplug one coil pack(3 wire connector) and start the engine
Should run OK, no misfires
Now do the same with other coil pack

This will tell you that all 8 spark plugs are working as they should
This engine can run fine with just 4 working spark plug, and it did from 1974 to 1988, lol, it just runs better with dual spark plugs, like any engine would/does, i.e. the Dodge Hemi


You have gone through the usually suspects, EGR being the big one.
The 2.5l was less "pingy" than the 2.3l because it runs lower compression, 9.1:1, 2.3l was 9.4:1

Has any one tested the compression.
Should be about 160psi cold
If it is 170psi or higher then there is a carbon build up issue, which is the cause of the pinging, carbon is a double whammy in that it keeps cylinder hotter and raises compression.
Pre ignition happens sporadically it doesnt matter if its cold or hot, clears up after i reset the pcm.. It might be carbon buildup but why clear up after i reset the pcm?

Running higher octane did calm the pre igition down but not eliminate it

Ill run it with one coil pack and get back with the results

I have tested the compression several times. 175 to 180, Tested while it was luke warm everytime. If it was carbon build up why clear up after i reset the pcm?

Yes i can shift manually from first to second
 

RonD

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Run it with one coil pack then switch and run it with the other coil pack, this will tell you if all 8 spark plugs are working and computer is running both coil packs correctly.

In 1995 Ford put the new EEC-V computer in Rangers
From 1995 thru 2001 Ranger computers used the MAF sensor and TPS sensor to calculate engine Load, instead of a barometric pressure sensor(MAP), which was add to the DPFE sensor in 2002 and up
When you reset a computer(unplug it from power) the computer has to reLearn MAF, TPS and barometric pressure settings, until then it runs on pre-programmed settings, which tend to be Richer fuel mixes to be on the safe side, and a different spark advance, less aggressive


If possible I would use a Live Data Reader, to see what "Baro pressure" is when engine is pinging mode, and then check it after a reset of computer and pinging stops for a bit.

Your local airport will have a website to see what barometric pressure is to compare to what computer "thinks" it is
Barometeric pressure can change hourly if a low pressure weather front is moving through your area, if there is a high pressure front(good weather) then its more stable


Your compression is higher than it should be on a cold dry test, so it does read like you have some carbon build up in the cylinders.

I have also read a few posts that said these Lima engines were less pingy using Motorcraft SP432 spark plugs, these are anecdotal posts so grain of salt but Ford did uses these as OEM so..............
 

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Run it with one coil pack then switch and run it with the other coil pack, this will tell you if all 8 spark plugs are working and computer is running both coil packs correctly.

In 1995 Ford put the new EEC-V computer in Rangers
From 1995 thru 2001 Ranger computers used the MAF sensor and TPS sensor to calculate engine Load, instead of a barometric pressure sensor(MAP), which was add to the DPFE sensor in 2002 and up
When you reset a computer(unplug it from power) the computer has to reLearn MAF, TPS and barometric pressure settings, until then it runs on pre-programmed settings, which tend to be Richer fuel mixes to be on the safe side, and a different spark advance, less aggressive


If possible I would use a Live Data Reader, to see what "Baro pressure" is when engine is pinging mode, and then check it after a reset of computer and pinging stops for a bit.

Your local airport will have a website to see what barometric pressure is to compare to what computer "thinks" it is
Barometeric pressure can change hourly if a low pressure weather front is moving through your area, if there is a high pressure front(good weather) then its more stable


Your compression is higher than it should be on a cold dry test, so it does read like you have some carbon build up in the cylinders.

I have also read a few posts that said these Lima engines were less pingy using Motorcraft SP432 spark plugs, these are anecdotal posts so grain of salt but Ford did uses these as OEM so..............
If it is the baro pressure what could i do to fix the problem?
 

RonD

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It would be a long shot if it is, have you checked it?

Its calculated by computer using MAF sensor and throttle position, and I think DPFE sensor before engine is started

Most likely cause with your compression is carbon build up
 


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