99 ford ranger 3.0 help

[Nunu]

Hello,

Anyone got any ideas on the problem for my symptoms? I’ve got a 1999 Ranger 3.0 4x4 automatic flex fuel and it seems like the truck is misfiring. When at idle if I hold the rpm around 1200-1800 rpm the engine shakes intensely but fast accelerations and higher rpm’s the truck drives completely smooth. Also when cruising and reaching a higher speed for example 65 mph and the rpm drops as i maintain steady speed it will also begin to shudder until either I let off the gas completely or rev it higher. Also during this engine shake my live data shows that the engine load percentage is extremely high(80%) even though the rpm is in the 2000 range, also during this I discovered my downstream B1S2 O2 sensor is reading very low which means it is running lean? So far I have replaced MAF, cleaned throttle body. Checked for any leaks behind the MAF. Cleaned EGR, tested fuel pressure, swapped fuel filter, spark plugs and wires as well as testing them. There are no codes on obd2 reader and everything else checks out.

Im planning to clean fuel injectors, swap ignition coil, and IAC to see if any of these fix the issue

I’d appreciate any info or tips. Thanks y’all

 

[pjtoledo]

basic stuff, start with a compression test. all plugs out, hold throttle wide open.
check the FF sensor output. those can really screw up the fuel ratios.
double check the coil connections, there are 2 versions of coils and they are numbered differently.
what did the old plugs look like?
do you have access to an IR thermometer? point it at the exhaust runners to see if one is colder.

 

[Nunu]

basic stuff, start with a compression test. all plugs out, hold throttle wide open.
check the FF sensor output. those can really screw up the fuel ratios.
double check the coil connections, there are 2 versions of coils and they are numbered differently.
what did the old plugs look like?
do you have access to an IR thermometer? point it at the exhaust runners to see if one is colder.

Additional information : I decided to run E85 at the beginning of this year but as far as I knew everything in the truck was flex fuel ready. I switched back to regular gas. Fuel trims are also good on my OBD2 reader. All within a difference of 3-4

I’ll conduct a compression test as soon as I can. Same for the ff sensor output.

The old plugs were perfect ie they showed no signs of running lean or rich and recently replaced at the beginning of this year but I wanted to completely rule them out so I swapped them again last week. As for the wires they were breaking apart and sticking to the old spark plugs I think because the engine is running hot. thus I swapped them out.

The exhaust note on the ranger seems okay but this is my first ford so I’m not sure if the extra pressure in the puffs are normal. The temperature of the exhaust when at operating temp is extremely hot. I cannot put my hand up to the exhaust at all.

As for acquiring a IR thermometer I can do that and test the exhaust runners like you said.

 

[pjtoledo]

excessively hot exhaust can be caused by a hot catalytic converter which can be caused by too much unburnt fuel entering the cat.

the Flex fuel sensor is supposed to relay alcohol content to the PCM. when screwed up they can cause the PCM to add way too much fuel.
I had one fail and it dumped so much fuel the engine wouldn't run.
the output is a digital signal, the frequency changes with alcohol content.
I would take a good look at the coil, make sure the numbers printed on the coil match. BTDT

 

[bills4065]

You flex fuel folks have to Google flex fuel alcohol content miscalculation. Depending on your situation your vehicle can run either rich or run lean.Lots of info on you tube on this.Try this one: E85 and driveability by the Garage Gurus.

 

[Nunu]

excessively hot exhaust can be caused by a hot catalytic converter which can be caused by too much unburnt fuel entering the cat.

the Flex fuel sensor is supposed to relay alcohol content to the PCM. when screwed up they can cause the PCM to add way too much fuel.
I had one fail and it dumped so much fuel the engine wouldn't run.
the output is a digital signal, the frequency changes with alcohol content.
I would take a good look at the coil, make sure the numbers printed on the coil match. BTDT

excessively hot exhaust can be caused by a hot catalytic converter which can be caused by too much unburnt fuel entering the cat.

the Flex fuel sensor is supposed to relay alcohol content to the PCM. when screwed up they can cause the PCM to add way too much fuel.
I had one fail and it dumped so much fuel the engine wouldn't run.
the output is a digital signal, the frequency changes with alcohol content.
I would take a good look at the coil, make sure the numbers printed on the coil match. BTDT

Swapped out so many parts today.

IAC, TPS, crankshaft position sensor
DPFE and checked the FFV wiring harness for correct voltage. Pin A is supposed to be at 5V and pin B at 12V. My reads were A : 5.17V and B : 14V and I am no longer running E85. Everything seems to check out and I still have 0 check codes. I pulled a ECU from the yard but I’d need to reprogram a key to get past the theft feature. At this point I’m lost because everything is checking out. One thing for sure is the studdering is very specific to low RPMs and especially when the truck drops rpm when stabilizing at a set speed. When it’s not shaking the truck is running great. One other thing is the studdering seems prefer hot weather IE driving during the day.

 

[Nunu]

You flex fuel folks have to Google flex fuel alcohol content miscalculation. Depending on your situation your vehicle can run either rich or run lean.Lots of info on you tube on this.Try this one: E85 and driveability by the Garage Gurus.

I just tested my FFV wiring harness and it seems to be working fine and I’m leaning on the truck running lean… and thanks for the info, I’ll try that video you recommended.