94 4.0 engine miss on drivers side

[hundley24]

hey everyone. i have a 94 ranger 4.0 that is missing and running rich on the the drivers side and drivers side only. i put new plugs and wires on it hopeing to cure the miss but it didnt change anything. so i pulled the plugs back out and looked at them and every plug on the drivers side is black. passenger side still looks brand new. i have also put a new o2 sensor on that side, a new fuel filter and cleaned the maf. my engine light is not on. it has a miss all the time but sometimes it worse then others. usually gets worse after you get out of the throttle. if anyone can give me a direction to go id sure appreciate it.

 

[crusin93]

You need to hook up to a diagnostic meter that will show you fuel trims on bank 2.
stft b2-
ltft b2-
Tell us what you read for these two measurements
Then tell us your voltage readings for bank 2 oxygen sensors. Both of them.

 

[hundley24]

im sorry bear with me im not a mechanic by any means but are you talking about a scan tool or doing that thing where you hook the voltage meter into the port with the jumper wire? if so exactly how do i get the readings you are talking about?

 

[crusin93]

Yes, a scan tool with graphing capabilities would be perfect. You'll have to take it somewhere if you are not mechanically inclined. The free scan at auto parts store will not cut it. If I were to guess you may have an exhaust leak before the 02's or an intake leak on bank 2. It is not effecting B1, so spend your time on the drivers side. The computer is richining up the mix on b2 because the 02's are seeing too much oxygen in the exhaust. Second guess would be an electrical problem effecting bank 2 injectors. You'll need a noid light to check for proper injector signal on B2.

 

[hundley24]

i talked to a friend that owns a shop. he said he could get the readings i need but his doesnt do graphs. im going to take it over to him monday and see what i come up with. thanks for info. ill post when i get the results.

 

[crusin93]

Yeah! Hopefully you will get some useful info. Understand, it can be difficult to diagnose FI problems with the vehiche in front of you. Darn near impossible over the internet, but sometimes you get lucky. Let us all know what you find.

 

[hundley24]

the truck runs pretty smooth until you give it gas. when you get out of the throttle is when it really starts to miss out. here are the readings we got.

running "better" the readings are

inj pw1 1.6
inj pw2 1.6
sftrim-1 10 +/-
sftrim-2 10 +/-
o2s1 82mv to 818mv
o2s2 28mv to 47mv
rms around 1300

running with the miss

inj pw1 1.46
inj pw2 3.30
sftrim-1 -23 +/-
sftrim-2 57 +/-
o2s1 965mv to 1013mv
o2s2 2mv
rms around 1000 or less

i already put a new 02 sensor on the drivers side. it was a boush the universal kind. i hope all of this makes sense to you im lost lol.

 

[crusin93]

You have a signal problem with the drivers side o2 sensor. It is most likely a wiring problem as you have already put a new sensor in. The reading above indicate the drivers side trimming rich. 3x as much as the passenger side. You've got a burnt or cracked signal wire comming from that 02 sensor. Dig in the loom and find the problem. look for discoloration or fraying of the insulation. You can do a "wiggle" test with the scanner hooked up to help narrow your search.

 

[hundley24]

i wont be able to use the scanner cause i have to haul the truck 35 miles to get it hooked up lol. but ill dig into the wiring and see what i come up with. i appreciate the help. ill post what i find.

 

[crusin93]

i wont be able to use the scanner cause i have to haul the truck 35 miles to get it hooked up lol. but ill dig into the wiring and see what i come up with. i appreciate the help. ill post what i find.

Look for the obvious first. It may not jump right right out at you, but if a spot in the wire it looks questionable replace it. Make the repair epair least 3" above and below the bad spot. Use solder and heat shrink on all connections here as road stuff will find it's way into a bad repair. In my world, I would use a "fault finder" to quickly locate the bad spot and make the repair. This tool makes quick work of this type of diagnosis. I recomend investing in this tool, if you plan on working on your own vehicles.