94 4.0 running on 3 cylinder

[Jamie]

HI GUYS, I joined the site after extensive searching, dead end after dead end. so yea I did use the search button.

I am a mechanic but, I do not have a obd1 scan tool to check trim levels.
my story, 2 weeks ago I came across a cool looking little xcab 94 4.0l ranger splash.
while test driving it, it seemed very! sluggish, weak and made a bogging sound on hard accel and had a low but fast-shaking/vibrating idle. I thought hell, I can fix it so I bought it.
on my way home I hit up the part store for
6 bosh double platinum spark plugs, new plug wires and a fuel filter
changed all of that and still have the same problem, maybe clogged cat?
nope gutted that thing, tho it was slightly melted. i have check a dozen times for vacuum leaks and did not find a single one. it has 16hg vacuum I have driven this truck 200 miles like this

CEL is telling me that I am running lean on bank 1, cylinders 1, 2 & 3

next, I ohm out the MAF because people on these forums, and my symptoms it sounded like my problem. the numbers was off slightly, I put a new one on anyways 236,000 miles couldn't hurt to put a new on. NO CHANGE still runs like crap

got out my fuel presser gauge
KOEO 45psi
KOER 32psi
FPR vac disconnected 36psi
these numbers might be on the low side but I don't think FP is bad


got out my compression gauge and started at plug #1
cyl comp. #1 175psi. #4 175psi
cyl comp. #2 175psi #5 175psi
cyl comp #3 175psi. #6 170psi

those numbers look great for a high mileage engine.

remember I have 200 miles on new plugs.
here is where it gets interesting, spark plugs 1, 2 & 3 are clean and white!
spark plugs 4, 5 & 6 are brown and look to be burning right

fuel injectors are all ticking like they are working and a I am absolutely sure its getting spark. that sh!t hurts

I can remove all the plug wires from 1 2 & 3 coil pack and the truck will run the same way, like crap. if I take off just 1 plug wire off of 4, 5 or 6 it will lope and stall

last night i drove 20 miles home and took out my point and shoot temp gun
and checked the temp at my exhaust manifolds, CYL 4,5 & 6
was 500deg. CYL 1, 2 & 3 are around 200deg.

should i pull fuel injectors? can 3 go out at one time? has anyone had this problem?

I will not let this dead end without solving the problem to help others

 

[enjr44]

Well you need spark, fuel and compressed air for a cylinder to fire. From your post the only guess left is fuel. You say half at clean and the other half are normal.

Pull the input to the coil so you get no spark. Crank her over and then pull one of the "clean" plugs. If wet you have fuel, if dry no fuel.

The injection sys on a 94 is batch fire. Don't know which fire in each "batch". But three at a time. There are two wires going to each injector. All six have one color. Three each also have a different color. The computer grounds three at a time on the different colored wire.

 

[Jamie]

Yea unhooked the coil turned it over for about 10 seconds, pulled plugs and they are dry

 

[Jamie]

After listening to all 6 fuel injectors with a stethoscope, the lean side injectors has a slight tick and the 3 on the driver side have a loud tick

Just wondering if the ecm could be the case. Its hard to figure 3 weak injectors just on one side

 

[97RangerXLT]

Check grounds.

Sent from my Samsung Galaxy Note 4 while sitting in my underwear

 

[enjr44]

After listening to all 6 fuel injectors with a stethoscope, the lean side injectors has a slight tick and the 3 on the driver side have a loud tick

Just wondering if the ecm could be the case. Its hard to figure 3 weak injectors just on one side

My guess is the ECM is good. They sort of tend to work or not (however??). Check the common wire back to the ECM (it is the injector ground) or the other one back to the ECM/EEC relay (supplies the 12v DC) . The diagrams below are not for your year; but, you get the idea.

This
http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Enginecontrols4_0_3_0_1of3.JPG

and then this.

http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Enginecontrols4_0_3_0_2of3.JPG

 

[adsm08]

Unless that truck has Cali emissions it should be a batch fire system. That means 3 injectors hit at a time. A wiring problem, particularly on the ground side, or a PCM issue could easily take out a whole bank. If something caused electrical damage to the injectors it is also easy to believe it could wipe out the whole bank.

Bust out the NOID light.

 

[Jamie]

UPDATE *SOLVED*

after hooking a noid light to injectors 1, 2 & 3 it had no power...

replaced ECM with part store reman truck runs on all 6 cylinders!

new issue: it runs pig rich and getting low speed fuel pump circuit failure
and 3/4 shift solenoid circuit code

on the bright side i was surprised at the power this truck has

 

[Andy D]

Oh yeah, The 4.0 in the Rat is its most endearing feature. New and improved is the new, used M5od . I carefully avoided a paper cut when I wrote out the check. The job was a first class tranny swap. The first M5od he got had the same trouble. 2nd was the charm. But it took time. The Rat accepted the transplant. Shifts are way easier too.

 

[Jamie]

I have the auto trans