14 CUX Code 34 Troubleshooting - Ideas Wecome

[eliaschristeas]

93 RRC excellent running history. Head service and major service; all new parts. Continued to run great until... engine detail. Ran great for 2 days following THEN:

truck started to run like balls... misses. popps. etc. operating temp not a factor. sometimes truck would come back to life. then re occur.

SO- CODE 34 - RICH/LEAN DRIVERS BANK
no change after basic parts swaps.... checked all spark plugs. 246 & 8 clean combustion. 135 FOULED. 7 clean combustion. INJECTORS all 16 OHM. spark confirmed at all cyl.

injectors 135 replaced. NO CHANGE.

into the wiring diagram, yellow white grounds to RH bank, yellow blue to LH - offending bank. one wire from ECU goes to each bank... then SPLITS OFF IN 4 wires of the same color to each bank. this junction is right behind where the O2 wiring meets the harness respectively. junctions look ok.

we know that 14CUX sprays gas... in 4 cyl. alternatively. RH all 4, LH all 4, RH all 4, LH all 4. The distributor is responsible for "timed fire."

tomorrow... I will replace with new plugs again to confirm 135 specific fault.

the big question IS:

how is 135 offending ONLY when 7 appears ok for the moment... they are all fed by the same yellow/blue lead from the ECU which tells them to ground - aka - spray.

could the yellow/blue from the ECU be damaged? unlikely since 7 appears ok...

SO:
A) - 3 bad injectors swapped in and they are overwhelming the cyl's as were the originals
B) - 3 bad yellow/blue leads to injector plugs grounding constantly
C) - ignition fault... meaning no fire at 135... thus the fouling.... but I HAVE spark at each.


going to sleep on it and attack in the morning. ideas welcome. PT rocking it from afar... thanks man. e

 

[robertf]

It is your ignition, I just went through this. Probably icm, but check everything

 

[az_max]

I'll bet you have a problem with injector #7 as well, since it's not fowling with the other 3.

I have no idea what the original problem is.

 

[eliaschristeas]

It is your ignition, I just went through this. Probably icm, but check everything

icm you mean the AMP? thanks, e


and actually.... what were your symptoms? what was your process? thanks

 

[robertf]

Same as yours, horrible idle, hunting rpm. Code 34.

Im guessing the distributor is either really worn out or the icm/amp is failing.

 

[eliaschristeas]

interesting to me that it would register bank specific since the dizzy services all... but what the heck! lets give it a whirl... will report soon, e

 

[robertf]

thats the only flag I see suggesting its the distributor pickup and not the module.

 

[cosmic88]

I assume you have a diagnostic hook up... can you see what fuel map it is running at during idle and the rough condition?

 

[eliaschristeas]

I assume you have a diagnostic hook up... can you see what fuel map it is running at during idle and the rough condition?

no way to read the 14cux anymore. but interestingly... when I yanked the amp from the distributor the contact grease was burned on the positive side of the pins only. not black... but brown...


changed amps TWICE. both seemed to resolve the problem during start up priming... 30-60 seconds later same thing....


I too suspect the pick up now and will try another dizzy....

 

[eliaschristeas]

rebuilt dizzy. no change. seems to run fine at start up.... then craps out.


looking more closely at o2's and circuits...

 

[robertf]

hmm, well I still think its ignition. so one last suggestion at parts to throw at it before I give up

that burned silicon you saw on the ICM... I've seen the coil arc through the coil wire to the terminals rather than the correct path. If you have replacements on hand I'd give it a shot.

It completely burned through two coils arcing to the - post on the coil on my disco throughout its life, one bosch and one msd.

 

[eliaschristeas]

didn't have too much time to spend... was jamming on a tranny swap... no new information other than injectors 3 & 5 feel like they are doing the humpty dance... touch all the injectors - nothing to feel. touch 3 & 5 and the homunculous is trying to break out of each...


so....


still seems to fire up fine... then slide into shitsville after priming. 02 sockets get 13.8v while running... I will try another set just for fun... but the big question is... the ghost in the machine.... are those power/ground branches compromised and if so would it manifest as im seeing it? meaning the chicken and the egg... 2 bad injectors swapped in where bad injectors were removed or is it wiring... and if so... why not all of them... but anyway...


im not beyond jumping new power/ground wires from the ECU plug just to rule out a break somewhere in the original wires...


will sleep on it...

 

[pdxrovermech]

recently had a fun one just like this. the thing would load up, hunt, and eventually die. swapped out everything but the distributor to no avail. then i decided to pull the vac hose to the fuel regulator and the car ran perfect. Like it was just getting starved for air, but even playing around with the base idle wouldnt affect it.

 

[eliaschristeas]

Okay.... I did it. Lets make this fun.... Ill send a 6-pack of your choice to the first person who can figure out what i did....

 

[cosmic88]

Harness plug, O2's or Brake lamp fluid?

 

[rover4x4]

janky cap and rotor or fuel filter

 

[az_max]

put both spring clamps on the distributor cap

 

[eliaschristeas]

good guess cosmic88! here's the answer and the story.... pm me your addy and Ill figure out how to get beer to ya!


after having swapped in just about a 1 good of everything, I was starting to suspect the crazy.... the upper intake apart... the entire wiring harness exposed for testing and/or rewiring at that point... UNTIL...


put another good runner right next to it. determined to rule out ignition or electrical fuel probs I was going to put the upper intake from the 93 on the other truck... and if the other truck ran fine, then 93 either A) had a crazy wiring problem... of B) an ignition fault... which I would have further ruled out by continued swapping from bad to good truck until the good truck ran like dick. all of that knowing if there was no change in the good truck... with the 93's parts on it... I would definitively have a harness problem, which I would now also have the room to conveniently rewire....


I couldn't let the fact go that this 93 ran like a truck with bad o2's despite not coding... and having put on a "good set."


so right before I tore the whole thing apart, the first swap I did was 93's 02's onto the good truck... and guess what...? the good truck ran just like the 93....


HOLY EFFIN POOPSMACK.


o2's!!!!!


ordered a new set and the rest is history.


there were a few red herrings in this for me... "knowing" that I put on a good set of tester 02's... suspicious of the engine detail a few days prior.... and clearly a shabby LH portion of the injector harness (which is now all freshy freshy anyway).


so while it was nice to revisit the ground floor engineering of the EFI system, never take for granted the "good used parts" you throw on a truck... and I know better.... I typically always go new... don't save anything I didn't run/test first hand.... but hey never say never.


thanks DWEB. PROBLEM SOLVED.