[AaronF]

Come to think about it, I have had intermitent problems with my cruise with the truck stopped for the last couple months. The cruise sometimes doesn't turn on at all. Other times the cruise turns on and the idle will increase slowly while holding the switch to the "set" position, but sometimes it will increase a couple hundred rpm and then kick off and return to a regular idle. Other times it will set at say a 1300 rpm setting (for livefloor work) for a period of time of say 1 min to 10 min, then it will kick off back to a normal idle. Other times it works just fine.

Cruise works fine while driving.

If the problem is in the ignition switch, could it also effect the cruise?

 

[AaronF]

5ek75056

 

[AaronF]

Well, after checking several things yesterday, the truck is still throwing the codes and stumbling/dieing.

Yesterday I visually checked all the wiring. Nothing looks wrong with it. All the connectors are secure and tight/clean. I changed the cam position sensor. I checked the circuit breakers, all are tight and connections are good. I checked the "run/ignition" relay, it is working and warm to the touch. If I remove it while the engine is running, I get a code 51, so the problem lies elseware. Battery cables are good/tight/clean on both ends. ECM ground is tight and clean.

Every terminal end that is on the engine control harness has been soldered/shrink wrapped. So I know they all have a good connection.



This morning, the truck fired right up. I set the cruise at 800 rpm and several seconds later it kicked off and returned to a regular idle. After a min or two, I reset it to 800 rpm and it held fine until aprox 3-4 min later the truck started to stumble, recovered, stumbled several times, recovered and then just died alltogether. I reached over and pushed the start button without shutting the key off and back on and it fired right back up, only to stumble and die a few seconds later.

The strange part of it is the order it threw the codes in this time. 72/74/73. :damnit:bash:gaah

 

[AaronF]

Upon further research, the codes 72/73/74 could be for cyl 1 or 2 for code 72 depending on the pid/sid (I don't have a code scanner, so I don't know what it is), 73 for cyl 3/4, and 74 for 5/6.

Most of the stuff I have found points back to the injector harness inside the covers.

Thoughts?

 

[AaronF]

Thanks, but I already have the diagrams.

What is agrivating is the intermittent part of all of this.

 

[AaronF]

sounds like the injector drivers in the ecm are fried your ecm is belly up

If this were the case, wouldn't the engine not run at all?

 

[AaronF]

More info.....

Replaced the main engine harness, and the injector wiring harnes with new ones from Cat.

Installed 3 new ground wires. One from starter ground to ECM stud. One from ECM stud to head (12 inches away). Finally one from Pass side of engine to framerail.

Checked the fuel pressure. Fluttering between 65-70 psi at idle. Engine sputtered and died. Fuel pressure then was fluttering between 45-55 psi. Floored teh throttle and the fuel pressure flutters between 65-80psi, but never goes past 80 psi.

After the engine died, the codes were present, whereas before it was a code 55.

I have to go pickup some fittings so I can make a return hose that is clear to see if there is air in the fuel.


Any new thoughts?


:bdh

 

[AaronF]

Checked the fuel return line for bubbles. Nothing at all. Even when the engine acted up and died.

Each time (out of the last 3 times that it has acted up) that it has acted up, I have removed the circuit breakers that power the ECM. After 15-20 seconds I reinstall them and the truck fires right up and will run for 2-20 min before acting up again.

Monday morning a trip to the locat truck yard is in the plans for another ECM.

beerdrink

 

[AaronF]

My bet is the ECM injector drivers are failing. Looking up the serial number this is a 355 Hp version of the 5EK. You will have to be careful about what ECM you install on this otherwise you could damage the engine. This engine has one piece aluminum pistons and can't take alot of fuel

It has been inamed once, it now has OR8333 packs. I am not sure ifthese are still one peice aluminum pistons or not, do you know or can look it up and what are your thoughts.

What is the CR of these piston packs?

I was planning on getting an ECM that is set at 355 as i know that my local yard has atleast half a dozen.

 

[AaronF]

That is what I figured when it cam to putting a higher hp rated ECM on this engine. Higher hp rated ECM would probably have a shorter pulsewidth, but the matching injectors for the ECM would flow more in that shorter period of time than the injectors that I have now.

According to my local Cat dealer, these packs max out at 355hp, and have a compression ratio of 16:1. I's like to know how they found these numbers if they are not on SIS as I assume that is what you are using Mr. Haney. They probably just looked up the specs of the original packs and told me those specs to make it sound like they had a clue what they were talking about.


Should I shim the releif valve to kick the fuel pressure closer to 78psi at idle? Shouldn't the fuel pressure be closer to 100psi at 1800rpm?

 

[AaronF]

Just a final answer to this thread.

A different ECM, and the truck is running like it should. (atleast as a 355):happydance