Dead RRC... Again

MountainD

Technical Excellence Contributor
Intermittant issues are the WORST! I remember someone convinced me a fuel pump was either good or bad and never intermittent. Finally when I got around to replacing tons of parts with seemingly intermittent success, I replaced it— but not before accumulating a ton of spare parts and tons of wasted time. But finally, success. For 3 days. Fuck. Fuel pumps are the worst part imho to change out. But wasn’t it. (And yes, the ABSOLUTELY can be intermittent as that has also happened to me). My point is that I was randomly replacing and buying parts that I thought were suspect for no other reason than a guess. There are tests for just about everything, but when it’s intermittent it compounds the difficulty. The fact that it won’t start after it dies gives you a great opportunity for some quick trouble shooting to try and solve it.

Ive been breaking down in rovers for 2 decades and I’ve spent a lot of money on random parts and then invested a lot less on a few troubleshooting tools. I now try and change only what I know is wrong, although I admit I’ve still made mistakes. a good multimeter is the cheapest and most helpful tool I have. But I also have a fuel pressure tester, a block tester (fluid is a must, but I also have a leak down tester), Cylinder pressure tester, an in-line spark plug tester and a workshop manual and a 14CUx diagnostic manual. Best, and most important to all, I know basic systems and how to go about diagnosing them.

This is a great resource: http://www.britishv8.org/articles/rover-14cux-efi.htm

This also has good info: https://landroverforums.com/forum/a...nagement-manual-1314cu_14cux_systems-info.pdf

This one has helped me on my RRC to learn how to diagnose components: https://www.landroverweb.com/Pdf-files/Manuals/Range-Rover-Manual-Fuel-Injection.pdf. (Your model may vary—not sure your year).

get the free rovegauge software and make a cable. This takes about it: https://discoweb.org/index.php?threads/14cux-diagnostic-software-libcomm14cux-rovergauge.79207/

i learned the difference between “its gotta be the...” and “it is...”

in the above situation, it was my ignition switch which separated causing intermittent random power loss, but I’ve also had a similar instance where the truck would idle fine and then die if I gave it gas. I replaced everything, finally convincing myself it was the cam, and changed it out. It wasn’t. That turned out to be a small white plastic washer/spacer thing under the rotor in the distributor had disintegrated.

Compression, spark, fuel.

something is out of spec. When it isn’t starting be ready to check spark (I always start there). Toss an in-line spark checker ($10) and learn the difference between a weak spark and a strong spark. Know how to diagnose your coil and check the voltage both under ignition on and ignition start conditions (diagnoses switch). Know how to use an inline fuel pressure checker on the fuel rail (or better yet if you have a Shrader valve on the rail!) and know your operating pressures. With those three 5 minutes tests, you have narrowed down significantly on where to check next. know how to check for vacuum leaks, timing issues, etc. nothing on these trucks is that hard to figure out.

There are tests for every component that I know of. Come Up with a routine of process of elimination— start big and narrow down. As you go, learn what components also DO. Try and find info on symptoms of a failed fuel temp sensor, coolant sensor, whatever. Can I put it in a limp mode, does that help? Try and learn the function and the test— it will help a ton! If you are confused on how to test something, just ask, but try and read up a little first. The above links will help. Personally I hate 13CU/14CU/14CUX systems— I’ve spent way too much time on them, lol.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I would suspect the coolant temp sensor. If you unplug it, it will run fine.

I have not done anything except to unplug the temp sensor to the ECU. so far so good, but only one drive so I may have gotten lucky.
If this keeps up, I assume it means that sender is bad. Is this the same thing that I have on top of my 300tdi that I don’t have plugged into anything? Can someone explain why a bad sender might cause the engine to shut down like this?
 

jymmiejamz

Founding Member
Callsign: KN4JHI
Can someone explain why a bad sender might cause the engine to shut down like this?

Usually when they fail they read super low (sub zero temperatures) which causes the fuel injection ECU to go full rich. This causes the engine to flood. In a 14CUX system the temp sensor defaults to 95F, so that's why unplugging it works.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I’m letting the truck cool, then I’ll try another drive. I guess my idea that it has something to do with the temp the ECU sees not being correct, was on the right track, just that I had no idea why! But maybe I’ll get some luck here and actually have a simple fix.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Baffled.

I've done three drives now without having any issues. In fact, even the high RPMs that I sometimes get seem to have gone away. So here's me thinking I might just keep driving it today and tomorrow, letting it cool to full cold between cycles in order to try to replicate my previous problems, but that I might as well take a look at the on board diagnostics display to see if anything shows. With the coolant temp unplugged, I am getting #14, which seems normal. but what is not normal is that there is no 14CUX plugged into this vehicle.

It's supposed to be plugged into the big set of cables with the giant connector under the right seat, correct? Nothing there. Empty.
 

Napalm00

Technical Excellence Contributor
Some days I think it would be easier on these trucks to just swap them to Holly sniper systems and be done with it
 

jymmiejamz

Founding Member
Callsign: KN4JHI
Some days I think it would be easier on these trucks to just swap them to Holly sniper systems and be done with it

I think a large part of the problem with 14CUX is that no one actually diagnoses the fault and starts by throwing parts of questionable quality at it which introduces more variables when you try to actually diagnose the issue.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Or they just remove it.
If you’d have asked me, I’d have guessed that the vehicle would not run, or not run very well at all without the computer. And where is the code coming from?
 

luckyjoe

Well-known member
Callsign: KD2PXL
Baffled... but what is not normal is that there is no 14CUX plugged into this vehicle.

It's supposed to be plugged into the big set of cables with the giant connector under the right seat, correct? Nothing there. Empty.

The 1995 RRC 14cux ECM is not below the seat, it is located behind the RH footwell kick panel, higher up toward the glovebox.

10821
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Yep! I just found that out today. I was looking at the pre-95' stuff because that's pretty much the only thing that pops up when you just do an internet search. The empty slot I was seeing was the air suspension control. Had me confused!

Going to be ordering a new sender. It seems like my ECU is working correctly. Next stop is trying to figure out if the knock is coming from the back left of the engine, or if it really is bell housing/transmission related.... hummmm......
 

rocky

NAS-ROW Addict
Do you have a spare good 14CUX that you can swap in? Only ask because after getting weird as sh*t erratic readings on my truck, I swapped in a another one and bingo, the intermittent start in cold or wet weather disappeared.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
The vehicle is probably a 6 or 7 out of 10. It is salvagable in many ways. The stepper motor is newish, not sure about the TPS.

I think it would be cool to do an EV conversion. But.... yeah. This isn't an off roader, this is my cold weather commuter, and something to drive when I need to work on the Defender. I'm hoping to preserve it for posterity.
 

blueboy

Well-known member
Throttle position sensor replacement certainly helped smooth out the idle on my ‘94 Rangie. It still freaks out sometimes and after restarting it, idles fine.
 
Top