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Discussion Starter #1
So I got my Rovergauge setup all ready to go, but....

It's loaded, comes up fine. Plugs in , hit connect, red light flashes, no reading on Rovergauge. I'm still running 13CUX (1988 YM RRC).
Any tips? Everything seems plugged in fine and all. Thinking about going to 14CUX as advised, but it's my understanding I should be able to read a 13CUX ECU with Rovergauge.
Thanks in advance!
 

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So I got my Rovergauge setup all ready to go, but....

It's loaded, comes up fine. Plugs in , hit connect, red light flashes, no reading on Rovergauge. I'm still running 13CUX (1988 YM RRC).
Any tips? Everything seems plugged in fine and all. Thinking about going to 14CUX as advised, but it's my understanding I should be able to read a 13CUX ECU with Rovergauge.
Thanks in advance!
The 13 and 14CU can't normally connect to Roverguage, only the 14CUX. I believe one of the grounds are different on the 14CU vs the X but no clue about the 13CU.
 

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Discussion Starter #5
Update:
Got new speed transducer today. Kind of a pain to install, but what's new...? Test drove it and no difference....dang!
I did bench test it with a drill and an ohmeter and the old one sent out a pulsing resistance while the new one was smooth. Hmmmm.
Current symptoms are:
Starts well, revs thru full RPM range while stationary.
Takes off and accelerates up to around 15-1600 rpm and 15-20 MPH, then starts bucking at a rate of about 2 bucks per second, very cyclically, while under acceleration. Let off and it will quit, try to accelerate and over a certian speed, right at 15-1600 RPM, the bucking starts again.
Pull over, disconnect the speed transducer and it will drive basically fine, but the exhaust smell tells me the fuel mapping has gone very rich.
As stated earlier, I now have Rovergauge, but it is not communicating. Checked install several times, all that seems fine, I get the red flashing light but not the green one. THought about switching to my back-up ECU, but Rover Guru shop seems to have kept it. Dang...!
So at this point I'm going to install Rover gauge in another computer (Windows 7 instead of XP) and see if that changes anything.
Also getting ready to pull the trigger on a 14CUX ECU, especially if anyone will second that move.
Driving my crazy, several dollars at a time....
 

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Rovergauge isn't going to work normally, don't waste your time.

Either it's your O2s, dying MAF, cam, a cracked intake tube or your ECU is just dying.
 

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I would suspect an ECU fault, disconnecting the speed transducer will force it to run a get Home map which is why it’s running rich (cat protection). If you can fit a spare ECU that would be my starting point.




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Discussion Starter #9
I have a 14CUX on order, my hopes for success are high.

I have read that there is a "kill-joy" function in the programming where "if the ground speed exceeds a certain point, the vehicle will cease to accelerate". If this is true, then there is some sort of governor built into the programming that might have gone wonky. Has anyone ever heard of this "kill-joy" function?
 

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I have a 14CUX on order, my hopes for success are high.

I have read that there is a "kill-joy" function in the programming where "if the ground speed exceeds a certain point, the vehicle will cease to accelerate". If this is true, then there is some sort of governor built into the programming that might have gone wonky. Has anyone ever heard of this "kill-joy" function?
yes it does exists and it is on the transducer circuit, if it exceeds 35 mph in low range it cuts 4 odd cylinders and sets misfire codes for cyl's 1,3,5,7.
I have had it fail on high gear while merging on highway or loading engine.
 

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Discussion Starter #11
yes it does exists and it is on the transducer circuit, if it exceeds 35 mph in low range it cuts 4 odd cylinders and sets misfire codes for cyl's 1,3,5,7.
I have had it fail on high gear while merging on highway or loading engine.
What failed and how did you resolve the issue? Speed transducer or did it think it was in low range?

So, where to go from here?
1) speed transducer is good.
2)unplug it and rig travels fine (at least no cutout), so signal is getting to ECU
3)No light on dash to tell rig it's in low range, does the signal to the ecu come from the same switch or is it a different switch? If different, where is it? Perhaps a bad ground at that switch or bad wire/connection??
4) Are we back at a corrupt interpretation of a good signal to the ECU and this is causing the issue? Keeping in mind that this has happened before and I have switched out ECU's with no joy to be had.
 

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I spoke with technical advisor of autologic diagnostics, after much testing and back and forth diagnostics the solution turned to be a defective speed sensor/transducer. unfortunately, they cater to shops only.
I believe up to model year 90 land rover used a resistor the size of a chicklet for emissions purposes, this was based on market. its described in detail on the rave. this has caused issues as well.

call atlantic british, ask to speak with Douglas he is their master technician and advisor, not sure how far his experience extends with older models but he may have a solution.

seems you're covering all your bases and still return to the same issue. is your transducer a good know unit or a new replacement?
the signal wire senses the pulses and based on this interprets speed thus governs the vehicle. the failure, no matter whether hi or low vehicle though it was on low and moving too fast thus would govern speed and engine rpm.

I have a few friends with whom we brainstorm on problem children, let me review all your posts and make notes so I can pick their brains.
may take a little longer but I will get back to you either way, good or not.
 

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Discussion Starter #13
95CLWB,
Thanks for all the replies and input. The transducer is new. I tested it with a drill prior to install and got a smooth increase in ohm readings between the 2 wires as the drill speed increased. I am fairly sure it is fine.
Thanks for talking it up with your brain trust. This one is a real heartburn and makes me want to sell the beast. I keep thinking someone will chime in and say "Hey, that happened to me, this fixed it", but other than the thread where the guy unplugged his transducer from his V8 MG, I can't find any other mention of then causing issues (other than your story of course).
Well, at least we have something to talk about if holiday family conversation turns to politics....
 

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Discussion Starter #14
" the failure, no matter whether hi or low vehicle though it was on low and moving too fast thus would govern speed and engine rpm."
Well, I'm fairly sure the signal is good, and since the transducer seems to be a switch that is operated by a rotating magnet that simply opens and closes, and unpluggin it ceases the bad behavior, I conclude the wiring is OK (a broken wire would be the same as unplugging it, a shorted wire would make the bad behavior continue even with the transducer unplugged...right??)
I keep coming back to bad ECU or bad switch that tells the ECU the rig is in low range.
Odd that it comes in right at 1500 RPM regardless of ground speed, if it's the governor, that's not many RPM to get you out of a mud hole or up that steep trail...
 

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ECU does not care what range you are in. There is nothing telling it. It gets speed from transducer & rpm via coil with the chiclet resistor inline. Have you tested the coil?
 

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Discussion Starter #16
Well, the 14CUX arrived and was installed.
IT'S A CHRISTMAS MIRACLE, THE RIG IS HEALED!!!!
Plugged the new ECU in and hooked up Rovergauge, it immediately began to communicate. Fired right up and idled well. Put the dogs in and we took off and it ran flawlessly. Idle was a bit high, not bad, but a little and i went thru the base idle adjustment procedure twice, but when I fire it up after the initial key on, unplug, key off, wait till click, plug in, key on, unplug, start process and both times I got a very high idle. Maybe the 13CUX system does not like the 13CUX base idle process running a 14CUX ECU. I can live with it.
So what happened, or was happening? I can only presume that the ECU was failing and perhaps the other one was too. Did extended rest reset something? Was it only able to process a limited number of faults (speed transducer, O2's, base idle???) and would go into some extended limp mode? Who knows? For now she's running fine (should be, new plugs, wires, cap, rotor, wires, coil, TPS, O2's, speed transducer, clean MAF, test pipes in lieu of cats, and other assorted special guests).
THANK YOU to all who read, responded, made suggestions, gave it thought and so on. This forum is what brought about the cure and everyone deserves a beer! Come to San Juan Island and I'll buy a round!
 

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The idle should settle down after a few runs once the ecu has adapted and learned what the engine likes. Having been powered down it is effectively reset to base values and will fine tune over time. Incidentally is the stepper motor and air way clean and degunged?

I have come across similar behaviour before, a friends car had a remapped chip on it and at traffic lights it would start cutting out. I flashed a new chip and replaced it now all is well


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ECU does not care what range you are in. There is nothing telling it. It gets speed from transducer & rpm via coil with the chiclet resistor inline. Have you tested the coil?
correct, in fact ecu does not know what range it is. all it knows is that rpms are exceedingly high for given speed thus reducing power on engine by cutting 4 cylinders (I/E 6,000 rpm at 25mph).
the over rpm condition is much easier to achieve while on low range, thus it is when ecu acts according to programming.

the chicklet has nothing to do with speed, it is there for the sole purpose of emission and as stated it varies between markets and if equipped with cats and o2 sensors, just sensors, or to saudi market only no sensors at all.
 

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Doug... glad the new ECU worked out for you!!!

correct, in fact ecu does not know what range it is. all it knows is that rpms are exceedingly high for given speed thus reducing power on engine by cutting 4 cylinders (I/E 6,000 rpm at 25mph).
the over rpm condition is much easier to achieve while on low range, thus it is when ecu acts according to programming.
Well that makes sense.... Thanks
 

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Discussion Starter #20
Final fix of the cutting out/hiccup issue was a bad TPS. I had replaced it w couple years back, and tested it recently, but not thoroughly enough it seems. Installed a new one and problems solved.
Thanks to all who helped and commented!
 
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