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Still having issues with flashing M&S on startup. Only about one out of ten starts is a successful one with either no M&S light or S lit on dash and that is being generous. When using one of the recommended scan tools from iCarsoft that is for Land Rover/Jaguar I get strange response when scanning A/T ecu. N__MOT invalid (flag F__N__MOT) and I can go ahead and erase whatever code the transmission is bitching about and go on about my daily drive without issue except for an ongoing Knock Sensor circuit 1 input voltage low message on the GM ecu which doesn't come back once cleared. I am pleased one start up out of the day if I have no cel or flashing M&S light. Whatever the issue is it's intermittent. Setup is : New Interstate battery and 150 amp Rover alternator, 2nd new ckps that is bosch, Relay on the two computers that used the switch wire from the swap and a direct positive wire from the battery terminal inside the uderhood fuse box. New MAF on the way for a 4th gear ration incorrect code. Enjoy the power and am getting between 14 and 16mpg just average all around driving so nothing there to complain about but I can't put my wife in it even for a minute by herself and expect her to be able to clear a code which I'm pretty sure is going to happen. I've read all the common issues with the flashing M&S lights and opted for the ACE wire harness support for the underhood portion. .016 gap on the ckps and tach is fine. I know i'm beating a dead horse here and there is likely a ground or power issue somewhere. I am using the stock mesh ground strap to the driver side LS head to firewall and have a ground wire from ecu to firewall plus engine to chassis cable to ground. Speartech LS harness is grounded to the stock LS ground bolt on the back of the engine behind the cam sensor. This is my one and only issue that is keeping me from loving this swap. It has been on an 1800 mile trip out to Taylor Park Co and back and did everything asked of it so it is a proven swap as far as i'm concerned. Just running out of ideas. Trans ECU flaky? XYZ switch flaky? Just continuing to trouble shoot this problem. What other code reader are folks using to read the transmission codes and has anyone else gotten the weird message MOT?
Before you dive into anything else further, check to make sure that your large power wires for your starter and alternator are not near the wiring for the crankshaft position sensor. If the wires for the starter are close the CKP wire or sensor, it can induce a current in the wiring when you engage the starter relay and cause the CKP sensor signal to get erroneous readings.
F_N_MOT is an engine speed (CKP sensor) code. So that is where is issue is.
For CKP wire routing, I’d keep it away from alternator, any large power wires, and coils. I have it running across the top near the fuel rail, down by the throttle body, and back behind the belt.
I will definitely check my gm ckps wiring. I believe it is short on my speartech harness and runs down the back but you may be correct. I've slept since then and it's possible I have it zipped directly to the starter cable. I guess this fault would be passed through the converter box and on to the shift computer and only once in awhile wouldn't cause this fault while starting. New item to check and I hope that I did unwittingly zip my ckps wire to the battery starter cable!!! Thanks for the input!
I will definitely check my gm ckps wiring. I believe it is short on my speartech harness and runs down the back but you may be correct. I've slept since then and it's possible I have it zipped directly to the starter cable. I guess this fault would be passed through the converter box and on to the shift computer and only once in awhile wouldn't cause this fault while starting. New item to check and I hope that I did unwittingly zip my ckps wire to the battery starter cable!!! Thanks for the input!
The Land Rover CKP wiring on the Land Rover harness was the one I was referring to. The GM CKP should have no effect on this. I'd keep the LR CKP wire as far as possible (at least 12 inches from all battery cables).
My rover ckps wiring runs along the top of the fuel rail zip tied and then down between the adapter plate for the alternator and the head with the sheathing pulled over it for heat protection. I need to ring out the wires from the connector to the computer plugs and make sure they are good. Could have a wire with a break in it internally I suppose. Although it ran fine in the 4.6 with the exception of a rod hammering away. LoL
Happy Thanksgiving everyone. Spent a few hours this morning under the dash of the Rover after unplugging the Crank Sensor and jumpering the black and black/yellow wires at the sensor harness plug (body side) and then ringing them at the pins on the ECU end of the harness disconnected with small T pins to extend for my test leads and was successful and feel confident that both wires are sound. Then I jumpered the black/yellow and the pink/black wire at the sensor harness plug (body) and verified continuity of the pink wire so I should have all the signal paths covered. Moved the sensor towards the front of the vehicle with a thin washer under the bracket at the front cover and still have the flashing M&S and the fault N__MOT and some other gibberish. Sets that fault every time I start it and clears and doesnt come back until I shut off and restart the engine. Have switched between two different new crank position sensors and the original bosch unit that was on the 4.6 when it was running. I have always had a tach signal so pretty sure the crank sensor isn't the issue but maybe a different spacing besides .016 and/or maybe not centered fore and aft on the pulse wheel? I'm an aircraft mechanic by trade so this seems like it should be really simple but for some reason i'm not able to grasp what the issue is. All your input has been helpful and I really would like to put this flashing M&S light business to rest for good. Otherwise this is a great engine swap. Once codes are cleared they don't present themselves until next startup. If you are running errands however, this becomes annoying for sure. Side note is the Rover ACE trouble shooting guide says something about the Rover throttle position yellow'green stripe wire being involved with the flashing M&S lights also. Wouldn't think this would cause the N_MOT fault though. Just trying to figure out if the conversion box would have anything at all to do with crank position sensor faults if it was bad. Not seeing any connection .
Happy Thanksgiving everyone. Spent a few hours this morning under the dash of the Rover after unplugging the Crank Sensor and jumpering the black and black/yellow wires at the sensor harness plug (body side) and then ringing them at the pins on the ECU end of the harness disconnected with small T pins to extend for my test leads and was successful and feel confident that both wires are sound. Then I jumpered the black/yellow and the pink/black wire at the sensor harness plug (body) and verified continuity of the pink wire so I should have all the signal paths covered. Moved the sensor towards the front of the vehicle with a thin washer under the bracket at the front cover and still have the flashing M&S and the fault N__MOT and some other gibberish. Sets that fault every time I start it and clears and doesnt come back until I shut off and restart the engine. Have switched between two different new crank position sensors and the original bosch unit that was on the 4.6 when it was running. I have always had a tach signal so pretty sure the crank sensor isn't the issue but maybe a different spacing besides .016 and/or maybe not centered fore and aft on the pulse wheel? I'm an aircraft mechanic by trade so this seems like it should be really simple but for some reason i'm not able to grasp what the issue is. All your input has been helpful and I really would like to put this flashing M&S light business to rest for good. Otherwise this is a great engine swap. Once codes are cleared they don't present themselves until next startup. If you are running errands however, this becomes annoying for sure. Side note is the Rover ACE trouble shooting guide says something about the Rover throttle position yellow'green stripe wire being involved with the flashing M&S lights also. Wouldn't think this would cause the N_MOT fault though. Just trying to figure out if the conversion box would have anything at all to do with crank position sensor faults if it was bad. Not seeing any connection .
F_N_MOT is almost always caused by an engine speed issue (e.g. from the LR crankshaft position sensor circuit). This either can be a problem with the sensor itself, the wheel, the position, or a voltage irregularity. The conversion box with the kit used now does not have to do with that circuit.Since your problem only happens at when you start the engine, it makes me think that the sensor, the wheel, and the position are probably okay, since it works all the time otherwise. That leaves voltage irregularity. These sensors are very susceptible to voltage irregularities and the sheathing from the factory does not seem all that great at blocking things out. Things that can cause issues:
- too few grounds from frame/body to engine block
- running power leads (especially the starter wire) too close to the sensor or its wire
- wire too close to electrically noisy parts (coils, alternators)
- electrical parts going bad (bad battery - voltage being pulled low during start, bad alternator - causing electrical noise)
- running wire in the same loom with higher voltage lines
- bad continuity from ECU pins to harness
I think you should take your CKP wiring out of the loom it is in and separate it. I’d move it around to different routing options and see if that improves. Since it only happens when you start the Disco, I’d double check how your starter power lead runs and move it as far away from the Rover CKP wiring and sensor as possible. I know this can cause issues because I just helped another person troubleshoot the same issue and this was the culprit. Basically, when the power is given to the starter, the large amount of power going through the starter line was creating noise in the close-by CKP wire, but it was fine otherwise when the power to the starter relay was off.
However, it's also possible that you need to change your sensor positioning relative to the wheel. Sometimes the sensor needs to be a little closer, just depends on the particular sensor.
I have developed an option that uses a different sensor in place of the Rover CKP sensor, which is much less sensitive to voltage irregularities and easier to align, but I have not finished testing it fully.
I will detach the ckps from everything else. Currently my positive lead to the starter is zipped to my shielded transmission cooler line that runs to the passenger side connection of the trans cooler. I will unzip the positive cable and re route it as far from the ckps as I can and hopefully it will do the trick. I will post pics of my current setup just so you can check it against known good systems. Thanks again for all the input. No wrong answers for sure.
kent
Over the years been following the AC Engineering updates..website, reading the forum, watching the Lost Cause Ranch videos dozen times or more, LS builds on YouTube. Decided to move forward on the swap and trying to get educated.
My 04 has had a recent transmission rebuild, upgraded drive shafts, lift etc so hopefully is a good candidate for this swap.
- Waterpump - Looks like going to an LS1 pump gives 3/4” space for steam block connection spacer. LS6 pump gives an additional 3/4”. Understand that 1.5 inch spacer will still be needed to line up the pulleys but the design still overall sticks out less by an inch or so. Will this setup work? Is it worth gaining some space forward of fan? Better option be going for electric fan setup?
- Intake Manifold - this would be just for looks. But would like to replace with something like a fabricated intake manifold from Summit racing along with throttle body. Understand that the last thing needed would be for that to move forward at all, since the stock setup is challenging enough to get the Intake hose routed.
- ECU Bracket - lost cause ranch used the GM bracket for this in the area where the SAI Pump etc was located. They had to also fabricate an additional bracket as well. Would like to know what you all used. Off the shelf hardware to avoid fabricating? Different location?
- LS Engine - Seems like a lot of builds leave off emission components. Delete the Knock sensors and install after-market valley pan to seal everything up. Thoughts ? Florida doesn’t have emission checks so I have a little leeway. Does the Rover side of things require anything ?
I deleted evap, cats but retained knock sensors. Speartech harness and ace harness support to help speed the process. Activated the fans in gm ecu with hp tuners software. Used the flex a lite thin puller fan set with a sheet of aluminum that I bent to hook over the top of the radiator and bolt to the frame on the bottom and it clears the stock water pump by an inch or so. The first elbow off the intake is tight.
I retained the EVAP and Cats as they are required in Colorado. Cats are easy but EVAP will be a pain if your Rover uses the "positive pressure" pump system as it's literally the opposite of the system used by GM to test for system leaks (GM uses vacuum to test for leaks).
I ran a Summit radiator with dual electric fans and aluminum shroud. In Florida, I bet you will appreciate the dual fans. You can activate the fans in HP Tuners by changing to discrete fans (versus variable speed) and then removing the speed adjustment (this reduces fan speed above 45mph but, with discrete fans, it ends up turning them off instead of slowing them). There are also in-line thermostats you can get that trigger fans at a specific temperature.
Below are some photos of my set-up if you're interested. Note that I swapped the intake and battery location to retain the factory GM airbox.
11-23-2022, 10:20 AM
