95 Disco, 129k, petrol 3.9, A/C, bought in January with bad motor, history of overheat. Rectified heads, block, gaskets (composite), bearings, valves and one piston which was broken along the 2nd ring. Rodded radiator which was 60% blocked and installed new thermostat (LR part with the wiggly plug on top, 82C).

Mechanic is an OK wrench, but does not know the car or it's systems. Was throwing a 14 on the OBD, parts are scarce here in Costa Rica, but somebody told me a 90 to 92 Nisson Sentra coolant sensor would work. It screwed right in, connected right up, but all of a sudden the engine will stop running, even from 2,000 RPM, somewhat routinely. I ran resistance tests (varying temps of water, all the way to boiling) on the sensor and all the numbers match, it seems to check OK, incidentally, so did the old one I replaced. The motor seems OK when cold, but within 1 mile of the house, when I slow down, it quits like somebody turned off the juice, liquid or electrical, suspect liquid. Cool the motor down for 15 minutes and she starts, but only after I advance the timing a bit. Tomorrow I will switch back to the old sensor and see if the problem duplicates, it should, but we'll see. I've been driving it for a week, intermittently, trying to get a trend and this problem cropped up yesterday. Once yesterday, it also threw a Road Speed Sensor code, (my speedometer does not work). I coasted the remaining 2 miles to my house to allow for a cool down and when I started the engine to complete the last 100 meters, the check engine lite went away as did all the codes. I thought that strange. Could I be having computer problems?

A seemingly unrelated problem is that I have no timing lite to check, but with the timing advanced far enough to start, it "rattles" or pings under load, although it actually sounds more like a rattle or very light pinging, not like any I have heard before. I stop on the side of the road and retard the timing just slightly with the engine running and the pinging will stop when back under load, but then the car does not want to restart when it stalls, specifically when at operating temp.

Thanks for taking the time to help out, I'm kind of stuck here in the mountains until I can get a handle on this thing! Bill Cocobills@yahoo.com

 

Attached is guide to various LR injection systems, includes sensor values.

Next time it does this, check the fuel pressure in the fuel rail - looks like a tire valve. Expect 32-34 PSI. Tire gauge will work. No fuel pressure - look at fuel pump wiring connector for toasted wires. Heat up, open, cool down, reset.

And have spark plug available to plug into a spark cable, lay on mainfold, check for sparks. No sparks suspect ignition amplifier.

 

I always point at the ignition amplifier, because I watched someone toss a bunch of money and parts troubleshooting an RRC. When it would get hot, it would either just shut down, or sometimes it would start misfiring first. So I'm probably a little biased against them.

 

A whacko ignition amp could also have something to do with strange timing shifts, but so could a slack timing chain.

 

perhaps the advance weights are stuck? Or maybe the vacuum advance is busted.

 

Thanks a bunch guys, I'm pretty far in the mountains, but I've been running some checks here in my garage. It's dark now so didn't take it out on the road again, the jungle is not as great place to be stranded at night! Here's what I've done this evening.
1..Re-soldered connections on coolant temp connector, no apparent change.
2..Reset base idle, no change.
3..Disconnected stepper while engine was running nicely, no codes, stopped and started a couple of times, what a relief to start the car without the usual rush to 2500 rpm followed by a "stepped" reduction to around 1000! Why do I even need it? Opinions? Sat there and idled pretty nice with what seemed to be normal throttle response right up to the time (5 minutes) when idle got erratic and died. It does that connected or not, at least it appears that way. Not a lot of consistency that I can lock onto yet, except that it will idle pretty nice up to a point followed by erratic idle and occasional death.
4..Disconnected VSS, no codes, my speedo is inop for unknown reasons and I read on the posts that one guy was running with it disconnected with no apparent ill affects. Opinions? No codes seems strange to me.
5..Disconnected coolant temp sensor, threw a 14 which seemed to indicate a normal sensor. Reconnected, all appears normal there.
Tomorrow I will try the following:
1. Take it on the road till it quits and look for spark.
2. Check fuel pressure before and after it fails. Am I correct in assuming that if fuel pressure is indeed the culprit, the fuel rail should have zero pressure after attempted start? That means I can just carefully punch the valve, if fuel comes out, it's not a pressure problem as long as key is switched to the on position. My tire gauge may be on it's last leg.
3. Check connections at pump irregardless.
In regards to the timing issue, I noted that when the mechanic was building the engine that the timing chain had about a solid inch of slop. He said it was normal! That probably explains the timing problem and might give you an idea of what I'm dealing with here! For all you guys who are helping, remember this. I have a guest house on my ranch, ya'll have a place to stay if you come to CR. Later!

 

One thing I failed to mention is that I disconnected the vacuum line to the fuel pressure regulator (good vacuum present) while the engine was running and noticed only a very slight increase in RPM. Throttle response seemed normal while disconnected and I wondered if it could be acting up. Thoughts anyone?

 

Fuel pressure does not have to be zero for problems, just lower.

Stepper motor controls at idle, not at elevated rpm. Can be cleaned with carb cleaner, and the bore it comes out of. Don't tinker with the pintle end, just squirt it clean. The computer moves it in like 180 steps.

FPR could be a problem and have a mind of its own. But I don't think you have ruled out other things yet. And without a gauge you are just throwing parts at it.

VSS unplugged will certainly kill speedometer, a module in the cluster sends pulse count over to the ECU for other uses. May not throw a code. Some Rover ECUs monitor VSS "speed" and start dropping off cylinders when speed exceeds somthing near 115 mph. It's a Rover, not a BMW, built to leave the Autobahn and make it on the trails. Rebuild on VSS in tech area. Work around is a GPS with "speed over ground".

 

First thing today I located distributor amp, beside coil, and then opened dizzy and found what looked like lousy connections through the base. Pulled magnetic unit out and did some tightening and cleaning on the connector, now I have no spark! 12 vdc at coil with key on, both posts, but no spark on turnover at plug. I am concerned about the air gap, looks adjustable and I had it out of the car. Is there a specific setting for it and how critical is that setting? A little out of my league playing electricion. Bill

 

In the d1 section, first listing is the tech area. Most of the way down is cosmic write up with pix of how to rework the dizzy.