The latest show-stopper: dies at idle, only runs above 2K rpm

[jaherring]

The next chapter in my D-90 saga began yesterday. I've only had it driving me to work for a bit over a week after getting it running on all 8 cylinders (bad fuel injector) and fixing an electrical fault that prevented the starter from engaging (besides all the other problems I've fixed: brakes down to metal-on-metal, exhaust completely shot, springs and shocks shot, clutch fan shot and causing overheating, belts looked like old twine...man did I get shafted on this "ready to be a daily driver take it across country" truck). I keep mentioning this mess I've got myself into as a warning to anyone considering buying 'sight unseen' with a local non-gearhead doing an inspection for you... I'd sell it myself and get a different one if I could do so with a clear conscience...

So yesterday I drove it to work 20 miles just fine, and then at lunch again everything was OK. However, the way home from work I was lucky to get it home. I noticed once I was on the interstate that when I was at a low RPM range in 5th gear the engine seemed to be 'bucking' a bit and momentarily cutting out. I downshifted to 4th and everything seemed OK, but then as traffic slowed and my RPMs dipped below 2500 it started bucking again.. in fact, the lower the RPMs, the worse it ran. I decided to pull off the interstate and it died on the exit ramp.

It would not start at first. Finally I managed to get it to start by playing with the accelerator as I cranked the started, but it sputtered furiously at low RPMs and I had to keep the idle somewhere above 2K to keep it running. With GREAT effort and a several more very badly timed stalls I got it home (the friendly Los Angeles commuters continuously showed their support for my dilemma).

I tried it again this morning and it had the same symptoms - being cold or hot it does not keep running. It will sometimes fire up and run for a few seconds, then sputter, hesitate and die. Other times it dies immediately or won't fire up at all.

I looked through the forums and didn't see anything exactly like this problem - similar issues mention fuel pump, ignition module, fuel filter, and stepper motor, but nothing seems an exact match to my symptoms.

As for fuel contaminants, I have only filled it up three times since buying it one month ago. However, each time I've ran it nearly dry, so if there was sediment in the tank I'd think it would have been a problem earlier. I am sitting just above 1/2 tank now. I don't think it's the fuel pump - I hear it come on and, if it was bad, why would the truck run better at high RPMs? I recently inspected the plug wires (when I did the fuel injector and replaced plugs) and replaced the rotor. The cap was OK, I just scraped a bit of corrosion off the contacts on the inside of the cap (and NAPA couldn't get me a replacement anyway). It shouldn't be the timing/advance system, as that should get worse with higher RPM if it wasn't advancing. My new exhaust shouldn't be the problem, since a plugged system should be worse at higher RPMs also...though I hope the O2 sensors weren't damaged during the exhaust install - they cut the factory exhaust just aft of the O2s and welded in new pipe.

I haven't checked the ECU codes since I didn't know how until reading the forums last night (no owners' manual). I'm going to start with a fuel filter replacement and try to blow out the fuel lines if the fuel filter seems cruddy on the inside - heck, it looks like a factory filter.

I thought I'd ask here before going beyond the fuel filter/lines to see if anyone has a suggestion. The engine has 82K miles on it, if that means anything to someone. I'll check the codes tonight.

[Abrooks]

TPS might be worth a try . . .

[Mike Hippert]

Check codes, report back:cool:

[waveridin1959]

Mine was actiong the same way. Ending up being a dirty stepper motor. When it started to act up again it turned up being mud caked in the ECU and corrosion on the terminals.

[evilfij]

Ok,

If there is a check engine light check code.

If not, you need to try the normal patches. Pull MAF wire, improvement? If not, clean and remove stepper. Next you are on to ignition. Crack in cap, bad rotor, bad module etc. The list goes on but this is about 90%

Ron

[redrover]

Hi Jason could be a bazillion things. But has your truck been fitted with a ignition module relocation kit? There is a tiny amount of info in the FAQ section / engine. I know alot of 94 owners who went this route. Check your plugs /wires / and distibutor cap. CHeck your ECU under pass seat for bad connection at plug/use contact cleaner. I wouldnt think steppor would cause stall between1000 and 2000rpm. Maybe change fuel filter-its easy and cheap. Welcome to the wonderful world of rover cluelessness and money draining. JP

[waveridin1959]

When it was dying on me was when I put the clutch in and RPM's fell below 2000. It would sputter and die. One day it finally quit and wouldn't start. Chris Cox came out to my rescue and it started up and never did it again. Stepper motor just needed cleaning. For a while I had to adjust my idle to keep it running in traffic.

[Seriesman]

Jason,

I have a friend who works at the office on our vehicle fleet. He is a certified mechanic and total gearhead (his newest acquisition is a Pinzgaur (sp?)). In any event, if you get really stuck maybe we could meet up and arrange to have him look at it. He found a problem with my Series 3 carb/intake manifold in 60 seconds that I, and about 10 other mechanics, could not figure out for over 3 years....although the system it totally different between the two vehicles the symptoms were similar. My Series 3 now goes 75 on the freeway, which is an ?@#!! miracle. Call me back on the cell if you are interested and I will see if he is available.

Michael

[jaherring]

Tonight's update: I replaced the fuel filter, and there was no noticeable change. The old filter seemed kindof blocked when I blew through it, but the engine had same symptoms when I fired it up with the new filter.

Next, I took out the stepper motor. I sprayed it down with solvent, wiped it off, sprayed it down, etc. It was fully retracted, so I thought I'd start the engine with it out to see if it actually moved (maybe I could clean the shaft, etc). I put my hand over the hole the stepper came out of and the engine ran smooth but at high RPM. The stepper started poking itself out of it's hole during this time until I think it was fully extended. I turned off the engine, cleaned it, and realized that the "plunger" unscrewed so I did so and cleaned it again. I soaked this thing quite a bit. Then I screwed the shaft back into the stepper housing...it there some kind of adjustment involved here? It did not seem to immediately retract. I turned on the engine for a brief moment again and it came back in a bit more.

I then replaced the stepper and it started up and ran somewhat better - it didn't die. BUT, it still runs rough at idle (rpm varies) and has poor response when coming off idle (almost as if the advance wasn't working on the distributor). I put vaccuum on the distributor by sucking on the hose and it increased the RPM, so the distributor advance is working. I sprayed solvent down the distributor vacuum fitting on the intake. All of this made no difference, of course.

Maybe I need a new stepper motor? How much more can you clean it besides what I've done?

As for error codes, looking at the digital display I don't see anything. Is there something special that I have to do to make it display the codes, or do they just happen naturally? Is there a self-test to force it to display *something*? On my older Dodge I would have to key the ignition three times to get the codes to display...

@brian,
I'll check the ECU terminals and if corroded, clean them and apply some dielectric grease.

@ron,
No check engine light and no visible codes. I will try the MAF wire. Messing with the stepper seems to have improved something, though. Should I just soak this thing in solvent overnight?

@jp,
I don't think the ignition module is near the coil, so does that mean it's been relocated? I didn't think this was the problem because I had symptoms even when completely cold.

@michael,
I'll keep that as my next option if I don't have this sorted out in a few days. It was running so good and smooth right up until it didn't....

Thanks for all the replies....

[Quimbola]

I was having close to the same problem, anything under 2500 rpm it would die, had to rev the heck out of it to go anywhere. It turned out to be the coil.

Hope this helps.

[jaherring]

Josh,
Coil huh? That's an easy one to replace & not too expensive -- anyone have recommendations on an aftermarket coil? Accel super coil? MSD? I'll put a new set of plug wires on it at the same time if I can find a set locally...but I'll probably have to order them. It has a new rotor, but NAPA couldn't get a new cap for me - they couldn't even special order it...

[Seriesman]

Jason,

You should be able to get a new cap, coil and the ignition wires from British Pacific without waiting--they have all of that in stock in their Santa Clarita store. Let me know if I can help you out on that one--I live right next to their office.

Michael

[Quimbola]

Yah the coil, tried the stepper motor, cap was fine, as were wires, also some tangent on the intake plenum. But it was the coil, hope yours is as easy!

-Josh

[Davis]

Just FYI, a relocated ignition module is by the coil. Normally this is the little rectangular thin box that is connected to the side of the distributor body opposite the vaccum advance mechanism. It has a single plug on the side and a three fork plug on top. If it has been relocated, there will be a wire from the distributor to over by the coal where this little black box is located (connected to a heat sink). There will be a similar "dummy" box connected to the distributor where the old one used to be before relocation. Some people have spent a couple hundred bucks on some kit, but you could easily build one yourself for about $10.

[jaherring]

OK, I tried the coil and that didn't fix the problem. I pulled out the MAF wire as Ron suggested and it did in fact run a little better.... so, that means something is wrong with the stepper motor? I took the stepper motor out and I'm soaking it in a mild cleaning solvent. Is there any other way to clean it, or should I replace it?

Since I disconnected the MAF sensor I'm getting a "check engine" light and a code of "12" - so I guess I know that the diag system works anyway....

Chris, there isn't any box near the coil or anywhere else I can see, so it must not have the relocation kit installed. I'll go ahead and move it from the distributor - pretty sure I can fabricate something....it sounds like something I need to do regardless..

[jaherring]

HELP!

OK, I put in a nearly-sterilized (soaked overnight in alcohol) stepper motor back on yesterday and there was no improvement.

Things I have done:

1) replaced fuel filter and blown out line to tank
2) cleaned stepper
3) replaced coil (and put original back when there was no improvement)
4) added fuel system cleaner
5) pulled MAF wire and noticed idle improvement (did not drive it like this)

Suggested things I have not yet done:

1) relocated the ignition module (problems exist cold - should I replace it?)
2) replaced plug wires or cap
3) replaced stepper motor
4) blown out fuel lines forward of the fuel filter (only aft - but the filter looked pretty good inside)
5) anything with the ECU
6) driven it off a cliff and collected insurance money

Any suggestions? Leaning towards #6...

[Abrooks]

again, try subbing in a known good TPS. Went through the same thing.

[jaherring]

Ah, forgot that one... OK, I'll try that. Thanks.

[jaherring]

In case anyone is wondering, a new stepper motor or a new TPS is about $250 each from Land Rover. Complete highway robbery if you ask me. I bought a couple used ones from a junkyard for a not-cheap $50 each. These are pretty simple pieces of technology, but when they have you over a barrel...

I'll install them tonight and see what happens..

[jaherring]

OK, I've replaced the TPS - twice - and it's not gotten any better. I'm about ready to tow it to a mechanic, because now it's basically immobile in my driveway.

Here is what I've done with the beast lately: I swapped in a different stepper motor - no change: it starts and runs poorly, dies after awhile.

I went to swap in a junkyard TPS when I realized it's a different connector. The guy at the yard said "splice the wires in" so I did it. In this configuration it wouldn't start at all - it did backfire a bit though. I put the original TPS back in and it fired right up! It ran really pretty good - though not perfect, just a few flat spots around 1500-2000rpm but driveable. OK, I thought, the TPS must be the problem - maybe a loose connection, or it was somehow dirty. I took it off again and soaked it in electrical contact cleaner overnight.

I put it on the next day and it wouldn't start at all.

I went to the junkyard and exchanged the incorrect part with the correct part (well, the correct connector and color wires) and it's exactly the same: won't start, sputters now and again. However, I notice a strong fuel smell as if it's getting far too much fuel.

I'm ready to give up.

[Doug]

Put it on a flat bed to Eddie Bostock in Irvine -- West Coast Rovers. Either that or buy or borrow a used ECU (any will work from around the same year disco or defender) and try it. Just unplug and exchange.

Eddie knows defenders cold. 949) 768-3777

[jaherring]

One of my next questions was going to be a recommendation for a good, fast and cheap LR mechanic (pick any two) in the LA area.

I did forget to mention that I disconnected/reconnected the ECU to see if there was any difference in performance or signs of corrosion... and there was not (though it did clear the error code I generated when I disconnected the MAF sensor). I don't know where I could find used ECU to swap in... the junkyard is not very accomodating in this area...

[Doug]

Eddie would probably have one around the yard. Any 94 or 95 Disco for sure would be fine to swap with for testing.

I bought a 95 disco ecu from roverlandparts.com in Florida for $250 a while back. Worked fine in my rig. You need a "14CU" or "14CUX" ecu. Triumphs and a bunch of other cars have 'em too.

Trust Eddie. He's done lots of work for me and he's a smart, honest guy.

DW

[Mike Hippert]

Hey if you bring it in don't forget to post what he finds wrong!

[jaherring]

I talked to Eddie at West Coast Rovers & I'm going to try to get the truck there this weekend. Seems like a nice guy. I'll let you know what he finds...

[evilfij]

pulled MAF wire and noticed idle improvement (did not drive it like this)

DRIVE IT LIKE THAT!

It gives an open loop mode and basically narrows it down to something electrical.

It may even start if you disconnect it.

[dante18]

I agree with Doug. Swap out the ECU with a known working unit. My 94 has had this dilema more than once. The symptoms you describe are almost spot on. On the 94's the ECU is just in a bad location, seems to be susceptible to moisture. Good luck.

[evilfij]

I have a spare if you want to try it. Disco chipped and ready to go.

Pay for it, try it, if it does not work just cover shipping and I will give you your money back.

[jaherring]

I took the truck to West Coat Rover -- well, I had it flatbedded there -- on Friday morning. Eddie said he has a spare to swap in & would be looking at it today sometime. Besides, now I can get in and out of the garage as it's not blocking the driveway anymore :)

Ron, if it turns out that the problem is the ECU I may buy it from you (depending on what WCR wants for a used one).

[evilfij]

Sure, you can buy it.

[mbreuer]

oh man after reading i was hoping to reach a resolution on the bottom of page two as i am having similar problems w/my '94 d90 - stalls at low RPM, shuddering/popping around 1000-2000 rpm, end even problems starting after a good rain (but not snow) jason - hope i can borrow your resolution...

[Wolfeie]

I've had similar symptoms in the past. Changing the coil worked for me once. Changing the stepper motor worked once along with cleaning out the "T" fitting (didn't read that you did that - "stearlize" it too).


Latest fix for similar symptoms that worked for me was changing the Fuel Temperature Sender and the Engine Coolant Temperature Sender.

PS - the shop manual has a ohm-meter check for the TPS...

[jaherring]

My resolution was a pretty unlikely one - the brand-new rotor I had purchased for the truck was in fact bad. I purchased it at NAPA and it was defective new from the box.

Along those lines, for the same symptom again I'd check the rotor, cap, coil wire and coil. And, just because you replaced one of those items, don't assume it's any good! That was the most expensive rotor I ever purchased...

[Wolfeie]

Now that you mention it - I've had the bad rotor too - been there!

I did teach me a great troubleshooting technique for a bad rotor.

Remove Dist cap and a coil wire from center of cap. Hold cap end, not touching but close over top center of rotor. Crank. If Spark then bad rotor. No spark, rotor is ok.

[Davis]

There is a way to check the rotor--you take off the cap, hold the high tension lead above the rotor (I think 3mm) and crank the engine--if you have sparking, you have a bad rotor.