Another Engine stumbling Question... - Land Rovers Only

9dawgs · 01-29-2006, 11:36 AM

Hi Guys, I've been working on a few ideas about what would be the cause of this problem. My '99 Discovery 4.0 has had an intermittent problem with stumbling and sometimes stalling but it only occured either at stops or starts. With this in mind and looking on this and other sites for possible fixes I replaced the stepper motor among other things.

Last week I took a quick 5hr trip to Ft.Lauderdale and noticed that along the way at appx. 75MPH it would loose power and stumble for about 10 seconds or so and then pick up speed again. This happened about 3 times during my return trip. When I got back I did a little more research and found that this particular pattern also occurs when the Vehicle Speed Sensor is going bad. Now before I go out and spend the $100 to have one sent to me I'd like the forums 2 cents on this fix.

Does this sound like a possible solution? Thanks for your input.

BTW this is what I've done so far:

New Magnacore 8mm plug wires
New plugs (Bosch Platinum) I know about the controversy here...
Cleaned PCV oil separator
New Stepper Motor

roverX · 01-29-2006, 11:57 AM

When was the last time you changed your fuel filter? I had a similar problem and that solved it. FRAM G3727 should fit and less than 10 bucks...

Rovin4life · 01-29-2006, 12:17 PM

Do you have any codes. It should throw a code.

Also check fuel pressure. it should remain constant at 40 psi. Turn the car off and check to see the fuel pressure doesnt drop.

It should stay around 34 psi.

If it drops you got a problem

roverX · 01-29-2006, 12:31 PM

Beezel, although I respect the fact that you work at a dealer and probably know more about fixing rovers in your pinky than I do in my whole arm, but when mine did this, it didn't throw a code. Based upon the fact that he didn't mention a code being thrown and it was happening intermitently, I think it might be a simplier fix like the fuel filter. Also, if he hasn't changed it in a while, it is a good idea to do that anyway. IMHO, of course.

Hank · 01-29-2006, 02:37 PM

When it's dark out side, pop the hood and see if the plug wires are arcing to metal brackets around the engine. It takes a minute for your eyes to adjust, but just stare at the wires for a few minutes in total darknes.

But, I put my money on carbon build up.....

Do you get a check engine light after a long trip? Does it reset after severl starts? Do you get a mis-fire code?

roverX · 01-29-2006, 02:54 PM

Ooooooo...never thought of a carbon build-up. Good call Dan. Nothing some BG44K can't cure...

Disco Mike · 01-29-2006, 03:14 PM

Quote:

Originally Posted by roverX

Ooooooo...never thought of a carbon build-up. Good call Dan. Nothing some BG44K can't cure...

If you are goit to use the 44K, buy their 3 pack, 44K for the fuel, their t/b cleaner and their induction cleaner. After cleaning the induction cleaner, turn off the engine and let it sit for 1/2 hour, then drive the crap out of it.
Good luck.
Mike J.

Bene · 01-29-2006, 06:06 PM

is that basicly the same stuff as SeaFoam?

wade · 01-29-2006, 06:51 PM

For what it is worth, I have a 97 Disco. Shortly after I bought it, I'd be driving along and at random, it would loose power. I replaced the fuel pump since it was a common problem and the Disco had about 100, 000 miles on it. The problem continued. I replaced the speed sensor and all was fine. (Replacing the speed sensor requires some contortion to get your arm up around the exhaust, over and down and with thumb and forefinger trying to fit and turn a hex screw which goes in at an angle...just so you'll know...)

Hey...if I didn't love this vehicle.......I don't know what it is about them. Maybe like Everest...its the challenge.

DiscoPilot · 01-29-2006, 07:08 PM

Quote:

Originally Posted by Hank

When it's dark out side, pop the hood and see if the plug wires are arcing to metal brackets around the engine. It takes a minute for your eyes to adjust, but just stare at the wires for a few minutes in total darknes.

But, I put my money on carbon build up.....

Do you get a check engine light after a long trip? Does it reset after severl starts? Do you get a mis-fire code?

yeah i always take a windex bottle full of water and spray around. If there is a grounding/arcing problem you'll see its acring around ALOT more than just by itself

9dawgs · 01-30-2006, 06:38 AM

These are all great suggestions. I'll try the fuel filter first as it's the most painless. I haven't replaced it and I'm not sure if the previous owner did. The plug wires are new and unless they are chaffing on some exposed metal I doubt they'll be arcing. I'll check tonight though just to be sure. As for the "check engine" light or any codes, there hasn't been and there isn't any... Just an intermittant problem that's got me scratching my head.

I've heard some comments on the Bosch Platinum plugs. Do they allow carbon buildup because they don't burn as hot as the NGKs? Just wondering. I've also seen in other posts that these engines do get carboned up pretty easy. I've only put 93 octane fuel in it since I bought it and the previous owner did the same to help combat this.

Thanks for all the replies. I'll keep you posted

roverX · 01-30-2006, 08:58 AM

No, those plugs don't do that. I have 50,000 miles on my Bosch plugs. I last ran a bottle of 44K when I did the change out. I am getting ready to do it again just a maintenance.

texasrover · 01-30-2006, 12:45 PM

Speed sensor... Would have been my guess!

Hank · 01-30-2006, 01:41 PM

If it were a seppd sensor, his Speed-o would also go nuts when it's missing.

The 44K stuff won't help, either. This is an exhaust valve problem. Once the carbon is built up, the only cure is to remove the valves and either clean or replace them.

Strange your not getting a mis-fire code, though.

wade · 01-30-2006, 05:05 PM

When my speed sensor was going out, the speedometer acted fine. An easy way to determine if it is the problem is to unhook the wiring going to it. The speedometer will not work, or the odometer, but if you drive around for long enough and don't have the same problem, then it is the speed sensor going out. (it sends feedback to the fuel pump and is supposed to shut it off when there is an indication that the motor is running too fast...not technical jargon, but someone else might explain it better....in short...if the system senses things turning too fast, the fuel pump shuts off temporarily). It doesn't cost anything to unplug it unless you get a speeding ticket.

01-29-2006, 11:36 AM	#1 (permalink)
9dawgs JesusIsLord Join Date: Jun 2005 Location: Tampa, FL Posts: 173 Gallery: 2	Another Engine stumbling Question... Hi Guys, I've been working on a few ideas about what would be the cause of this problem. My '99 Discovery 4.0 has had an intermittent problem with stumbling and sometimes stalling but it only occured either at stops or starts. With this in mind and looking on this and other sites for possible fixes I replaced the stepper motor among other things. Last week I took a quick 5hr trip to Ft.Lauderdale and noticed that along the way at appx. 75MPH it would loose power and stumble for about 10 seconds or so and then pick up speed again. This happened about 3 times during my return trip. When I got back I did a little more research and found that this particular pattern also occurs when the Vehicle Speed Sensor is going bad. Now before I go out and spend the $100 to have one sent to me I'd like the forums 2 cents on this fix. Does this sound like a possible solution? Thanks for your input. BTW this is what I've done so far: New Magnacore 8mm plug wires New plugs (Bosch Platinum) I know about the controversy here... Cleaned PCV oil separator New Stepper Motor __________________ 9dawgs '99 Discovery I '99 Chevy Astro 4X2 w/4" Lift (family truckster) 17' Basstracker w/40HP Mercury 11' Jon Boat w/numerous antique outboards

01-29-2006, 11:57 AM	#2 (permalink)
roverX Elephantitis penisitis Join Date: Apr 2005 Posts: 5,439 Gallery: 0	When was the last time you changed your fuel filter? I had a similar problem and that solved it. FRAM G3727 should fit and less than 10 bucks... __________________ What? Is this where I'm supposed to write some profound statement that boggles the intellect of the genius that you think you are? Why would I waste my time with that when I can be getting free lap dances from your sister AND your girlfriend at the same time?

01-29-2006, 12:31 PM	#4 (permalink)
roverX Elephantitis penisitis Join Date: Apr 2005 Posts: 5,439 Gallery: 0	Beezel, although I respect the fact that you work at a dealer and probably know more about fixing rovers in your pinky than I do in my whole arm, but when mine did this, it didn't throw a code. Based upon the fact that he didn't mention a code being thrown and it was happening intermitently, I think it might be a simplier fix like the fuel filter. Also, if he hasn't changed it in a while, it is a good idea to do that anyway. IMHO, of course. __________________ What? Is this where I'm supposed to write some profound statement that boggles the intellect of the genius that you think you are? Why would I waste my time with that when I can be getting free lap dances from your sister AND your girlfriend at the same time?

01-29-2006, 02:54 PM	#6 (permalink)
roverX Elephantitis penisitis Join Date: Apr 2005 Posts: 5,439 Gallery: 0	Ooooooo...never thought of a carbon build-up. Good call Dan. Nothing some BG44K can't cure... __________________ What? Is this where I'm supposed to write some profound statement that boggles the intellect of the genius that you think you are? Why would I waste my time with that when I can be getting free lap dances from your sister AND your girlfriend at the same time?

01-29-2006, 06:06 PM	#8 (permalink)
Bene Magicly Delicious Join Date: Nov 2005 Location: Phoenix, AZ Posts: 1,030 Gallery: 0	is that basicly the same stuff as SeaFoam? __________________ Kevin Owning a Land Rover is like dating a super model. Sure she has expenive tastes, complains a lot, and requires constant attention... but damn... 1994 Discovery

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01-29-2006, 12:17 PM	#3 (permalink)
Rovin4life Former NAS LR TECH, Current AUS LR TECH Join Date: Oct 2005 Location: DOWN UNDER Posts: 1,691 Gallery: 0	Do you have any codes. It should throw a code. Also check fuel pressure. it should remain constant at 40 psi. Turn the car off and check to see the fuel pressure doesnt drop. It should stay around 34 psi. If it drops you got a problem

01-29-2006, 02:37 PM	#5 (permalink)
Hank Banned Join Date: Feb 2005 Location: VA Posts: 914 Gallery: 0	When it's dark out side, pop the hood and see if the plug wires are arcing to metal brackets around the engine. It takes a minute for your eyes to adjust, but just stare at the wires for a few minutes in total darknes. But, I put my money on carbon build up..... Do you get a check engine light after a long trip? Does it reset after severl starts? Do you get a mis-fire code?

01-29-2006, 06:51 PM	#9 (permalink)
wade Senior Member Join Date: May 2005 Posts: 131 Gallery: 0	Speed Sensor symptoms For what it is worth, I have a 97 Disco. Shortly after I bought it, I'd be driving along and at random, it would loose power. I replaced the fuel pump since it was a common problem and the Disco had about 100, 000 miles on it. The problem continued. I replaced the speed sensor and all was fine. (Replacing the speed sensor requires some contortion to get your arm up around the exhaust, over and down and with thumb and forefinger trying to fit and turn a hex screw which goes in at an angle...just so you'll know...) Hey...if I didn't love this vehicle.......I don't know what it is about them. Maybe like Everest...its the challenge.

01-30-2006, 06:38 AM	#11 (permalink)
9dawgs JesusIsLord Join Date: Jun 2005 Location: Tampa, FL Posts: 173 Gallery: 2	These are all great suggestions. I'll try the fuel filter first as it's the most painless. I haven't replaced it and I'm not sure if the previous owner did. The plug wires are new and unless they are chaffing on some exposed metal I doubt they'll be arcing. I'll check tonight though just to be sure. As for the "check engine" light or any codes, there hasn't been and there isn't any... Just an intermittant problem that's got me scratching my head. I've heard some comments on the Bosch Platinum plugs. Do they allow carbon buildup because they don't burn as hot as the NGKs? Just wondering. I've also seen in other posts that these engines do get carboned up pretty easy. I've only put 93 octane fuel in it since I bought it and the previous owner did the same to help combat this. Thanks for all the replies. I'll keep you posted __________________ 9dawgs '99 Discovery I '99 Chevy Astro 4X2 w/4" Lift (family truckster) 17' Basstracker w/40HP Mercury 11' Jon Boat w/numerous antique outboards

01-30-2006, 08:58 AM	#12 (permalink)
roverX Elephantitis penisitis Join Date: Apr 2005 Posts: 5,439 Gallery: 0	No, those plugs don't do that. I have 50,000 miles on my Bosch plugs. I last ran a bottle of 44K when I did the change out. I am getting ready to do it again just a maintenance. __________________ What? Is this where I'm supposed to write some profound statement that boggles the intellect of the genius that you think you are? Why would I waste my time with that when I can be getting free lap dances from your sister AND your girlfriend at the same time?

01-30-2006, 12:45 PM	#13 (permalink)
texasrover Senior Member Join Date: Dec 2004 Location: Ft. Worth, Texas Posts: 490 Gallery: 0	Speed sensor... Would have been my guess! __________________ That is not a leak! That is undercarriage rust inhibitor. 98 Discovery

01-30-2006, 01:41 PM	#14 (permalink)
Hank Banned Join Date: Feb 2005 Location: VA Posts: 914 Gallery: 0	If it were a seppd sensor, his Speed-o would also go nuts when it's missing. The 44K stuff won't help, either. This is an exhaust valve problem. Once the carbon is built up, the only cure is to remove the valves and either clean or replace them. Strange your not getting a mis-fire code, though.

01-30-2006, 05:05 PM	#15 (permalink)
wade Senior Member Join Date: May 2005 Posts: 131 Gallery: 0	Speed Sensor When my speed sensor was going out, the speedometer acted fine. An easy way to determine if it is the problem is to unhook the wiring going to it. The speedometer will not work, or the odometer, but if you drive around for long enough and don't have the same problem, then it is the speed sensor going out. (it sends feedback to the fuel pump and is supposed to shut it off when there is an indication that the motor is running too fast...not technical jargon, but someone else might explain it better....in short...if the system senses things turning too fast, the fuel pump shuts off temporarily). It doesn't cost anything to unplug it unless you get a speeding ticket.

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