98 Disc. Lost of Power Off and On ? - Land Rovers Only

supremei · 01-17-2005, 09:12 AM

New to the board ,

I have a 98 Disc. for eight months now. When I first got it, it ran fine, then after a month it would hesitate off and on the HWY it would drop about 500 rpm and jump back up again ever 1/4 mile. Checked under the hood I notice that vacuum line on the valve cover breather was bad so I replace both, problem went away. Great ! A few months went bye and again some problem this time I removed the little plastic part thats in the valve cover breather hole and removed the carbon build up on it. Ha problem went away. Well now its back again and checked everything I did before and it's not working. The truck seems to run fine in park and I hold the rpm high no hesitation at all, but anytime I drive over 30 it starts up again. Any advise out there ? Thanks

Disco · 01-17-2005, 04:14 PM

Could be a number of things. Check your fuel filter as this could be semi clogged with crud, especially if you have run the fuel in your tank low. if the fuel filter checks out ok, you should have a look at your spark plug leads as they could be on the way out.
Lets know how you make out.

Tirewall · 02-14-2005, 08:15 AM

Supremei,

I have a '97 Disco that is hesitating on and off and it only happens after I have been on the hwy for 25 minutes or so...Have you diagnosed your problem yet?

Thanks,

Tirewall

LANDY96 · 02-14-2005, 10:07 AM

Try unplugging speed sensor, you will lose your speedometer, odometer, but it should tell you if that is the problem. As far as both of you, like me, I have a 96, these have the adaptive memory on the computer. If you have changed the air flow inside the engine, this will change the fuel/air mixture. The computer cannot re-learn the new mixture. You may have to get the adaptive memory purged. This WAS my problem, WITH the speed sensor. The cost was $75.00 at my independant Rover Tech. Feel free to contact me if you have further questions.

Tirewall · 02-14-2005, 10:41 AM

Landy96, the first time it happened, i lost my speedometer for a few seconds...would this support the bad VSS diagnosis?

Thanks,

Tirewall

LANDY96 · 02-14-2005, 12:27 PM

That is pretty much a dead giveaway!! They cost about $100.00 I got mine at roverconnection.com

Tirewall · 02-21-2005, 10:44 AM

Landy96 and supremei,

Turns out it was my Vehicle Speed Sensor (Speedometer Transducer). Took no time to change.

Thanks,

Tirewall

disco96 · 03-01-2005, 12:16 AM

I been having same problem going to try to remove speedo and see if it helps. but I havent noticed my speedo droping or anything when it happens it just kinda stays where its at,.

LANDY96 · 03-02-2005, 02:02 PM

My Speedo never changed either. Sometimes, if it is real bad, the speedo will jump up and down. I had thought about this some time last year. Since the speedo didn't jump around I had dismissed it. Did more checking, and just decided to unplug it for a while. What do you know, it worked. Good luck

01-17-2005, 09:12 AM	#1 (permalink)
supremei Member Join Date: Jan 2005 Posts: 1 Gallery: 0	98 Disc. Lost of Power Off and On ? New to the board , I have a 98 Disc. for eight months now. When I first got it, it ran fine, then after a month it would hesitate off and on the HWY it would drop about 500 rpm and jump back up again ever 1/4 mile. Checked under the hood I notice that vacuum line on the valve cover breather was bad so I replace both, problem went away. Great ! A few months went bye and again some problem this time I removed the little plastic part thats in the valve cover breather hole and removed the carbon build up on it. Ha problem went away. Well now its back again and checked everything I did before and it's not working. The truck seems to run fine in park and I hold the rpm high no hesitation at all, but anytime I drive over 30 it starts up again. Any advise out there ? Thanks

01-17-2005, 04:14 PM	#2 (permalink)
Disco Super Moderator Join Date: Dec 2004 Posts: 1,819 Gallery: 0	Could be a number of things. Check your fuel filter as this could be semi clogged with crud, especially if you have run the fuel in your tank low. if the fuel filter checks out ok, you should have a look at your spark plug leads as they could be on the way out. Lets know how you make out. __________________ No hand signals, driver playing with his transfer Knob.

02-14-2005, 08:15 AM	#3 (permalink)
Tirewall Member Join Date: Feb 2005 Location: Litchfield, CT Posts: 7 Gallery: 0	Power On/Off Supremei, I have a '97 Disco that is hesitating on and off and it only happens after I have been on the hwy for 25 minutes or so...Have you diagnosed your problem yet? Thanks, Tirewall

02-14-2005, 10:07 AM	#4 (permalink)
LANDY96 Senior Member Join Date: Jan 2005 Location: Beaumont, Texas Posts: 782 Gallery: 0	Try unplugging speed sensor, you will lose your speedometer, odometer, but it should tell you if that is the problem. As far as both of you, like me, I have a 96, these have the adaptive memory on the computer. If you have changed the air flow inside the engine, this will change the fuel/air mixture. The computer cannot re-learn the new mixture. You may have to get the adaptive memory purged. This WAS my problem, WITH the speed sensor. The cost was $75.00 at my independant Rover Tech. Feel free to contact me if you have further questions. __________________ Eric The Red 93 Range Rover Classic We will never "arrive" so the goal is to keep moving forward on our journey so we can periodically declare, "I am not what I want to be, but I am not what I used to be!" 96 DISCO SE7 5-SPEED SOLD ....okay couldn't live without a disco! 96 DISCO SD 5-SPEED -ARB Bumper -OME 2" Lift -2" spacers -Safari snorkel -15" steelies

02-14-2005, 10:41 AM	#5 (permalink)
Tirewall Member Join Date: Feb 2005 Location: Litchfield, CT Posts: 7 Gallery: 0	loss of power Landy96, the first time it happened, i lost my speedometer for a few seconds...would this support the bad VSS diagnosis? Thanks, Tirewall

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02-14-2005, 12:27 PM	#6 (permalink)
LANDY96 Senior Member Join Date: Jan 2005 Location: Beaumont, Texas Posts: 782 Gallery: 0	That is pretty much a dead giveaway!! They cost about $100.00 I got mine at roverconnection.com __________________ Eric The Red 93 Range Rover Classic We will never "arrive" so the goal is to keep moving forward on our journey so we can periodically declare, "I am not what I want to be, but I am not what I used to be!" 96 DISCO SE7 5-SPEED SOLD ....okay couldn't live without a disco! 96 DISCO SD 5-SPEED -ARB Bumper -OME 2" Lift -2" spacers -Safari snorkel -15" steelies

02-21-2005, 10:44 AM	#7 (permalink)
Tirewall Member Join Date: Feb 2005 Location: Litchfield, CT Posts: 7 Gallery: 0	Loss of power on and off Landy96 and supremei, Turns out it was my Vehicle Speed Sensor (Speedometer Transducer). Took no time to change. Thanks, Tirewall

03-01-2005, 12:16 AM	#8 (permalink)
disco96 Member Join Date: Jan 2005 Location: Calif, USA Posts: 64 Gallery: 0	I been having same problem going to try to remove speedo and see if it helps. but I havent noticed my speedo droping or anything when it happens it just kinda stays where its at,. __________________ Stock '96 Disco v8 100k Miles Upgrades: Optima Yellowtop Battery Switched to synthetic engine & power steering fluid. Garmin 176 GPS CB

03-02-2005, 02:02 PM	#9 (permalink)
LANDY96 Senior Member Join Date: Jan 2005 Location: Beaumont, Texas Posts: 782 Gallery: 0	My Speedo never changed either. Sometimes, if it is real bad, the speedo will jump up and down. I had thought about this some time last year. Since the speedo didn't jump around I had dismissed it. Did more checking, and just decided to unplug it for a while. What do you know, it worked. Good luck __________________ Eric The Red 93 Range Rover Classic We will never "arrive" so the goal is to keep moving forward on our journey so we can periodically declare, "I am not what I want to be, but I am not what I used to be!" 96 DISCO SE7 5-SPEED SOLD ....okay couldn't live without a disco! 96 DISCO SD 5-SPEED -ARB Bumper -OME 2" Lift -2" spacers -Safari snorkel -15" steelies

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