Help...My 98 Land Rover Discovery 4.0L won't Accelerate pass 30mph-40mph. I press on Gas pedal it jerks/hesitation, press again same, 3rd time it starts going a little faster with slight muffler poping noise -if I release gas pedal I go back to square A jerks/hesitation. Trouble codes that came out were (P1179, P1177, PO300, PO305, P1316, P1313, P1314,PO420,P1316). I've changed Electric Fuel Pump-New/ New Fuel Filter, added fuel injection cleaner to gas tank, changed spark plugs, changed 3 coil packs, check both catalytic converters. I took off spark plug wire #1 while turned on, you can see spark/fire, did same on all. Did the same to coil pack, you see spark/fire. It turns on fine in park, you can hear good strong motor compression, you press gas you can hear some hesitation, as you start driving the jerking/hesitation begins.

Please give me feedback if this has happen to you?? Is it the cam sensor? crank sensor? maf sensor? fuel pressure regulator? speed sensor? throttle position sensor?

Thanks,

Leo

 

Before more parts are purchased, get a pressure gauge and check the schrader valve on the fuel rail. Should be 32-34 PSI running. Could be fuel pressure regulator, or vac line to it. Schrader valve is on battery side of motor, FPR on opposite side toward the rear. Once you are sure you have good fuel all the time, then start on the sensors.

 

Bad VSS (vehicle speed sensor), it is the speed limiter for the truck, it slows you down by killing spark to the cylinders one at a time, when it fails it kills spark no matter the road speed and almost always under load, i.e. while trying to accelerate.

 

Hello,

Thanks for the quick responses, any help is greatly appreciated!
The fuel pressure is great (LR turns on quick from cold start), all fuel lines are good -no leaks or issues. Is the Vehicle Speed Sensor on Transmission?
Update on codes, I erased the other ones after putting new plugs, fuel pump/filter &
3 coil packs. Current codes: P1313, P0340,P1187,P1179,P0300,P1316...I will be replacing camshaft sensor today.
Any of you know where I can find the Vehicle Speed Sensor inexpensively or do they interchange with other cars/trucks/suvs or range rovers? The new fuel pump I purchased drained my wallet a little, not to mention the rear main seal job 2 months ago or the rod main bearning 3 months ago.

Thanks in advance,

Leo

 

From the RAVE:

Vehicle speed sensor

The vehicle speed sensor is located on the side of the
Transfer box adjacent to the parking brake. The
sensor provides road speed data to the ECM. The
ECM in turn detects vehicle movement from the road
speed input and ensures that idle air control mode is
disengaged. Should the vehicle speed sensor fail in
service the ECM idle air control would become erratic.
The sensor also provides road speed data to the

electric speedometer and cruise control ECU.


If need to purchase consider a number of the web sites and even a dismantler before dealer.

 

I'm not being rude, but I see some problems here.
You claim to have good fuel pressure, but never did check the actual pressure, did you?(just because it's new, doesn't mean all the problems go away)
You keep replacing parts without testing them for faults.
You don't listen and follow the advice given.
And you complain about draining your wallet(which wouldn't happen if you listened to the advice given.)
You have main bearings and rod bearings, but no main rod bearings in the engine.(no worries there, easy to get confused on that)

Download the RAVE, test your components, and report your findings and we can hopefully help you fix it without spending more money than needed.

 

LuckyEagle77,

Sometimes for diagnostic purposes I will pull a decent looking sensor from a salvage truck in the local boneyard, usually dirt cheap. And even with a new pump and filter, you could have bad fuel pressure from the fuel pressure regulator or the vac line to it. Pressure gauge can borrow/rent from auto parts store. Rovers will get expensive if you start buying a new one one part at a time. And I'm so cheap I can squeeze a nickle and make the buffalo jump....

 

Well, its your money, you can do what you want.
I know what I would do and it what order, but here are the parts you seek.

Sensor - Camshaft | Land Rover Engine Parts at RoverParts.com

Speed Sensor / Transducer - Vehicle - Road - Vss | Land Rover Electrical Parts, Batteries, Relays, Lamps & More

 

Hello,

My 98 Land Rover Discovery 4.0 has same problems-turns on fine, once you start driving it doesn't accelerate, the fastest I can go is 50mph after pressing gas pedal on and off. So far, I've changed the following:

Vehicle Speed Sensor
Fuel Regulator
Throttle Position Sensor
Crank Sensor
Cam Sensor
Knock Sensor
Mass Air Flow Sensor
Spark Plugs
Electric Fuel Pump

Does a bad oxgyen sensor cause land rover not to accelerate? I was really betting it was the Throttle Position Sensor or Mass Air Flow Sensor bad, but guess not??Would the vehicle computer be going bad?

 

No the O2's should not cause this, they usually only cause poor mpg.
Yes it could be the computer, you can buy a used one for pretty cheap, just make sure you also buy the alarm computer with the "new" truck computer otherwise it will not start.
You can also remove and open your computer to check for water, if the watertight seal leaks and it gets water inside it it can short out and cause all kinds of problems, remove the water, let it dry, clean it up and put it back.
It is on the passenger fender under the hood.
Just make sure you unhook the battery before you unplug the computer.