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Discussion Starter #1
I've been noticing some engine hesitation while on the highway with my 95 LWB. It seems to happen around 55 to 70 mph. At first, I thought it would be a clogged fuel filter but the hesitation from that would happen at all speeds, not just highway speeds. I double-checked all my spark plugs, wires, and rotors and all check out o.k.

When keeping the throttle steady, the engine kind of "pulls" and hesitates. I still have good power though and will jump when I press down on the gas pedal.

Then, coming come from work today I noticed the hesitation started right after the transmission shifted from 3rd to 4th, which happens around 55 mph. Ok, I thought, must be a transmission issue. However, all the normal shifts work fine and are normal.

Does anyone have any ideas what would cause this type of engine hesitation after the shift from 3rd to 4th?

Thanks,
James
 

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From my limited experience, could be the fuel pump. My 92 Rover had a tough time accelerating at highway speed. Got a new fuel pump and problem was fixed.
 

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Discussion Starter #5
Just for clarification, do you mean a throttle potentiometer?
 

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Have you checked your OBD error code read-out? My '89 is too old for that really cool feature, but yours has it.

Scott
 

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1995-2002 Range Rover P38A
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Check your data link connector. On the older Classics it's behind the passenger seat (NAS) I think it's behind your passenger facia (dash knee panel?) on 95MY. There's a jumper plug that stays in this connector when it's not used and it can cause what you're describing if the pin/socket contact loosens.
 

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Discussion Starter #9
Thanks for everyone's input. Here is an update:

I don't think it would be a fuel filter or pump, otherwise the condition would happen at all speeds. I did a compression check about 10k miles ago and it was surprisingly good so I'm not too worried about that. It also had a full 120k tune up in the last year or so.

I checked the OBD and there are no codes being displayed.

I looked at the throttle potentiometer (or throttle sensor as the manual describes it) and wiggled it a little bit to make sure it was at least connected. The next day, the condition didn't happen right away but did after a few miles down the road. I may remove and inspect it to make sure all the connections are good.

I will try to check the other connection suggested when I find it in the next few days.

James
 

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here is my 2 cents worth if you haven't alreasy resolved this issue. I was getting a bad hesitation at freeways speeds, but also it wasloosing battery power and wouldn't start if it had been sitting a while. A new 160 amp Bosch Alternator soved the problem, and was under 200 for everything. (I installed it.) hope you get it fixed.
 

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Or..normal lack of power in mid range.,dunno.. I have a tornado chip installed my -92 RR and i am pleased the results..but my RR is little bit modifyed..4.6 engine.. ;)
Rgds:Jukka
 

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Similar hesitation problems, but only after went out to start and looked like battery dead. Disconnected ground and checked battery, was fully charged. Tried to start after reconnecting battery ground and was okay. Turned off and battery light on. After this driving got highway hesitation at speeds above 60mph. Putting in new alternator.
 

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We had symptoms like that a few months ago when an alternator cable disconnected from its cable end inside the insulation blanket. I couldn't see it from the outside, but it was arcing or not conducting at all inside the insulation at the cable end. I resoldered the cable end on, and all has been well since.

So, test the alternator on a test stand before buying a replacement. If the alternator is good, test the cables or look for corrosion at the ends.

Scott
 

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I'd like to semi-hijack this thread as I am suddenly now having an issue. My 92 RR classic is suddenly hesitating.(seems like a missfire almost) at all speeds. Seems to be a little better after warm up, but basically feels like it is going to die on you. accelerating firmly makes it a little better. I have a good battery and a new Bosch 160 amp alternator. any thoughts? plugs/wires/ timing? I pulled off one of the capt wires while replacing the alternator and it was corroded, so maybe that is it and it is simple? Thanks!
 

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To close this loop, I put new spark plugs, wires, cap and rotor, and it seems to have fixed the issue almost completely. I still feel like there is an occasional slight hesitation when driving, but almost imperceptable. It is surprizing how much better it is running now. discernably more power and higher revving and the tranny will even shift down more readily than it did before.
 

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throw me into the mix with replacing the alternator. I had similar hesitation issue resolved by replacement alternator. I also did wires, plugs, cap, rotor and coil-cheap insurance.
 

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ok, I am back. I am still getting some hesitation at higher speeds and especially more pronounced under a load, such as pulling a small trailer or 4 people in the car. so far I have replaced the fuel filter, air cleaner, alternator (Bosch 160), spark plugs, wires, cap, and I ran a tank of injector cleaner through. As well, I cleaned out a completely obstructed PCV flameout preventer, and a new muffler.

one thing I know is wrong, is there is a crack or bad hose or something atop my gas tank, because if I fill it up full it overflows under the car. (A bit of a mess) I am planning on replacing soon. Could this be the cause still? I would really like to get rid of the hesitation, it is almost like a missfire and just jolts the passengers a little. other than that, it never ran better.

Anyone have additional thoughts? thanks a million. Doug
 

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Seattle92RR said:
...there is a crack or bad hose or something atop my gas tank, because if I fill it up full it overflows under the car. (A bit of a mess) I am planning on replacing soon. Could this be the cause still?
Yes, that could completely explain it. It's a vacuum leak, and it will result in unmetered air entering your intake plenum through the vapor recovery hoses. On newer cars a split fuel filler hose or loose cap will trigger a "Check Engine" light on its own. It may be as simple as a loose hose clamp, but it may be a loose or torn hose. Look it over carefully, and if there is any doubt just replace all the hoses and tighten them well.

Your Rover isn't the only one with this sort of problem. We have a variation of this problem. When we top up (doesn't happen much anymore now that topping up is illegal in Oregon) it would fill the vapor separator with raw gasoline and the rig would run poorly for about 40 miles. We used to have to tell every pump jockey to never top it off... just pull the filler out when it clicks off the first time.

Scott
 

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It's a vacuum leak or the vacuum advance, had the same problem on the 4.2 I had in my '91 Classic. Just felt like a little stumble while cruising down the freeway.
 
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