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Discussion Starter #1
So, I have an 88 Range Rover, 3.5.

It starts after a few cranks, idles (a little bumpy), and when I depress the accelerator, it spools up to 1200-1500 and then bogs out. To bring it back to idle, I need to feather the throttle until it is back.

I have done the following:
plugs,
wires
cap
rotor
coolant sensor
idle air by-pass motor
fuel filter
fuel pump


With all of that, the exact same thing occurs. I have researched the same symptoms, and everybody seems to fix it with the fuel pump...that was my last effort.


Can somebody please guide me. What should I do from here.

Thanks
Jason
 

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Have you checked for air leaks, allowing unmetered air into the engine? Easiest way to check is to spray some wd40 or similar around areas that air could leak into - if the revs rise (due to the wd40 burning in the cylinder) then you can track the leak down. Obviously the downside of this is the whole spraying a combustible oil around the engine thing, but you can do the same thing with water spray, and listen for changes to the revs.
 

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Clogged PCV system, clean from flame trap to hose into plenum. If these hoses are broken or clogged this will give you acceleration problems.
 

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You don't hear of this problem too much these days, but clogged catalytic converters will cause exactly those symptoms. They are obviously too costly too change on a "maybe" so I guess you would have too narrow it down further. Or, if you're friendly with your neighbors you could drop the exhaust and take it for a spin. `)

Dave
 

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Discussion Starter #5
Could it be from a "leaky" valve cover gasket? I do seem to hear a slight hissing sound from front right...There is not much leaking oil anywhere from the engine though...
 

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More likely an intake manifold gasket, than a valve cover gasket.
unmetered air into the mix will throw off the AFR, which could cause the bogging.
 

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Discussion Starter #7
I now can get RPM's with no O2...

Update-

So I took both O2 sensors out...and now the truck will start, idle and accelerate like normal...

Are the O2 sensors junk? Catalytic converters junk? Or what is my next step of action?

Jason
 

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Discussion Starter #9
Another update...

"Cleaned" both O2 sensors and put the right one back in...still ran good, then put the left back in, and seemed to be all good.

It accelerates ok, and drives ok, it can up shift to the passing gear when you floor it...so I dont know what the deal with it was or how long it will last.

Chris, if your around tomorrow or this weekend sometime...you should stop by and give it a spin. Let me know how it compares to yours (acceleration, power, etc). Give me a call tonight.

Thanks for all the help on this board. This is a vast knowledge pool that I think is fantastic!

Until next week when it acts up again.

Jason
 

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Re: I now can get RPM's with no O2...

knie0012 said:
Update-

So I took both O2 sensors out...and now the truck will start, idle and accelerate like normal...

Are the O2 sensors junk? Catalytic converters junk? Or what is my next step of action?

Jason
"Cleaning" an O2 sensor may only solve part of the problem, but the sensors themselves become less sensitive with time, and the mixture richens as a result over time. This aging of the O2 sensors results in fuel economy going from not-so-good to just plain miserable on a Range Rover, and with the EFI light on the catalysts will clog with soot. This is why all manufacturers require replacing O2 sensors between 40,000-60,000 miles. I replaced mine with the same size O2 sensors from a Nissan V-6 pickup for a lot less than the OEM replacements, and it made quite a difference. I got them for about $55 each on-line.

New, high-flow catalytic converters are available that are much smaller than the OEM units. A few years back we had to replace the single cat under our full-size Olds wagon so it would pass the smog test. The local muffler shop came in with the low bid using a generic cat rated for 300 hp V-8 engines (overkill for the wimpy Olds Rocket V-8 in the Custom Cruiser). It weighed all of 15 lbs. and was less than a foot long with huge inlet and outlet pipes. The car passed smog easily afterward, and continued to run fine. The whole job was $200. Two of those little cats would be overkill for a Range Rover, but they would work very nicely. (Yeah, they're not original, and you'll lose points in a concours, but most folks on this forum are more concerned with performance, so keep them in mind.)

Scott
 

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knie0012 said:
Chris, if your around tomorrow or this weekend sometime...you should stop by and give it a spin. Let me know how it compares to yours (acceleration, power, etc). Give me a call tonight.

Allright, Let's Race 8)
glad to hear you got it running better,
i'll call you after work tomorrow.
 
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