| Author |
Message |
    
M.J. (Kekule)
| | Posted on Friday, March 15, 2002 - 04:54 pm: | 
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My 97 Discovery (81000 miles)is experiencing sputtering and engine vibration at all speeds especially uphill. Check engine light also came on. Could this be caused by bad o2 sensor, vss, or do i have valve problems? I know it's hard to diagnose with just a description, so what I am really saying is could a bad o2 sensor really make your truck run this bad? I know the sensors should be replaced around 80000 miles. Just trying to check the cheap remedies before i fork over $2500. |
olered
| | Posted on Friday, March 15, 2002 - 04:57 pm: |
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I'm experiencing the same thing. Refer to the "vibration" seed on the tech issues section. |
Randall Smith
| | Posted on Friday, March 15, 2002 - 05:28 pm: |
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O2 and VSS sensors definately not the problem. The O2 sensor wouldn't cause any drivability problems evn if you unplugged them. If the VSS was faulty then most likely your speedometer and cruise control would be malfuntioning as well.
Randall |
PerroneFord
| | Posted on Friday, March 15, 2002 - 06:34 pm: |
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How about a fuel filter? |
jec
| | Posted on Friday, March 15, 2002 - 06:57 pm: |
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How about having someone read the code from the check engine light? That should give a hint. Also, were the 97s still subject to valve problems, or was it only the earlier models? On our 95, the valves manifested themselves as an intermittent, but frequent, cutout at highway speed (like you feel when the cruise control kicks on and off to maintain speed); and on severe uphills, a loss of about 25% power and engine noise a little like jake brakes being engaged.
Good luck
John |
Kyle
| | Posted on Friday, March 15, 2002 - 07:20 pm: |
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Could be the valves , wires or plugs.... Any of those would be worse under load...
Kyle |
james
| | Posted on Friday, March 15, 2002 - 07:33 pm: |
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John/Jec,
I have a 95 disco with 167,000 miles. I have had very few problems but I am begining to experience a problem similiar to what you stated above. At a constant highway speed, just keeping my foot on the pedal to maintain speed, the truck all of a sudden feels like I take my foot off the pedal and the RPM drops a little. When I push on the pedal, everything is fine and the truck accelerates as normal. Any clue??? |
JEspelien (Superj)
| | Posted on Friday, March 15, 2002 - 08:01 pm: |
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Boy Kyle is right I have a hell of time holding a steady speed when I have a load of NUDERs in the disco! Sometimes you can also experience swerving or even rocking from side to side Sorry Kyle I just couldn't resist such a tempting freudian slip. |
Carl Muckenhirn (Carlmuck)
| | Posted on Friday, March 15, 2002 - 08:28 pm: |
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I've got a late '96 (same engine as the '97) and had severe drivability problems, turns out the right cat was clogged, plus a hole in the down tube from the manifold to the cat. The front right o2 sensor is a real pain to un-plug, so I did the next best thing, simply cut the wires at the sensor (I've got a replacement that went in to the new cats). Interesting thing happened, drivability cleared right up. The cat problem (or maybe the o2 sensor) was causing the right bank to run very lean (never richer than 0% trim, almost always at -8% or higher). Cutting the sensor put the engine into "open loop" and the engine ran much better (trim on the right bank stayed at +24% (oh yeah!)). Having replaced the cats now with high flow units and the muffler with an edelbrock one, it runs great, and sounds much better.
I disagree that a bad o2 sensor couldn't cause this, but as usual YMMV.
carl. |
Carl Muckenhirn (Carlmuck)
| | Posted on Friday, March 15, 2002 - 08:51 pm: |
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MJ, I just re-read your message, who's going to hit you up for $2500 to do the o2 sensors? Its about $1000 for the sensors from Rover (about $500 mailorder, or about 350 if you use the nissan sensors and salvage the plugs from you old ones) and about and 1.5 hours work (according to the shop manual). So i guess you dealer charges $1K/hr for service wow!!
carl. |
M.J. (Kekule)
| | Posted on Friday, March 15, 2002 - 09:10 pm: |
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2500 for a valve job, not sensors |
Randall Smith
| | Posted on Friday, March 15, 2002 - 11:56 pm: |
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M.J.
You could try disconnecting the O2 sensors to see if that makes the engine run better. If the engine runs good without the sensors making corrections to the fueling then that would indicate replace them.
Sometimes the O2 sensors detect major problems upstream such as vacuum leaks, irratic ignition, or the dreaded sticking exhaust valve. When a sensor detects a problem the light turns on on the dash. A problem with the wiring will also turn on the light.
The exhaust valve sticking is unique to the American market and affects 96-98 4.0 engines. Using regular gasoline and slow driving will aggravate the problem. The ultimate solution is to reprogram the computer.
Randall |
Alyssa
| | Posted on Saturday, March 16, 2002 - 01:27 pm: |
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Checking the codes is really well worth it. It will tell you if it's an O2 sensor, a valve, misfire, blown head gasket, whatever. Check all your plug wires, make sure you've been using premium fuel, and floor it to clear out the gunk every once in a while. Have you ever overheated your engine? And, from personal experience, an 02 sensor can cause those symptoms. Unfortunately, there is a good chance that it needs a valve job. |
Anonymous
| | Posted on Saturday, March 16, 2002 - 01:31 pm: |
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Would be possible to check for codes on a 99D1? |
Alyssa
| | Posted on Saturday, March 16, 2002 - 01:32 pm: |
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oops. The codes won't tell you all those things, especially not the head gasket bit. I've got a massive head cold. I got a little confused. :-) |
jec
| | Posted on Saturday, March 16, 2002 - 02:25 pm: |
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James:
With our valve misfire at highway speed, there was no noticeable rpm drop on the tach - just something we could barely feel (driver and passenger both). With 167k on your truck, I wouldn't know what to say to start looking at - but wow! it gives me hope that ours will keep chugging along.
Anon:
codes can be checked on a 99 either by the dealer or another shop equipped with an OBD II scan tool or by yourself with a scan tool (search the previous posts for "OBD II"
John |
Anonymous
| | Posted on Saturday, March 16, 2002 - 07:30 pm: |
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I HAVE GOOD IDEA.
HOW ABOUT BRINGING IT TO SOME ONE WHO KNOWS HOW TO CHECK IT OUT PROPERLY? OR SHOULD WE TRY TO FIX IT USING YUGO PARTS AND JUST COMPLAIN THE CAR AND THE MECHANIC IS TOO EXPENSIVE..
HINT:IF YOU COMPLAIN PRICE IS TOO MUCH.
BUY A CHEVY |
Scott Hayes (Scott_H)
| | Posted on Saturday, March 16, 2002 - 07:42 pm: |
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thanks for that enlightened response anon.
MJ
Same thing happened to me. I found out it was a plug wire that was broken in the boot. It was almost touching so it would work when I floored it...cause the spark would jump further. I replaced the plug wire and it went away.
Good luck |
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