Why is my truck doing this?

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Author Message   Greg French (Gregfrench) Posted on Saturday, January 18, 2003 - 08:33 pm:    Whenever I accelerate, it acts as if I have water in the distributor...Shakes and sputters and the lot. 97 Disco, so no distributor. No water lately. Ceck engine light not on. It idles fine. Anybody know? Thanks   Chad Meyer (Ccdm3) Posted on Saturday, January 18, 2003 - 08:56 pm:    What speeds. Mine does this at highway speeds and it is the VSS. I have a new one on the way from dicountrovers. Chad   Greg French (Gregfrench) Posted on Saturday, January 18, 2003 - 09:13 pm:    No...I have a bad VSS too, but this is different. It started Thursday night on my way home, but only in 1st gear when I was taking off. Now it does it whenever I shift or accelerate (5-speed)   Rover God Posted on Saturday, January 18, 2003 - 10:06 pm:    it does it because its a Rover and wants attention   muskyman Posted on Saturday, January 18, 2003 - 10:27 pm:    greg, start by changing your plugs. sounds like one may have a crack   Blake Luse (Muddyrover) Posted on Sunday, January 19, 2003 - 01:35 am:    what is the vss for me who doesn't know even though i have problems other than this   Greg French (Gregfrench) Posted on Sunday, January 19, 2003 - 09:57 am:    VSS; Variable speed sensor. From what I have read, It is some little device that reads where the throtle is and tells the computer how much gas to give to the engine. Occasionally they wear out or have dead spots and need to be replaced. It would feel like you let completely off the gas while driving at speed.   Greg French (Gregfrench) Posted on Sunday, January 19, 2003 - 09:59 am:    I changed my plugs about a month ago. Do you think it might be something else? Since that seems to be the quickest and easiest potential fix, I will do that today. Anybody have any other ideas? Plug wires maybe?   Brendan Kearns (Howboucha) Posted on Sunday, January 19, 2003 - 08:51 pm:    Mine is doing the same thing too. At 55 mph, it shutters and shakes pretty bad. It is getting embarrasing on my work commute. I have several large hills to traverse, and I am usually the one slowing traffic down. Even had a Yugo pass me up hill! (not really, if that happened I would pull over, and shoot my Disco to put it of it's misery). I put spark plugs in my 95 today. I need to order new wires. After the plug install, I took it for a spin at highway speed (55) and it kept on shaking and shuttering. It does seem to be intermittant. I will order the VSS thing to see if it makes a difference. Brendan 95 Disco "Mayberry of the Midwest", IN   Greg French (Gregfrench) Posted on Sunday, January 19, 2003 - 10:27 pm:    Brendan...Yours sounds like a VSS. Still don't know what mine is. Checked the plugs today. Still acting up. It only does it when I first take off or accelerate after switching gears. Anyone have an idea?   ron morgan Posted on Monday, January 20, 2003 - 12:47 am:    stepper motor (idle speed control valve) my 96 disco was bucking and the rpm would drop down at about 2500, it felt like the engine just quit then fired up again. I took it out and cleaned it up with some solvent and now it runs like a new truck, after I cleaned it, it did not idle and by morning, after it dried out, it ran great. The valve cover vents upstream of it and I guess after awhile it gets gummed up.   Jim Posted on Monday, January 20, 2003 - 10:53 am:    I had similiar problems and I ignored many a post on this board that told me to replace the plug wires if I was at all unsure as to when it had last been done. I (reluctantly) replaced the wires, cap, rotor, plugs and, lo and behold, that was the problem. Start with the small things that probably need to be done anyway, if problem persists, THEN look at the VSS. -Jim   Mike Rupp (Mike_Rupp) Posted on Monday, January 20, 2003 - 11:33 am:    Greg, the VSS is the sensor mounted on the back of the transfer case that measures the movement of the drivetrain. What you described the the Throttle position sensor.   Peter Matusov (Pmatusov) Posted on Monday, January 20, 2003 - 12:00 pm:    Greg, does if only happen when you accelerate? at which speed? you have a '97, so you shouldn't have a roto in the rear driveshaft. if you do have it, though, check it - a cracked roto manifests itself just like you described, bad vibration upon acceleration. Usually around 25-35 mph. peter   Andrew Clarke (Aclarke) Posted on Monday, January 20, 2003 - 12:17 pm:    I had a similar problem and it was the spark plug wires. One of them actually broke into 3 pieces when I pulled it off. 7.5mm Magnecors did the trick for me.   Tommy (Tommy) Posted on Monday, January 20, 2003 - 02:17 pm:    I too have a similar problem. My 96 D1 shakes and sputters when the RPM's reach just over 2000 or so. It's not the plugs, wires, O2 senors or fuel delivery. I gave up, I dropped it off today at an independent LR shop here in San Antonio today. I pray it's not the valves.   Geoff 93 RRC (Geoff) Posted on Monday, January 20, 2003 - 02:24 pm:    Chiming in with also having had the bad plug wire causing these symptoms ('97 Aussie spec Disco). The stock wires are surprisingly poor quality.   Greg French (Gregfrench) Posted on Monday, January 20, 2003 - 03:35 pm:    Thanks all. I will change the wires. That is what is sounde/felt like to me. I replaced them this summer, but used the el cheap-o Auto Zone brand. I'll try replacing them. Which are the best? AB has a $49 set or a set of Genuine for $79 Are the genuines that much better? Also, Rovers North has a set for $52, but no info on what they are. Thanks   Andrew Clarke (Aclarke) Posted on Monday, January 20, 2003 - 03:45 pm:    Whatever you do, don't use the Genuine ones. I second what Geoff said above about the LR wires sucking. Honestly though I'd think that even cheap wires would have fixed the problem for a little while at least. Maybe you're just getting a bad connection, I dunno. I'm hardly an expert on this. I do know though that getting the Magnecor wires and some NGK plugs promptly solved all my ignition woes!   Brendan Kearns (Howboucha) Posted on Monday, January 20, 2003 - 03:48 pm:    Now my wheels are turning big time. Like I mentioned, I am having the same symptoms that Greg has. I e-mailed discountrovers.com about the VSS part, but is that really what I need to look at? It was noted that the VSS is really something else then the throttle dohickie. Shuttering and shaking right at 55 mph. Is intermittant. Throttle control can be strange. Pushing down on the throttle pedal can actually make it go slower (at 55 mph zone) similar to a "flooding out" feeling. I have not replaced the wires yet, and I am not sure who to buy them from (advice?) I put new plugs in Sunday and it didn't fix anything. My average MPG is 10, but my Disco has a roof rack with Hella lamps and a gear bag. I also put some 265's on the wheels, but the problem started about 500 miles after installing the bigger tires. My disco has about 126K on the clock. So whatta you think? Brendan   Greg French (Gregfrench) Posted on Monday, January 20, 2003 - 11:52 pm:    MIke...Thanks for the clarification. Throtle position sensor, huh? Ok...then what exactly IS a VSS?   muskyman Posted on Monday, January 20, 2003 - 11:57 pm:    vehicle speed sensor   Jon Oldham (Jons99disco2) Posted on Saturday, January 25, 2003 - 09:54 pm:    You might want to try replacing the mass air sensor. 145.00 at dealer. Mine was doing the samething but it also ran poor when it was cold. I had 18 different engine codes go off and three hours later and 345.00 dealer fixed the problem with a new mass air and new air filter because a mechanic did not get the airbox sealed and it bent my filter and was causing a vaccum leak. Good luck.   Jon Oldham (Jons99disco2) Posted on Saturday, January 25, 2003 - 09:56 pm:    You might want to try replacing the mass air sensor. 145.00 at dealer. Mine was doing the samething but it also ran poor when it was cold. I had 18 different engine codes go off and three hours later and 345.00 dealer fixed the problem with a new mass air and new air filter because a mechanic did not get the airbox sealed and it bent my filter and was causing a vacuum leak. Good luck.   Jason Vance (Jason) Posted on Saturday, January 25, 2003 - 10:14 pm:    I could be wrong, and maybe somebody wants to kick me while I'm speaking, but the vehicle speed sensor is only used in conjuction with the stepper motor (oh, yeah...forgot about the speed "governor," too). The VSS lets the ECU know whether a "closed throttle" event is occurring simultaneously with the vehicle slowing down (e.g. coming to a stop at a red light) or while the vehicle is already stopped. If the vehicle is still moving, as the VSS would detect, the ecu would operate the stepper motor differently than while the vehicle is already stopped. VSS problems includes the vehicle stalling when coming to a stop because the ECU controlled the stepper motor incorrectly. I would suspect the TPS...maybe having a "bad" spot along the travel of the potentiometer, though not enough to trip a code, might still cause problems during acceleration...or possibly 02 sensor problems (I'm having similar acceleration issues and I am not currently running 02 sensors...don't ask why right now).   muskyman Posted on Saturday, January 25, 2003 - 10:44 pm:    a bad VSS can cause a number of different conditions. I would guess the nature of the way it shows its self as bad has alot to do with the condition of other sensors and devices. a bad VSS can cause the cruise control to kick off for no reason for one, while the vehicle has no other apparent problems and without throwing a code. my first VSS did this, when replaced it went away completly. my next VSS problem a year latter then manifested itself very much as is being descibed above. as you are backing off at very low throttle positions the motor would feel like it had a very sudden miss like some one was turning the key on and off very quickly. this is where the IAC motor(stepper in rover lingo)kicks in to prevent the motor from stalling in case you are stopping or completly closing the throttle. under acceleration the IAC is never running and the vehicle speed is not a factor in the ECU calculation of fuel, just air in and throttle position because speed varies with gear of the transmission. the strangest thing is both my VSS's failed on one of the coldest days of the winter a year and 40,000 miles apart? the VSS is a really cheap piece of shit, it dosent surprise me that they go bad or partially bad/inconsistant and cause a number of quirky conditions. hell look close it says made in england right on it.   charles pastrano (Charles) Posted on Sunday, January 26, 2003 - 08:06 am:    Greg I would do the VSS before your wires if you did them last year.   Greg French (Gregfrench) Posted on Sunday, January 26, 2003 - 05:55 pm:    I know it isn't the stepper. I re-did it last summer, as it was stalling at idle when the ac was on. Fixed that problem. I'll try the wires. If that doesn't work, I'll do the vss   muskyman Posted on Sunday, January 26, 2003 - 06:05 pm:    greg, one other free thing to try is to reset the ecu to default map settings . just disconnect the negative battery cable for a couple hours then reconnect and fire her up . sometimes weather extremes or strange driving conditions such as towing or crawling can confuse a ECU. by cutting the power most systems revert back to the base map instead of the current map they are running . if nothing else it is a free thing to try thom   Jack (Olered) Posted on Monday, January 27, 2003 - 12:42 pm:    I to suffered from the vibration/shutter/loss of power etc... The dealership replaced the "bad" VSS 4 times. I kepts telling them that I thought that it was a valve sticking. Upon trip number 5 for a VSS, the dealer sucked it up and provided the valve job under warranty. Runs like a champ since.   Jack (Olered) Posted on Monday, January 27, 2003 - 12:56 pm:    I to suffered from the vibration/shutter/loss of power etc... The dealership replaced the "bad" VSS 4 times. I kepts telling them that I thought that it was a valve sticking. Upon trip number 5 for a VSS, the dealer sucked it up and provided the valve job under warranty. Runs like a champ since.