so here is the deal, this just started happening and I'm not sure what the cause might be. I'll be driving down the road (over 50) and the engine will lag hard all of the sudden, as if i just let of the gas or something, RPMs don't seem to drop and it only last 1 to 5 seconds and then goes back to normal. The first time it happened about 3 time over an hour, to day it happened about 5 time in less the a half hour, once in a set a couple seconds apart, then again three times within 30 seconds, just did an oil change and used Lucas but it happened before the oil change as well. If anyone has an idea i would really appreciate the help, even if its a suggestion that might help. Its a manual 4.0 1996 discovery, just under 100,000.

 

Are you using the same gas station every time?
Is the check engine light on?
It could be the VSS (vehicle speed sensor) starting to act up but lets explore the free stuff first.
When was the last time it had a tune up?
Fuel filter?

 

I was just thinking fuel filter, and I am using chevron now, i switch drove 250 miles no problems, filled up at a 7-11 as I was heading back and the end of that trip back was the first time it had happened. Decided to stick with chevron and it hadn't happened again until today, a couple weeks since the first time. As far as tune up, don't think i could afford a full one right now, just moved, what would be the basics on top a a new fuel filter? I try to treat her good, K&N long oil filter, mobile 1 synthetic with the quart of Lucas.

 

does it feel like someone is switching off the key?

any backfiring going on when it happens?

any warning lights come on when it happens?

engine hot or cold or doesn't it matter?


uphill/downhill or no matter what?

is it hard starting? when hot? when cold?

I know it sounds like a bunch of questions but, all those questions will help you get your answer.

 

I was just thinking fuel filter, and I am using chevron now, i switch drove 250 miles no problems, filled up at a 7-11 as I was heading back and the end of that trip back was the first time it had happened. Decided to stick with chevron and it hadn't happened again until today, a couple weeks since the first time. As far as tune up, don't think i could afford a full one right now, just moved, what would be the basics on top a a new fuel filter? I try to treat her good, K&N long oil filter, mobile 1 synthetic with the quart of Lucas.

 

sorry about the double post, hot cold doesn't matter, nor does up hill down hill, flat road both times. no warning lights and no back firing. hard to describe the feel, its like it is just going to keep slowing an dye but then it'll just keep on going and the rpms don't seem to drop, but i might not have noticed, but the engine doesn't sputter it just loses power for a moment.

 

When was the last time you changed your plugs and wires. This was happening to mine and I changed my O2 sensors first and no result so I went to the plugs and wires and it hasent happened since, almost 5k later. Something to think about.

 

I would have thought O2 sensors as well. Mine had actually failed and then caused something similar to this when they would start to work again but sending horrible signals.

Could definately be the fuel filter as well, chances are it has never been replaced and for the age it has had fuel going through it for quite a while and may have some debris causing flow issues.

 

just to make sure, you're running premium fuel, right?

 

Just switch to Mobil 1 and use a Wix or Purolator oil filter.
Do not add Lucas oil treatment to your oil, it will react to the oil and you will be wasting your money.

http://www.carbibles.com/engineoil_bible.html

http://minimopar.knizefamily.net/oil....html#champion

You can buy your fuel filter at Wal-Mart for $15.
You can do a cheap tune up for ~$50.

But I think your problem is with the VSS (vehicle speed sensor)