2 questions

[infurno]

When the car is under load it jerks back in forth like power is getting cut off and put back on. Like pumping the gas peddle in first gear, but its not very violent. This happens especially when accelerating and letting the rpm rise to 3,500 - 5,000. What could be the likely cause of this?

This is my first manual car, could this be a "slipping clutch"? Or is there something mechanically wrong?

This reminds me of an incident which may be unrelated... I was pulling out of a parking lot and accelerating to 45 mph while the engine just dies at ~3,500 rpm or so. Completely lost power in gear. It started back up again when I turned the key and has not happened since.

2) So many engine treatment products out there, but I have not found any mention of them here... besides sea foam... Is there any that I should use? What brand is recommended for our cars? Im about to change my oil and I was wondering if I should add anything.

[bubba966]

Go to the auto parts store and pick up a bottle of iso-heat fuel drier. Toss that in there with a few gallons of new fuel (don't fill it up) from a good source, ie Chevron, Texaco, Shell, Citgo. Avoid BP, 76, Arco.

Have no idea what car you have, but that sounds like water in the fuel to me. And a bottle of iso-heat costs about $1.50, so it's cheap to try and see if that's what your problem is.

And make sure that after you add the iso-heat and a couple of gallons of fuel (so it mixes well) run it until it's nearly empty and then fill up again.

[infurno]

Sorry I keep forgetting to mention the actual car..

1990 525i ~270,000 miles m20

[bubba966]

Oh, and after trying the iso-heat I'd put a bottle of Techron concentrate in the next tank. Keep them separate, so that you use the iso-heat in your current tank of gas, then the Techron in the next tank of gas.

And you may even want to run another tank w/Techron in it after the first tank w/Techron considereing the miles you have on that car. If after a tank of fuel drier & two tanks of Techron you still have these problems then you can start looking at other possible causes.

But it sounds like you've got wet fuel, and a dirty engine.

[infurno]

Thanks for the tips, ill do exactly that.

It could be water, I noticed im losing antifreeze slowly and its not leaking.

[bubba966]

You don't get water in the gas from the cooling system. It's either in there when you buy it, or it's in there from condensation forming in the tank. Not so uncommon this time of the year due to the temp drop & increase in rain.

[infurno]

Not sure why but at first I thought you meant water is mixing with fuel in the cylinder, not that its in the actual gas tank.

I have been running it on 1/4 - empty for a while now and the condensation is probably catching up.