98 Sienna - Sludge or no Sludge

[ozzie32]

My 98 Sienna just started to act a little weird. When driving and I don't push on the accelerator too hard, it runs perfect, but if have to push it down quickly, it acts sluggish like it's not getting it's gas. Could this be a sludge problem or maybe just the fuel filter?

165 kms onthe van with frequest oil changes every 5000 Kms

Thanks

Ozzie

[Brian R.]

I doubt it's a sludge problem with oil changes of your frequency, unless you drive only a couple of minutes a trip and you never really warm up the engine.

Unless you have put in dirty gas, I don't think it's the fuel filter either. They don't normally have to be replaced.

The first thing I would do is put in a fuel injector cleaner in the gas tank and see if that makes a difference. If it does, consider having your injectors cleaned by a shop.

Do you have the "Check Engine" light showing? That would indicate the source of your problem.

Have you put in new plugs recently? I would put in new OEM plugs if you haven't in the last 75,000 km.

Can you accelerate briskly from a standing start without any hesitation? If not, it may be the fuel filter, but do that last.

[ozzie32]

Brian

Thanks for the response.

Engine is normally warmed up on trips.

No check engine light.

Plugs have not been replaced for some time.

Cannot accelerate briskly from start most of the time.

Sometimes I can accelerate well, but mostly if I put the gas pedal down fast the van sputters and has no power. If I let off the pedal it gets going well. The power is there and acceration is good when I only lightly press on the gas pedal. It's when I push down quickly and far that the problem arises.

A friend of mind also suspects the fuel filter and since it's easier to replace than the plugs I'll try that first.

Feel free to offer any other tips.

Ozzie

[Doug Tatham]

The fuel filter isn't too easy to get to, I had to take off the breather and several hoses and stuff to get to it. The connection on the bottom is especially hard to remove. Good luck. While you're at it I would recommend that you get a can of carb cleaner and clean the throttle body and idle stabilizer. Be sure if you clean the idle stabilizer that you remove the rubber gaskets first, the carb cleaner will cause them to swell really bad and you have a real time getting it back together if that happens. You can check to see if you have a sludge problem by removing the front valve cover. This is easy and quick. If you do and it's bad, you can even see it inside the oil fill cap without taking anything apart. When you clean the throttle valve be sure to clean the mass air flow sensor.

[ozzie32]

Thanks for the tips. I had already anticipated removing the breather.

As for seeing the sludge, what should I be looking for? Is it like rally thick black oil? I checked the oil cap and I could not see anything obvious.

Thanks

[Doug Tatham]

You can google the internet for info on sludge and they have great pictures of it. It has a consistancy like soft icecream and is jet black. I don't recommend tasting.