Acceleration Problem

[Quicksilver]

I hated to use the word hesitation in my topic, because there are so many threads with that caption, but that is the crux of my problem. None of the other topics are quite the same description and they all appear to deal with slightly older models.

I have a 99 sc300. When I am running between 10-20 mph, the car will hesitate very slightly and then smooth out. It's kind of like a small lurch. It seems to do it more when going uphill. For instance, there is a RR track here that you drive down a small hill to get to and then up a small hill after you cross it. It almost always does it when accelerating away from the track and I'm usually at about 12 - 15 mph. This aspect is what makes me wonder if it is the fuel pump, or maybe just some bad gas.

Does anyone have any thoughts? I bought the car in February with 105K on it and the problems didn't start until about April. Any help is appreciated. I've currently got 107K on it.

[over40driver]

My 95 400 does it when its cold and is shifting around to see what gear it wants to be in, but only once a day.

[UCF3]

Have you ever cleaned out your throttle chamber? Also, are you still using Premium Fuel?

[Quicksilver]

No on premium fuel.

I have only had the car since Feb, so I'm not sure if the previous owner ever had the throttle chamber cleaned. The previous owner drove the car for about 4 years, but don't know if she ever did more than routine maintenance. I am about to change the timing belt just as a precaution.

[Chad in SC]

Have you ever cleaned out your throttle chamber? Also, are you still using Premium Fuel?

How exactly do you clean out your throttle chamber, this sounds similiar to a problem i'm having and would like more information about the process

[Chase Croft]

fuel injectors maybe

old bmw used to have a whole lot of trouble at low speeds in neighberhoods goin uphill when it was cold outside or had been sitting not driven for awhile

[JIBBBY]

Spray out your throttle body, clean your injectors and change your fuel filter and you should see improvements....

I use STP carb cleaner to spray clean the throttle body....Two ways to do this....

Car off - Simply remove the long rubber big intake snorkel hose that is held down by 3 or 4 bolts...Remove the snorkel tube to expose the throttle body located at the very top of motor...You will see a butterfly inside the throttle body that opens and closes with throttle action to allow air to enter into the engine...Simply spray the heck out throttle body and fly, open the fly by manually pulling the throttle cable and spray some more...Then wipe what you can with a clean lint free rag and reinstall everything tight...Allow a few minutes for the Carb cleaner flooding of the motor to evaporate and dryout and then start.. A smooth steady idle is what you will then get...

Car on (most effective)- I keep the car running when I clean out my throttle body which helps with the cleaning...The motor has to be idled manually or it will stall when disconnecting the snorkel tube....I spray into the throttle body while manually pulling on the throttle cable...(note: the car will bog and choke and even stall but just start and repeat) It takes just a few minutes and is a very easy proceedure...I do my car every six months or so because of my custom intake and it always seem to get a better idle and no hesitation after the proceedure...

A half arsed way to clean the injectors is to wait til your almost on empty (gas tank) then go to any auto parts store and get two bottles of concentrated fuel injector cleaner and pour both into the tank...Drive around til your just about out of gas...That should help some with injector cleaning...

Fuel filter, buy a replacement filter at any autoparts store locate and change....

Do all of that and your car will run better....

[jzz30]

before you do anything why dont you just use premium fuel...