Dirty Throttle Body equals poor acceleration?

Hi Guys!! :)

I hope you're OK.

Could a dirty throttle body cause a car to accelerate poorly?

My 1993 Lexus LS400 takes about 13 seconds to reach 60 mph. It should take only about 8 seconds. Otherwise - the car drives fine. [idles fine, etc.]

Everything else has been looked at and/or replaced or cleaned. [that would effect acceleration] I just want to know if I should get my hopes up regarding the cleaning of the throttle body.

Thanks,
Craig!! :)

somehow, i just doubt it... sounds like some diagnostic work may be needed. but just for grins, change your fuel filter

i doubt the throttle body could cause enough of a restriction to slow you down thaty much. there might be something else wrong with your car, have some general maintenance done to your car you could have some bad spark plugs or your car could be running rich. just bring it to a mechanic and have them fix it up. is there black smoke coming out of the tailpipe? do you notice a big loss of power under normal driving? is the check engine light on?

Just because everything "works," doesn't mean that the car will perform like it did when it was new. If you get the major mechanicals replaced and/or overhauled, then you might expect the time to be better. Sadly, having the moving bits and pieces "looked at" doesn't make them perform like they're new =\

For extra entertainment, have your car dynoed and see how it performs compared to the rated horsepower -- you may be surprised at how much power 13 years sucks away ;)

even a brand new car will show less horsepower than it's rated as having when you dyno it. this is because you are measuring wheel horsepower not crank horsepower. lots of power is lost through the transmission, differential, etc.

I'm not saying that it should perform like new im just saying that the dirty throttle body alone couldn't cause acceleration times like that, something has to be wrong other than that.

if you really want, take out your throttle body, don't lose any of the screws or fittings, it should be pretty easy with some basic hand tools but you might have to remove your air box and hoses first. anyways take it out and clean it yourself, use some acetone (used it nailpolish remover and paint thinner) to disolve away gunk and whipe it down with a cloth or something, make sure to use gloves and don't inhale the fumes. let the thing sit for a while to let it dry, it shouldn't take very long because acetone has a low boiling point. once it's dry put it back in and see what improvements it has made. post your results.

even a brand new car will show less horsepower than it's rated as having when you dyno it. this is because you are measuring wheel horsepower not crank horsepower. lots of power is lost through the transmission, differential, etc.When I said rated horsepower, I didn't mean that he should look at the dealer's brochure, and compare it to a rear wheel test. Car manufacturers have been historically unreliable when it comes to engine power ratings, this should go without saying. Yes, he would need dyno data from his car at the rear wheels, this also goes without saying.

If the car is a manual, he can even find a dyno to backdrive it to get a rough estimate of the drivetrain loss. Remember, 5sec off a 0 to 60 time isn't going to be a simple matter of a few horsepower, so the error from this estimate should be insignificant compared to the actual power loss that 13 years of use has incurred.

My comment was more of a joke than anything. The money he would spend on testing and overhauling to make a 13 year old Lexus perform like new, would probably be better spent on a new car.

they haven't really been that reliable, at least not lately. in the muscle car days yes they have been, rating a 400hp car as a 325hp car so that their customers could have lower insurance costs. but if the manufacturer sais it's, let's say, 200 sae hp that means it has been certified by the sae as the cars actual crank horsepower. meaning when they dyno'd the car they conformed to the society of automotive engineers' regulations and had the ac compressor, powre steering pump, alternator, etc attached to the car as well as having the actuall intake and exhaust attached. the horsepower you see will generally be the horsepower you're getting before the transmission.

and getting the car to run like new might or might not cost as much as a newer car. it depends on the problem, it could be as easy as replacing the ecu or intake (which would only cost 1-2k maybe more but not the price of a new car) or it could be something more serious. he could only need a tune up. if i was in his position, i'd replace the oil, oil filter, fuel filter, spark plugs, and get some intake cleaner to clean out the intake, if it still ran crappy 9which im guessing it would) i'd take it to a mechanic and get a quote on fixing it.

I vote for the catalytic convertor.

they haven't really been that reliable, at least not lately. in the muscle car days yes they have been, rating a 400hp car as a 325hp car so that their customers could have lower insurance costs.Do you mean they "haven't really been that unreliable?"

It also goes without saying that certain manufacturers have overrated an engine's output. And I'm not talking about "back in the day" either -- the Mazda RX-8 controversy is a recent example that should ring a very clear and obvious bell.

and getting the car to run like new might or might not cost as much as a newer car....or like most 10+ year old cars it could be a huge money pit just to keep it running. The poster hasn't given any history behind the car, so any conclusions that people draw are pure speculation.

yes sorry, i meant that they are reliable. anyways, it COULD become a money pit, but im willing to bet that that wouldn't for at least a few more years. cars, especially from abroad, are lasting longer than before. both my parents drive cars that are around 10 years old (one is a 96 mazda b3000, the other is a 97 honda accord) with no major repairs or tune ups needing to be done. all the general maintenance has been done, changin oil and filter every few thousan miles, etc. my sister drives a, 89 honda accord with nothing other than a clutch replaced. my other sister drove an 88 pontiac 6000le, that one had a few repairs but i wouldn't concider it a money pit. what im trying to say is that this car could be brought up to good running condition for relatively cheap and could last for at least a few more years. it's a lexus, they are known for being reliable so it shouldn't be at the end of its string.

Hi Guys!! :)

Thanks for responding. I appreciate it.

Let me tell you more about my car. [and what's been done - so far]

My 1993 Lexus LS400 has about 82,000 miles.

The following things have been replaced with new in the past 2 years. [since I've owned it - in other words]

- spark plugs and spark plug wires
- distributors, rotors and PCV valve
- fuel pump and fuel filter
- timing belt and accessory belt
- water pump and power steering pump
- throttle position sensor
- air filter
- MAP sensor
- O2 Sensors [the two front ones]

Plus all 32 valves have been adjusted.

All in an attempt to improve the poor acceleration. [plus - of course - just to keep it well maintained]

The oil and filter have been changed several times and the transmission and differential fluids have been changed twice.

I've been asking a lot of people for help and just recently I was told to have the MAF sensor cleaned. Only my car doesn't have one. The first generation Lexus LS400's [1989 to 1994] used a Karman Vortex Airflow Meter. So there goes that idea.

Here's what happens. [are you still reading this?! lol]

Car is stopped. I press gas pedal to floor. Car begins slowly and then picks up speed. Other LS400's [of my year and older] with 3 to 4 times the mileage can reach 60 mph in just over 8 seconds. [I know this because a few guys emailed me videos of their gauges while going from 0 to 60] IF the car is ALEADY moving - it can [sometimes] accelerate nicely - but most of time - it doesn't. IF I'm driving like an old lady - the car is fine.

Interestingly enough - if I ease up on the gas pedal [after having pressed it to the floor] the car will accelerate MUCH smoother. While on the floor [and as the car gains speed] the engine FEELS as though it's starving for AIR. It's also just as quick to 60 mph with the gas pedal 3/4's of the way down as it is ALL the way down.

The 'cats' are fine. The torque converter is fine. The transmission is fine. [so I've been told]

QUESTION:

Could it simply be a matter of an improperly adjusted throttle CABLE?! [or does that only happen in someone's dreams!!]

Well... there you have it. Any ideas?!

Thanks again,
Craig!! :)

i think i stated it already... change your fuel filter. its a maintenance item that you probably have never done. thats what i would do if it were my car

i think i stated it already... change your fuel filter. its a maintenance item that you probably have never done. thats what i would do if it were my car
Hi mazdatech177!! :)

I appreciate the advice. But as you'll notice in my previous message - not only has the fuel filter been changed but so has the fuel pump.

Thanks,
Craig

Hi mazdatech177!! :)

I appreciate the advice. But as you'll notice in my previous message - not only has the fuel filter been changed but so has the fuel pump.

Thanks,
Craig

I stand by my original post. Check the cat.