Schuyler

Hello,

I have a '93 ES300 that has developed a bad idle and upon putting in gear and/or accelerating bucks/surges like crazy unti it gets up to speed. I did a search on the idle air valve and it appears that only controls idle, not the acceleration surging issue. does anyone have any idea what may be my problem (I should say the car's problem, I don't need opinions on my problem)?

One interesting fact is that it doesn't do it upon putting it into reverse, but starts surging in drive. Please don't suggest I drive everywhere in reverse!

Thank you for any assistance.

92ES5sp

Check your Throttle Position Sensor

GrahamHill

Mine did that and it was a badly cracked bridge from the MAF sensor (by the air filter box) to the throttle body... pics in a sec...

Schuyler

Thank you for replying.

I did notice a small crack in the rubber body between the air filter and the throttle body. It is probably worse than it appears. I guess I can test that theory by taping/sealing the crack and see if it improves? If so, what is the best sourse for replacing old rubber parts like that? I assume junkyard parts would be just as old and brittle.

Thanks again.

GrahamHill

Temporarily ive redneck engineered mine with tighly wrapped black tape and duct tape (yes, sue me lol).

Any 'leak' on the engine side of your MAF sensor is a vaccum leak and is serious business. Its unmetered air entering the engine which causes the motor to run lean and the O2 sensors to read it and not know why its lean. Not only can it damage parts, but it drives the computer crazy trying to adjust for the problem.

Be sure to take the air intake tube off and clean it with something like dishwashing liquid before you tape it up. Otherwise all the grease/dirt wont let tape or superglue adhear to the rubber and it will never seal.

When you take it off you will probably notice more cracks. While installed on the car, mine appeared flawless!

Schuyler

Well, I've got electrical and duct tape on hand, so we'll see if that's the cause. And, the tube is so brittle, I'm sure if it's not badly cracked now, it will be when I remove it!

Thanks again.

Schuyler

Do you think the fuel filter could affect this? I don't think it has been changed and someone mentioned that possibility. The car has 90,000 miles on it.

Thank you.

GrahamHill

Dunno. The air intake leak could be a free fix so id start there if you haven't already.

gwydo125

if your getting the surge in low ranges and idle you might want to try changing the EGR position sensor(3 screws and a 45 dollar part) my 98 es 300 had same problem that fixed it immediately. code was either p0402 or p0401 same problem. doesnt always trigger codes when it happens tho so try the part and if its not it return it.

gwydo125

88Legend

I would say it might be your O2 sensors. My car had a bad idle and it hesitated a lot and had much lower power. I replaced my two O2 sensors. The two on the exhaust manifolds.(Mine car only has two, none near the cat.)

And...no more idle problem. It had more power and doesn't hesitate anymore. The strange thing is that my O2 sensors were not giving off a code even though they were bad.

llcoolpass

1 bad [ie CRACKED OR CHUNKS MISSING] intake tube .
2 or messed up [common problem] MAF [ie VAF] try cleaning it

.... or other problem.

bloodyj410

How do you clean the maf in a 98 es 300 and the idle air control valve screws on mine are stripped and I think it's clogged I'm having the same acceleration problem
From stop or roll and idling stumble , my car started with the idle air control Unplugged I had forgot to plug it back and it just made the problem I'm having more harsh by like 80 percent. I found that it was unplugged so I'm pretty sure that's what's clogged ? Since it's the same problem when unplugged just enhanced the issue making it more noticeable