2000 Celica GT-S. Engine 'bucking' anywhere from idle to wot
2000 Celica GT-S. Throttle response and power is good. But when driving constant speed, often in lower gears, often starts 'bucking', engine speed rises and falls 100-300 rpm in a second or so, does this continuously until I change something, like stepping on the gas, changing gears or putting it into neutral. Also, when driving hard, after shift from 2nd at redline to 3rd (this is not exactly the smoothest shift), engine will 'buck' for 3-5 times as I keep my foot on the floor, before it settles out to its normal good acceleration. Sometimes, when engine is idling in neutral, it will unexpectedly stall. Starts again immediately but it is very annoying. Sometimes driving over bumps or road irregularities will seem to cause the problem, but not always. There is no check engine light or codes showing. Car is driveable, but only barely. Over about a month time, it has been getting progressively worse.
I suspected maybe something with the fuel delivery system or pressure regulator. One mechanic thought it is a worn timing chain, but he's not sure. I really have no idea what it might be.
You are absolutely right. Mass airflow sensor was the problem + one broken wire at the sensor. The check engine light eventually came on and it made it easier to find. I think it may have been caused by a broken support stay for the AEM intake which left a small hole in the intake pipe behind the filter. I fixed the hole long before any serious problems appeared, but enough dust may have been sucked in behind the filter to foul the sensor.You are absolutely right. Mass airflow sensor was the problem + one broken wire at the sensor. The check engine light eventually came on and it made it easier to find. I think it may have been caused by a broken support stay for the AEM intake which left a small hole in the intake pipe behind the filter. I fixed the hole long before any serious problems appeared, but enough dust may have been sucked in behind the filter to foul the sensor.
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Re: 2000 Celica GT-S. Engine 'bucking' anywhere from idle...
Locate the mass air flow sensor. it's located inline with the air intake. it should be right after the air filter. disconnect the plug and see if the car runs better. also, when tapping on it lightly on the sensor with a screwdiver handle and the engine skips, could also indicate a bad sensor. these sensors will not always set the check engine light. suspecting the fuel system is also a possibility
Testimonial: "You were right on the money. The problem was the mass airflow sensor. Its amazing how one bad sensor can make an otherwise great engine run like a pig. The sensor has been replaced and a broken wire to the sensor fixed, now it runs flawlessly. "
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WHAT YEAR? CAR. the engine tachometer reads what. that whole post is a contradiction. ahh, you mean the engine does not accelerate, or the engine bogs. 600 RPM is why below, 800 normal (most cars) the engine stalls, well sure it will as low idle speed will surely do. so the real post is my engine stalls. and if i try WOT ,it will go above 600 rpm in or out of gear? wot means wide open throttle. can the engine race to 3000RPM in PARK (or neutral) if engine power is ok, full WOT power up a hill and is only and idle problem say some. and we work bad idle.
the top reason for stalls (besides #1 never ever doing the 60k mile service,repeats at every 60k)_ is a stuck open EGR (part of same service to do that but Ill add that) or stuck closed ISC (electric IAC)
Here are the most common causes of idle surge, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake
Hi
The clutch perssure plates seems worne off. you will have to replace them .
You can start by adjusting the clutch setting ...drive for a few days and if still problem persists then go in for a pressure plate change..
Regards
Berry
Check your idle control valve most likely has become faulty; some has better luck and others, it very expensive to replace which new will cost 280-290 bucks, being 2000, I would check on ebay or a junk yard. This part is responsible for the regulation of idle speed; Ensures that the right amount of air flows around the throttle to achieve optimum fuel efficiency and engine performance. do not get from the dealer, 200% mark up on theirs, check with autoparts wearhouse.com
Probably the "idle speed controller",(the ecu is programmed with target idling speeds values to respond to different engine conditions, coolant temp, a/c on/off etc,sensors transmit signals to the ecu which controls the flow of air through the bypass of the throttle valve and adjust idle speed top target value)
however this what the manual says,
check for defective throttle linkage or cable
check idle up-up vacum switching valve
check coolant temp sensor
check throttle position sensor.
Usually if its major, then the check engine light comes on,
SOUNDS LIKE THE T.P.S. IS NOT FUNCTIONING. ALTHOUGH IT MAY TEST OK, IF IT IS NOT RESPONDING, THEN IT MUST BE REPLACED. UNLESS YOU HAVE A FUSE FOR THE TPS, THEN IT MUST BE THE ONLY REASON FOR NO THROTTLE RESPONSE. HOPE THIS HELPS. PLEASE KEEP ME POSTED. THANKS FOR USING FIX-YA. AND FOR AN HONEST RATING IN ADVANCE. GOOD LUCK.
i also have a 2000 celica with a little over 100,000 miles; i was having the same problem and had to have my driving belt and my mass air flow meter replaced.
You are absolutely right. Mass airflow sensor was the problem + one broken wire at the sensor. The check engine light eventually came on and it made it easier to find. I think it may have been caused by a broken support stay for the AEM intake which left a small hole in the intake pipe behind the filter. I fixed the hole long before any serious problems appeared, but enough dust may have been sucked in behind the filter to foul the sensor.
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