2001 Corolla does not accelerate when going on HWY

[corollaBOB]

I've got about 145,000 on it right now.

Well my mechanic suggested changing the catalytic convertor. The cost was around $160, so not too bad.

It's an automatic. I'll do a compression check on the cylinders today and hopefully that will be it. I'm really hoping it's not a transmission problem.

Things to do:
- Compression check on your cylinders
- Check if injectors are getting enough fuel & fuel pressure is high enough
- Direct coil packs
- Check throttle gasket or intake manifold gasket for a leak
- Check for bad temp sensor and o2 sensor

[triniguy]

Oh yes i forgot they come with coil packs.

See if any of them needs changing or if the cam sensor needs changing.

[AVANT]

I would have unhooked the exhaust post header to determine if it was a clogged cat... surprised your mechanic didn't say something along those lines and jacked you for $160 instead.

[EBR]

STOP throwing parts at it. This is a very expensive way to fix a car. It sounds like the Mass Air Flow Meter. Cleaning it will not usually do anyhting.

Swap it with one from a car that you know is good. It is only 2 screws and a harness connector.

Faulty reading from this sensor will not usually throw any codes. If it does throw a code it is usually p0171 or p0172.

Have your dealer read the data stream with the diagnostic tool. They can compare the readings the ECU is getting to the readings it should be getting.

I replace these sensors at least 3 time a month at the dealership where I work.

This part is about $187-$272 CDN from the dealership. I think cant remember off the top of my head right now.

[corollaBOB]

Work Done:
1) Spark plugs
2) Catalytic Converter
3) Front Rotors + Brake Pads
4) Fuel injectors cleaned
5) Mass air flow sensor cleaned.

Things wanted to do:
- Compression check on your cylinders
- Check if injectors are getting enough fuel & fuel pressure is high enough
- Direct coil packs
- Check throttle gasket or intake manifold gasket for a leak
- Check for bad temp sensor and o2 sensor
- Check Mass Air Flow Meter (Code p0171 or p0172)

Great news! I finally got my car fixed! Turns out...it was the Mass Air Flow Meter as "EBR" mentioned. I did clean the MAF, but apparently i only cleaned the air sensor...there is also a temp sensor? The temp sensor needed cleaning and ..puff! Problem solved. Sure enough...the computer showed code "p0171".

Everything is so much better now....the car has so much power it's unbelievable....thanks for everyones advice ...hopefully this thread helps someone else in the future.

[Juditha]

Just wondering, got the same problem on my 2001 Corolla Ces, 92k and would prefer to try and resolve on my own due to $$, can just anyone figure it out? not afraid to get my hands dirty and want to learn but also don't want to ruin anything

[corollaBOB]

Why not try cleaning your MAF, which solved my problem. I did some reading and watched this video before starting. Make sure you get the correct cleaner though. That's important.

MAF Video:
http://videos.streetfire.net/video/4...6f015c3dac.htm

Maybe someone with more experience will jump in

[4lbhammer]

Excellent thread and info.
My 2001 Corolla had a mass air flow sensor problem that developed slowly with the following symptoms. About 200,000 km the car started losing a bit of power, I switched to higher octane fuel which reduced the symptom. About 205,000 km, new plugs and air filter at a Calgary Toyota mechanic. Again a slight improvement. About 220,000 km I took it to a local (non-Toyota) mechanic who again replaced the plugs and assured me that he'd installed irridium plugs. The car then would run good only on the highway but nearly got me into a few accidents around town when it would stall at traffic lights and stop signs. Often when trying to accelerate it would bog. Another interesting symptom was a rattle that reminded me of old fashioned lifters clicking or a loose timing chain type noise at low idle (which was rough). No engine lights. Always started good.

I took the car to a Toyota dealer in Edmonton a few weeks ago when I got a chance and they found the mass air flow sensor was dirty and cleaned it. They also replaced a missing capscrew that had disappeared while at the Calgary Toyota mechanic and the rattle has disappeared.
Costs to me:
car out of service for a month
troubleshoot - $100
clean mass air flow sensor - $50
replace wrong plugs that local mechanic had installed - $120

The car now runs as good as it did at 100,000 km and still gets 6.0 to 6.2 l/100km. My major learning experience was how much impact a dirty maf can have and how much better a Toyota trained technician is at troubleshooting a Toyota.

[rollatuner110]

First off, there is no such thing as bad gas. You should take your car to a different mechanic.

[BigTDogg (MA)]

Originally Posted by rollatuner110

First off, there is no such thing as bad gas. You should take your car to a different mechanic.

For the most part, I agree. But around here (Boston) last year a half dozen or so shops got busted watering down gasoline. One shop in NH fcuked a bunch of bikers coming back from Laconia. But I think that was diesel in gas dispensers. Anyway...

My 01 is throwing p0171 and p0420. I'm going to clean the MAF and change the plugs tonight, and I'll also look/listen for any vac leaks. Hopefully this will fix the CEL and slight hesitation issue I'm having. I adjusted the throttle cable last night, as it was very loose. Foot to throttle body connection is tighter, but it just gets me to the lag quicker.

The p0420 I don't care about that much as long as it's only the cat. I just got inspected last week and passed with flying colors. I'll replace that when I do the exhaust next spring.

This is a great thread I found thru searching. I done good

[BigTDogg (MA)]

Originally Posted by BigTDogg (MA)

My 01 is throwing p0171 and p0420. I'm going to clean the MAF and change the plugs tonight, and I'll also look/listen for any vac leaks. Hopefully this will fix the CEL and slight hesitation issue I'm having.

So I cleaned the MAF last night and it definitely helped. The hesitation isn't 100% gone, but it's better, and I don't throw a CEL any more. I replicated the 2nd grear 4500RPM wind-out which originally threw it as well, no issues. Doing plugs tonight along with the vac leak check.

CEL came on at lunch, under normal driving. I'll clean and clear again tonight. Where is the coolant temp sensor located on our cars?

[BigTDogg (MA)]

I changed the plugs and inspected coil packs, also replaced the pass side ground wire with some extra 8 gauge I had laying around. that pic came out shitty.

Lil test drive and no CEL, but basically the same performance. Will see what happens with the commute tomorrow. If what I think is the coolant sensor is the coolant sensor, then I'll clean that next.

I have a manual coming, but the eBay seller is slow to ship.

Update, (tripped CEL on way to work next morning). The plugs I used were Bosch platinum plus, and they sucked. I went back to NGK IFR5T11, and it runs much better now. I also re-cleaned the MAF, spraying up along the long axis, into an opening to get two hidden wires, not the two which were obviously visible. Car runs like a dream now, no issues. No need to touch the coolant temp sensor in my case.

[FoxProGT]

that video is great.... would be awesome to have videos on how to clean most of the sensors that are easily accessible !