For over two years I’ve had this problem. About every 50 to 100 miles or so of city driving (25 to 45 mph) the car suddenly looses power and will not go over 30 mph. If I slowly give it more and more gas it won’t accelerate above 30 mph. This condition might last for about 10 to 20 minutes of driving UNLESS I floor the accelerator and then it goes into passing gear and really speeds up. Of course I let up on the accelerator (can’t do 60 in a 30 zone!) and it goes back to the problem of about 30 mph maximum speed. After the “10 to 20 minutes” of driving this way (30 mph or floored into passing gear and speeding up over and over again) it will suddenly return to normal operation and run smoothly at any speed. It is an automatic.
I’ve had the code P0441 concerning emission control problem with the purge flow. But a description of this code mentions that there should be NO driveability problems with this emission problem. So I don’t think it is the reason for my problem.
There was a thread here back in 2015 about this driving condition in a 1998 Prizm, but it was not resolved at the end of the thread.
Any help?
One possibility is that your catalytic converter is deteriorating, so that loose debris sometimes restricts your exhaust flow until you accelerate hard and shift the debris around.
Could a '98 Prism ever do 60mph???
I don’t know the other thread you are talking about, but this does kinda sound like an exhaust restriction. Has the catalytic converter ever been replaced on this 20 year old car?
If you never fixed the original P0441 code and still have the CEL light there might be other codes present. Have you had the codes read recently?
The exhaust restriction sounds very plausible.
I own a 99 Corolla,basically the same car.I replaced my catalytic converter last year because of the same symptoms you are having.The honeycomb inside it deteriorated so bad, it clogged everything…no power.Don’t wait until something like this happens to you,replace it.
No other codes. I have a code reader.
Ha! Yes 60 is possible when floored going downhill with a trailing wind!
Original cat. converter.
Not sure the material inside cat. is being affected by my flooring it because the problem persists as soon as I let up on the gas and “goes away” as soon as I floor it again. I have driven two to three miles doing this “flooring and letting up” procedure maybe twenty or more times in that 2-3 mile distance. Each of those twenty sequences it reacts exactly the same: speed up then back to no power beyond 30 mph. Then suddenly it gets over this funk and tools down the road as if nothing was ever wrong.
Also this problem will happen when the engine is cold or completely warmed up, makes no difference. Seems completely random.
Are there any codes associated with a failing catalytic converter?
Does your car burn oil? izzfe engines are notorious for that
No I have not fixed the problem causing the code P0441. What ever that problem is it has been suggested to me that I may drop a bundle to have it fixed. And this car is not worth a bundle especially when the code problem may not be causing the drive ability problem.
It does not burn oil. Gets good gas mileage (even with driving around town in passing gear!!)
Runs smooth most of the time. Starts great always! Idles fine even when in the funk.
This code is also present in my Corolla.There is no drivelability problem associated with this code.
Yup. That’s what I’ve read somewhere. Don’t remember where.
Try cleaning the throttle body and plate, see if it improves something.Could be full of carbon deposits.
One way to check if it’s catylitic converter is to remove the forward O2 sensor and drive it like that. If it does not act up, it’s exhaust restriction.
I will try to find and disconnect the O2 sensor. Will be a day or two before I can do that but will get back with results.
Not sure about “throttle body and plate” comment. What or where is that on your 99 Corolla?
Not disconnect- remove it totally. This will give the exhaust airflow somewhere to go. Don’t drive around too long like this, though, as this could leak exhaust into your cabin and cause health issues.
Your problem might be caused by a faulty MAP sensor.
The MAP sensor detects how far the throttle is opened by measuring the Manifold Asolute Pressure compared the atmospheric pressure. The computer then adds more fuel and advances the spark timing to provide more power from the engine when accelerating.
One of the things that can have an effect on a MAP sensor is engine heat.
Tester
Here is a link to the thread in 2015 about a 1998 Prizm which I referred to above. Car loses acceleration but not power while driving
Yes will take the sensor out and be cautious while it is out.
Do you know if there is a code for a faulty MAP sensor?
Also, remember that this is a 1999. If the sensor is difficult to remove abandon this idea unless you have the proper tools. It’s not worth making another mess when there may be other options. They sell 02 sensor wrenches reasonable.
Yes there are. But a Check Engine light won’t always turn on if a MAP sensor is intermittent in operation.
Just like a bad crankshaft sensor doesn’t always turn on the Check Engine light
Tester.