I have a 1991 celica gt 5sfe hatchback. I am getting a surging at constant speed, at idle it's fine as well as acceleration. It only does it when trying to maintain a constant speed in the range of 10-50 mph or so. It's feels like I'm pushing the gas and letting off repeatedly. I took it to get an emissions test and it failed on the low side test with high co2 reading, everything else is fine and one place couldn't do the test because the surging kept kicking the computer out since they have to keep it at a constant 15 mph speed. I think whatever is causing the surging is causing me to fail the low side emissions. Any ideas?? Could it be the iecu?
No, the engine light has never came on, I haven't taken it anywhere to hook up on a computer since the light isn't on I'm not sure they would get anything. If I take it somewhere for them to hook it up to a diagnostic computer would it show the problem if the engine light isn't on? I know they will hook it up free at autozone or somewhere like that.
No, the engine light has never came on, I haven't taken it anywhere to hook up on a computer since the light isn't on I'm not sure they would get anything. If I take it somewhere for them to hook it up to a diagnostic computer would it show the problem if the engine light isn't on? I know they will hook it up free at autozone or somewhere like that.
Possibly. I've the 02 sensor go out and not throw a code.
Hows your mileage? Have you noticed a decrease in MPG?
Possibly. It does have alot to do with how much fuel is sent. A bad 02 sensor will usually make you run rich and lessen your MPG.
When's the last time you did an ignition system tune up?
Also, a bad catalytic converter could also affect exhaust flow, causing surges and make you fail an emissions test.
But like I said, it could be many things.
I just did a complete ignition tune up a month ago. I went and got an o2 sensor and will try that first once the car cools off. I just read that the 02 sensor should be replaced every 30,000 miles and as far as I know it's never been replaced. It's a start and I'll post back if that fixes the problem.
honestly 30,000 is a little excessive, but they can save you over time if you replace them when the begin to foul. An o2 sensor could cause this and with it being an OBD I system it isn't sophisticated enough to really recognize if a sensor is barely out of spec.
Ok, put in the new sensor and it seems to run better, but I won't get to really drive it until tomorrow. I ran around the block a couple times and it isn't surging like it was, maybe just slightly but until I get to really drive it around a bit it's seems to have got it. Hope that was the reason for the low speed fail on the emissions too, it was only the co2 that was high on the low speed, everything else on the emissions was right in order.
Was the car sufficiently warmed up before the test, as in at least ten minutes or so of steady driving?
Edit: also, if you perhaps get a CEL light 9even just for future reference), most parts people have no clue how to do an OBDI test, places like autozone, advance, etc usually can only do OBDII ('96+) scans and thats only with the CEL on. You can check codes simply with a jumper wire, or even a paper clip.
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