# 1991 Stanza...hesitating when going over 45mp



## ljcs357 (Apr 8, 2008)

What's everybody..obviously i'm new...i just purchased this car 


When i accelerate and begin to drive at higher speeds (45mph)..the car will drive fine for about 10 minutes then begin to hesitate and sputter for the rest of my trip...If i come to a complete stop and turn it off and on it will do the same thing...good for about 10 minutes and does the same thing.

Suggestions or a good place to start please!!

thanks


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## StanzaBonanza (Feb 3, 2007)

after market air intake?


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## PapaCap (Dec 8, 2007)

That could be a multitude of things. But it sounds like your ECM is going bonkers when the car is at operating temperature.

Have you replaced the coolant temp sensor, maf, plugs or wires, distributor cap/rotor, fuel filter, air filter, o2 sensor recently?

How do your hoses look? If they are cracked, they may be sucking air and need replacing. Hose is so cheap, there's no reason to have rotted hoses (I redid 90% of all my vaccum lines for like $5).

But the first thing I would do is adjust the timing. If you don't have a timing light, tinker with it, drive it, tinker with it some more. Maybe that'll help.

pc


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## ljcs357 (Apr 8, 2008)

No. I thought it was the air flow meter and I changed that and it was still doing it. 





StanzaBonanza said:


> after market air intake?


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## ljcs357 (Apr 8, 2008)

ECM? What is that. Sorry I'm indiot. 

I'm going to take a look at the other stuff. Thanks for giving me a starting point.




PapaCap said:


> That could be a multitude of things. But it sounds like your ECM is going bonkers when the car is at operating temperature.
> 
> Have you replaced the coolant temp sensor, maf, plugs or wires, distributor cap/rotor, fuel filter, air filter, o2 sensor recently?
> 
> ...


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## PapaCap (Dec 8, 2007)

Oh, don't be so hard on yourself 

The ECM is the onboard computer (electronic control module, I believe). It adjusts the air/fuel mixture and ignition timing as the motor conditions change. When a motor is cold, it needs less air (rich condition) to run properly. As a motor warms up, it needs more air and less gas to run at optimal/best gas economy settings (lean).

Since your motor is running rich at operating temperature, the ECM isn't leaning out the air/fuel mixture which is why you're getting carbon build up.

Unfortunately for these computer controlled cars, they are a pain in the rear to diagnose all the problems of a rich mixture since the air, fuel, ignition and emissions systems affect motor performance. Not to mention if the motor itself has damage (bad rings, valve guides, etc).

And to add to the horrors of dx'in this, I forgot all about the emissions; the EGR valve and sensors. They should be checked, as well. But I'd start with the timing, vaccum leaks, cleaning sensors, and the coolant temp sensor. They are the cheapest and most likely to cause performance probs.

pc


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## ljcs357 (Apr 8, 2008)

Aight. Cleaning/Replacing sensors, and the hoses i can do. What do mean by timing?




But I'd start with the timing, vaccum leaks, cleaning sensors, and the coolant temp sensor. They are the cheapest and most likely to cause performance probs.


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## ljcs357 (Apr 8, 2008)

Oh ignition timing right? I probably just need to replace the ECM to be safe then.


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## PapaCap (Dec 8, 2007)

Actually, I wouldn't replace the ECM. It is a computer and only reacts to the information given via the sensors. The possibility of a computer providing false data is very slim. Usually, a computer works or doesn't. If you have one sitting around, you could swap it out. But IMO, it's more likely to be a dozen other things before the ECM. And speaking of the ECM, you can check the error codes on it to see if it can give you any info on your problems.

Far as ignition timing, it takes a little skill to time it 'by ear' as opposed to using a timing light. You can always move the timing and drive it, move it and drive it if you don't have a light.

pc


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