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Peter Bagley
Peter Bagley, Auto Service Technician
Category: Toyota
Satisfied Customers: 731
Experience:  master tech at Toyota dealer
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93 Toyota Camry. I have been working on a '93 toyota Camry

Customer Question

93 Toyota Camry. I have been working on a '93 toyota Camry that will run fine when cold and after about 10-12 minutes it starts to run horrible. Leads me to believe it's obviously a sensor that is not working when vehicle gets to operating temperature. I don't want to start replacing expensive sensors and guessing. It seem as if its not getting fuel or it is missing on all cylinders etc. I have to hold the gas to the floor just to get home at about 15mph. Sometimes will stall out but will always start right back up. I have replaced the following: Fuel filter, Fuel pump, Temperature sensor.... I have also removed and cleaned each injector and gutted out the Catalytic converter. I am running out of answers... My only other guess is Crank sensor however; it is not throwing any codes. And I don't have a diagnostic tool for the OBD I system. Any educated answers please?
Submitted: 11 months ago.
Category: Toyota
Expert:  AZTechBrian replied 11 months ago.

Hello. Usually when a car runs good in open loop (cold) and bad in closed loop (warmed up), it's a bad oxygen sensor.

Customer: replied 11 months ago.
Relist: Answer quality.
Need more information as to why that answer was to replace that particular part. Sounds more like part replacement.
Expert:  Peter Bagley replied 11 months ago.

Hello and welcome to just answer and allowing me to assist you. sorry about your problems , your year Camry doesn't have OBD 11 it has OBD1 I will give you a link how to pull the codes for that , you can do this. it uses a break out box to retrieve codes but only shops have them. Here is the link to check for codes yourself. do that and get back to me with what you find. What I'm suspecting is the air flow meter, that's the box near the air filter on the intake hose. Also check that hose fore tightness and cracks. I will also send some pics what to look for. I s yours a 6 or 4 cylinder?

Customer: replied 11 months ago.

I know it's OBDI and know how to pull codes. There are not any codes. In all of my years I have never seen a mass air flow problem cause such horrible running conditions, especially when only the vehicle is in closed loop.

Expert:  Peter Bagley replied 11 months ago.

Well I have replaced many and there is a thermister built in to it for different temps to enriches fuel. it's sort of a pre tps mass air flow sensor combination. it's more mechanical then electronic and the contact fingers inside loose contact and some times the thermistor acts up. Did you put a vacuum gauge on it to check for manifold vacuum?The only other thing I can think of that was a common problem was the distributor. there were two problems within the distributor we ran into ,(1) oil getting into the inside of it from a bad shaft seal, (2) check picup air gap, (3)look at the coil where it is the closest point to the lobs on the shaft , we have seen many blow the spark out there to the lobs on the shaft and you will notice that by a small dark burnt spot on the center of the coil. Now, a long-shot guess. The engine coolant temperature (ECT) sensor may be going bad. Computers work on micro and milliseconds, engines and humans don't. If the ECT is sending bad information to the computer, even if just for a fraction of a second, the computer could be reacting oddly. Sometimes what can happen is the sensor can tell the computer the coolant temperature is below zero degrees. The computer is programmed to respond to that condition by cutting out the ignition. That could cause both symptoms of the RPM dropping to zero and the stall. You could take a chance on that and replace the ECT sensor, they aren't difficult or expensive. Otherwise, a scan tool and oscilloscope to check sensor and computer data may ultimately be the only way to track this one down. Hope this helps you with your problem and if you require further assistance I'll be happy to do so. Please rate my answer, thank you and good luck.