'93 V6 Camry Drinks Gas and won't idle
#1
10-14-2011, 08:08 AM
'93 V6 Camry Drinks Gas and won't idle
Greeting and thanks in advance for any help. Here is what I am working on:
1993 Camry 3.0 V6 manual transmissiona and 175K miles.
It was running fine and then it started to get really bad gas mileage and now it won't idle. The gas is down to like a gallon per mile, and it started smoking blue and black smoke, both coming from under the hood from the back side of the engine and from the tail pipe.
So far I have replaced the IAC valve with a used part, checked the intake for air leaks, check vacuum hoses for leaks, check plugs (they are new but have heavy carbon deposites), checked the air filter, changed the PCV valve with a new one and that's it.
I have read that the coolant temp sensor could cause this, but does anyone know where that sensor is on a '93 V6? Could it be the fuel filter? I don't have a factory service manual so I am at a distinct disadvange here.
Any other suggestions?
Thanks for your input.
1993 Camry 3.0 V6 manual transmissiona and 175K miles.
It was running fine and then it started to get really bad gas mileage and now it won't idle. The gas is down to like a gallon per mile, and it started smoking blue and black smoke, both coming from under the hood from the back side of the engine and from the tail pipe.
So far I have replaced the IAC valve with a used part, checked the intake for air leaks, check vacuum hoses for leaks, check plugs (they are new but have heavy carbon deposites), checked the air filter, changed the PCV valve with a new one and that's it.
I have read that the coolant temp sensor could cause this, but does anyone know where that sensor is on a '93 V6? Could it be the fuel filter? I don't have a factory service manual so I am at a distinct disadvange here.
Any other suggestions?
Thanks for your input.
Last edited by Toy4runr; 10-14-2011 at 08:13 AM.
#2
10-14-2011, 09:35 AM
What engine model number?
The AutoZone website may have some specific info in the sites vehicle repair guide section.
Determine if the engine a cold start injector, an additional injector mounted on the intake manifold to inject fuel when engine cold. It is possible the system is not turning off and excess fuel is being pumped into the engine. The injector would be on a timer.
You can unplug the wiring connector to determine if the injector timing it bad (engine now runs OK) and remove the injector to determine if it is leaking when the engine is warmed up.
The computer coolant sensor would be installed on a coolant manifold. Follow the large radiator hoses to the engine, one hose goes to the water pump, the other to a manifold with lots of sensors. You should be able to see them. T
The engine has coolant temp sensors for the coolant fans and coolant temp gauge on the dash, you want the right one. It will have two wires, not one and they may be brown and green.
The AutoZone website may have some specific info in the sites vehicle repair guide section.
Determine if the engine a cold start injector, an additional injector mounted on the intake manifold to inject fuel when engine cold. It is possible the system is not turning off and excess fuel is being pumped into the engine. The injector would be on a timer.
You can unplug the wiring connector to determine if the injector timing it bad (engine now runs OK) and remove the injector to determine if it is leaking when the engine is warmed up.
The computer coolant sensor would be installed on a coolant manifold. Follow the large radiator hoses to the engine, one hose goes to the water pump, the other to a manifold with lots of sensors. You should be able to see them. T
The engine has coolant temp sensors for the coolant fans and coolant temp gauge on the dash, you want the right one. It will have two wires, not one and they may be brown and green.
#3
10-15-2011, 07:10 AM
I fixed it. Turns out it was the number four fuel injector. I replaced the IAC valve and the PCV valve, cleaned the the throttle body, etc and then I started pulling the plug wires while the engine was running looking for a dropped cylinder. Sure enough, number four was dead. So I determined that I did have spark coming from from the plug wire, I then tested the plug by switching it with one from the number two cylinder. Number four was still dead so I listened to the fuel injectors by place a long screwdriver on the side of the injector and put my ear to the handle of the screwdriver. I could clearly hear number two and number six clicking away, but the number four injector was not firing. So I replaced that injector and the car is fixed!
Yay!
Yay!
#5
10-19-2011, 07:04 AM
Gal dang it, the car is NOT fixed after all.........
OK, here is the deal; I replaced the above stuff and the car was running good until it got hot, then it would commence to burning fuel gallons per mile and smoking like a train. To fix this all I did was unplug the ECT coolant temp sensor and the car straigthened right out, so I went to the auto plarts store and bought a brand new ECT temp sensor and put it on the engine and plugged it in. The car runs great when cold but when it reaches normal operating temps it goes to drinking the fuel like it did with the old ECT in, and unplugging the new tempt sensor caused the engine to run normally, just like before.
So does this mean the new ECT temp sensor is bad or is the brain bad? I'm working without a manual and it's not my car, it belongs to a friend, and we can't afford to take it to the dealership so I really appreciate any help you guys offer. What is the ECT supposed to read in ohms when cold and when at normal operating temps? If I have that info I can test it to see if it's sending the correct signal to the brain. Thanks again.
OK, here is the deal; I replaced the above stuff and the car was running good until it got hot, then it would commence to burning fuel gallons per mile and smoking like a train. To fix this all I did was unplug the ECT coolant temp sensor and the car straigthened right out, so I went to the auto plarts store and bought a brand new ECT temp sensor and put it on the engine and plugged it in. The car runs great when cold but when it reaches normal operating temps it goes to drinking the fuel like it did with the old ECT in, and unplugging the new tempt sensor caused the engine to run normally, just like before.
So does this mean the new ECT temp sensor is bad or is the brain bad? I'm working without a manual and it's not my car, it belongs to a friend, and we can't afford to take it to the dealership so I really appreciate any help you guys offer. What is the ECT supposed to read in ohms when cold and when at normal operating temps? If I have that info I can test it to see if it's sending the correct signal to the brain. Thanks again.
#6
10-19-2011, 10:05 AM
The ohm reading of the sensor will decrease as the coolant temp raises. The graph is fairly linear (temp versus ohm reading) but does has a slight curve.
From the chart it appears:
68F approx 3 ohm.
104F approx 1.2 ohm
140F approx 0.6 ohm
212F approx 0.2 ohms
These are approx numbers.
From the chart it appears:
68F approx 3 ohm.
104F approx 1.2 ohm
140F approx 0.6 ohm
212F approx 0.2 ohms
These are approx numbers.
#8
10-20-2011, 09:33 AM
OK, it looks like the ECT sensor is working properly. I figured it was since it was new.
Right now it is cold in the mornings and the car does not want to idle in the cold or really run at all when it's cold with the ECT unplugged. So we can plug in the ECT when it's cold and it will idle up and run fine until it warms up to normal operating temps and then it goes to drinking fuel, smoking grey/black smoke, and won't stay running at an idle until we unplug the ECT sensor, then it goes into limp mode and runs fine. What other sensor could cause it to run so poorly and get such terrible mileage when it warms up? Any help is tremendously appreciated. I don't have the factory service manual and am really in the dark here.
Right now it is cold in the mornings and the car does not want to idle in the cold or really run at all when it's cold with the ECT unplugged. So we can plug in the ECT when it's cold and it will idle up and run fine until it warms up to normal operating temps and then it goes to drinking fuel, smoking grey/black smoke, and won't stay running at an idle until we unplug the ECT sensor, then it goes into limp mode and runs fine. What other sensor could cause it to run so poorly and get such terrible mileage when it warms up? Any help is tremendously appreciated. I don't have the factory service manual and am really in the dark here.
#9
10-20-2011, 10:34 AM
Suggest you try your library for spec info and wiring diagrams. Some libraries have access to AllData which has wiring diagrams.
Have you checked out the cold start injector system (if the engine has one)?
Other things that could effect the engine are air flow meter, 02 sensors, TPS.
Make sure the EGR valve is off at idle.
Check out what kind of fuel pressure regulator system the engine uses. If the pressure is being set too high after the engine warms up.
The engine settings for cold may be OK but not for hot due to the problem. Something may be stuck open, not turning off, etc. Versus something changing when the engine is hot. It may not change just does not turn off from being on when the engine was cold.
Have you checked out the cold start injector system (if the engine has one)?
Other things that could effect the engine are air flow meter, 02 sensors, TPS.
Make sure the EGR valve is off at idle.
Check out what kind of fuel pressure regulator system the engine uses. If the pressure is being set too high after the engine warms up.
The engine settings for cold may be OK but not for hot due to the problem. Something may be stuck open, not turning off, etc. Versus something changing when the engine is hot. It may not change just does not turn off from being on when the engine was cold.