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Discussion Starter #1
1990 Camry base 2.0 It doesn't want to start at a normal cold start idle speed. If I give it some throttle it will start as long as I hold the throttle at a high idle. If I let up on the throttle before it warms up some it will start to sputter but if I hold it at a high idle for a couple of minutes and then let up on the throttle it will idle down and keep idling. It only does this during a cold start. Other than that it runs great. Also please note that I have owned, driven and worked on nothing but full sized Ford pickups for the last 45 years. A lot of the basics are the same with the Camry but I am noticing things about the Camry that are completely non existent with the Ford trucks. I figure it's better to first ask people who know Toyota's before I rack my brain out digging through books or websites. The code 22 (engine coolant temperature sensor) I'll know more about when I drive it tomorrow as I put a new one in and haven't driven it yet. Whether the code 22 has anything to do with the 25 and 26, I have no idea. I was hoping someone would though. Thanks...any info will be appreciated.
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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A bad engine temp sensor could definitely cause 25/26. Make sure you get the temp SENSOR (two wires, green and brown), not the temp sender (only used for the gauge).

-Charlie
 

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Discussion Starter #3
A bad engine temp sensor could definitely cause 25/26. Make sure you get the temp SENSOR (two wires, green and brown), not the temp sender (only used for the gauge).

-Charlie
New sensor installed and codes cleared but they came right back, all three 22, 25 and 26
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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Do you have a California emissions vehicle or the fed emissions vehicle? (CA has two O2 sensors and the main sensor is a 2-wire heated sensor) Also check the wiring harness where it runs up from the transmission to the fuel injectors, it can be damaged there by the EGR pipe. How's the vehicle running otherwise?

-Charlie
 

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Discussion Starter #5
Do you have a California emissions vehicle or the fed emissions vehicle? (CA has two O2 sensors and the main sensor is a 2-wire heated sensor) Also check the wiring harness where it runs up from the transmission to the fuel injectors, it can be damaged there by the EGR pipe. How's the vehicle running otherwise?

-Charlie
Other than the cold start problem it runs great. I swapped the cold start injector with one from a working 1990 camry and it made no difference. I also swapped the way over priced cold start injector timer thingamajig with the known good one and still no difference. Should the ECT sensor have voltage when the key is turned on. With the voltmeter hooked to the ECT connector with key on I'm getting zero voltage but if I reverse the voltmeter probes I'm getting minus voltage. I think it was -5 volts. I'm on my way out to check the wires where you mentioned. THANKS..and yes, it is a California emission vehicle. If I don't have a voltage problem to the ECT sensor then I'll start looking at the 02 sensors. The one that sticks out like a sore thumb right down in the front side of engine is a single wire one. Not sure where the other one is as of yet. Thanks again....any and all information is pertinent whether it relates to the problem or not. I've driven and worked on nothing but full sized Ford pickups for like 45 years now and even though a lot of the basics are pretty much the same I'm finding this Toyota to be somewhat "foreign" if you can imagine that....LOL!!
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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Should the ECT sensor have voltage when the key is turned on. With the voltmeter hooked to the ECT connector with key on I'm getting zero voltage but if I reverse the voltmeter probes I'm getting minus voltage. I think it was -5 volts. I'm on my way out to check the wires where you mentioned.
The ECT sensor is an NTC Thermistor, just like the temp sensors used in just about every vehicle.

Here are some reference values for it:
FI WATER TEMP. SENSOR
10–20KΩ(–20°C,–4°F)
4–7KΩ(0°C,32°F)
2–3KΩ(20°C,68°F)
0.9–1.3KΩ(40°C,104°F)
0.4–0.7KΩ(60°C,140°F)
0.2–0.4KΩ(80°C,176°F)

Those are resistance values measured at the sensor (engine off, unplugged). Are you using a (modern-ish) digital multimeter or an old-school analog meter? An analog meter checking voltage would give bad readings if you are testing the voltage at the sensor while the engine is running. I would expect 3-5V when the engine is cold and much lower voltage (<1V) when the engine is hot. The ECU supplies 5V through a fixed resistor to the variable resistance sensor. The changing sensor resistance changes the output voltage. The brown wire is ground, the green wire is the connection to the ECU. Make sure you have continuity to the ECU (check with car off) on that green wire, which is the bottom corner of the largest connector on the ECU.

If the Idle Air Controller is stuck close (or nearly so), it might also act like you are describing. The extra fuel from the cold start injection system could be overwhelming the low amount of air making it in to the engine. I'd suggest trying a good cleaning of that too.

There are a few 'phillips' screws on there - take note that they are NOT Phillips screws! They are JIS cross-head screws and are very likely to strip if you don't use the correct cross-head driver. This is a common complaint from people about Japanese vehicles and their 'cheap' phillips screws. Get the right tool and you'll be much happier.

-Charlie
 

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Discussion Starter #7
Other than the cold start problem it runs great. I swapped the cold start injector with one from a working 1990 camry and it made no difference. I also swapped the way over priced cold start injector timer thingamajig with the known good one and still no difference. Should the ECT sensor have voltage when the key is turned on. With the voltmeter hooked to the ECT connector with key on I'm getting zero voltage but if I reverse the voltmeter probes I'm getting minus voltage. I think it was -5 volts. I'm on my way out to check the wires where you mentioned. THANKS..and yes, it is a California emission vehicle. If I don't have a voltage problem to the ECT sensor then I'll start looking at the 02 sensors. The one that sticks out like a sore thumb right down in the front side of engine is a single wire one. Not sure where the other one is as of yet. Thanks again....any and all information is pertinent whether it relates to the problem or not. I've driven and worked on nothing but full sized Ford pickups for like 45 years now and even though a lot of the basics are pretty much the same I'm finding this Toyota to be somewhat "foreign" if you can imagine that....LOL!!
The ECT sensor is an NTC Thermistor, just like the temp sensors used in just about every vehicle.

Here are some reference values for it:
FI WATER TEMP. SENSOR
10–20KΩ(–20°C,–4°F)
4–7KΩ(0°C,32°F)
2–3KΩ(20°C,68°F)
0.9–1.3KΩ(40°C,104°F)
0.4–0.7KΩ(60°C,140°F)
0.2–0.4KΩ(80°C,176°F)

Those are resistance values measured at the sensor (engine off, unplugged). Are you using a (modern-ish) digital multimeter or an old-school analog meter? An analog meter checking voltage would give bad readings if you are testing the voltage at the sensor while the engine is running. I would expect 3-5V when the engine is cold and much lower voltage (<1V) when the engine is hot. The ECU supplies 5V through a fixed resistor to the variable resistance sensor. The changing sensor resistance changes the output voltage. The brown wire is ground, the green wire is the connection to the ECU. Make sure you have continuity to the ECU (check with car off) on that green wire, which is the bottom corner of the largest connector on the ECU.

If the Idle Air Controller is stuck close (or nearly so), it might also act like you are describing. The extra fuel from the cold start injection system could be overwhelming the low amount of air making it in to the engine. I'd suggest trying a good cleaning of that too.

There are a few 'phillips' screws on there - take note that they are NOT Phillips screws! They are JIS cross-head screws and are very likely to strip if you don't use the correct cross-head driver. This is a common complaint from people about Japanese vehicles and their 'cheap' phillips screws. Get the right tool and you'll be much happier.

-Charlie
I'm using a Fluke digital multimeter. I did get +5 volts ON THE ECT connector with the engine running and cold. There is continuity between the brown wire connector pin and battery ground. The ECT sensor is brand new but I tested it anyway and it was just under 1KΩ with a warm engine as the outside temperature was 93°. After driving the 20 mile round trip drive from my house to the store and back yesterday I checked the codes again and I'm still getting the ECT sensor code 22 but I'm now getting a code 24 along with it. On my way out right now to see what's up with that. I'll give the IAC a good cleaning also. I don't think the previous owner did much upkeep on this car. I replaced the fuel filter a short while back and I don't know how it was even running at all. It was well beyond dirty fuel coming from it. It was actual brownish blackish colored sludge that came out and it came out very slowly. I did look inside the fuel tank after that and thankfully it was clean. I'm sure the injectors could use some cleaning or most likely a cleaning and rebuild since they'll be out anyway. What else could cause the code 22 to come up? Thanks again and thanks for the heads up about the "phillips" screws. I do know how to make a phillips screwdriver though....vodka, orange juice and some milk of magnesia....okay, okay...back to work...
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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5V at the harness plug with the sensor unplugged is correct, if you get that with the sensor plugged in (back probing on the harness, maybe?), then there is something up.

Code 24 is for the IAT sensor, but that is over in the AFM (air flow meter) on the airbox. Those should be unrelated, other than they draw the from the same 5V power supply in the ECU. Oh, and speaking of screws - leave the screws on the AFM body alone! The connector there is removed by moving the small metal c-clip that goes around the plug. If those screws are removed, you can easily damage the AFM.

I'm assuming these are all 'live' problems and that you have reset the ECU a few times (pull the EFI fuse for a bit)?

-Charlie
 

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Discussion Starter #9
5V at the harness plug with the sensor unplugged is correct, if you get that with the sensor plugged in (back probing on the harness, maybe?), then there is something up.

Code 24 is for the IAT sensor, but that is over in the AFM (air flow meter) on the airbox. Those should be unrelated, other than they draw the from the same 5V power supply in the ECU. Oh, and speaking of screws - leave the screws on the AFM body alone! The connector there is removed by moving the small metal c-clip that goes around the plug. If those screws are removed, you can easily damage the AFM.

I'm assuming these are all 'live' problems and that you have reset the ECU a few times (pull the EFI fuse for a bit)?

-Charlie
I still have the cold start problem but I'm thinking maybe there's a problem with the check engine light itself. I can pull the fuse or undo the battery cable for any length of time but the check engine light won't go away even for a minute after the car starts. It functions like it's supposed to though when pulling up codes. If the codes are cleared shouldn't the check engine light go away at least until the ECU again realizes there's a problem? Or maybe it realizes there's a problem the second the car starts. I always assumed it had to be driven a little ways at least so the ECU has time to figure out what's going on. I know the code 24 should be unrelated. Sometimes the vehicle will actually run better with the IAT unplugged. I'm gonna go out and back probe the ECT sensor harness and check the voltage with it hooked up in a few minutes. Thanks again....
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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Sometimes the vehicle will actually run better with the IAT unplugged.
The IAT is part of the MAF sensor on the airbox and can't be unplugged separately. If the MAF is unplugged, the engine should die nearly immediately (shuts off fuel pump, among other things). What exactly are you unplugging when you think it is the IAT?

The check engine light can go on immediately for problems it doesn't need multiple-cycle logic for... (it will take a while to show speedo signal missing or O2 sensor codes, but missing or out of range sensors will be immediate)

-Charlie
 

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The IAT is part of the MAF sensor on the airbox and can't be unplugged separately. If the MAF is unplugged, the engine should die nearly immediately (shuts off fuel pump, among other things). What exactly are you unplugging when you think it is the IAT?

The check engine light can go on immediately for problems it doesn't need multiple-cycle logic for... (it will take a while to show speedo signal missing or O2 sensor codes, but missing or out of range sensors will be immediate)

-Charlie
The IAT is incorporated into the MAF. Got it. That would be the wide connector right above and on the intake side of the air cleaner I assume. I didn't actually drive the car with that connector unplugged but with the car just idling and working the throttle by hand it didn't seem to run any different at all whether it was plugged in or not. And like I was saying, other than the cold start problem it runs fine. It never dies or stalls out or misfire in any way and it's got as much "get up and go" as you could expect for close to 300,000 miles on the engine. It passed California smog just a few months back. Nothing is explaining the code 22 still though. The sensor is brand new which I know doesn't always mean it's a good one what with all the after market products but it does test good as far as voltage and resistance as does the wires going from the connector to the ECU. You say it has two 02 sensors. I see the one that sticks out like a sore thumb but where is the other one? Time to look into that area. Thanks again for your input Charlie. When it comes to vehicle repairs there is no such thing as "too much knowledge."
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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You say it has two 02 sensors. I see the one that sticks out like a sore thumb but where is the other one?
It will only have two O2 sensors if it has the California Emissions package. The second sensor would be below the main catalytic converter, can't remember if it is on the cat pipe or at the top of the front exhaust pipe. It has been ~10 years since I have worked on a 3s-fe... ;)

-Charlie
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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8,273 Posts
The IAT is incorporated into the MAF. Got it. That would be the wide connector right above and on the intake side of the air cleaner I assume. I didn't actually drive the car with that connector unplugged but with the car just idling and working the throttle by hand it didn't seem to run any different at all whether it was plugged in or not.
To be a bit pedantic, there is no MAF on the car, it is a Vane Air Flow Meter (AFM or VAFM). There is a little flapper door in that box on the airbox that opens relative to the amount of air flowing into the engine. Also associate with that flapper (vane) is a microswitch that turns on the fuel pump relay (Circuit Opening Relay, in Toyota parlance). If the AFM is unplugged, the fuel pump will shut off and the engine will die.

If the engine doesn't shut off with the AFM unplugged, a previous owner may have put a jumper wire in the diagnostic connector (on the driver's strut tower) between the Fp and B+ connections - which might indicate a previous problem.

-Charlie
 

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Discussion Starter #14
It will only have two O2 sensors if it has the California Emissions package. The second sensor would be below the main catalytic converter, can't remember if it is on the cat pipe or at the top of the front exhaust pipe. It has been ~10 years since I have worked on a 3s-fe... ;)

-Charlie
Thanks. it is a California vehicle and I was getting ready to crawl under and look by the catalytic coverter for the second 02 sensor. Okay, one more question..can a one wire 02 sensor be replaced with a two wire sensor if you ground the connector's ground? That is assuming it fits in the hole and matches up. Just asking for financial reasons as I do have another Toyota although it's a Corolla. Both are 1990 but different engines. I notice some things are the same.
 

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3s-gte in a Camry?!?
'89 Camry Alltrac
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8,273 Posts
The sensor is grounded through the exhaust. The second wire is a heater connection and can be left open (probably, I don't think the ECU will throw a code for that). The shield for the 02 sensor connections should also be left floating.

-Charlie
 

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The only problem with troubleshooting every sensor is the first step would be to check for any vacuum leaks, including Stuck EGR, Intake Air filter and Mass air flow AFM sensors plus your AIC and Throttle body air bypass idle control must be thoroughly checked and cleaned none of these sensors can work properly or deliver the proper information to the engine management system with out the standard conditions . Likely the computer hasn't been properly times or has a faulty computer timer, memory or failed capacitors , batteries. Timing is always an issue as there is little or no other adjustments.
 
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