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My 99 Solara developed a problem out of the blue. First thing in the morning when the engine is cold, the idle will go up and down (500-1500). Eventually, the idle goes low enough to stall the engine. If I apply any throttle, the engine bogs down and dies. However, if I can get the car to run long enough to even slightly warm up, the idle returns to normal and the car runs perfectly. It is then good to drive for the remainder of the day. Since I noticed the exhaust smelled of gas during the fluctuating idle, I figured I could lean it enough to run by heating the throttle body with a heat gun. Sure enough, it starts running perfectly once the throttle body gets warmed up. I'm assuming a bad sensor, but which one? I've cleaned the IAC and it didn't make a difference. I'm not sure the symptoms indicate a bad IAC anyway since I think I'd have idle problems when warm as well?
IAC may have been cleaned but it may be broken. The vanes should be almost closed when cold and fully open when warm.
Coolant temperature switch may be bad? Or cold start injector, if fitted, may be clogged or broken.
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I'm not sure the symptoms indicate a bad IAC anyway since I think I'd have idle problems when warm as well?
Not necessarily, the IAC is basically just an electronic choke. So once the IAC opens when triggered by engine heat, it is out of the loop and will not affect engine starting or idle until the next cold start.
My guess would be a bad engine coolant temperature sensor. Toyota calls it an ECT sensor in their manuals. You can check it when the engine is cold. You will need the specs from any manual and a digital volt/ohmeter.
My guess would be a bad engine coolant temperature sensor. Toyota calls it an ECT sensor in their manuals. You can check it when the engine is cold. You will need the specs from any manual and a digital volt/ohmeter.
Mike
That's my guess also.
The OP needs to check the IAC to see if it's functioning properly, as well as the ECT. A vacuum leak could also cause the problem by making the vehicle too lean when it needs to be rich (when cold).
Quote:
Originally Posted by marc780
IAC may have been cleaned but it may be broken. The vanes should be almost closed when cold and fully open when warm.
Coolant temperature switch may be bad? Or cold start injector, if fitted, may be clogged or broken.
Quote:
I'm not sure the symptoms indicate a bad IAC anyway since I think I'd have idle problems when warm as well?
Not necessarily, the IAC is basically just an electronic choke. So once the IAC opens when triggered by engine heat, it is out of the loop and will not affect engine starting or idle until the next cold start.
Vanes in the IAC? Do you know how an IAC functions? Apparently not. It's basically a little motor with a pintle at the end. This pintle blocks a port that bypasses the throttle plate. The ECM moves the IAC to allow the correct amount of air into the engine to maintain a preset idle speed.
There isn't a cold start injector.
The IAC is not basically an electronic choke. I found you something that you can read to help you understand what an IAC is and what it does: http://www.crossfire.homeip.net/tech/iac.pdf
Why do you insist on spewing out your crap onto threads all the time? It's clear that you don't know what you're talking about. I'll add this to your partial list of crappy information that you post.
marc780 should not be trusted for his technical advice. He apparently has a mission to give out bad information to others.
Here is some more of his technical advice blunders:
1)Toyota requires a specific P/S fluid and not Dexron - Toyota has recommended Dexron and Dexron II for decades. Check the online manual.
2) Just moving the TPS around until the car idles correctly is acceptable. You cite that because you do it that it's fine. Actually, you need a scan tool or voltmeter to set it within specs. Check the online manual for verification.
3) Impact wrenches are just as good as torque wrenches for installing wheels and not causing any problems. Again, you cite that because you do it that it's proper. That's not true. You can search ANYWHERE for supporting facts that you are incorrect.
4) You also recommend that someone with a faulty accelerator pedal sensor replace the TPS instead. That will do nothing. The accelerator pedal sensor relays it's information to the ECU. The ECU decides what exactly the driver is trying to accomplish and signals the throttle body what to do. The TPS that's integrated into the throttle body tells the ECU what position the TB is at.
5) Here you suggest that an I4 2AZ-FE (with a timing chain) has a timing belt and cover by saying Quote: remove the timing belt cover and run the engine and listen for the noise. Be very carefull but put your hand or an object on the timing belt pulley to affect its operation - (use care not to get that thing tangled inthe engine!) and listen.
6) Here marc780 states that this person should the timing belt, waterpump, and idlers for no reason. The car comes with timing chain and the water pump is external.
8) Here is a thread that he started because he couldn't even figure out that his power steering belt just needed to be readjusted because it stretched slightly. Belts needing to be adjusted is COMMON knowledge after a new belt is run. He can't even figure that out on his own.
9) Here is his contribution by adding a "TECH" article to the forum. He suggests smashing battery cable ends with hammer or smashing a penny with a hammer to make a battery cable "shim". His "TECH" write up also suggests starting a stored vehicle every two weeks and letting it idle to charge the battery...
10) In this thread he recommends jamming a screwdriver into the throttle body and throttle blade. This can easily damage the throttle body itself, the throttle blade, and any coatings by scratching it.
11) Here marc780 couldn't even figure out why his car vibrated when the brakes were applied. He doesn't even understand that you can't see the rotor warpage with the naked eye. He also suggests that he thinks an alignment problem could cause his braking vibration. Again, this just shows he doesn't even grasp the basic principles!
12) Apparently, marc780 has a learning disability because after being told over and over that the 2AZ-FE has a timing chain instead of a belt he STILL gives advice about 2AZ-FE's and timing belts or covers:
13) Here is were marc780 tells someone to "solder" a PLASTIC radiator tank as the only good repair. Of course, solder doesn't adhere to plastic and would be completely worthless just like most of his advice.
14) marc780 strikes again! This is a thread where he tells someone to dilute coolant that comes premixed (Toyota Super Long Life). As usual, he doesn't have a clue what he's talking about but passes along inaccurate information anyways.
15) marc780 never gives up. Here he states that an IAC motor is basically a engine temperature regulated choke and that it has vanes in it. He also suggests to check a cold start injector on a '99 Solara.
The OP needs to check the IAC to see if it's functioning properly, as well as the ECT. A vacuum leak could also cause the problem by making the vehicle too lean when it needs to be rich (when cold).
Thanks guys. I'll take a look at the coolant sensor. Is this something that's easy for the backyard mechanic like myself to replace?
Replaced the coolant sensor... no change. So I bit the bullet and took off the throttle body and removed the IAC. Sure enough, when I tested it using the battery it was sticking. My earlier efforts of cleaning it without removing it didn't work. Sprayed some throttle body cleaner in it and tested it again, and it worked like a champ. Put it all back together and my car is happy again. Thanks all for the help.
I take it back. It happened again this morning. So far I've replaced the engine coolant sensor and taken the IAC out and cleaned it. Pretty sure IAC is good as it goes full open and full closed when applying battery voltage to the corresponding pins. Any ideas on what sensors I should be looking at next? TPS maybe?
In case anyone else runs into this... I couldn't find the problem so I took it to my indy. The water pump was severely leaking causing the crank sensor to go bad.
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