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1994 Toyota Camry problem with idle.

Adv3nture

By Adv3nture
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Adv3nture Enthusiast

Adv3nture

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Turning on the air conditioning or shifting into gear causes my 1994 Camry to drop approximately 250 RPM, shakes violently, and frequently stalls. Additionally, the idle RPM is totally unpredictable when in park; I've found that when I shift into gear or activate the air conditioning, the RPM will be 100 rpm higher or lower than it was before I did either of those things. The intake boot was replaced, the idle air control valve was cleaned, and the throttle body washed. Lastly, speeds exceeding 50 mph are not possible.

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PopeyeR Enthusiast

PopeyeR

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I would wait to purchase any additional parts until you have performed basic testing, considering that you have already cleaned the throttle body, replaced the cracked intake boot and IAC valve, and replaced the throttle body.

For the 2.2L 5S-FE, I recommend checking the vacuum switching valve (VSV) and the air conditioning idle-up valve first. When the air conditioner compressor turns on, that system is meant to take up the extra load. The engine can decrease several hundred RPM, shake, or even stall if the valve isn't opening, the solenoid isn't being energised, or if one of the vacuum hoses is leaking or disconnected. Instead of assuming that the new IAC has handled everything, make sure to check the hoses, electrical connector, and valve operation.

The vacuum lines and idle-up valve for the power steering system should also be checked. Even when you're not moving the steering wheel, an irregular idle might be caused by a circuit leak. While you're there, make sure the new IAC is working properly and that its air vents are unobstructed.

Because the idle speed is so unpredictable when I go from Park to Drive or turn the air conditioner on and off, I'm starting to suspect the throttle position sensor, specifically its closed-throttle signal. Along with the engine coolant temperature sensor and the park/neutral position switch input, I would make sure to check that. Proper idle control is dependent on the ECU receiving accurate data from those components.

First things first: check the OBD-I trouble codes. Turn on the key while the engine is off, connect the diagnostic connector under the hood by jumping the TE1 and E1 wires, and then count the number of flashes of the check engine light. There might be stored code that indicates the issue even if the warning light is off.

Forget about the idle; what really gets under my skin is the car's inability to go faster than fifty miles per hour. I would never attribute that to the air conditioner's idle-up valve or IAC. Verify the mechanical and ignition timing, check for a restricted catalytic converter, and test the fuel pressure under load. The engine may have trouble running smoothly under load and at idle due to a partially clogged exhaust, a timing belt that has jumped a tooth, or inadequate fuel delivery.

If you're experiencing rough idle or stalling, another thing to check is the EGR valve. Make sure it's not stuck open. An inaccurate signal from the MAP sensor or a vacuum leak could be to blame for the engine's poor performance and inconsistent idle.

In my opinion, the order of operation should be as follows: first, inspect the vacuum hoses, trouble codes, air conditioning idle-up valve, fuel pressure, and IAC operation. Then, proceed to test the timing, fuel pressure, and exhaust backpressure. So long as we don't keep replacing good parts, that should keep things under control.

Do you find it difficult to increase the engine's RPM after reaching 50 miles per hour, or does it rev normally even when the car isn't moving faster? A lot of time and effort could be spared in troubleshooting if that difference was made.

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