My son recently purchased high mileage 99 4-cyl Camry. The car is in excellent condition.

After owning it for a week, it is suddenly no longer able to idle when cold. Only way to start the car when cold is to press the gas pedal little bit to keep the rpm at 1500-2000. If I let the gas pedal go, it will immediately stall until the ngine warms up. Once warmed up, it will idle very smoothly at 650 rpm. On warm restart, the tacometer jumps to 1000 rpm for 0.1 second and drops to 650 and holds steady (the scanner shows the speed to be rock solid at 650-653)

If this symptom had developed gradually, I would be replacing many consumable parts as they probably do need replacing such as spark plugs, wires, fuel filter, PCV valve etc. But since the car had no problem high idle'ing until yesterday, I suspect something else such as IAC sticking. Could somebody point me towards IAC troubleshooting procedure? Where is it located? FAQ did not have a reference to it.

Until the day before yesterday, cold idle was approximately 1500-2000 rpm. Yesterday, the cold idle was 850 rpm but after I bleeped the gas pedal it had gone to 1200 and stayed there. Today the cold idle was at 530 rpm and bleeping would increase it only temporarily.

I have a scanner and have already verified:
- No check engine light or any stored codes
- Coolant temperature is correct
- Air temperature is correct
- TPS readings are correct
- O2 fuel trims are reasonable

Turning on the air-conditioner does increase the idle speed. Is the mechanism to increase cold idle or to increase idle under A/C same or different?

I have just added STP fuel system cleaner (well it was free after rebate at Autozon) although I believe in Techron and/or BG444 products.

I have searched this forum for cold idle related topics and one person reported that his cold idle related problems only went away after replacing the fuel filter.

Thanks in advance,
- Vikas

 

http://www.camrymanuals.com/index.ph...&topicid=0

Go down the list to "SFI" sequential fuel injection and then to page 35 for IAC. Since your not getting any codes I would start by cleaning the IAC. You can use a spray cleaner W/O taking offIAC but I would not use the straw as that could come detacted and be sucked in the intake. The A/Cidle should be controlled by the Idle-up Valve, but I'm not sure on a 99. The manual I linked you to will have an A/C section. No cold operation sounds like temp switch but you said you checked those. If you want to see if you are not getting cold start rich fuel you could see if spraying carb cleaner or such down throttle when cold helps idle.

 

Thanks Pedro! Today morning, the car behaved fine. It immediately started and was fast idling at 1900 rpm and then gradually dropped down as expected. All I have done since yesterday is to feel the vaccum hoses around that area to make sure there was no obvious leak. I have a feeling that the problem will come back up sooner or later. I have already picked up CRC-brand throttle body cleaner spray which is supposedly safe for O2 sensor, catalytic converter and Teflon-coated throttle plate.

What is the purpose of the vaccum operated dashpot with extending plunger acting as a throttle stop underneath the accelerator linkage. Initially I thought it was connected with A/C idle speed increase but I have observed that the plunger extends on cold start and retracts when engine is warmed. This leads me to believe that it might be sticking which could give me the cold idle problem.

On the different topc, how do I remove the PCV valve? Do I just pop it up using flat-blade screw driver? Is it OK to use after market PCV valve? Fram looked extremely cheap in construction but Toyota dealer is not on my way. Also for general tune-up parts, is the following list reasonable?

1) Fuel filter - dealer only?
2) Spark Plugs NGK platinum
3) Wires - NAPA aftermarket or Bosch
4) Aircleaner - whichever is available at walmart i.e. Fram or STP or Purolator
5) PCV valve - dealer only or Fram OK?

Does the car have Cap/Rotor? I hope not!

- Vikas

 

Aaarg, it happened again yesterday but NOT today :-(

I took off the air inake hose. The throttle body was relatively clean but I sprayed the cleaner. I also applied liberal dosage to the square hole (IAC opening?). I also made sure that idle speed increases when I short the two diagnostics terminal as listed in the service manual, although the increase was only about 150rpm but it is within the specified range.

When this condition happens, manually pressing the gas pedal a little keeps the car running with no problems. This leads me to believe that it can NOT be plugs/wires/injectors/timing etc.

What is the funtion of the throttle opener dashpot stopper right underneath the throttle linkage? That plunger is working but I would like to know when is being commanded to retract or extend. Is that part of idle control or A/C idle control or is it only for coasting?

Taking it to a mechanic for this type of intermittant problem will be exercise in futile. My scanner gives standard general OBD2 data such as fuel system (open/closed loop status), Engine load, Coolant temperature, Manifold Pressure, Engine Rpm, Vehicle speed, Timing advance, Intake air temperature, Throttle position etc. The last time when I had hooked it up while the car was misbehaving, all these parameters seemed alright although the engine was barely idling at 530 rpm.

Does opened IAC simulate opening of throttle plate by providing extra air, somewhat similar to keepin the throttle plate opened during the choke operation of a carburated car? Please excuse the analogy but it had been years since I had to monkey with fuel/ignition systems on a modern car and my experience was in 80's carburated cars.

- Vikas

 

Maybe the dashpotis theidle-up throttle control for the A/C?? But there will be a VSV somewhere in the system to actuate it. Why don't you hook upa vacuum pump and see how it affects the rpm's. You can get someone to turn off/on A/C and see what ups the idle.

If your PCVconnects to the top of the valve cover through a rubber grommet then a screw driver can be used as a pry. But be careful as the grommet gets hard with age and you might split it and have it fall inside the valve cover. As well when thegrommet is hard it is difficult to remove thePCV. I replaced my grommet with a new PCV when I also replaced the valve cover gasket. I was too afraid the grommet would come apart and fall inside the valve cover.I just purchased fromdealer as the cost is minimal, but an aftermarket one will do.

Why don't you check out www.sparkplugs.comfor the plugs and wires. As for the fuel filter I don't think Toyo recommends replacing (lifetime)?? Check your ownersmanual.

Just read your latest post.The IAC operates with the throttle plate closed. Slightly opening the throttle plate will override the IAC. I don't know what the dashpot is for. Give me some time to take a look. The manual I linked you to should tell you.

 

Thanks Pedro! I spent couple more hours of debugging on it today. I suspect the IAC is sticky for some temperature range. I tried to disconnect the IAC electrical connector but could not figure out how to release the latch.

I sprayed the hell out of throttle body and in to the square hole but what I really want to do is to disconnect the IAC electrical connector and jumper the IAC so that I can open/close it manually while spraying with the cleaner.

The access to the connector is not that great. I can really use some pictorial help for disconnecting that connector. I have the electrical wiring diagram and shows some screwdriver type of tool for disconnecting various type of connector on the Camry. I tried to use small flat blade screwdriver and later even tried smaller jeweler style flat blade screwdriver.

Some people have even recommended to connect/disconnect it while engine is running! So it can not be that difficult but I always had problems in figuring out how to disconnect electrical conectors on the cars.

Somebody please tell me how to disconnect that connector!

- Vikas

 

A lot of those Japanese connectors usea wire clip to secure them. You remove the clip first then the connector just pulls off. To reinstall just replace the clip and push the connector on.

That dashpot is described as a idle control valve and can be referenced in the manual link under SFI pages 29-30. The manual only describes check and adjustment, not what makes it actuate. The A/C section refers to the ISC valve for idle-up operation but I don't know where that is located. It could be the dashpot. It looks like if you remove the IAC valve you need to replace the o-ring - be prepared.