6G Celicas Forums

Hello, I would like to say that this forum has helped me tremendously over the past few months from repairs to ideas for the future. I would like to return the favor since I have seen plenty of post about their Celica's having trouble on cold starts resulting in stalling. This is my first post on a repair so if I am not clear on anything, I apologize and I will verify whatever I missed on.I have covered almost every trouble shoot to fix the problem replacing the spark plug wires, coil, distributor, spark plugs, reset the ecu, cleaned the IAC motor, replaced IAC motor from another 5sfe at pick n pull,disassembled the IAC valve to give a thorough clean, topping off a little more of the oil with Lucas stabilizer, adjusting the throttle opener vacuum, and although some of what I replaced I needed anyway, it still did not fix my problem. Mind you I have been trying to figure out this problem with my father-in-law who is an ASE certified mechanic for over ten years and specializes work on Toyota engines.

The problems I have with my Celica are when it is parked on my driveway (inclined), on a cold start I am able to start the engine but eventually stalls unless I fix my foot on the accelerator to keep the engine from stalling and to warm it up; the other problem is the mixture in the morning is too rich. The other day, I was studying the vacuum diagram and verified that everything was connected until I came across one vacuum actuator called 'idle up valve'. I asked my father-in-law and noticed it was strange since the Camry 3sfe has a part similar to the 'idle up valve' but on the 3sfe, the vacuums are directly connected to the TB eliminating the need for another actuator. On the diagrams for the vacuums, look for the actuator with dotted lines going from the IAC/EGR to the 'idle up valve'.

*note; I am writing this for the Celica's with the 5sfe, although the 7afe has the same actuator but different locations.

Here you can see it is below and behind the TB on the left side if you were looking straight at the engine or standing at the fender on the passenger side.


This is another angle just to get a better idea of where it is actually placed.


So I learned from my father-in-law that this actuator will, on a cold start, compensate the ratios of fuel and air(hence I would run rich in the mornings) since the colder air is dense. Going with the new information and knowing all of the work I have done to try and fix the problem in the past, I began performing test to determine whether or not actuator was the problem or my connection. I used a simple test with a tester light, with the engine off and connecting to the positive terminal, I prodded the connection to verify there was power. One more test that should be performed and is easier with another person is to disconnect one of the hoses, start the engine(on cold start), and check to feel if there is any suction.

Here is a view of the connection unplugged and where I tested the circuit.

Positive charge test with engine off.



The next test will be with the ignition on, and testing prong on the negative terminal, perform the same test.



It goes without saying, if there is no light indicating a charge, then a fuse is most likely the problem. So if the problem does not lie with the connection then it is the idle up valve.


There are only two bolts on the harness which are 10mm and two vacuum hoses, very simple unless the hoses are old and brittle in which I ended up doing myself. As for the actuator, I grabbed a few from Camry's of the same engine from 92-01. The only problem is that some of years do not have the exact same engineering for the 5sfe so beware.


Here it is removed


Here is another photo of the newly replaced part; as you can see it has a different orientation which will break any brittle hose.


There is a slight difference in the design for the Camry 5sfe idle up valve but that is only in regards to the orientation of the actuator, but the brackets mount just the same. One other thing to consider are the hoses, I had to replace the hose facing down since it began to crack as well as the fact that with the new orientation of the actuator, it requires a shorter hose to complete the vacuum line. After this change, my cold start has stablized even when I am inclined and putting it into gear.

I hope this helps anyone else with stalling on cold start and I apologize if this did nothing for your Celica.

~Rawrssell

This post has been edited by Rawrssell: May 4, 2014 - 12:51 AM