Try new spark plugs and fuel filter before anything major (ie catalytic converter)

Check the wires and distributor cap while you're doing the plugs too...

 

Could also be your coil, do you have any trouble starting when its raining?

 

since you "just purchased it," you may need to do a major tune up.

As was mentioned, spark plugs, spark plug wires, distributor cap and rotor, oil and oil filter change, fuel filter, air filter.

and while everything is apart, carefully clean out the throttle body with Deep Creep and a toothbrush.

 

Hello everybody.

Im new to this forum, and a new owner of a 1990 white Camry V6 2.5L GX-i (MT). I have to say, this forum is simply great! Ive learned a lot about my Camry and cars in general thanks to it. Im very new to cars and how they work, but ive started reading a lot and wish to fix as many issues as i can by myself.

Anyway my car has got some issues seemingly very related to this thread so i post it here instead of creating a similar one.

When started cold, its no problem. But when the engine starts to warm up and the car is in motion, it starts to hesitate and or knock at low RPM such as <2500-3000, especially at gear 1-3. Other times, this doesnt happen at all. And usually, after the engine and car in general is thoroughly warm, the knock only starts at very low RPM such as <1300. It idles pretty rough as well, and the rough idle happens at the same times as i told about the car while it is in motion. When the car doesnt knock or hesitate in motion, it also performs perfect idling. At worst tho, it might stall, but that has only happened couple of times.

When i drove the car the first time, and the first week after i bought it, it had much less trouble with this "knocking/hesitating". It started to get noticable after i drove the car almost out of gas one time and when i drove to the gas-station it really knock'ed a lot. After filling up some 10-15L tho, it still continued with the knocking as i told earlier.

After talking to friends and colleagues about this, i got hints that the issue might primarely be that the gas tank might contain some moist that gets to the fuel injector and is causing it to mix wrongly air and gas, or something like that. After hearing this i bought a small bottle of anti-icer for aprox. right gas tank and filled it up and also filled the gas up full correctly according to the instruction of the de-icer. Not at first, but slowly and firmly the knocking, and hesitation in the throttle has started to fade away almost back as it were before it first started to elevate to the really annoying level. But i feel there is something more wrong, the engine still knocks way more than im used to normally, and it is still more of an rough ride than i wish of this or any car. Also, the gas mileage seams to be poorer than usual cars with similar specs, but im not so sure since i havent really checked it thoroughly enough. But its something to have in mind as well. Also, seems like the weather effects all this as well, air humidity etc. But i cant be sure, the issue seems random at times.

Are there parts that i especially should look further into for tuning the engine to run smoother? Help is heartly appreciated :thumbup:

 

I used to have the same problem. I found that after i got my timing belt replaced that shuttering is gone. This leads that the timing is off. Check that out! Do you know how long its been since you got the timing belt replaced?

 

I made write-up on cam timing check procedure(sorry, no pictures)Hope this helps:

Camry 3S-fe cam timing check

The most common reason for timing belt to jump the tooth if the engine is rotated counterclockwise (S. Kornienko), or the belt is too loose. The properly tensioned timing belt must allow to be twisted no more then 90 degrees between the water pump and camshaft sprockets (L. Carley).
The incorrect valve timing must be suspected if:

• The engine has sluggish acceleration, low fuel economy and incorrect idle speed
• The distributor must be rotated too far to obtain 10 degree setting

The crank sprocket (Figure 1, position 2) has 24 teeth; each tooth is equal to 15 degrees of crankshaft revolution. The camshaft sprocket (Figure 2, position1) has 48 teeth, with one tooth equal 7.5 degrees of camshaft revolution.
So in case the belt is one tooth off, the ignition timing will also be 15 degrees off 10 degree BDTC mark.
If there is a suspicion that the cam timing is off (the belt jumped) the test could be made as follows:

• Remove the 4 inch rubber plug from the upper timing cover to expose the cam sprocket;
• Using inspection mirror locate the alignment hole in the cam sprocket
• Remove the spark plugs, except for cylinder number one
• Rotate the engine clockwise by placing socket head on the alternator pulley nut, until the hole in the sprocket aligns with the mark on the bearing cap;
• Now take look on the timing scale near the crank pulley--- if the belt jumped, the timing mark will be off by 15 degrees (it must be on the 0).

As a side note, it makes much more convenient to align the cam sprocket by placing the additional alignment mark on the sprocket rim and timing cover number 3. (This is done on my car). The misalignment by one tooth will throw marks almost 8 mm apart, making such event hard to miss.
In addition the cam timing may be off due to following reasons:
· Broken camshaft –to–cam sprocket drive pin (on both sprockets the timing marks will match, but the cam will be “late” relative to sprocket)
· The rubber in the crank pulley will deteriorate and the outer section containing the timing mark will drift counterclockwise as a result of alternator belt tension (this will lead to the wrong conclusion that the cam is advanced), therefore is good idea to match mark the pulley hub to its outer section (where the timing mark is).
· Damaged crankshaft-to-crankshaft sprocket woodruff key — the cam timing will be retarded and timing marks will not mach. This needs to be checked if belt is tight.

 

Thanks, i will check out the timing. I have the 2VZ-FE engine, is the timing belt test the same as with the 3S-FE engine?

 

No, 2VZ-fe is checked differentlu and it is much harder to check.

 

Ill read the manual and camrymanuals.com for further instructions, and see what i can do about it.

Btw, is the engine supposed to knock/drag on these cars at low RPM around 1500-2000? The manual says the car should be operated between 2000 - 3000 RPM, but i would at least think that it started knocking when its under 1000-1500, like most(new) cars.

Edit: I also have a question about the throttle. My Camry really hits the engine as soon as the throttle is pushed in. It doesnt need to be pushed all the way in for this, just normal throttling is enough for a rough "accelration"(but when i slowly push the throttle more and more in as the car speeds up, this doesnt happen), and when i take the foot of the throttle suddenly it gives the same rough thing just the other way naturally. It doesnt feel right.

 

Ok so i did a diagnostic check and got these results:

xx xxxx
xx xxxxx
xx xxxxxx

Which means something can be wrong with(right?):
- code 24: Intake air temp. sensor signal
- code 25: Air/Fuel ratio lean malfunction
- code 26: Air/Fuel ratio rich malfunction

While i was at it i cleaned the throttle body to some extend and damn was it dirty inside there.
I didnt drive the car that much after i cleaned it, but i drove it enough so the engine got warm. And it seams to have helped already. Now the car is very good at cold start(as always, that has never been the problem), and when it warms up a little hesitation takes place especially up hills but nothing biggie like before. Idle is also a little unstable still when the engine is warmed up, but very little. Usually its stable at 750RPM but at worst +/- 100 RPM from the ideal idle.

I did a search on "throttle body cleaning" and sow ppl at the forum which use throttle cleaner, toothbrush and a clean cloth to remove the dirt out of the valve. But i just used a toothbrush and some cleaning spirit. I didnt have any throttle cleaner available. Will the result will be a lot better if i used the throttle body cleaner? And can someone be kind and explain me how its supposed to be used? I got confused since ive read some start their engine while the valve is open, and spray the cleaner inside. How should i do this?

 

Well, if you would be able pull the codes earlier it will make trobleshooting easier:


Intake air temp. sensor signalOpen or short circuit in intake air temp. sensor signal (THA).

• intake air temp. sensor circuit
• intake air temp. sensor
• ECU

The other two codes are probably result of code 24
remove air flow meter and check condition of both sides of the connector, making sure that no female terminals are bent or pushed in.
Then do the bench test for AFM.
Visually inspect the sensor-It looks like small white pin 1/4 in dia, 1/2 in long sticking into the airlow channel.

 

"But i just used a toothbrush and some cleaning spirit. I didnt have any throttle cleaner available."

This is not a very good idea. If your cars use O2 sensors in Norway, chemicals that are not O2 sensor safe can easily destroy the O2 sensor. Next time use only O2 safe throttle body cleaner or O2 safe carb cleaner.

Here is a link with some pictures that should help you through the procedure; and be sure to clean the back side of the throttle valve while you are inside the throttle body:

http://www.4x4wire.com/toyota/maintenance/30_V6/throttle_body/

Mike

 

Well, if you would be able pull the codes earlier it will make trobleshooting easier:

Sorry, i just found out how to.
I'll try checking the AFM with ohm meter.

This is not a very good idea. If your cars use O2 sensors in Norway, chemicals that are not O2 sensor safe can easily destroy the O2 sensor. Next time use only O2 safe throttle body cleaner or O2 safe carb cleaner.

Ouch! Yes the car is basically the same i think. It definitively has a O2 sensor. Hope i didnt ruin it....
And thank you for the link, ill do it right this time.

 

Now the throttle body is cleaned with carb cleaner. The car runs a little bit smoother when warm but no big difference.

I didnt know how to remove the last mutter on the air flow meter, so ill check it again later. The mutter is behind some kind of alu cover which i couldnt get off. But i did check the resistance values while AFM was onboard:

VS - E2 = 296 ohm <-- should be between 200 - 600 ohm.
VC - E2 = 280 ohm <-- should be between 200 - 400 ohm.
THA - E2 = 3210 ohm <-- should be between 4000 - 7000 ohm @ 0 degress celcius, but it was maybe +5 degrees celcius outside.
FC - E1 = Infinity <-- should be infinity.

It seams good till now huh?

Btw, what makes the car want to hesitate when its got warm, and not while its cold? Its perfect while its cold, until the gauge is right in the middle!

 

I did a volt and ohm troubleshoot...

I checked the oxygen sensor with a ohm meter and got these results:

Cold engine: 33 ohm
warm engine: 38 ohm

While it should be(according to the manual at http://www.camrymanuals.com/manuals/90/EFI.pdf page 132 (FI 131):

Cold engine: 5.1 ohm
Warm engine: 6.3 ohm.

So the oxygen sensor has to be fried, right? Anyone else done this check before and remember their results?

Also, i did a voltage check between the THA and E2 connectors at the ECU(the connectors that gives power to the AFMeter, while disconnected from the AFM), while the engine was warm and the electric power @ ON. The result was 5 volt. The manual page 70 says the voltage should be between 1 - 3 volts. But is that while the AFM is connected to the ECU? Cause the 5V i got was without the load of the AFM.

Btw, the connector between ECU and AFM seams really solid, so it should be ok. I also took a look at the AFM sensor, and it looked ok i guess. It wasnt white tho, the colour have probably been changed over the years and was more like yellow.

What more can i do? Is it likely that the O2 sensor is causing all this? Any suggestions are welcome.

 

Yes, the heater for the O2 sensor could be defective.Unplug the sensor and measure resistance on the sensor (to eleminate wiring problems)
The voltage between THA and E2 could be 5V. With ignition OFF, measure resistance between E2 and negative battery terminal.The reading must be continuity.
You may have to change sensor and clear the codes, then drive the car to see if the condition improves and codes will not reappear.

 

Thanks again for answering. I will try these things asap and be back here.

I noticed today, after driving almost 40 miles, that the problem doesnt go away after the engine is thoroughly warm. I dont know what that means, but others might have a clue. Btw the temperature is about -2 to 6 celcius degrees now-a-days (28F - 43F) and the air has probably about 30% - 40% humidity(snowing).

 

When i got simultaneous CEL codes 25 and 26, i changed out the O2 sensor, reset the EFI, and the codes didn't return.

 

I had the same hesitation problems with my 5-speed V6 a year or so ago, and I wasn't getting any codes. Then one day the check engine light did come on after the car had warmed-up (it was a winter morning). The code was a faulty o2 sensor, which I replaced. The hesitation went completely away.

You asked why the hesitation only occurs when the car is warm. As far as I can remember, on cold start-up the ECU does not read input from the o2 sensor. Therefore, it runs smoothly. Once up to normal op temp, the ECU tries to read the o2 sensor's haywire input--and you get a check code.

Congrats on getting a manual V6, they're getting rediculously rare these days! I love mine more than any sports car I've owned...well, more than most!

 

"You asked why the hesitation only occurs when the car is warm. As far as I can remember, on cold start-up the ECU does not read input from the o2 sensor. Therefore, it runs smoothly. Once up to normal op temp, the ECU tries to read the o2 sensor's haywire input--and you get a check code."

TBayToyotaBoy is correct. That's how the O2 sensors work. They must be brought up to a certain operating temperature before they give any input. That's also why around the mid 1990's cars started coming with electrically heated 4 wire O2 sensors. They are electrically heated to reach operating temperature more quickly.

Mike

 

I've also noticed the I4 3SFE sensors are two-wire while the V6 2VZFE are four-wire...

P.S.: Thanks for vindicating my recollection of o2 sensors...it's nice to be right sometimes.

 

Thanks guys :thankyou:, and yes TBayToyotaBoy this car is wickedly rare especially in Norway(3 of them as far as i know), and i love it.... Now i feel confident that it is the 02 sensor heater which is defect. Ill try removing it from the cord first and see what happens when engine warms up. If that works without the hesitation, then i know for sure whats going on and what to replace.

Also, i have to find out why the code 24 came up. But i am feeling close to finding the defect part thanks to doctor j. Lets hope its something cheap thats broken... :naughty:

 

Maiser, do you have any scrap yards near you? Almost all of the major parts I've found for my V6 like the AFM, alternators, and throttle body have come from wrecked cars. It's the least expensive source for dealer-only parts.

 

It was the oxygen sensor!

I disconnected the power to the oxygen sensor heater, and started the motor, drove around for some miles until the engine was warm. I noticed right away after i removed it that the hesitation was over. The engine runs really well now, even on low RPM's as 700-1000, and it also seams to use less gas.

So, now im driving around without the oxygen sensor heater plugged in. That cant be too good, can it? Thanks TbayToyotaboy :=) Ill try the scrapyard(wherever it is). Thanks for the all the help guys, its really appreciated!

Next to do:
Change O2 sensor heater.
Find out why i get error 24, fix that.
Change dust-caps.
and some minor things....