Question on testing the AFM on '89 3SFE

[ChevyToughRebel]

I have an '89 Camry LE with the 3SFE engine, 185k miles. Over the past couple years I have been trying to figure out off and on the slight lack of power my car has been having. There are no DTC's and never have been. So far the things I have done are:

- Replaced TPS (purchased from dealer), and adjusted according to shop manual. Adjusted timing to 10 BTDC with pins E1 and TE1 jumped
- Replaced coil (purchased from Napa)
- Flushed & replaced screen on tranny
- Fuel filter replaced about a year ago
- regular maintenance (plug gaps @ .043")
- tested water temperature sensor, checked ok
- Tried replacing o2 sensor, no difference
- compression check with 160psi across all 4 cylinders
- replaced throttle body & cleaned out intake, no difference (already covered in oily sludge again!)
- EGR valve functioning properly
- Tried tesing AFM, with only one issue that is consistent with 5 different used AFM's I have. Will explain below.

Problem in more detail, unless im crazy, the car has a slight lack of power upon acceleration and under load. Upon acceleration, unless im puttin my foot into it, it always shifts into 3rd at 28mph and seems to require more throttle than necessary to accelerate at a decent speed. Is this about right for this car? It seems like it should be more like 35mph when it shifts into 3rd at normal acceleration. When the car is under a load, like going up a steep incline between 20-45mph, 2nd or 3rd gear, it pings, and sometimes pings really bad. When I back off or step on the throttle even more the ping goes away. Pinging is generally caused by incorrect timing, air/fuel mixture, or bad fuel right? I dont think its fuel since I have bought gas from many different stations. Possibly this newer E10 fuel blend we are running these days?

The one thing I cant figure out is one test on the AFM. I dismissed it at first as possibly a typo in the book. But both the chilton shop repair manual and downloadable shop manual from this site say the same thing about this resistance test. Upon testing terminals VC & E2 of the AFM, the resistance, for the 3SFE engine, should be between 3,000 to 7,000 ohms. I have 5 AFM's and they all test at about 280 ohms on these terminals. I called the dealer for the correct part number on the AFM for my car which was 22250-74100, the one on my car, and 3 others I had were 22250-74101, off by one digit. So I went to the wrecking yard and found the AFM with the part# the dealer gave me, still had the same resistance as the others.

Am I doing something wrong? Or are all 5 of these AFM's I have testing bad? I need to figure this out before I assume testing the other components on my car, as this could be my whole problem. Does anyone have any answers for this testing issue with the AFM?

Thanks in advance!

~ Shane

[Jimnist]

First of all, don't use E10. I used it and i notice a drop in power and an increase in fuel consumption.

Can't help with the AFM thing. These cars aren't really all that fast to begin with and coupled with the fact that they're around 20 years old now, don't expect too much from them

Just my 2c

[mcx]

...reset the initial timing to 15 degrees... you'll find that low end power/response!!

[kesando]

Is E10 that 10% ethonol gas? If so that stuff is everywhere!

[ChevyToughRebel]

Yeah I thought the E10 blend was everywhere. I still would like to know the deal with testing the AFM. I might just call up a dealership and try getting a hold of a tech. Thanks for the help so far.

Note: After readjusting the tps and putting the original factory o2 sensor back in, I have noticed a difference in acceleration. Those bosch o2 sensors must be junk?

~ Shane

[white90dx]

The trans is supposed to shift into 3rd at 29-32mph under light throttle applications... that sounds normal. Have you tried driving in the "power" mode? It should shift in the 36-39mph range and give a more 'modern' driving feel.

My Auto Alltrac Camry (different trans, but similar shifting patterns) keeps the RPMs in the 2000-2500rpm range under light/normal accelleration in the 'normal' mode.

As for the pinging, have you tried 89 octane fuel instead of 87? My first Camry would ping on 87, even with correct timing but did great on 89. Its not much different in cost...

-Charlie

[ChevyToughRebel]

Now you have me curious about another possible problem. I always drive with the "power" mode on, it always shifts around 28mph and I never really watch the tach but it seems like it shifts around roughly 2k under normal acceleration. Also when its in overdrive there are times when it seems it should kick down a gear or kick it out of "lock out" (if I remember right, there was something about this trans where each gear locks out at a certain point, maybe its the torque convertor I cant remember) when I give it a little more throttle coming up a hill but it seems to wait till it comes down to about 45mph before it downshifts to 3rd. I usually either punch the throttle enough to force it to downshift or turn the overdrive off. 45mph is pretty much where it always shifts into overdrive under normal acceleration which brings the rpms down below 2k until it picks up speed. At 60mph the rpms are 2k even.

I will look it up after a while, but isnt there a seperate computer that controls the transmission and when pushing the ETC power mode button? I wonder if perhaps this is faulty? I have tried switching it from power to normal and have never really noticed a difference in shift patterns. I will double check this again tomorrow. But then that also makes me wonder if this problem should bring me back to the AFM and that test issue I had, like maybe the AFM is one component that helps deicide shift points.

Thanks for the great input so far! Also I will try 89 octane on my next fillup, your right the price difference is not enough to worry about.

~ Shane

[white90dx]

I don't see anything in the diagrams that would directly link a problem with the AFM to early shifting in the trans.

I think there is a good chance that the power level you are getting is just how the car was made.

Oh, just thought of another thing... are you 100% sure the fluid level in the trans is correct? Just an extra 1/2 quart will cause shifting problems... (mine wouldn't downshift after some time on the freeway when coming to a stop when mine was overfilled a bit)

-Charlie

[ChevyToughRebel]

Well I tried driving with the power mode in normal and did notice a difference, shifted from 2nd to 3rd around 20 mph under normal acceleration. I will double check the transmission fluid level sometime but im pretty sure it was at the proper level. I still gotta figure out this AFM thing though, other than that everything else seems to be ok. I will see in a week or so what my mileage will be after the little bit of changes I did. So far I have put around 120miles on the first quarter tank. Around here where I live its pretty hilly so I have been getting around 26mpg which is horrible for this car I think. So now we will see if anything really has changed and my mileage improves.

~ Shane

[white90dx]

26mpg isn't bad at all if you are doing short trips, stop signs/lights or hilly terrain. You should get over 30mpg for highway trips if the car is in good shape (keep the speed reasonable though! driving over 75mph or so really kills the mileage in these cars).

In my Auto Alltrac, I'm happy when I get 26mpg (rated for around 22-24mpg in mixed driving).

If the only issue you have with the AFM is the odd reading from testing it (and they are all the same), I wouldn't worry about it.

-Charlie

[mcx]

i agree...26 around town is fine, its what i get and its in top tune shape!!..on the hiway its 34mpg...2.0/auto

[ChevyToughRebel]

That sucks lol. I figured I should get way better mileage. There was one time when I pushed about 37mpg out of one tank, but that was on flat dessert terrain (central Oregon) and mixed highway and in town driving. I think it needs a valve adjustment, I can hear top end noise when its cold especially, and it goes in and out or away completely when its warm. I know the valves require shims when adjusting and I have never done that, so I am kinda leary of pulling the top end apart since this car is my daily driver, I would have to be prepaired to borrow someones car for a while. I rolled new bearings in the bottom end about a year ago.

Thats a bummer that your alltrac only gets about 26mpg. I wonder if the manual alltrac did better on fuel economy. There is one for sale nearby that looks to be in clean good shape, 153k miles, auto, its brown and has the sun roof! It needs a few minor repairs but seems to be in decent shape. They are asking $2,990 for it. If I could come up with a downpayment I would go over there and make an offer! But no one wants to buy anything I have for sale lol.

[white90dx]

It probably doesn't need any valve adjustment. These motors almost never need one (unlike Honda motors that need them every 30k).

I think everything is just fine with your car. Just drive it!

-Charlie

[ChevyToughRebel]

I dunno im pretty sure something just isn't quite right and I will keep tinkering with it, and I will keep driving it like it is, its never done me wrong.

~ Shane

[qetzal]

Shane -

Newbie here. Having problems w/ my own 1990 Camry & found this forum & thread.

FWIW, I have a Haynes manual. It says E2 - VC resistance for 87-91 Camrys should be 200-400 ohms, which matches your reading. Also FWIW, the AFM on my Camry is the same part #22250-74101.