boggy takeoff

[fredk]

I might be on the way to figuring out why my 3sfe auto car is so slow off a stop, I put my airflow meter off my 5 speed car that is 3 teeth lean on my auto car and took off with it, it is slightly quicker off a stop but it was surgy above 3000 to about 4500 floored and the big push at 3500 was gone, returned and put the other meter on and everything was normal again, bogg off a stop but ran like hell after 3500, raised it up and took the pipe off the manifold so I could hear it and it was loud, took off in the parking lot and right off a stop it sounds like an all over miss, some kind of combustion problem, not a dead skip like a dead cylinder but like the mixture is way off, but 3500 came along it got its crap together and took off with a steady hum all these tests were done with a warm motor and close together in time it acts like my injectors are dripping instead of spraying a fine mist or a spark not strong enough to lite the fire at low rpm with the throttle plate open, anybody gone farther with testing?

[Doctor J]

One time I ran the wire from Vf terminal in diag box to inside and hooked it up to the positive probe of analog voltmeter set at 5 Volt DC scale; the negative probe of meter was hooked up to the ground.
While driving on steady speed it gave me the a/f ratio [aka fuel trim] such as 5v lean, close to 0 rich and 2.5+/-0.5 volt is normal; at acceleration the needle goes toward the rich / close to 0;
on idle it was 3.6V - small intake leak through the worn throttle shaft bushings

[fredk]

vf terminal?

[fredk]

I put the modded airflow meter back on and drove it home yesterday the surge went away and the big push at 3500 came back, I guess just from computer relearn of the fuel map but the off line takeoff is a little better, especially in the morning but it is still nothing like my other auto car

[white90dx]

Originally Posted by fredk

vf terminal?

It is a pin available in the diag box in the engine bay. With long enough leads (or extra wire) you can hook up a voltmeter to it.

The Vf stands for "voltage feedback." It tells you the short term fuel trim on the car like Dr. J described above. If it is way off one way or the other, you might have found your problem.

Have you checked for a leaky cold start injector? How is the rest of the ignition? How about fuel filter and all that other stuff?

-Charlie

[fredk]

I checked the plugs today, they along with the rest of the ignition is new, anyways I pulled the plugs out and they were white-lean and gapped at .35, I gapped them at .45 and put them back in and unplugged the cold start injector, the motor was cold so I took off out of the shop parking lot, it is better off the line hot and cold now, this told me that its lean, real lean on take off for some reason and at 3500 it takes off but it feels like the low rpm is a little stronger now.

[fredk]

progress? I drove another old camry auto today and it took off like normal off the line but had no big rush at 3500, kinda ran out of air, but it came off the line like any other car, it had no tach but it sounded like i could stall the converter much higher than i can mine witch is at 1600 but the shifts in that car were much softer than my car, this leads me to believe that my converter is not slipping enough making the stall speed very low and acting like a very tight converter, another thing I noticed is at 60 in that car the motor in 4th was going fast enough to hear but with no tach i was at a loss so on the way home I made my car do 60mph in 4th and it turns exactly 2000 rpm

[fredk]

ok doc, played with it over the weekend and noticed something, took a volt meter and plugged it right into the o2 connector and put the meter inside with me, started off cold motor and it putted a little but the o2 was cold so it was in open loop and boggy, drove it till the o2 started moving around and stopped at a lite, watching the meter, it started to slow and then I took off, it went way down and putted and bogged right off the line and kinda stayed low until it hit 3500 then it woke up and took off.

[Doctor J]

I will attach meter to Vf terminal in my car and see if I can get meaningful data [my O2 Sensor is working but engine is not in a great shape];I am predicting that it will show high voltage at low rpm[5V], due to the valve leaks [idle missfire]

[Nusdogg]

i was three to four teeths off to the right side(towards the headlight). It picks up slow as hell but then as i hit higher RPM, it gave me a good kick.

[fredk]

tidbit, I notice that if i hop in and start it up and take off right away with a warm motor it puts and trys to die right off the line but at the usual 3500 it takes off, but if i start it up and mess with the radio or something it doesnt do it?

[fredk]

got my blue 89 3sfe 5 speed car going today, holy crap is that motor worn out, smokes noisy, idled it in 1st gear and stomped it, the thing took off like it got rear ended by a dump truck, next week i am going to run all the specs on both cars, fuel psi, timing advance and all to see whats wrong with my auto car

[fredk]

well, spark is not the issue, blue and will fly about 2 inches, but its getting worse, if i stomp the gas from idle it will sputter and bog, psi testing is next

[fredk]

it was 48 this morning and it took off from the house almost perfect, but as soon as the motor warmed up it was back to the boggs

[Mike Gerber]

Originally Posted by fredk

it was 48 this morning and it took off from the house almost perfect, but as soon as the motor warmed up it was back to the boggs

I had this problem once on my 86 2SE engine. It turned out to be a defective O2 sensor, even though it never threw a code. (I talked to Toyota corporate about this and the customer service rep said he had worked on these cars himself and those early generation OBD1 systems weren't always the most reliable about detecting defective sensors.) Had a friend who was a former Toyota tech and we had an extra Toyota O2 sensor (not really the right one for my Camry) lying around. We unplugged my O2 sensor and plugged this extra one in to the harness and just hung it over the side of the fender. Then we took a ride. Car ran great. Got the right sensor and installed it properly in the car. Never had the problem again. Might be worth a try if you have an extra O2 sensor around or worth buying another sensor. You might even consider pulling the one out of your other car and trying it in this car as a test.

Mike