MSefi.com read only forum (Jan.15,2018)

Ok, I know that I have several problem with my setup as my datalog is suggesting. The setup is tuned and it's driving fine, but I'm in the fine tuning protion of the whole thing. I have located some problems that need to be fixed to have a perfect setup.

Always look at my datalog to follow the thread (I'll refer to it lot of times)

1: I have some noise in the coolant sensor. It jumps from 192F to 196F with no reasons. Please, tell me what are the ways to fix this. I'm supposing that this is a ground issue, but all the sensors have the same ground on the body and the other sensor seem fine.

2: In my datalog, at Time = 431.739, you will notice that the PW spike from 2.8 to 3.1ms. I want to know what can cause this. As you can seen, I used the cruise control to keep RPM, MAP and TPS at all the same level during a part of the datalog. So, what can cause PW to spike if RPM, TPS, MAP are all the same. Note that the Ego control isn't activated (look at my .msq file (I'm using MSII version 2.88))

3: In my datalog, at time = 503.357, the accel enrichment come on even if the TP doesn't move. The TPS doesn't move but the TPSdot says 108 during only one record. What can cause TPSdot to spike like this if the TPS is always the same. This kind of enrichement by accel when it's no needed results in a missfire.

4: I don't know why, but my AFR aren't really flat like it supposed. It vary a little bit. If you look at the part when i'm on the cruise control (flat RPM and flat MAP), the AFR can vary about 0.5 AFR. Does this can be flattened. My AFR gauge is showing the same thing. BTW, I'm using AEM UEGO gauge and controller AFR unit.

5: When i'm coasting down a little slope, the throttle is close and the MAP is very low, the AFR are all over the place, is there a way to make it more stable? I know that someone here is trying to fix this by stoping the fuel injection when coasting down a slope (VE = 0 where MAP < 20kpa). So, the AFR will read always super lean. My question about this, can it hurt something to stop injecting fuel while coasting down a slope and decelerating?

Another information that would be nice to know is :

On a 70F day, what are some normal IAT when driving lets say 80-100 km/h. Mine seems to be a little high (110-120F).


Thanks a lot in advance to all of them who will answer my long post.

Any help would be very appreciated.

Regarding the drop in pulsewidth, notice the battery voltage changed from 13.1 to 10.6. This means it takes longer to open your injectors because the battery is weaker. To compensate, the processor extended the PW time to try to keep the fuel squirted th same.

good catch, i didn't noticed it. So what can cause a battery voltage to go down that low? I didn't turn on the headlight or any other electrical components... What can it be?

As far as the voltage drop what kind of set up do you have for radiator fans? And do you know when they come on?

For this datalog, I wasn't using any radiator fan, I installed a rad fan the last weekend, so, this dip in voltage drop is not related to my radiator fan.

But thanks a lot for the reply, keep them coming!

Sam

pit_celica wrote: 5: When i'm coasting down a little slope, the throttle is close and the MAP is very low, the AFR are all over the place, is there a way to make it more stable? I know that someone here is trying to fix this by stoping the fuel injection when coasting down a slope (VE = 0 where MAP < 20kpa). So, the AFR will read always super lean. My question about this, can it hurt something to stop injecting fuel while coasting down a slope and decelerating?

No, stopping the fuel from injecting won't hurt anything.

Ok, thanks a lot for the reply, I'll try it as soon as I have some spare time to work on the car. I'll let you know if it fix my problem when coasting and decelerating (coasting down a little step for example).

pit_celica wrote:
5: When i'm coasting down a little slope, the throttle is close and the MAP is very low, the AFR are all over the place, is there a way to make it more stable? I know that someone here is trying to fix this by stoping the fuel injection when coasting down a slope (VE = 0 where MAP < 20kpa). So, the AFR will read always super lean. My question about this, can it hurt something to stop injecting fuel while coasting down a slope and decelerating?

My car "backfires" if I lean it out too much on overrun. I tried shutting the fuel off, but that caused a bad lurch when the throttle was opened again and the engine restarted, IIRC. As for the AFR "are all over the place" , it's harder to ignite a lean mixture so if you can you might want to bump up the timing advance in that area (a miss-fire will cause the AFR to bounce)

I don't know (and please correct me if I'm wrong) but it would seem under decel with the throttle plate closed you would be trying to pull a vacuum in the exhaust system as well as the intake and if there were a leak the O2 sensor could see excess O2 -hence a bouncing AFR reading.

pit_celica wrote:My car "backfires" if I lean it out too much on overrun. I tried shutting the fuel off, but that caused a bad lurch when the throttle was opened again and the engine restarted,

If the injectors are off completely, the engine should act as an air pump to slow you down. It won't be lean as there is not any fuel to calculate an AFR. Personally, I don't do this either, but when asked if it will hurt anything, the answer is no, it won't.

66fb wrote:I don't know (and please correct me if I'm wrong) but it would seem under decel with the throttle plate closed you would be trying to pull a vacuum in the exhaust system as well as the intake and if there were a leak the O2 sensor could see excess O2 -hence a bouncing AFR reading.

You shouldn't be pulling a vacuum through the exhaust since there is still a small amount of fuel being injected into the combustion chamber during decel, (unless you cut the injectors completely as mentioned above). Even in the event of a fuel cut, the piston is at the top of it's stroke when the exhaust valve is open, so it shouldn't pull much, (if any), air into the combustion chamber. Either condition should cause a lean reading on the O2 sensor.