WOT TPS %

[drjonez]

^ So true DR. J

Ask the wrong question, get the wrong answer.

So when does the ECU go into open loop?

good q. it depends on a variety of things- engine up to temp, etc. but the best rule of thumb is >70% throttle and above 4k RPM or so (isn't it like 3800? i can't remember...).

 

[87_7MGTE]

Found this with a google search. I dont know if this helps at all:

Q: What is the difference between 'Open Loop' and 'Closed Loop'?

A: When the engine is first started, and rpm is above 400 rpm(<-- crank exit speed), the system goes into 'Open Loop' operation. In 'Open Loop', the ECM (ECU) will ignore the signal from the Oxygen (O2) sensor and calculate the air/fuel ratio based on inputs from the coolant and MAF (AFM) sensors, but mostly from a pre-programmed table in the memcal (EEPROM i think for stock TCCS?).

The system will stay in 'Open Loop' until the following conditions are met:

1. The O2 sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature)
2. The coolant sensor is above a specified temperature about 40oC/104oF.(<-- operating temp for us)
3. A specific amount of time has elapsed after starting the engine.

The specific values for the above conditions vary with different engines and are stored in the mem-cal. When these conditions are met, the system goes into 'Closed Loop' operation. In 'Closed Loop', the ECM will calculate the air/fuel ratio (injector on-time) based on the various sensors but mainly the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.

I dont know how much of this stuff actually pretains to this subject or even the stock TCCS for that matter, but im sure that some of it is relevant.

 

[drjonez]

Closed loop means there is feedback. You meant open loop ...

sure did....see my edit...:3d_frown:

 

[87_7MGTE]

JJ: I wasnt directing this at you at all, just posting it for info's sake (sorry if it came off that way). I am still very much learning about all this EFI stuff (running around between a few different standalones and piggybacks). Just thought it may be helpful for others, but hell maybe my post was unnecessary.

 

[Nick M]

MDC, how fast does it go over rich and stall at idle, after decel?

 

[MDCmotorsports]

Nick:
As soon as you come off cruise to idle it reads instantly "lean". It then takes less than a second to run rich. The idle climbs, and then the car stalls. Total time of 2 seconds.

 

[dbsupra90]

Nick:
As soon as you come off cruise to idle it reads instantly "lean". It then takes less than a second to run rich. The idle climbs, and then the car stalls. Total time of 2 seconds.

that almost sounds like a bov issue.

jj- i see what you were saying. we were on the same page after all

 

[Nick M]

That does sound kind of like vent to atmoshpere problems, but I don't remember you posting stalling otherwise with shifting. That could be a problem.

JJ, I do often post in simplified terms. I don't try to over simplify it though. I think if it is easier to understand what is going on, they will be able to diagnose what went wrong.

 

[MDCmotorsports]

Nick, just an interesting tidbit from today.

Like a dumb@$$ I didn't do a process of elimination, only due to all three things happening at once.

I changed the air filter today to a new K&N. While doing so:

-I finally cleaned the wires off the water temp sensor plug. I then found a junk harness in the shop and snip snip wire wire - Vialo! New plug on the water temp sensor

-I noticed that the last owner of my lexus afm has cut part of the screw off. Almost the entire passage of the lower part of the afm housing was clear. I screwed it all the way in. Now there is rougly 1/4" of clearance in the lower passage.

The stalling issue has reduced in frequency, although its still there.

Also, the AFR durring idle is now 15.8 ~ 17.1

Cruise is around 14.1 ~ 15.2

Also, Jet Im not ignoring you on your posts or your sugestions, but simply I have a lack of knowledge on the eletrical items such as testing the IDL circuit. So, Im starting off with the simple stuff first (simple to me, or more mechanical Im not sure).