Testing VF,confusing results...

[supraman74]

I've been trying to figure out my rich idle (mid 10's afr when warmed up) :1zhelp:
I checked for codes and found none...
I did the three tests listed here, http://www.supramania.com/forums/showthread.php?t=39856

Results of each test in red...

1. Oxygen Sensor Feedback Mode.

* T1 and E1 Connected (In the diagnostic block.)
* Engine Running at 2500 rpm

Result of Ox sensor signal processing:
0v=Lean or Open loop condition
As soon as the throttle is pressed it goes to 0v and stays there.
When I let off the throttle it takes a bit and then reads 5v.
AFR is in 10 to 11 area during this test.
_______________

2. Diagnostic Mode

*T and E1 connected
*Engine off

Results of Diagnosis:
5v=Normal, No trouble codes stored.
________________
3. Learned Value Mode

*T and E1 not connected
*Any operating conditions, RPM's, or speed.

Results of Diagnosis:
Constant 2.25v
AFR is in 10 to 11 area during this test also.
________________

I know rich idle can be many things so I was hoping the vf results could start me off in the right direction on what to check next.
Any ideas on what to do now?:1zhelp:

 

[7MGTEsup]

I've been trying to figure out my rich idle (mid 10's afr when warmed up) :1zhelp:
I checked for codes and found none...
I did the three tests listed here, http://www.supramania.com/forums/showthread.php?t=39856

Results of each test in red...

1. Oxygen Sensor Feedback Mode.

* T1 and E1 Connected (In the diagnostic block.)
* Engine Running at 2500 rpm

Result of Ox sensor signal processing:
0v=Lean or Open loop condition
As soon as the throttle is pressed it goes to 0v and stays there.
When I let off the throttle it takes a bit and then reads 5v.
AFR is in 10 to 11 area during this test.
_______________

2. Diagnostic Mode

*T and E1 connected
*Engine off

Results of Diagnosis:
5v=Normal, No trouble codes stored.
________________
3. Learned Value Mode

*T and E1 not connected
*Any operating conditions, RPM's, or speed.

Results of Diagnosis:
Constant 2.25v
AFR is in 10 to 11 area during this test also.
________________

I know rich idle can be many things so I was hoping the vf results could start me off in the right direction on what to check next.
Any ideas on what to do now?:1zhelp:

As far as I'm aware 2.25v on the fuel corection means it is not making any alterations or less than 3%

 

[GrimJack]

This is a fantastic example of how to ask for help. You've done the research, you've provided relevant details, you can type, and understand what punctuation and grammar are used for.

A couple questions... what do you have the mainscale on your MAFT set to? What base fuel pressure are you using? Have you tried pulling fuel using the MAFT yet?

Not related to the first theory, but this could be a boost leak, too. You'd see a rich condition at idle (And anytime you're not in boost) and the MAFT would add in more fuel at WOT so it wouldn't show up there as easily. I'm not going to rank this one very high on the possibility list, I suspect that anyone with your level of mods is using all silicone couplers with proper t-bolt clamps...

 

[supraman74]

This is a fantastic example of how to ask for help. You've done the research, you've provided relevant details, you can type, and understand what punctuation and grammar are used for.

A couple questions... what do you have the mainscale on your MAFT set to? What base fuel pressure are you using? Have you tried pulling fuel using the MAFT yet?

Not related to the first theory, but this could be a boost leak, too. You'd see a rich condition at idle (And anytime you're not in boost) and the MAFT would add in more fuel at WOT so it wouldn't show up there as easily. I'm not going to rank this one very high on the possibility list, I suspect that anyone with your level of mods is using all silicone couplers with proper t-bolt clamps...

Thanks, I have done nothing but research. I'm no mechanic but I can do some things like read and follow directions so I've been trying to diagnose this issue for quite some time now.
I bought it last June with pretty much all the mods already done but it also came with the rich idle. :nono:

Fuel pressure is set in the middle of the specs in the TSRM,
No vac and line pinched, about 36 psi. Vac connected its about 26 psi.

My Maft settings are as follows,
Mode swithes
1 off
2 off
3 on
4 off
Aux = 0
Base = D
Idle = 9
Mid = 0
Wot = 0

I havent tried messing with this or my safcII mainly because I'm scared I'll F something up, I have no clue when it comes to tuning...
I know, it could be a simple adjustment on the maft or safc.
The only dyno/tune shop I know of around here has a bad rep and I dont want to pay someone to blow my car up when I can do it myself for free.
As far as boost leak goes, I wish it was boost leak. :icon_bigg

 

[jetjock]

The readings are confusing because Vf is meaningless when the system is in open loop. After all the "f" in Vf means feedback. In other words you're attempting to use a part of the system for troubleshooting a fuel control issue, a part of the system that is only useful when the engine is in fuel control. Yours isn't. See the problem?

Ignore Vf and troubleshoot for an open loop condition. The fault likely lies in the aftermarket electronics, either in wiring or configuration.

 

[GrimJack]

OOps... appears I stuck my foot in my mouth there, I read your mod list and saw a maft PRO instead of the actual unit you have.

Just to be sure, that's the older unit without direct wideband input, right?

 

[Buddafucco]

Which signal(s) that are being used by the aftermarket electronics would contribute to open loop?

 

[supraman74]

Yes, its the old maft.

 

[Buddafucco]

TPS- VTA
AFM- KS
RPM- IGt
IAT- THA
12v- +B
grnd- E1

 

[supraman74]

Which signal(s) that are being used by the aftermarket electronics would contribute to open loop?

Not sure on that one

 

[3p141592654]

Reinstall the AFM back in the car if it was removed, and then directly connect it to the ECU (bypass the MAFT), then see if you get proper operation. I believe the other connections are all inputs to the MAFT and should not impact anything if left connected.

 

[supraman74]

I dont have an afm. I bought the car with most of the mods already done.

 

[starscream5000]

Check the for sale sections or post a WTB thread.

 

[GrimJack]

Or just borrow one from another Supra driver for 20 minutes.

 

[JimR]

My intuition tells me to inspect the oxygen sensor. Have you diagnosed it with a voltmeter yet? (TSRM, pg FI=118)

 

[jetjock]

^ He already has. See post 1. Besides, the O2 sensor can't be the problem. Not possible.

 

[JimR]

Not possible because of open loop, right? What about just lean? Closed-loop and vf1 is outputting an (assumed incorrect) lean signal of 0v?

Or is this also not possible? hehe ;-)

I am basing my assumption on this sentence: "Result of Ox sensor signal processing:
0v=Lean or Open loop condition"

 

[jetjock]

He's in open loop, that's obvious by his a/f ratio. You might be inclined to thing the sensor is bad but based on his idle a/f ratio something else is involved.

The O2 sensor is a trim sensor and has the least authority of any trim sensor in the system. Because it's the primary emissions device the ECU is programmed to limit it's authority even when working and prevent the mixture from wandering too far if it fails. Think about it: Do you want the sensor to have the authority to put as much fuel as it wants into the engine should the signal go full lean? Or remove as much as it wants when it goes full rich? That would be a bad thing.

This lack of authority and how the TCCS deals with sensor failure can be easily demonstrated. The sensor outputs a maximum of around 800 mv when rich and around 200 mv when lean right? Take a 7M operating in closed loop. It'll be running at stoich with the sensor cross counting, the amplitude of the signal swinging between those two points (or nearly so) as the mixture is continuously corrected.

While monitoring a/f ratio unplug the sensor. The mixture will default to around 13 or so. Now ground the sensor input to the ECU to simulate a full lean condition. Following that apply 1 volt to simulate a full rich condition. In each case the mixture will default to the same slight richness.

It sure won't cause an a/f of 10. To allow a deviation in mixture that great would fly in the face of the system's emissions intent and after all, that's why the sensor is there in the first place. In fact it's why the entire OBD EFI thing exists at all.

Course, all this applies to an engine that is otherwise operating correctly. He has a more serious problem, one that allows the open loop idle mixture to be 10. A properly functioning TCCS would never permit that to happen, even when open loop.

 

[JimR]

Thank you for explaining, I do appreciate it. Still learning!

 

[jetjock]

You be welcome. You have to remember EFI was invented to increase efficiency and reduce emissions, not to make the engine run "right". An engine will run perfectly fine with much sloppier mixture control, especially when warmed up. Carburetors had no problems doing it and compared to EFI they have atrocious fuel metering.