Running rich 12afr

1989toyotasupraandpickup · 06-16-2012, 02:28 AM

Hello all and hope someone can help me. I own a 1989 toyota supra turbo and the car is idling very rich. its weird because when im cruising the a/f ratio goes to 17+ until i press the throttle down. while boosting the a/f ratio goes to 10-11.2. occasionally the a/f ratio at idle will go to 17 and stay there. When the car is cold the a/f ratio is 14.7 and when it warms up the a/f ratio will drop down to the low 12s. here is a link to show you what is going on http://www.youtube.com/watch?v=3pYrfDnYew4 . could a intake manifold gasket leak cause the car to run rich and lean while cruising? Bad Egr cause lean condition while cruising? its driving me nuts... dont want to drive it like this because i know something is wrong and not right. Timing is set to 10* jumpered. goes to 12* unjumpered. What is the problem.

cre · 06-16-2012, 07:23 AM

Unless you are failing emissions due to the idle richness or the idle is irregular then you are best off dismissing that as a means of performing any form of diagnosis. When the engine is in open loop the ECU does not try to maintain a stoichiometric mixture and the mixture will always be on the rich side. Open loop mode is entered under the following conditions: Engine cold, defective ECU temp sensor, invalid or no OX signal, >70% throttle, RPM >6000 (I can't remember the exact number but it was fairly high... There are other conditions but I can't recall all of them and I haven't the time to look it up (my 10mo puppy broke her leg today and requires constant supervision so I'm just checking in).

You've done as mentioned in your previous thread and downloaded the manual for the wideband sensor, verified the wiring is all correct and sound, made sure the narrow band and wideband are not both connected to the ECU and have performed a sensor calibration?

It's best that you not start a new thread half way into a diagnosis which you started in another thread. Newcomers and even people who've been trying to help will often get lost and miss things which you've already tried or fail to mention things which they expected you to have already done.

I seldom say this about diagnostic hardware, but if you don't know how to use it and what conditions will cause a given reading then you probably shouldn't be using it until you've done more research.

Quote:

Originally Posted by 1989toyotasupraandpickup

a/f ratio goes to 17+ until i press the throttle down.

It should go to about 22 when you're coasting above fuel cut RPM. The ECU does not inject fuel when coasting unless the engine speed is around 1K or less.

Quote:

Originally Posted by 1989toyotasupraandpickup

while boosting the a/f ratio goes to 10-11.2

This is appropriate as you're in open loop operation and if it were too much leaner when boosting and you'll melt pistons.

Timing is controlled by the ECU and will always vary. You put in the jumper to lock it to its base advance where the ECU cannot adjust it. It's fine.

EGR... No. The gasses introduced into the cylinders are inert. They contain neither fuel nor oxygen and shouldn't affect your mixture at all.

An intake leak can cause mixture problems. An exhaust leak can cause your sensors to misread the data. Personally, I'd look at the intake, exhaust, vacuum hoses, test the ECU temp sensor, TPS and AFM. Don't bother with ANY of this until you've checked all of the wideband's wiring (ESPECIALLY THE POWER AND GROUNDS!!!!!), read the manual cover to cover, and calibrated it.

I don't have time to look at the video, I've got a whimpering puppy to take to bed now... Hopefully someone else will chime in if I missed something of note. Good luck with it.

1989toyotasupraandpickup · 06-16-2012, 08:31 AM

Ya i didn't want to start a new thread but no one was chiming in quick enough on the other one. I thank you for chiming in and helping when i need it. Your very knowledgeable on the supra. The wideband gauge goes to the gauge only and not to the ecu. Already checked. Will check the power and ground to the sensor and remove it to calibrate it to see if its malfunctioning. ECU temp sensor is new. My electric fan is probably turning on to early keeping the engine a little cooler.

Took the narrowband sensor out and it tested fine with the propane torch .988v with the flame and .012v with no flame. The on car diag Vf1 and e1 indicates the sensor is not working correctly. It does not fluctuate 8 times in 10 seconds. I will take pictures of the spark plugs and post them here. If you get time take a gander at the video. You will see where the a/f ratio sits. Even when i rev the engine. Does not move barely. Im going to take the manifold off today and seal it with copper rtv gasket sealer and see if that helps. The only thing i can think of that would cause my rich running condition. Does it act like a boost leak if the intake gasket has a leak? Its worth a shot and i am going to clean my injectors to make sure they are not leaking or clogged.

Saw on youtube a nice injector cleaner setup. Cant test the flow but you can clean the gunk out of them. Looks like it works good. i went to school for electronics and know how to diag electronics but the manual gives you nothing on how to diagnose the problems. like you said the manual is a broad repair method. My brother is a mechanic but he has no time to help me out. The AFM may even be toast but no code. Engine wont rev with
AFM unplugged but will idle. no code with oxygen sensor unplugged either. When i unplug the AFM i get a code along with the ecu temp sensor when thats unplugged.

Sorry to hear about the puppy. I hope he gets better. My puppy broke is back 2 legs when he ran out the door and into the main road. Doing good now all healed and happy to be alive. Thanks for the help i appreciate it.

cre · 06-16-2012, 04:42 PM

This isn't a high traffic forum. Responses come slowly from time to time and there is no paid staff, we volunteer our own time to help. Just bumping your original post if you haven't seen a response in a day is better form.

Please post the make and model of the wideband. The power source and grounding of the wideband are critical if you want to avoid false readings due to linear or (worse) logarithmic voltage offsets. Also remember that improper wiring or hardware placement will cause readings to shift as connectors, wires and or hardware are heated up... If any of the wideband's hardware sits in the engine bay you should consider moving it. The preferred ground would be to a stud near the one that the ECU is grounded to on the driver's side of the head.

The torch method of testing isn't the whole picture. The sensor doesn't report with a flat voltage signal, it's frequency must match the IGf signal (with an offset). This is what looking at Vf tells you but they don't explain it well or tell you how to read it even more accurately with a scope on both signals. Really, it's a cheap part an I'd just replace it if you still don't trust it after going through the diagnostics in the TSRM. EDIT: If the ecu doesn't see the correct frequency in the OX signal it will regard the O2 sensor as defective and go into full time open loop operation. The ECU gives the O2 sensor a set period of time to start providing a valid signal before it writes it off. No error code will be presented if I remember correctly.

Unfortunately, I don't know anyone at present who has Toyota's publication on testing the KVAFM with a scope... I really wish I did though. I'm going to have to start asking my friends from a couple dealerships if they can get me a copy.

You may also want to check the ECU for any signs of leaking caps.

I still have no reason to have any faith in your wideband. When cold all of your AFR readings should be on the rich side not stoich; 13.5:1 or so or lower.

I'll try to take a look at the video in a just a few minutes. I have some documents I need to finish working on before a courier arrives for them.

EDIT2: Yes, ANY intake leak between the turbo and the head will leak the most as the intake charge is at a higher pressure. It's just called a boost leak if it's leaking specifically while the system is pressurized. Check for any leaks in the intake and vacuum plumbing. Ok, gotta go. I'll try to get back in a bit.

EDIT3: Don't let me forget to give you a list of what AFR you should see and when. 10 to 12 while boosting is NOT a rich condition. 22 when coasting is NOT a lean condition. 17 while cruising IS a lean condition unless you're feathering the throttle, coasting down hill, etc.

cre · 06-16-2012, 05:33 PM

Okay, well, I figured it'd probably be a quickie so I watched the video now.

First, diagnostics mode should be engaged when the ECU is off.

I think I've mentioned it before, but if not the MKIII and other TCCS equipped Toyota's are notorious for rich or varying AFR at idle. It's very common. Typically 13 is the richest you'll see and around 15.5 the leanest. Also the ECU uses a richer open loop fuel map after a warm start than it does after a cold start. Temporarily inserting a 4.7K to 10K resistor in place of the ECU temp sensor will ensure that the ECU runs the cold start fuel map. Only do this for diagnostic purposes and only diagnose when the engine is running from the same initial state (ie after restarting once the car is warm).

Don't rely on the car's tach for an accurate RPM measurement. Get a calibrated gauge on it. I've seen the dash unit read hundreds of RPM high and low in the past. IMO, Vf diagnostics are rather worthless as there are many factors which can affect the results and it's really only good for diagnosing gross failures in that specific mode.

You'll find more detailed information here:
http://www.well.com/user/mosk/Vfsignal.htm

Feel free to replace the O2 sensor but until you're POSITIVE the wideband doesn't have a voltage offset, is properly calibrated, set for the correct fuel type and the sensor is good STOP RELYING ON IT... Hell, put tape over it. Once you're sure it is 100% you should seriously consider using it to emulate the narrowband signal to the ECU and ditching the actual narrowband sensor. Narrowband sensors aren't worth much when it comes to diagnosis they're a switch with no grey are or middle ground between results: RICH - Perfect (300mV window right in the middle) - LEAN

From what's shown in the video I'm inclined to believe the ECU isn't even entering "closed loop" operation. I've already detailed the main conditions under which it isn't in "closed loop" (or in other words when it is running "open loop").

There are no error codes present, correct?

Lastly, make sure the cold start injector isn't leaking.

1989toyotasupraandpickup · 06-16-2012, 09:15 PM

the wideband is an AEM 30-4100 gauge-type UEGO controller with the bosch LSU3.2 sensor. I believe i have to remove it to calibrate it to see if it bad or just slow. i can hook the sensor into the computer. there is a 0-5v analog output. there is also a serial output for data logging. would i be better off using the analog output on the wideband to make sure that the stock narrowband sensor is not bad. i mean why buy a part if i dont need it. Knock sensors should give a code if its detecting knock correct? AFM Bad? Cant find no vacuum leaks but i heard alot of people talking about the vsv's under the intake manifold go bad and cause a vacuum leak. i saw somewhere on the internet how to test the afm meter with the ossciliscope. however you spell that. i believe it is a square wave. thats all i know. caps dont look like they are bad. any specific ones that would leak. i mean you could tell if they were leaking by looking at the board.

cre · 06-17-2012, 12:45 AM

Quote:

Originally Posted by 1989toyotasupraandpickup

I believe i have to remove it to calibrate it

For the most accurate calibration, yes. There are other ways but I'm not going to go into them as results vary and I want to be as sure as possible that yours is properly calibrated.

Quote:

Originally Posted by 1989toyotasupraandpickup

would i be better off using the analog output on the wideband to make sure that the stock narrowband sensor is not bad.

As I said, if the wideband can emulate a narrowband output on the analog out then I would remove the stock narrowband and use the wideband to supply the ECU with the OX signal permanently.

Quote:

Originally Posted by 1989toyotasupraandpickup

i heard alot of people talking about the vsv's under the intake manifold go bad and cause a vacuum leak.

If it's a concern then test them, it's simple.

Quote:

Originally Posted by 1989toyotasupraandpickup

Knock sensors should give a code if its detecting knock correct?

No.

Quote:

Originally Posted by 1989toyotasupraandpickup

I saw somewhere on the internet how to test the afm meter with the ossciliscope. however you spell that. i believe it is a square wave. thats all i know.

Oscilloscope. I don't know where that info has been posted online. If you find it please post a link.

Quote:

Originally Posted by 1989toyotasupraandpickup

caps dont look like they are bad. any specific ones that would leak. i mean you could tell if they were leaking by looking at the board.

Yeah, they're often easily identified by the expanding casing and/or leaking electrolyte. I don't think this is your problem though.

First things first, check the wideband's power and ground points and recalibrate it. Then, if you have time, setup the narrowband emulation on the analog output and connect it to the ECU in place of the oem sensor's input. THEN post back.

1989toyotasupraandpickup · 06-18-2012, 06:33 PM

hey cre this is what i found on the kvafm. "To properly test the 7mgte AFM, one needs an oscilloscope. I suppose thats why Toyota didn't publish the test procedures in the TSRM. I took my car to a local shop where they hooked up an oscilloscope and checked the wave pattern. Its supposed to be a constant square wave that gets higher frequency as the rpms go up. A bad AFM will show an erratic signal, sometimes just flatline or much lower frequency than normal. The test in the TSRM is just for air temperature." have not got around to wiring the wideband sensor into the computer. have to calibrate the wideband also.

06-16-2012, 02:28 AM	#1
1989toyotasupraandpickup Stock Join Date: Jun 2012 Location: ny Posts: 26	Running rich 12afr Hello all and hope someone can help me. I own a 1989 toyota supra turbo and the car is idling very rich. its weird because when im cruising the a/f ratio goes to 17+ until i press the throttle down. while boosting the a/f ratio goes to 10-11.2. occasionally the a/f ratio at idle will go to 17 and stay there. When the car is cold the a/f ratio is 14.7 and when it warms up the a/f ratio will drop down to the low 12s. here is a link to show you what is going on http://www.youtube.com/watch?v=3pYrfDnYew4 . could a intake manifold gasket leak cause the car to run rich and lean while cruising? Bad Egr cause lean condition while cruising? its driving me nuts... dont want to drive it like this because i know something is wrong and not right. Timing is set to 10* jumpered. goes to 12* unjumpered. What is the problem.

06-16-2012, 04:42 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	This isn't a high traffic forum. Responses come slowly from time to time and there is no paid staff, we volunteer our own time to help. Just bumping your original post if you haven't seen a response in a day is better form. Please post the make and model of the wideband. The power source and grounding of the wideband are critical if you want to avoid false readings due to linear or (worse) logarithmic voltage offsets. Also remember that improper wiring or hardware placement will cause readings to shift as connectors, wires and or hardware are heated up... If any of the wideband's hardware sits in the engine bay you should consider moving it. The preferred ground would be to a stud near the one that the ECU is grounded to on the driver's side of the head. The torch method of testing isn't the whole picture. The sensor doesn't report with a flat voltage signal, it's frequency must match the IGf signal (with an offset). This is what looking at Vf tells you but they don't explain it well or tell you how to read it even more accurately with a scope on both signals. Really, it's a cheap part an I'd just replace it if you still don't trust it after going through the diagnostics in the TSRM. EDIT: If the ecu doesn't see the correct frequency in the OX signal it will regard the O2 sensor as defective and go into full time open loop operation. The ECU gives the O2 sensor a set period of time to start providing a valid signal before it writes it off. No error code will be presented if I remember correctly. Unfortunately, I don't know anyone at present who has Toyota's publication on testing the KVAFM with a scope... I really wish I did though. I'm going to have to start asking my friends from a couple dealerships if they can get me a copy. You may also want to check the ECU for any signs of leaking caps. I still have no reason to have any faith in your wideband. When cold all of your AFR readings should be on the rich side not stoich; 13.5:1 or so or lower. I'll try to take a look at the video in a just a few minutes. I have some documents I need to finish working on before a courier arrives for them. EDIT2: Yes, ANY intake leak between the turbo and the head will leak the most as the intake charge is at a higher pressure. It's just called a boost leak if it's leaking specifically while the system is pressurized. Check for any leaks in the intake and vacuum plumbing. Ok, gotta go. I'll try to get back in a bit. EDIT3: Don't let me forget to give you a list of what AFR you should see and when. 10 to 12 while boosting is NOT a rich condition. 22 when coasting is NOT a lean condition. 17 while cruising IS a lean condition unless you're feathering the throttle, coasting down hill, etc. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar ---> Last edited by cre; 06-16-2012 at 04:52 PM.

06-16-2012, 05:33 PM	#5
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Okay, well, I figured it'd probably be a quickie so I watched the video now. First, diagnostics mode should be engaged when the ECU is off. I think I've mentioned it before, but if not the MKIII and other TCCS equipped Toyota's are notorious for rich or varying AFR at idle. It's very common. Typically 13 is the richest you'll see and around 15.5 the leanest. Also the ECU uses a richer open loop fuel map after a warm start than it does after a cold start. Temporarily inserting a 4.7K to 10K resistor in place of the ECU temp sensor will ensure that the ECU runs the cold start fuel map. Only do this for diagnostic purposes and only diagnose when the engine is running from the same initial state (ie after restarting once the car is warm). Don't rely on the car's tach for an accurate RPM measurement. Get a calibrated gauge on it. I've seen the dash unit read hundreds of RPM high and low in the past. IMO, Vf diagnostics are rather worthless as there are many factors which can affect the results and it's really only good for diagnosing gross failures in that specific mode. You'll find more detailed information here: http://www.well.com/user/mosk/Vfsignal.htm Feel free to replace the O2 sensor but until you're POSITIVE the wideband doesn't have a voltage offset, is properly calibrated, set for the correct fuel type and the sensor is good STOP RELYING ON IT... Hell, put tape over it. Once you're sure it is 100% you should seriously consider using it to emulate the narrowband signal to the ECU and ditching the actual narrowband sensor. Narrowband sensors aren't worth much when it comes to diagnosis they're a switch with no grey are or middle ground between results: RICH - Perfect (300mV window right in the middle) - LEAN From what's shown in the video I'm inclined to believe the ECU isn't even entering "closed loop" operation. I've already detailed the main conditions under which it isn't in "closed loop" (or in other words when it is running "open loop"). There are no error codes present, correct? Lastly, make sure the cold start injector isn't leaking. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Running Rich! Help needed	mc_p0pe	MKIII Supra	13	05-23-2008 12:31 AM
Running Sooooooo Rich! Help!	godgaveussid	MKIII Supra	4	08-29-2007 08:46 PM
Running very rich	OmeGa	MKIII Supra	3	12-09-2006 09:59 PM
Running rich!	grygst76	MKIII Supra	6	09-29-2006 01:56 AM
fixed the running rich problem	djalkyd	MKIII Supra	6	05-04-2006 04:31 AM

06-16-2012, 08:31 AM	#3
1989toyotasupraandpickup Stock Join Date: Jun 2012 Location: ny Posts: 26	Ya i didn't want to start a new thread but no one was chiming in quick enough on the other one. I thank you for chiming in and helping when i need it. Your very knowledgeable on the supra. The wideband gauge goes to the gauge only and not to the ecu. Already checked. Will check the power and ground to the sensor and remove it to calibrate it to see if its malfunctioning. ECU temp sensor is new. My electric fan is probably turning on to early keeping the engine a little cooler. Took the narrowband sensor out and it tested fine with the propane torch .988v with the flame and .012v with no flame. The on car diag Vf1 and e1 indicates the sensor is not working correctly. It does not fluctuate 8 times in 10 seconds. I will take pictures of the spark plugs and post them here. If you get time take a gander at the video. You will see where the a/f ratio sits. Even when i rev the engine. Does not move barely. Im going to take the manifold off today and seal it with copper rtv gasket sealer and see if that helps. The only thing i can think of that would cause my rich running condition. Does it act like a boost leak if the intake gasket has a leak? Its worth a shot and i am going to clean my injectors to make sure they are not leaking or clogged. Saw on youtube a nice injector cleaner setup. Cant test the flow but you can clean the gunk out of them. Looks like it works good. i went to school for electronics and know how to diag electronics but the manual gives you nothing on how to diagnose the problems. like you said the manual is a broad repair method. My brother is a mechanic but he has no time to help me out. The AFM may even be toast but no code. Engine wont rev with AFM unplugged but will idle. no code with oxygen sensor unplugged either. When i unplug the AFM i get a code along with the ecu temp sensor when thats unplugged. Sorry to hear about the puppy. I hope he gets better. My puppy broke is back 2 legs when he ran out the door and into the main road. Doing good now all healed and happy to be alive. Thanks for the help i appreciate it.

06-16-2012, 09:15 PM	#6
1989toyotasupraandpickup Stock Join Date: Jun 2012 Location: ny Posts: 26	the wideband is an AEM 30-4100 gauge-type UEGO controller with the bosch LSU3.2 sensor. I believe i have to remove it to calibrate it to see if it bad or just slow. i can hook the sensor into the computer. there is a 0-5v analog output. there is also a serial output for data logging. would i be better off using the analog output on the wideband to make sure that the stock narrowband sensor is not bad. i mean why buy a part if i dont need it. Knock sensors should give a code if its detecting knock correct? AFM Bad? Cant find no vacuum leaks but i heard alot of people talking about the vsv's under the intake manifold go bad and cause a vacuum leak. i saw somewhere on the internet how to test the afm meter with the ossciliscope. however you spell that. i believe it is a square wave. thats all i know. caps dont look like they are bad. any specific ones that would leak. i mean you could tell if they were leaking by looking at the board.

06-18-2012, 06:33 PM	#8
1989toyotasupraandpickup Stock Join Date: Jun 2012 Location: ny Posts: 26	hey cre this is what i found on the kvafm. "To properly test the 7mgte AFM, one needs an oscilloscope. I suppose thats why Toyota didn't publish the test procedures in the TSRM. I took my car to a local shop where they hooked up an oscilloscope and checked the wave pattern. Its supposed to be a constant square wave that gets higher frequency as the rpms go up. A bad AFM will show an erratic signal, sometimes just flatline or much lower frequency than normal. The test in the TSRM is just for air temperature." have not got around to wiring the wideband sensor into the computer. have to calibrate the wideband also.