No VF signal during operating or Idle.

[supraguy31]

Its been quite a while since I have had this harness in the car and Im hoping that I can get some Direction on that I can do to fix this problem. I start the car up in the morning and using my MAFT Pro I know that Im not suppose to get a VF signal for atleast 30-45 Seconds and during that time period my VF should read 0.00.

Problem that Im having is that im not getting a VF signal until about 15-20 minutes if not longer. I have pulled the Harness out and replaced the Gray wire that the signal runs through but Im still getting the same Issue. Changed out ECUs and no help. I cant drive the car or anything during this time.

After 20 minutes of Idle without a VF signal I can turn the car off, then back on and Instantly the VF signal Picks up and my A/F ratios steady out. What can I do or what should I be looking for to get this resolved. This is the only problem that I have with this harness. I dont want to pull it and hunt down another harness if this can be fixed.

Please Advise.

 

[grimreaper]

any codes? what do you mean no vf reading? is the reading 0.00v? or is there a lack of voltage altogether?

 

[gottadiesel]

Hey GR, not sure where you were headed with that - are you thinking, what I am thinking, could be throwing a O2 heater circuit code? Not sure how long it would really take for the O2 to reach 600 degrees without the heater...

To OP, I 2nd GR's question - like you, we are both running MaftPros so if you have Vf connecting into the MP, (trying to get your issue straight in my mind) so your Aux01 is reading what when you say no voltage? What AFRs are you seeing during this "15-20 minutes" Rich, Lean or bouncing?

 

[supraguy31]

No codes.

On the MAFT Pro you have a AUX Imput 1 selection that allows you to see when you cars VF signal picks up. Im sure you are aware of this Setting. Anyways When I start the car its reads 0.00v as it should until (and correct me if I wrong) the car goes into closed loop, (Ive seen this Signal Pick up in 30 seconds) once this happens you should get a VF reading of 2.5v (Optimal reading). Now, With my car I start the car up, Reading is 0.00v but my issue is that I can let the car sit there at Idle for 20 minutes and my VF will still be at 0.00v and A/F are Pegged lean. If I turn the car off, Instantly turn it back on, the VF starts to read all of a sudden and the A/F ratio goes to normal. It seems to have to be atleast 15-20 minutes for this to take place. If I turn it off and back on at 5 minutes my VF will still be at 0.00v.

Just to make sure that the Grey wire was good I pulled one from a Scrap harness and replaced it. No change but then again if it was the wire, I would never get a Signal. I have the Purple wire connected to the VF wire and it is tightly secured. I have went over it like 4 times to make sure. I used the Diagram below minus the HAC and THA-E2 resisters that I have in place.

Im stumpted here. I need some help.

 

[gottadiesel]

No codes.

On the MAFT Pro you have a AUX Imput 1 selection that allows you to see when you cars VF signal picks up. Im sure you are aware of this Setting. Anyways When I start the car its reads 0.00v as it should until (and correct me if I wrong) the car goes into closed loop, (Ive seen this Signal Pick up in 30 seconds) once this happens you should get a VF reading of 2.5v (Optimal reading). Now, With my car I start the car up, Reading is 0.00v but my issue is that I can let the car sit there at Idle for 20 minutes and my VF will still be at 0.00v and A/F are Pegged lean. If I turn the car off, Instantly turn it back on, the VF starts to read all of a sudden and the A/F ratio goes to normal. It seems to have to be atleast 15-20 minutes for this to take place. If I turn it off and back on at 5 minutes my VF will still be at 0.00v.

Just to make sure that the Grey wire was good I pulled one from a Scrap harness and replaced it. No change but then again if it was the wire, I would never get a Signal.

Im stumpted here. I need some help.

So one additional question to make it clear in my thick skull , What happens if you leave it idle for 30 minutes? Does it never come off of 0.00 without a shutdown and restart? If that is a yes, then even when you do shutdown and restart, it has to already been idling for 15-20 minutes?

So next question, what happens when you idle at 2500 rpms or there about, does the time reduce at all?

Have you checked voltage at the O2 sensor connection? (Heater circuit, not sensor)

Did this problem just start out of the blue or did something change with your tune? (If you increase after-start enrichment, do you get any change?)

By the by, your question on Vf is correct, my Vf signal that goes to diag block is paralleled into my Aux01 on MaftPro, so that I can monitor and log, not everyone agrees with tuning for Vf satisfaction, personally I do not do any tuning in closed loop, I allow the TCCS take make all of those decisions, BUT I do set my Main-scale so that in closed loop operation my Vf are close to satisfaction (my last log with general driving my average Vf was 2.41) then I simply tune in VE table for Open loop operation... Sorry got off topic, but once Vf came up, just clarifying how I use the information...

 

[supraguy31]

So one additional question to make it clear in my thick skull , What happens if you leave it idle for 30 minutes? Does it never come off of 0.00 without a shutdown and restart? If that is a yes, then even when you do shutdown and restart, it has to already been idling for 15-20 minutes?

So next question, what happens when you idle at 2500 rpms or there about, does the time reduce at all?

Have you checked voltage at the O2 sensor connection? (Heater circuit, not sensor)

Did this problem just start out of the blue or did something change with your tune? (If you increase after-start enrichment, do you get any change?)

By the by, your question on Vf is correct, my Vf signal that goes to diag block is paralleled into my Aux01 on MaftPro, so that I can monitor and log, not everyone agrees with tuning for Vf satisfaction, personally I do not do any tuning in closed loop, I allow the TCCS take make all of those decisions, BUT I do set my Main-scale so that in closed loop operation my Vf are close to satisfaction (my last log with general driving my average Vf was 2.41) then I simply tune in VE table for Open loop operation... Sorry got off topic, but once Vf came up, just clarifying how I use the information...

First Reply: NO, It doesnt come off 0.00v even if I just let it run. Ive done it for longer than 30 minutes before and the VF stays steady 0.00v. As long as I shut the car down and turn it back on the VF signal is like its not there. Doesnt matter if I rev the engine or Hold the RPMs to 2500 prior to restarting nothing I do will change the VF signal. Heck, Ive even driven the car for 10 miles as I had to get it to the new house and once I was about a mile out, I opened the glove box and my VF was still 0.00v, Shut it off, turned it back on and it picked right up.

Car has to be Idling for atleast 15-20 minutes prior to be doing the Initial shutdown and startup. If I let it run for 5-10 minutes and do a restart the VF just stays at 0.00v. Its like its in Hibernation mode until a certain amount of time has gone by, then it picks up.

Its been this way since Ive had this harness. I pulled this one and replaced it with another on and with it the VF picked up just find 30-45 Seconds. Unfortunately the seller didnt tell me that there were alot of other Issues with it so I had to pull it back out and try to figure out what is wrong with this harness instead. Getting tired of Purchasing harnesses with the agreement that there is nothing wrong with them, get them installed and its a totally differnt story.

Im glad that you mentioned the 02 sensor connection. When i removed the Grey wire I also removed all 3 O2 sensor wires and replaced them with Known good wires from my other scrap harness. There is no cuts or breaks in any of the 4 wires going from the ECU Plug to the O2 Sensor (3 wires) or the VF grey wire going to the check connector.

 

[gottadiesel]

Car has to be Idling for atleast 15-20 minutes prior to be doing the Initial shutdown and startup. If I let it run for 5-10 minutes and do a restart the VF just stays at 0.00v. Its like its in Hibernation mode until a certain amount of time has gone by, then it picks up.

HHmm, what I am having a hard time wrapping my head around is this - IF it is time based, when you shutdown and restart, anything time based should start over?? If it was temp based (EGT) then enough time it should function?

Have you checked voltage on Ox IIRC on the diag block to see what the O2 sensor is doing? Do you have a different ECU to swap with? Never-mind you did already...

Its been this way since Ive had this harness. I pulled this one and replaced it with another on and with it the VF picked up just find 30-45 Seconds. Unfortunately the seller didnt tell me that there were alot of other Issues with it so I had to pull it back out and try to figure out what is wrong with this harness instead. Getting tired of Purchasing harnesses with the agreement that there is nothing wrong with them, get them installed and its a totally differnt story.

So regardless of all other thoughts - this statement seems to say that it is in the wiring... I'm going to have to think on this one and may still not come up with anything intelligent ;-)

Hopefully when GrimReaper is back on-line he may have some ideas, he has a lot more experience with the Supra than I do...

 

[supraguy31]

Ok. I went out to the Area that I have the car stored so I can take some Pics to show you a little better about what Im working with. These MAFT Pro Monitor shots will Explain a little better what Im having Issues with. Keep in Mind that with Pictures 1 and 2 my A/F ratio is a _ _ _ on my wideband which is signs for its reading higher than 18.0.

Pic 1, Time taken was at 1:23pm with car running about 2 minutes so far.

Pic 2, Time taken was 2:00pm. Car as been Idling for about 35 minutes now.

Pic 3, Time taken was 2:01pm. I shut the car off, waited for the MAFT Pro to power off and then started the car right back up. A/F at this time went up to 14.5 and help pretty steady.

Hope this gives you a little better understanding of what Im dealing with here. I dont understand it anymore than you and I agree what does the shutdown and startup have to do with this starting to read properly.

Robert

 

[gottadiesel]

Before we get wrapped around the axle here, can you do this - verify the Vf readings with a meter at the diag block... lets just make sure this has nothing to do with MaftPro... I doubt it does, as the AFRs should not be affected, assuming you are not using the MaftPro with AFR Tracking? Or are you?

 

[supraguy31]

Nope, AFR Tracking and PTT tracking are Disabled. Nothing has changed in the Box between harnesses, Just said harness is having this one Issue and the others did not but multiple other Issues. I will see what my VF readings are at the Diag Box tomorrow when I go out there.

 

[3.0 GT]

hey guys its not the amount of time that changes vf when you restart, it the engine temp. i know this because i tested it. with the engine cold i put a resistor in the ecu coolant temp sensor circuit that told the ecu it was warm. even though the car had not been started in hours, vf went to the normal 2.5ish volts. i removed the resistor and plugged the sensor back in and when i started the car again and vf showed 0v. whenever my vf is doing the 0v thing until warm restart the engine runs lean and bunces or bucks while accelerating. very annoying and im in the habbit of restarting the car when it warms up every time i drive. VERY FUCKING ANNOYING! but to everyone else having this problem, is your o2 sensor unplugged? mine is so the maft pro can control afr with PTT. im thinking that may have something to do with the problem.

 

[gottadiesel]

hey guys its not the amount of time that changes vf when you restart, it the engine temp

I understand the theory, but it is not engine temp only, otherwise it would go to close loop like it is suppose to after so many minutes of idling... OP said he let is idle for 35 minutes, that is surely enough time to warm up enough is it not? Like you said - It would appear that it wants it to be at that temp at startup and not get to that temp while running... not normal operation, so something is wrong with an input value or an output value to or from the ECU, which could be the ECU or the wiring or a sensor sending info to the ECU etc...

To my understanding, his O2 sensor is plugged in and he has disabled PTT... Not say that someone has not, but I haven't met anyone that has been successful removing the O2 sensor and running PTT on a 7mgte with MP... not to say that you can't it just doesn't seem real stable IMO, I have not tried it myself as I had not heard any success with it...

 

[supraguy31]

Stock O2 sensor is still plugged in and AFR Tracking and PTT is Disabled. Ive never used these functions. I like to let the ECU control Idle and Cruise and use the MAFT Pro to control everything else ie...WOT. I only know of one person that isnt running a Stock O2 sensor and has tuned his car via VE Tables to get it to run correctly but his fuel economy has suffered tremendously.

GOTTADIESEL.... Can you give me a link to the correct page of the TSRM to check what I need to tomorrow. I want to make sure I dont have any Doubt that Im checking everything correctly. Stock O2 sensor is fine, Ive replaced that also without any change.

 

[gottadiesel]

I went to look at your profile to see what year you have, as the ECU and harness are different for different years... but I see you are an upgraded MarkII, which I am sure I saw you Tacoma back in November as Sonic did I not? Nice setup by the way... anyway I need to know what year harness and ECU you are running to be of more help...

 

[supraguy31]

ok. Its a 88 Supra turbo Manual Tranny. You might have seen my Friend mike or Bob. Both of them have silver 7M MKIIs. My setup is totally Different from theres and Ive only been out to sonic once which was 2 weeks ago this friday and there was only like 6 cars that showed up. I want to get out there more if I can get this issue resolved.

 

[gottadiesel]

OK, yeah must have been, just saw your picture and looked familiar...

Anyway, ok that should be easy enough, since mine is an 88, let me find it and I will add to post in a bit...

 

[supraguy31]

Heck, If I have too, I will drive the car down there to you since you arent that far from me anyways and let you personally have a crack at it. This is a Pic of my Car. It was part of Import tuner Magazine PNW Supra Nationals photos.

 

[gottadiesel]

Yeah I am open to doing that if need be...

Here is the link
http://www.turboninjas.com/mk3supra/1987/04-EFISystem.pdf

Pages 58-72 are trouble shooting ECU and EFI sensors...

Let me know if you get anywhere...

 

[supraguy31]

So I didnt get anywhere today. Frustrating as this is getting Im about ready to Purchase a new Harness and call it a Day. Its easy for me to convert to a 89 Manual Harness and there are only 3 left in the country per Mark at Vancouver Toyota. Might be worth it in the long run.

Anyways, I went and did the VF jump connector test today. Let the car warm up to Normal Operating temps, Jump the VF and E1 and what I see for a reading when the AUX1 is at 0.00 is the same 0.00. Shut the car off and turn it back on, VF starts to read VIA MAFT Pro but the VF Check connector is reading 0.09v. Push the throttle really Quick and it jumps up to 0.14v and drops back down to the 0.09v.

Nothing I did during that 2 hour span would get the VF to read anywhere close to 2.5v at the check connector. This is with the T and E1 jumped also, Tried both ways.

 

[jetjock]

Why would you short Vf to ground? And you understand with the diag block jumped Vf is no longer Vf right?