No close loop on 88 7MGTE

[supraguy31]

Found out that my car isnt going into closed loop. What causes this and is there anyway to correct this Issue. Sometimes It Idles just fine and then all of a Sudden it just drops to 10.0 on Wideband and starts to sputter and eventually shuts off. No VF Signal at all (0.00) after warmup or attempting to drive per MAFT Pro and Basically no OX signal either (0.05) after complete warmup.

Any help will be greatly appreciated.

 

[jdub]

Any codes?

 

[metaphysico]

I think these cars only need temp sensor signal to be high enough and the sensor to be warm and ready. Where are u getting the voltages from, the maft pro or the diag connector or from the sensor itself. Check the engine coolant temperature sensor, make sure to check that one and not the guage sensor. The guage sensor is the one wire sensor on the thermo housing, cant rember where the other is i think it just below the thermo housing on the pass side, make sure the computer knows how warm your engine is.
Dont know much about the maft pro does it use a heated o2 sensor or not and are the settings for wideband and normal or not.

 

[supraguy31]

The only code that I have is a Code 43 (Starter Signal) but I dont think that would have anything to do with this.

 

[supraguy31]

I think these cars only need temp sensor signal to be high enough and the sensor to be warm and ready. Where are u getting the voltages from, the maft pro or the diag connector or from the sensor itself. Check the engine coolant temperature sensor, make sure to check that one and not the guage sensor. The guage sensor is the one wire sensor on the thermo housing, cant rember where the other is i think it just below the thermo housing on the pass side, make sure the computer knows how warm your engine is.
Dont know much about the maft pro does it use a heated o2 sensor or not and are the settings for wideband and normal or not.

This car is a MK2 with a 7MGTE so all the Snesors on the thermostat housing we dont use. Im running Electric fans also so I have a 185on/170off electric fan sending unit.

 

[grimreaper]

The computer assumes the car is at operating temps if the ecu temp sensor is disconnected. You'll get a code, but idle should still be 14.7af ratio or in normal closed loop range. And open loop idle for me is in the 12's af ratio if i disconnect the o2 sensor (forcing open loop). It doesn't continue to drop or stall the car.


csi could be stuck open.

 

[jdub]

The STA signal is used for start engine start injection control...might want to look into the wiring...you want it to work.

You do need the ECU coolant temp sensor shown in this pic...an ECU temp sensor problem should generate a code 22:

The TCCS requires coolant temps to be above a predetermined level for closed-loop ops...fail-safe mode uses 180 deg for an inop ECU temp sensor.

Check Vf at the diagnostic block:
- Warm the engine to at least 180 deg F
- Multimeter (set on DC volts) connected to Vf (+) and E1 (-)
- T and E1 jumped (like you're setting timing)
- Warm-up O2 sensor...run at 2500 RPM for at least 2 minutes
- Maintain 2500 RPM and check Vf voltage on multimeter...it should fluctuate 8+ times in 10 seconds. An analog meter is best for this...the needle reacts faster than a digital meter
- You can also check O2 sensor voltage as well...it should fluctuate 0-1 volt

 

[supraguy31]

Would a TPS being out of Adjustment cause this?

As for the VF Signal, Ive tested this a Few times with my Multimeter and if it does anything at all, It will move a little bit between 0.00 and 0.02v at the check connector and this is with the car completely warm at 2500rpms. It does jump when the electric fans kick on but as soon as they shut off, it drops back down to said reading.

Do you think I have a Electric fan temperature sensor that is kicking the electric fans on too early? as for the Sensors, We do use the ones that arent on the Water neck, Its the ones that are we dont use...

This is the Sensor that I bought but they do also have one that is a 200on/185off also.
http://store.summitracing.com/partd...M%2D890017&N=700+-151712+115&autoview=sku

And they do have this one Avaliable.
http://store.summitracing.com/partd...art=SUM-890018&N=700+-151712+115&autoview=sku

 

[jdub]

- TPS has nothing to do with closed-loop
- Electric fans have nothing to do with closed-loop...disconnect and re-test per above to prove it...the "jump" was a voltage spike
- Coolant temps have to be above 180 deg F for the ECU to go into closed-loop...you would have to have an oversize rad and big CFM flow fans to over-cool.
- You do need to be running a 190 deg F coolant t-stat...you need to check it's not stuck open.
Where is the needle pointing on the coolant temp gauge?

Did you test the O2 sensor?

 

[supraguy31]

- TPS has nothing to do with closed-loop
- Electric fans have nothing to do with closed-loop...disconnect and re-test per above to prove it...the "jump" was a voltage spike
- Coolant temps have to be above 180 deg F for the ECU to go into closed-loop...you would have to have an oversize rad and big CFM flow fans to over-cool.
- You do need to be running a 190 deg F coolant t-stat...you need to check it's not stuck open.
Where is the needle pointing on the coolant temp gauge?

Did you test the O2 sensor?

Yes, My O2 sensors are working, Ive replaced it with a new one and I have also checked the reading on my MAFT Pro for 02.

Im running a Aftermarket 3 core radiator with Ford Contour electric fans and my Temps just go over a 1/4 gauge most of the time unless Im sitting Idle for a long Period of time and I dont have a thermostat in the car currently to remove that as a Problem.

So basically, I have a 3 Core radiator
Electric fans that blow hard, Stand behind the car and you can feel the heat from the fans
No thermostat
a Fan temperature sending unit of 185on/170off

 

[jdub]

Install a 190 deg t-stat...not having one causes a problem
Cut the jiggle valve off and orient the hole at the top of the housing...you'll need the rubber gasket too. If your fans are kicking on at 185 deg, that should be warm enough for the ECU to go into closed-loop...that temp fan switch is fine BTW. The problem is you may be keeping coolant temps right around 180 (or less) with no t-stat...that will depend on how accurate your ECU temp sensor is.

I thought you said no O2 signal after warm-up in the 1st post?

Time to start tracing wires for continuity
I would also check the MAFT wiring to make sure all the input/outputs as correctly wired to the harness.

 

[3p141592654]

No thermostat, temps at 25% FSD, probably running too cold to be in closed loop. But its all covered above anyway.

http://www.supramania.com/forums/showthread.php?t=47479

 

[supraguy31]

Well, If I check the OX signal at teh check connector its setting a 0.07 and doesnt move but If I go to the O2 setting on the MAFT Pro, Its reading anywhre between 2 and 3v, mostly around 2.70 or so after warmup.

I heard and since Im uping a 185on/170off sending unit that I counldnt put a 190 Degree thermostat in as that would make my fans stay on all the time. If this isnt infact true then Im going to go down to the Store and get one. I had a 160 degree in before and thats the one I removed. come to think about it, I didnt have this Problem until after the fan Installation.

 

[jdub]

You want coolant temps at 190 deg or so...for the reasons stated. You will also run rich (ECU in warm-up enrichment) at coolant temps <180 deg.
Fan operation is not a good reason to run a colder stat.

 

[supraguy31]

Ok, great.......

So would you recommend me getting a 200on/185off sending unit or just stick with this one. I mean if its not going to hurt anything then I will go down to the parts store right now and Pick up a thermostat.

 

[jdub]

I would keep the one you have...it does get hot in the summer in El Paso

The 190 stat will keep you were you need to be coolant wise. BTW - get a Stant SuperStat if you go aftermarket. Before you cut the jiggle valve off, I would test it in a pot of water with a thermometer to make sure it is opening as advertised. I've caught more than one stat (OEM and Stant) that opened up late.

 

[supraguy31]

I will be moving to Fort Lewis Washington in Late march, Early April and the normal temps up there are alot different than here thats for sure.

Going down to the Store and getting a Thermostat now. Hopefully this solves my Problems and I can feel comfortable again. Ive been Afraid to drive the car because of this Issue. I dont like it when things arent running Properly. Should have just stayed with the Fan clutch maybe.

 

[jdub]

Army guy huh....USAFR here
Flew in to Biggs many times when I was stationed in Del Rio, Tx (AD at Laughlin AFB) back in the day.

With colder OATs you may want to run the 200 deg switch...it's up to you. In hot climates, it's usually better for the fans to come on early vs late.

 

[supraguy31]

Yep, 18 1/2 Years here. Looking forward to retirement which means more time to Tinker with the Supras. Not for sure where in going to retire as Im originally from North Carolina but If I like it up there enough I might just retire there. I dont mind the cold but I hate the Heat. Been here for 4 Years now and Its time to go.

 

[jdub]

26 years last June for me...they'll kick me out at 30. If I could get an AD retirement now I'd be history
I'm in Phoenix for pretty much the same reason...I was stationed at Luke AFB back in '97 when I left AD.