Code 21 or Lack of

[dumbo]

Here's the story.

I have the maftpro speed density. With the stock o2 sensor UNplugged I don't get a code 21? With it plugged it it doesn't change anything.

When I unplug it for PTT it doens't throw the heater circuit code how could this be? And with it unplugged I still get a VF voltage ranging from 1v-3v or so????

If there is an open I should get the code, and if the 5volt reference(I think) was to short to ground wouldn't I blow my EFI fuse??

My question is how come it would do this, I don't understand.

I also get codes 24,31,32(maftpro stuff) and 34 boost pressure. For some reason I think with the o2 sensor unplugged I'm still in CLOSED loop and don't know why.

jetjock or anyone else with knowledge of the TCCS please throw me a bone, this is driving me crazy.

As always, thanks a lot.

 

[JimR]

Are you getting any voltage at your oxygen sensor connector, specifically for the heater element?

 

[dumbo]

Just checked, with the car running I get 13.xx, like 23mvolts, and 0v on the third. Code 21 will keep the CIL on solid right?

 

[grimreaper]

yes, and should force open loop and a vf of 0v. when its unplugged.

 

[dumbo]

Yah I don't get this at all.

 

[JimR]

Yeah, code 21 due to heater circuit failure keeps the light on. It's one of the few codes that do. However, I'm showing it for a GTE ecu only. Do you have a 7M-GTE ecu? If so, what year? Apparently the early ecu's did not check the heater circuit. Ref: http://www.supramania.com/forums/showthread.php?t=22958

You saw 23 millivolts across the heater pins in the connector? That seems incredibly low. I couldn't find the spec, but I believe it should be around 12 volts. Can someone confirm or correct this?

 

[dumbo]

I dont know what wires the heater circuit are but all 3 wires are below.
I have 13.xxvolts on one wire
23mvolts on the second
and 0.00v on the third

I can tell you exactly what wires tomorrow if that will help but for some reason thats prolly right eh?

My harness, ecu, ect. are all from a 87-88 cant remember 100% what year. and all GTE parts.

Im all ears for suggestions, Ill be putting in GTE intake cam tomorrow. Im not sure if that will effect the AFR at all due to VE.

 

[grimreaper]

Yeah, code 21 due to heater circuit failure keeps the light on. It's one of the few codes that do. However, I'm showing it for a GTE ecu only. Do you have a 7M-GTE ecu? If so, what year? Apparently the early ecu's did not check the heater circuit. Ref: http://www.supramania.com/forums/showthread.php?t=22958

You saw 23 millivolts across the heater pins in the connector? That seems incredibly low. I couldn't find the spec, but I believe it should be around 12 volts. Can someone confirm or correct this?

checking voltage at the harness connector showed 12v or rather what ever the battery voltage was reading (12.6 off, 13.3 running).

 

[JimR]

checking voltage at the harness connector showed 12v or rather what ever the battery voltage was reading (12.6 off, 13.3 running).

Thanks grim.

OK Dumbo, Code 21 due to heater circuit failure is a red herring in your case, because AFAIK your year of ecu does not check for it. It only checks for the sensor voltage itself.

13.xx volts is fine. That's battery/alternator voltage.
0.00 volts is also fine. That's the ground wire.
The 23mvolts must be trace leakage of some sort... I don't think that's a problem either.

Time to work on your other codes.

 

[dumbo]

Well I changed my cam today, and put on the gte throttle linkage to get 100% throttle. My car is a whole new car now

afr are a solid 15-16 cruise, and boosts a solid 11-11.5. I even got a code 21 solid CIL for part of a drive until I shut it off. What do you make of that eh? I'm not sure if this has to do with the cam changing the VE of my engine or my moving the harness to do the cam.?? But wow:love: Hope my mileage improves.

EDIT: Ohh and my afm hz is only getting to 1330hz, dont know if thats good or not?