Running Rich,A9M ECU and Oxygen Sensor question

90silverstang

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Nov 5, 2003
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Palm City, Fl.
Just want to verify if I have the correct ECU ---- A9M is what is on the ECU. I have a 1990 GT Vert with a manual.
Checked KOEO and Passed with a 11. Checked timing advance and OK, but-----------
I am getting a code 41 which indicates system indicate lean KOER test. The engine is running rich I think its because the ECU thinks its lean and making the AFR rich. I tested the O2 sensor heaters and checks OK-- 5.5 ohms, and I do get 12 volts to the heaters, I removed the o2 sensors and I checked with a propane torch voltage in flame .900 volts and goes to 0 volts out of flame-- check OK. checked wiring harness to ECU and signal wires 43 and 29 are OK to ECU. Checked the HEGO ground wire 49 to ground and OK. Am I missing something?
I am running Ceramic Long Tube Headers
Thanks,
Mike
 
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Cobra1741

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Mar 9, 2010
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my thought is when both banks of the motor are rich or lean, i typically look at mass air. if they were lean id say vac leak or MAF. i dont know if im confused but is it running rich or lean??? i personally havent heard of a9m only a9p for auto and a9l for manual, but im sure someone will chime in!
 

BK_CAULEY

it's built for speed not longevity, woman
Dec 26, 2006
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check and make sure all of you sensors have good ground. the ground for the 02's are a seperate lead that bolts to the back of the head/bell housing
 

90silverstang

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Nov 5, 2003
142
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Palm City, Fl.
my thought is when both banks of the motor are rich or lean, i typically look at mass air. if they were lean id say vac leak or MAF. i dont know if im confused but is it running rich or lean??? i personally havent heard of a9m only a9p for auto and a9l for manual, but im sure someone will chime in!
Thanks Cobra,
Ok ran the KOEO test and dumped a code 66, I don't know how it happened but the MAF connector was not seated all the way. Drove car around and dumped KOEO codes and I get a code 11-- pass.
Now I ran the KOER test I get code 94 and 44. I don't have air injection pump or the associated plumbing.
I have Dart 190CC heads and Long tubes which does't have ports for the air pump plumbing. The solenoids that control the pump air are electrically connected but the outlet of the vacuum ports are sealed off.
Is this hurting anything?
 

HISSIN50

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Nov 29, 1999
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If you don't have any of the A.I.R. components (including cats), it should be ok. The EEC/O2's can note a delta in the trim when the AIR system components are functioning properly. If the components are absent, you can get the codes you're getting.

Be sure you're clearing codes after changes.
 

90silverstang

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Nov 5, 2003
142
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Palm City, Fl.
If you don't have any of the A.I.R. components (including cats), it should be ok. The EEC/O2's can note a delta in the trim when the AIR system components are functioning properly. If the components are absent, you can get the codes you're getting.

Be sure you're clearing codes after changes.
Thanks Hissin---
Hissin, What changes were you refering to? There is no cats or AIR components, just the control solenoids that are sealed. (vacuum ports). I am not getting any hego codes but the exhaust smells rich. Is it because I'm not running cats?
 

HISSIN50

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Nov 29, 1999
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Thanks Hissin---
Hissin, What changes were you refering to? There is no cats or AIR components, just the control solenoids that are sealed. (vacuum ports). I am not getting any hego codes but the exhaust smells rich. Is it because I'm not running cats?

Re changes: I.e., if you found your MAF connector unseated, clear the codes to be sure the old ones don't show up on future tests even though the issue has been fixed. The easiest way to do it (and to unlearn behavior adapted around having no MAF connected) is to disco' the battery and create a draw for about 30 seconds. It sounds like you might be doing this already.

If you don't have the AIR codes (44/94), you're good to go. If you get them, it's because the O2's and EEC know the trim should change when the smog pump solenoids allow air into the system. If there's no change (as there would be none now), you can get codes. It's no biggie - just info.

You're right about the smell. No cats = some stink. Colder weather can make it seem worse too (IMHO).
 

90silverstang

Member
Nov 5, 2003
142
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16
Palm City, Fl.
If you don't have any of the A.I.R. components (including cats), it should be ok. The EEC/O2's can note a delta in the trim when the AIR system components are functioning properly. If the components are absent, you can get the codes you're getting.

Be sure you're clearing codes after changes.

Re changes: I.e., if you found your MAF connector unseated, clear the codes to be sure the old ones don't show up on future tests even though the issue has been fixed. The easiest way to do it (and to unlearn behavior adapted around having no MAF connected) is to disco' the battery and create a draw for about 30 seconds. It sounds like you might be doing this already.

If you don't have the AIR codes (44/94), you're good to go. If you get them, it's because the O2's and EEC know the trim should change when the smog pump solenoids allow air into the system. If there's no change (as there would be none now), you can get codes. It's no biggie - just info.

You're right about the smell. No cats = some stink. Colder weather can make it seem worse too (IMHO).
SO codes 44, 94 do not hurt performance or Mileage in my case? Can a tune or chip be programmed to ignore the AIR system being deleted?
 

HISSIN50

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44/94 in and of themselves do not hurt performance or mileage.

A tune can indeed get those codes ignored (if you're in there tuning for the LT's/O2's or something else anyhow). Otherwise, most folks just ignore the AIR codes (if you get a CEL, resistors should be able to take care of it).
 

90silverstang

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Nov 5, 2003
142
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Palm City, Fl.
44/94 in and of themselves do not hurt performance or mileage.

A tune can indeed get those codes ignored (if you're in there tuning for the LT's/O2's or something else anyhow). Otherwise, most folks just ignore the AIR codes (if you get a CEL, resistors should be able to take care of it).

Thank you for sharing your experience, I did see a post from JRichter on those resistors, 80 ohm, 2 watt and they get wired across the TAB an TAD solenoid +- terminals?

One last question about the A9M ECU, Is this the ECU used for a 1990 manual transmission?

Again, Thanks!
 

liljoe07

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Feb 18, 2009
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That won't clear codes 94 and 44. 94 and 44 are codes that are detected by the O2 sensors when the absence or Thermactor AIR is not present. TAB and TAD codes are 80 something codes
 

90silverstang

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Nov 5, 2003
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Palm City, Fl.
Update: When I removed the ECU from the kick panel to troubleshoot the oxygen sensor wiring, I forgot to mention I removed moates chip I had on the J3 connector. When I ran the KOEO and KOER test I ran it without the chip installed. KOEO code 11 pass-- KOER code 41 Hego sensor voltage low/system lean. I repaired code 91 by going through the wiring harness and cleaned up the grounds. Ran KOER test again thats when code 94 and 44 appeared. Then I installed the moates chip on the J3 connector. Took the car out for a ride to warm things up for 1/2 hour. When I returned I ran the KOEO and KOER and both codes 11.
I wanted to mention when I purhcased this 347 crate engine the Moates chip came with it. I guess they know that the engine was not running the AIR system so they can program it out.
Thanks
 

HISSIN50

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Joe is correct about the resistors and not them affecting the codes. In post 9, I was not as clear as I had hoped apparently - having AIR codes logged in the system and having a CEL are different issues.