Emissions help
06-14-2009, 09:28 PM
#1
Rennlist Member
Thread Starter
Emissions help
My '89 will not Texas emissions for some reason. I have replaced the cats which helped the Nox, but it seems to be running really rich.
In the last year and a half, I have replaced the Hall sensor, the temp2, the TPS, the ISV, the crank position sensor, and the O2 sensor. I have had the MAF rebuilt and the LH rebuilt. I changed plugs and plug wires, checked all the connectors, and changed distributor caps and rotors.
My HC is 278 (standard is 148)
CO is 4.79 (standard is .94)
Co2 is 11.9 (no standard)
O2 is 0.1 (no standard)
Nox is 144 (standard is 1047) I just replaced my cats
Dilution is 16.69 (standard is >6.0)
This is the high speed reading (25 mph) at average 1212 RPM
Anybody have any further suggestions?
In the last year and a half, I have replaced the Hall sensor, the temp2, the TPS, the ISV, the crank position sensor, and the O2 sensor. I have had the MAF rebuilt and the LH rebuilt. I changed plugs and plug wires, checked all the connectors, and changed distributor caps and rotors.
My HC is 278 (standard is 148)
CO is 4.79 (standard is .94)
Co2 is 11.9 (no standard)
O2 is 0.1 (no standard)
Nox is 144 (standard is 1047) I just replaced my cats
Dilution is 16.69 (standard is >6.0)
This is the high speed reading (25 mph) at average 1212 RPM
Anybody have any further suggestions?
06-15-2009, 11:33 AM
#2
Rennlist Member
Thread Starter
Is it possible that the MAF has gone bad? Just guessing here.
I can swap a different MAF into the car. Would that even make a difference in my numbers?
I can swap a different MAF into the car. Would that even make a difference in my numbers?
06-15-2009, 01:08 PM
#3
Rennlist Member
It does look like it is running rich. The LH should be running in closed-loop mode (after warmup), with feedback from the O2-sensor controlling the air/fuel ratio around 14.7. So the question is whether the LH is really running in closed-loop mode.
I don't think it is the MAF, but it is an easy swap and if you get unlimited free tries then give it a go.
I assume you went through the sensor checks outlined in the WSM? Those are important because a missing Temp-II sensor signal for example would kick the LH out of closed-loop for example. Check at the LH connector, not just at the sensor.
If you have one, a Wideband O2 sensor would tell you if the LH were running closed-loop-- WBO2 reading would hunt a few tenths either side of 14.7 around as the LH fiddles with fueling.
You can also put a voltmeter on the regular O2 (NBO2) sensor signal, once the car warms up it should be hunting up and down between zero and 1 volt (approx) as the LH adjusts fueling. You'll need to splice into the O2 sensor signal and add a test point-- do this on the sensor side of the disconnect at the CE panel, where it is a simple wire and not shielded. There will be one black signal wire and two white heater wires, tap into the black one.
That will most likely show that the NBO2 signal is stuck near 0 or 1 volt indicating that the LH is running open-loop. (If it is outside the 0-1 volt range after warmup then the sensor is toast, and you've found the culprit).
Without a ST or a diagnostic tester to identify the bad sensor signal you need to go through each sensor check methodically. The NBO2 sensor itself is a good bet unless it has been changed recently.
Happy hunting!
I don't think it is the MAF, but it is an easy swap and if you get unlimited free tries then give it a go.
I assume you went through the sensor checks outlined in the WSM? Those are important because a missing Temp-II sensor signal for example would kick the LH out of closed-loop for example. Check at the LH connector, not just at the sensor.
If you have one, a Wideband O2 sensor would tell you if the LH were running closed-loop-- WBO2 reading would hunt a few tenths either side of 14.7 around as the LH fiddles with fueling.
You can also put a voltmeter on the regular O2 (NBO2) sensor signal, once the car warms up it should be hunting up and down between zero and 1 volt (approx) as the LH adjusts fueling. You'll need to splice into the O2 sensor signal and add a test point-- do this on the sensor side of the disconnect at the CE panel, where it is a simple wire and not shielded. There will be one black signal wire and two white heater wires, tap into the black one.
That will most likely show that the NBO2 signal is stuck near 0 or 1 volt indicating that the LH is running open-loop. (If it is outside the 0-1 volt range after warmup then the sensor is toast, and you've found the culprit).
Without a ST or a diagnostic tester to identify the bad sensor signal you need to go through each sensor check methodically. The NBO2 sensor itself is a good bet unless it has been changed recently.
Happy hunting!
06-15-2009, 05:22 PM
#4
Rennlist Member
Thread Starter
Jim,
I changed the O2 sensor last week, as my thoughts were that my previous richness may have destroyed my O2 sensor. I know it is possible for a sensor (Temp2) to go bad, but since I replaced them all or had the MAF and LH rebuilt, I was just wondering if anyone had a BTDT thing.
Thanks for the hints,
John C.
I changed the O2 sensor last week, as my thoughts were that my previous richness may have destroyed my O2 sensor. I know it is possible for a sensor (Temp2) to go bad, but since I replaced them all or had the MAF and LH rebuilt, I was just wondering if anyone had a BTDT thing.
Thanks for the hints,
John C.