Failing smog, waay too rich
Posted: Tue Jul 10, 2018 10:50 pm
1986 635 auto 99,000 miles NA
Failed smog last year:
CO GPM 106.62 Failed
allowed 20.0
HC GPM 2.45 Passed
allowed 2.5
NOx GPM 1.48 Passed
allowed 4.5
First thing I did was new O2 sensor, then a different one still failing.
So far I have:
1.Replaced wires and distributor cap. Fine
2.Replaced coolant temp sensor, old one ohms out same as new one at different temps. Fine
3.Ohmed out cabin temp sensor.Fine
4.Lubed and checked idle control valve, vibrates at idle, opens and closes fine.
5.Plugged cold start sensor at fuel rail .
6.Have different AFM's, one I use as a base is out of friend's 86 635 ( never been opened ) his 635 runs fine.Have "mapped " one spare to correct voltages by adjusting potentiometer sweep arm to new carbon track and slightly adjusting sweep arm to read lower voltages.This has helped slightly.
7.Plugged in friend's ECU, no change.
8.Smoke test and seafoam treatment doesn't show any leaks.
9.Installed new correct sprk plugs, they go black and fluffy in minutes just like when I clean the old ones.
10.Installed new FPR, no change from old one.
11.Reference sensor and speed sensor ohm out correctly, if I switch them car doesn't start, so they seem to be working.
12.Have contact cleaned every connection found and have wire bushed all ground connections.
Introducing small air leak at manifold ( disco cabin temp sensor hose ) makes it idle higher 1100 and smoother.
TPS is a problem , linear voltage readings and ohm readings go in the wrong direction .
Idle speed is a rough 950 with the TPS connected, give it the gas and the tach will drop to about 700 and then rise to 950.
From my old carb tuning days this means too rich.
Idle speed is a rough 950 with the TPS disconnected, give it the gas and the tach will drop to about 700 and then rise to 950.
Apparently it makes no difference if the TPS is connected or not, this is at all RPMs.
Ohm test TPS disconnected
Idle ohms should be 2.0 actual is 4.2
Floored ohms should be 10 actual is .62
Voltage test
Idle volts should be .7 increasing to about 5.0 when floored with ignition ON and backprobe of connector.
Idle actual is 4.52 decreasing to .9 when floored.
Tests done on 2 different DMM's give same readings.
Really stuck on why I'm running rich.
Failed smog last year:
CO GPM 106.62 Failed
allowed 20.0
HC GPM 2.45 Passed
allowed 2.5
NOx GPM 1.48 Passed
allowed 4.5
First thing I did was new O2 sensor, then a different one still failing.
So far I have:
1.Replaced wires and distributor cap. Fine
2.Replaced coolant temp sensor, old one ohms out same as new one at different temps. Fine
3.Ohmed out cabin temp sensor.Fine
4.Lubed and checked idle control valve, vibrates at idle, opens and closes fine.
5.Plugged cold start sensor at fuel rail .
6.Have different AFM's, one I use as a base is out of friend's 86 635 ( never been opened ) his 635 runs fine.Have "mapped " one spare to correct voltages by adjusting potentiometer sweep arm to new carbon track and slightly adjusting sweep arm to read lower voltages.This has helped slightly.
7.Plugged in friend's ECU, no change.
8.Smoke test and seafoam treatment doesn't show any leaks.
9.Installed new correct sprk plugs, they go black and fluffy in minutes just like when I clean the old ones.
10.Installed new FPR, no change from old one.
11.Reference sensor and speed sensor ohm out correctly, if I switch them car doesn't start, so they seem to be working.
12.Have contact cleaned every connection found and have wire bushed all ground connections.
Introducing small air leak at manifold ( disco cabin temp sensor hose ) makes it idle higher 1100 and smoother.
TPS is a problem , linear voltage readings and ohm readings go in the wrong direction .
Idle speed is a rough 950 with the TPS connected, give it the gas and the tach will drop to about 700 and then rise to 950.
From my old carb tuning days this means too rich.
Idle speed is a rough 950 with the TPS disconnected, give it the gas and the tach will drop to about 700 and then rise to 950.
Apparently it makes no difference if the TPS is connected or not, this is at all RPMs.
Ohm test TPS disconnected
Idle ohms should be 2.0 actual is 4.2
Floored ohms should be 10 actual is .62
Voltage test
Idle volts should be .7 increasing to about 5.0 when floored with ignition ON and backprobe of connector.
Idle actual is 4.52 decreasing to .9 when floored.
Tests done on 2 different DMM's give same readings.
Really stuck on why I'm running rich.