Running rich on one side
#1
Running rich on one side
D1, 202K, head gasket done already. MPG dropping below 12. Carbon fouling all plugs on cylinders on left side of engine. Plugs on other side look great. Have observed black smoke output at high idle. Black, not blue, white, gray, or brown. Suspected stuck open thermostat because low coolant temp sensor readings. Coolant temp readings did not agree with dash gauge (8:30) or infrared thermometer reading of radiator inlet. Changed thermostat from 180 (have run for a few years) to 195 (what store had in stock).
With new thermostat the coolant temp sensor is reading 15 or more degrees lower (185) than IR sensor used to spot check radiator inlet temp (202F) Coolant sensor (two wire, not the one wire gauge sender) removed, clean and shiny, no coral build up. Coolant flows out the open port vigorously, do not think it is internally blocked.
Scanner says we are in closed loop (both sides) well before thermostat opens. On the road going to wide open throttle makes system go to open loop as expected, drop back to cruise and it is closed loop on both sides.
Scanner shows downstream O2 sensor on side with fouling has very low output voltage. Like .005, does change, but no where near the voltages of the other three sensors.
So is the poor mpg and fouling more from sensor telling CPU the wrong coolant temp, or the down stream O2 sensor? Or both? Anyone have a chart of expected resistance vs temp for the coolant sensor?
Many codes, as expected, related to misfire, emissions, etc.
Thoughts?
With new thermostat the coolant temp sensor is reading 15 or more degrees lower (185) than IR sensor used to spot check radiator inlet temp (202F) Coolant sensor (two wire, not the one wire gauge sender) removed, clean and shiny, no coral build up. Coolant flows out the open port vigorously, do not think it is internally blocked.
Scanner says we are in closed loop (both sides) well before thermostat opens. On the road going to wide open throttle makes system go to open loop as expected, drop back to cruise and it is closed loop on both sides.
Scanner shows downstream O2 sensor on side with fouling has very low output voltage. Like .005, does change, but no where near the voltages of the other three sensors.
So is the poor mpg and fouling more from sensor telling CPU the wrong coolant temp, or the down stream O2 sensor? Or both? Anyone have a chart of expected resistance vs temp for the coolant sensor?
Many codes, as expected, related to misfire, emissions, etc.
Thoughts?
#2
I would speculate the coolant temperature sensor is not the culprit because that would affect the fuel trim for both banks. Temp sense is not per bank. The O2's are per bank. However, I thought the downstream O2 were primarily relevant to catalyst efficiency and not fuel trim. I don't really know. Are you sure it's not actually the upstream O2 that is bad? Do you also see abnormal fuel trim on the bank with fouling?
#3
BUZZ ITS GREAT TO SEE YOU!
what do the readings look like on live data stream for the upstream o2, the upstream should both be rapid fluxuating on closed loop
I wonder if that fuel rail coolant sensor would screw it up?
guess there is also the possibility of a vacume leak on one side leaning it out and causing other side to appear rich
downstream are just for cat efficiency, will trip bad cat code that's it afaik
what do the readings look like on live data stream for the upstream o2, the upstream should both be rapid fluxuating on closed loop
I wonder if that fuel rail coolant sensor would screw it up?
guess there is also the possibility of a vacume leak on one side leaning it out and causing other side to appear rich
downstream are just for cat efficiency, will trip bad cat code that's it afaik
#4
#5
Buzz, great to see your still kicking. Miss your words of wisdom from time to time.
Coolant temp sensor could be failing, hence the difference between actual temp(ir gun) and measured temp(sensor)
Or the connector itself could have corrosion, throwing off the reading.
O2 sensor sound weak based on your description.
And as Tom said, the possibility of a vacuum leak is very high.
Coolant temp sensor could be failing, hence the difference between actual temp(ir gun) and measured temp(sensor)
Or the connector itself could have corrosion, throwing off the reading.
O2 sensor sound weak based on your description.
And as Tom said, the possibility of a vacuum leak is very high.
#6
Anyone have a chart of expected resistance vs temp for the coolant sensor?
Yours is a good method to find difference between sensor output and actual coolant temps. Thanks for that and will be doing the same soon to ensure temps I'm seeing are accurate. It would probably a good cooling system PM item.
Engine coolant temperature sensor (ECT Sensor)
This sensor consists of a temperature dependant
resistive metal strip. The resistance of the strip varies
considerably with coolant temperature, i.e. from 28K
ohms at - 30°C to 90 ohms at 130°C, and 300 Ohms
at 85°C. The ECT Sensor signal is vital to engine
running, as the correct fuelling is dependant upon
engine temperature i.e. richer mixture at low
temperatures. If the sensor is disconnected or failure
occurs a default value will be supplied to the system.
The initial default value selected will be based on the
value of the air intake temperature. This will increase
to a nominal warmed up value over an individual time,
programmed for each default value. The fault may not
be evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
This sensor consists of a temperature dependant
resistive metal strip. The resistance of the strip varies
considerably with coolant temperature, i.e. from 28K
ohms at - 30°C to 90 ohms at 130°C, and 300 Ohms
at 85°C. The ECT Sensor signal is vital to engine
running, as the correct fuelling is dependant upon
engine temperature i.e. richer mixture at low
temperatures. If the sensor is disconnected or failure
occurs a default value will be supplied to the system.
The initial default value selected will be based on the
value of the air intake temperature. This will increase
to a nominal warmed up value over an individual time,
programmed for each default value. The fault may not
be evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
Last edited by number9; 02-03-2016 at 03:10 PM.
#7
Readings from scanner at idle:
ST FTRM1(%).......24.2
LT FTRM1(%)......-24.2
ST FTRM2(%)......-25.0
LT FTRM2(%)......-24.2
FUEL SYS 1.........CLOSED
FUEL SYS 2.........CLOSED
COOLANT............189F
O2S11 (v)...........0.990 (not charging much)
O2S12 (v)...........0.000 (goes up to .005 at 2K rpm)
O2S21 (v)...........0.015
O2S22 (v)...........0.025
ECT OHMS = 258 at 185F, so somewhat out of spec, but most likely no problem. Did not find any vac lines loose, etc.
Work and health issues have kept me off the site, plus college offspring was driving Rover maybe 75 miles a week. I was just doing underhood check. Bought her another ride, retired my Mercedes wagon, and starting driving the Rover again. So it may have been having problems and just haven't been looking. CEL is burned out from previous owner, I go by the MIL indicator flag on the scanner when hooked up.
So which O2 sensor should I swap out?
ST FTRM1(%).......24.2
LT FTRM1(%)......-24.2
ST FTRM2(%)......-25.0
LT FTRM2(%)......-24.2
FUEL SYS 1.........CLOSED
FUEL SYS 2.........CLOSED
COOLANT............189F
O2S11 (v)...........0.990 (not charging much)
O2S12 (v)...........0.000 (goes up to .005 at 2K rpm)
O2S21 (v)...........0.015
O2S22 (v)...........0.025
ECT OHMS = 258 at 185F, so somewhat out of spec, but most likely no problem. Did not find any vac lines loose, etc.
Work and health issues have kept me off the site, plus college offspring was driving Rover maybe 75 miles a week. I was just doing underhood check. Bought her another ride, retired my Mercedes wagon, and starting driving the Rover again. So it may have been having problems and just haven't been looking. CEL is burned out from previous owner, I go by the MIL indicator flag on the scanner when hooked up.
So which O2 sensor should I swap out?
#8
That will affect trims, which affect fuel economy.
Once switched out, if it doesnt affect fuel trims, them you either have a leak , and may require a smoke test, or the MAF is on its way out.
I hear you, life catches up with us all. Good to see you're still kicking old friend.
#9
When I said vacuum leak I meant plenum or intake gasket
Down streams do nothing on these old obd2 mine are bypassed with no cats
the one that's not changing much, its showing how rich you are running
Ntk are cheap on amazon if you wanted to do both upstream for good measure, pull coil packs to access the plugs
I'm not sure it the issue
Down streams do nothing on these old obd2 mine are bypassed with no cats
the one that's not changing much, its showing how rich you are running
Ntk are cheap on amazon if you wanted to do both upstream for good measure, pull coil packs to access the plugs
I'm not sure it the issue