Fuel mileage improvements on the 3vze
05-31-2015, 03:49 PM
#101
Good job of making the correct measurements! Unfortunately (from a diagnostic standpoint), the results indicate that the ECU is happy about how things are running, and the closed loop control is working. The low voltage on the VF1 terminal does indicate that things are biased toward rich, which means that whenever the engine is running open-loop (cold, hard acceleration), it is likely running a bit rich, but I don't think that explains your low fuel mileage or your black exhaust pipe.
I think millball's suggestion to check the engine coolant temperature sensor is the next place to look. The coolant temperature sensor should measure about 300 ohms when the engine is properly warmed up (~180 degF). If it's higher than about 600 ohms when the engine is warmed up, it means the ECU never thinks the engine is warmed up, and will be calling for a richer than normal mixture.
I think millball's suggestion to check the engine coolant temperature sensor is the next place to look. The coolant temperature sensor should measure about 300 ohms when the engine is properly warmed up (~180 degF). If it's higher than about 600 ohms when the engine is warmed up, it means the ECU never thinks the engine is warmed up, and will be calling for a richer than normal mixture.
05-31-2015, 03:51 PM
#102
Check the engine temp sensor that talks to the ECU, (different one than for the gauge)
If it does not function properly, the fuel trim system will not go into closed loop. This continuous operation in open loop definitely will result in poor fuel mileage.
You might consider a new upstream O2 sensor too, but look at the temp sensor first.
Edit: RJR beat me to it, and with a much more helpful and comprehensive reply.
If it does not function properly, the fuel trim system will not go into closed loop. This continuous operation in open loop definitely will result in poor fuel mileage.
You might consider a new upstream O2 sensor too, but look at the temp sensor first.
Edit: RJR beat me to it, and with a much more helpful and comprehensive reply.
Thanks,
I will check that next. When I previously read your post I thought this check was covered in the checks RJR suggested.
Thanks for the input.
11-10-2017, 07:06 AM
#103
Good job of making the correct measurements! Unfortunately (from a diagnostic standpoint), the results indicate that the ECU is happy about how things are running, and the closed loop control is working. The low voltage on the VF1 terminal does indicate that things are biased toward rich, which means that whenever the engine is running open-loop (cold, hard acceleration), it is likely running a bit rich, but I don't think that explains your low fuel mileage or your black exhaust pipe.
I think millball's suggestion to check the engine coolant temperature sensor is the next place to look. The coolant temperature sensor should measure about 300 ohms when the engine is properly warmed up (~180 degF). If it's higher than about 600 ohms when the engine is warmed up, it means the ECU never thinks the engine is warmed up, and will be calling for a richer than normal mixture.
I think millball's suggestion to check the engine coolant temperature sensor is the next place to look. The coolant temperature sensor should measure about 300 ohms when the engine is properly warmed up (~180 degF). If it's higher than about 600 ohms when the engine is warmed up, it means the ECU never thinks the engine is warmed up, and will be calling for a richer than normal mixture.
11-10-2017, 07:17 AM
#104
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All answers are found in The Good Book.
The normal range for the ECT Sensor is about 100-2000 ohms. http://web.archive.org/web/201003261...98engineco.pdf (600 ohms would be close for a warmed-up engine).
Code 22 is thrown for an "open or short" of more than 0.5 seconds. http://web.archive.org/web/201211190...85diagnosi.pdf So we can tell from the definition of the code that a "short" would be much, much less than 100 ohms, and an "open" much more than 2000.
11-19-2018, 07:53 AM
#105
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Guys - rather than start a new thread, couple questions sorting out a one owner 91 5spd xtra w/ 265k on the clock I picked up. All fluids changed to synthetic. New denso plugs. stock af and looks clean. Stock intake configuration. Haven't driven frequently enough to track mpg's yet but they seem pretty low. I have a noticeable pinging that sounds like detonation but its constant w/ rpm I'm assuming is the rotor? Appears to be original rotor and wires. What i'm getting in second and third is the truck suddenly pulls noticeably hard as rpm approaches 3k - damn near like a small turbo kicking in. My guess culprit is dirty injectors, rotor & wires or O2 sensor (or some combination of).
Where would you start at quieting the excessive rotor pinging noise (is it on the way out if its that noticeably noisy?)
I haven't pulled the o2 sensor sensor but from the outside it appears to definitely have some age.
Where would you start at quieting the excessive rotor pinging noise (is it on the way out if its that noticeably noisy?)
I haven't pulled the o2 sensor sensor but from the outside it appears to definitely have some age.
11-19-2018, 02:15 PM
#106
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Not sure what you mean by "rotor pinging noise", and I can't really help you with that given the limited info. I'll make a few other comments, however.
Starting to "pull hard" at 3k rpm is normal for the 3vze. It doesn't have a lot of low end torque, and for sure makes its best power between 3000 and 4500 rpm. If I'm trying to accelerate at all briskly, I never upshift before the tach hits 4K. Believe it or not, the impact of driving it hard like that on mileage is negligible.
As far as mpg's go, I get about 18-19 around town, 20-21 at 55-60 mph, and around 17.5 if I push it to 75 mph. Calibrate your odometer against a GPS, and then calculate mpg using corrected miles divided by gallons. Always fill to the same point and do that for a few tanks and take the average. Don't try to speculate on fuel mileage issues until you have a significant amount of good data.
Changing out the O2 sensor is probably worth doing. It will likely help emissions, and maybe mpg's a little bit, but probably won't affect the pinging noise.
Starting to "pull hard" at 3k rpm is normal for the 3vze. It doesn't have a lot of low end torque, and for sure makes its best power between 3000 and 4500 rpm. If I'm trying to accelerate at all briskly, I never upshift before the tach hits 4K. Believe it or not, the impact of driving it hard like that on mileage is negligible.
As far as mpg's go, I get about 18-19 around town, 20-21 at 55-60 mph, and around 17.5 if I push it to 75 mph. Calibrate your odometer against a GPS, and then calculate mpg using corrected miles divided by gallons. Always fill to the same point and do that for a few tanks and take the average. Don't try to speculate on fuel mileage issues until you have a significant amount of good data.
Changing out the O2 sensor is probably worth doing. It will likely help emissions, and maybe mpg's a little bit, but probably won't affect the pinging noise.
11-19-2018, 04:54 PM
#107
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Thx RJR. Yes definitely run her a bit here now to figure out the mpg’s. 31’s def have the clock spinning a little slower than it should be. I’ll do the o2.
As for the pinging - sounds like constant knock that would vary with rpm - I can only imagine it’s coming from the rotor. Are they noisy when they’re on they’re way out?
edit- also read about a guy hearing pinging and ended up being a loose crossover pipe which I was also suspecting as a culprit. Soon headers will eliminate that possibility.
As for the pinging - sounds like constant knock that would vary with rpm - I can only imagine it’s coming from the rotor. Are they noisy when they’re on they’re way out?
edit- also read about a guy hearing pinging and ended up being a loose crossover pipe which I was also suspecting as a culprit. Soon headers will eliminate that possibility.
Last edited by mkivbren; 11-19-2018 at 05:06 PM.
11-20-2018, 04:08 AM
#108
The rotor is a no contact device. When it goes bad, the space between rotor and contact increases. I will not make any noises.
Ping: high pitched with a ringing component for a certain duration. (high bell)
Tick: high pitched, short duration (screwdriver against aluminum)
Knock: lower pitched, short duration. Sometimes with equal parts echo) (Hammer against plasic)
Now, we need a video or a soundfile. Best in a new thread I think.
On the subject of fuel efficiency: I have noticed on my 22re, that cruise control uses WAY more gas pedal that I would. It also ignores slight hills, just gives 3/4ths throttle. I would say it is very inefficient concerning fuel savings.
Ping: high pitched with a ringing component for a certain duration. (high bell)
Tick: high pitched, short duration (screwdriver against aluminum)
Knock: lower pitched, short duration. Sometimes with equal parts echo) (Hammer against plasic)
Now, we need a video or a soundfile. Best in a new thread I think.
On the subject of fuel efficiency: I have noticed on my 22re, that cruise control uses WAY more gas pedal that I would. It also ignores slight hills, just gives 3/4ths throttle. I would say it is very inefficient concerning fuel savings.
Last edited by ev13wt; 11-20-2018 at 04:10 AM.
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