Spark Plugs and Wires
07-30-2018, 07:22 AM
#1
Spark Plugs and Wires
Trying to address very poor fuel economy (8.5mpg) on a 3zve with A/T. I have replaced the fuel filter, cpc valve, O2 sensor, air filter, cleaned the throttle body, checked for vacuum leaks, and probably a few other items over the last couple of years. Nothing has helped.
Before I purchased the pickup, the engine was completely rebuilt, but I recall the previous owner saying he did replaced the spark plugs and wires but I've also read on here that if they are not the right kind (even though the auto parts store may say they are) you can have poor performance. Can someone tell me what the best spark plug and wire set is?
Also, it was suggested to me to change the engine coolant sensor and thermostat as this may be a cause. Can anyone confirm this could be an issue?
I'm not an experienced auto repairman, but I am smart enough and equipped enough to tackle most part replacements.
Thanks,
Before I purchased the pickup, the engine was completely rebuilt, but I recall the previous owner saying he did replaced the spark plugs and wires but I've also read on here that if they are not the right kind (even though the auto parts store may say they are) you can have poor performance. Can someone tell me what the best spark plug and wire set is?
Also, it was suggested to me to change the engine coolant sensor and thermostat as this may be a cause. Can anyone confirm this could be an issue?
I'm not an experienced auto repairman, but I am smart enough and equipped enough to tackle most part replacements.
Thanks,
07-30-2018, 11:20 AM
#2
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Has it been that way since you bought it? Any check engine codes? How's the power (recognizing that a 3vze with A/T is no race car engine even when running properly.)
WIth mileage that poor, I'd look for evidence of
- extremely rich mixture - should throw a code and leave the plugs black and/or wet with fuel.
- retarded ignition timing (possible knock sensor problem - should throw a code)
- misfiring (pull the plugs and look for carbon and fuel buildup)
- wrong valve timing (timing belt aligned wrong when rebuilt?)
- poor compression (also possible rebuild problem - check compression when you pull the plugs)
Pull the plugs, take pictures, and post them here. Also post the compression numbers. Might tell us something.
WIth mileage that poor, I'd look for evidence of
- extremely rich mixture - should throw a code and leave the plugs black and/or wet with fuel.
- retarded ignition timing (possible knock sensor problem - should throw a code)
- misfiring (pull the plugs and look for carbon and fuel buildup)
- wrong valve timing (timing belt aligned wrong when rebuilt?)
- poor compression (also possible rebuild problem - check compression when you pull the plugs)
Pull the plugs, take pictures, and post them here. Also post the compression numbers. Might tell us something.
08-11-2018, 03:56 AM
#3
Trying to address very poor fuel economy (8.5mpg) on a 3zve with A/T. I have replaced the fuel filter, cpc valve, O2 sensor, air filter, cleaned the throttle body, checked for vacuum leaks, and probably a few other items over the last couple of years. Nothing has helped.
Before I purchased the pickup, the engine was completely rebuilt, but I recall the previous owner saying he did replaced the spark plugs and wires but I've also read on here that if they are not the right kind (even though the auto parts store may say they are) you can have poor performance. Can someone tell me what the best spark plug and wire set is?
Also, it was suggested to me to change the engine coolant sensor and thermostat as this may be a cause. Can anyone confirm this could be an issue?
I'm not an experienced auto repairman, but I am smart enough and equipped enough to tackle most part replacements.
Thanks,
Before I purchased the pickup, the engine was completely rebuilt, but I recall the previous owner saying he did replaced the spark plugs and wires but I've also read on here that if they are not the right kind (even though the auto parts store may say they are) you can have poor performance. Can someone tell me what the best spark plug and wire set is?
Also, it was suggested to me to change the engine coolant sensor and thermostat as this may be a cause. Can anyone confirm this could be an issue?
I'm not an experienced auto repairman, but I am smart enough and equipped enough to tackle most part replacements.
Thanks,
08-13-2018, 09:15 PM
#4
I have got my wires and sparkplugs from sparkplugs.com and am happy with them.
I heard that Sumitomo makes the OEM wire. Mine are wither NGK or Denso and work well.
08-13-2018, 11:47 PM
#5
You have been putting up with this for years ?
Just what year??
Other then poor fuel mileage you don`t mention a poor running engine
You never changed the plugs and wires on a poor running engine??
Over the years I have heard all sorts of normal maintenance called rebuilding the engine from the clueless
How did you come up with the 8.5 figure ?
What kind of driving is this used for ?
What gear ratio? Tire pressure ?
What sort of extra weight are you hauling around ??
Just what year??
Other then poor fuel mileage you don`t mention a poor running engine
You never changed the plugs and wires on a poor running engine??
Over the years I have heard all sorts of normal maintenance called rebuilding the engine from the clueless
How did you come up with the 8.5 figure ?
What kind of driving is this used for ?
What gear ratio? Tire pressure ?
What sort of extra weight are you hauling around ??
08-14-2018, 06:19 AM
#6
You have been putting up with this for years ?
Just what year?? Since I bought it in 2012. I only drive it about 1000 miles per year, so I can live with it but it is still aggravating. The truck is kept remotely so I am only able to do maintenance a couple times per year.
Other then poor fuel mileage you don`t mention a poor running engine Engine doesn't misfire or run rough, just doesn't have much power (even for a 3vze).
You never changed the plugs and wires on a poor running engine?? Nope, they were shiny, clean, and obviously new when I purchased the truck. Just hadn't gotten around to it.
Over the years I have heard all sorts of normal maintenance called rebuilding the engine from the clueless Not clueless, but not an expert either. Was told the engine was rebuilt in a machine shop with new/bored cylinders, pistons, valve seating, all lower bearings, etc. Engine does not smoke, rattle, tick, etc.
How did you come up with the 8.5 figure ? Based on the odometer and fuel consumption, I get only 7.4-7.5 mpg. I then compared the odometer reading based on driving 20 miles on the interstate counting the mile markers. Doing the math, there is a 14.2% difference between distance driven and the odometer reading. Distance driven/Odometer = 1.14. This was also confirmed by driving at a constant speed and comparing it to my GPS speed. This gives me pretty much the exact same ratio.
What kind of driving is this used for ? Based on distance, roughly 80% paved country roads at around 50 mph, and 20% dirt roads at less than 15 mph.
What gear ratio? Tire pressure ? Fairly certain it has the 4.30 gears and I usually run about 35 psi pressure in the 9"x32" tires.
What sort of extra weight are you hauling around ?? None
Just what year?? Since I bought it in 2012. I only drive it about 1000 miles per year, so I can live with it but it is still aggravating. The truck is kept remotely so I am only able to do maintenance a couple times per year.
Other then poor fuel mileage you don`t mention a poor running engine Engine doesn't misfire or run rough, just doesn't have much power (even for a 3vze).
You never changed the plugs and wires on a poor running engine?? Nope, they were shiny, clean, and obviously new when I purchased the truck. Just hadn't gotten around to it.
Over the years I have heard all sorts of normal maintenance called rebuilding the engine from the clueless Not clueless, but not an expert either. Was told the engine was rebuilt in a machine shop with new/bored cylinders, pistons, valve seating, all lower bearings, etc. Engine does not smoke, rattle, tick, etc.
How did you come up with the 8.5 figure ? Based on the odometer and fuel consumption, I get only 7.4-7.5 mpg. I then compared the odometer reading based on driving 20 miles on the interstate counting the mile markers. Doing the math, there is a 14.2% difference between distance driven and the odometer reading. Distance driven/Odometer = 1.14. This was also confirmed by driving at a constant speed and comparing it to my GPS speed. This gives me pretty much the exact same ratio.
What kind of driving is this used for ? Based on distance, roughly 80% paved country roads at around 50 mph, and 20% dirt roads at less than 15 mph.
What gear ratio? Tire pressure ? Fairly certain it has the 4.30 gears and I usually run about 35 psi pressure in the 9"x32" tires.
What sort of extra weight are you hauling around ?? None
08-15-2018, 12:26 AM
#7
Not that your clueless people selling vehicles .
Was told engine rebuilt was shown an Invoice for timing belt job things like this
Trust but Verify !!
Since the truck is far from home .
Any thoughts on a slight fuel leak you would not see or smell anything?
*** Just a thought how long between uses?? Do you use Gas without Ethanol in your area ?
The gas could just be the cause of poor mileage and poor performance unless it gets drained after each use and fresh gas installed every time
Since it is not run that often any warm up idling the mileage your getting is about what my 4runner gets using it for my 5 mile commute to work .
I venture mine idles more then it drives
Since it seems to run good rings never seated or Cam timing is off .
Do you have another 3.0 as your daily driver your comparing it with as for performance ?
Was told engine rebuilt was shown an Invoice for timing belt job things like this
Trust but Verify !!
Since the truck is far from home .
Any thoughts on a slight fuel leak you would not see or smell anything?
*** Just a thought how long between uses?? Do you use Gas without Ethanol in your area ?
The gas could just be the cause of poor mileage and poor performance unless it gets drained after each use and fresh gas installed every time
Since it is not run that often any warm up idling the mileage your getting is about what my 4runner gets using it for my 5 mile commute to work .
I venture mine idles more then it drives
Since it seems to run good rings never seated or Cam timing is off .
Do you have another 3.0 as your daily driver your comparing it with as for performance ?
Last edited by wyoming9; 08-15-2018 at 12:35 AM.
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08-15-2018, 03:52 AM
#8
Not that your clueless people selling vehicles .
Was told engine rebuilt was shown an Invoice for timing belt job things like this
Trust but Verify !!
Since the truck is far from home .
Any thoughts on a slight fuel leak you would not see or smell anything?
*** Just a thought how long between uses?? Do you use Gas without Ethanol in your area ?
The gas could just be the cause of poor mileage and poor performance unless it gets drained after each use and fresh gas installed every time
Since it is not run that often any warm up idling the mileage your getting is about what my 4runner gets using it for my 5 mile commute to work . Typically when I use it, I use it for quite a while (25miles or so).
I venture mine idles more then it drives
Since it seems to run good rings never seated or Cam timing is off . I'm going to check the cylinder pressures next visit. Wouldn't the Cam timing being off cause a bigger issue than I'm having?
Do you have another 3.0 as your daily driver your comparing it with as for performance ? Yes, but it is a manual 5 speed that gets about 15 mpg
Was told engine rebuilt was shown an Invoice for timing belt job things like this
Trust but Verify !!
Since the truck is far from home .
Any thoughts on a slight fuel leak you would not see or smell anything?
*** Just a thought how long between uses?? Do you use Gas without Ethanol in your area ?
The gas could just be the cause of poor mileage and poor performance unless it gets drained after each use and fresh gas installed every time
Since it is not run that often any warm up idling the mileage your getting is about what my 4runner gets using it for my 5 mile commute to work . Typically when I use it, I use it for quite a while (25miles or so).
I venture mine idles more then it drives
Since it seems to run good rings never seated or Cam timing is off . I'm going to check the cylinder pressures next visit. Wouldn't the Cam timing being off cause a bigger issue than I'm having?
Do you have another 3.0 as your daily driver your comparing it with as for performance ? Yes, but it is a manual 5 speed that gets about 15 mpg
08-16-2018, 08:58 AM
#9
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Maybe the check engine light is not working or someone prior to you buying it removed the bulb? I would verify this first if it was me. These engines are notorious for knock sensor wiring issues.....even after a complete rebuild. If the ECM doesn't "see" the knock sensor, the ECM retards the timing and makes the fuel run richer. That would definitely cause the low fuel mileage and performance issues you are describing.
08-16-2018, 09:14 AM
#10
Maybe the check engine light is not working or someone prior to you buying it removed the bulb? I would verify this first if it was me. These engines are notorious for knock sensor wiring issues.....even after a complete rebuild. If the ECM doesn't "see" the knock sensor, the ECM retards the timing and makes the fuel run richer. That would definitely cause the low fuel mileage and performance issues you are describing.
08-16-2018, 11:13 AM
#11
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09-10-2018, 05:56 PM
#12
Okay, so I checked out a compression tester from O'reilly's last weekend and all six were right around 160 lbs. so that was not a problem. Also, I borrowed a set of wheels and tires from a friends (without asking) truck that are the same as the stock wheels that came on mine (225/75R15) as marked in the door frame. This is something I should have done a long time ago. I knew the 32's I have on there were a little big, but had no idea how much it would penalize the mileage. Drove about 100 miles with this wheel/tire setup and got right at 16 mpg. Also, the odometer matched almost exactly with my gps mileage, so dividing the odometer mileage by the fuel used gives me a pretty accurate mpg. I guess being an automatic the tire size just keeps the transmission in lower gears so often that overdrive is a rarity. 8.5 mpg is the crap. So, contrary to my post above I am not certain what gear set I have in this truck. Assuming the previous owner did not swap them out, is there a place on the vehicle to check for this information (VIN, door tag, stamp on differentials)? to see what was stock. Also, with 32" tires, and an automatic transmission what would be the best gear set if I wanted to change? Thanks.
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