JT20's running Infiniti J30 condition assessment and maintenance thread

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Glad to see this thread is going well...

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If you have an engine makes less power. How can RPM remain the same?
Say you have a bicycle and two different riders. One rider is stronger than the other. By your logic, the weaker rider is going to have to pedal faster to go at the same speed. Not the case. Each one of them will be pedaling at the exact same rate (RPM) in order to maintain say 10 mph because the gearing hasn't changed from the time the first rider got off the bike to the time the second rider got on the bike. The only difference is the weaker rider will get tired sooner.
 

JT20

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Say you have a bicycle and two different riders. One rider is stronger than the other. By your logic, the weaker rider is going to have to pedal faster to go at the same speed. Not the case. Each one of them will be pedaling at the exact same rate (RPM) in order to maintain say 10 mph because the gearing hasn't changed from the time the first rider got off the bike to the time the second rider got on the bike. The only difference is the weaker rider will get tired sooner.

Oh nice. Okay.

Now we are getting somewhere.

Let me re-read this a few times, I just might get it.
 

JT20

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Say you have a bicycle and two different riders. One rider is stronger than the other. By your logic, the weaker rider is going to have to pedal faster to go at the same speed. Not the case. Each one of them will be pedaling at the exact same rate (RPM) in order to maintain say 10 mph because the gearing hasn't changed from the time the first rider got off the bike to the time the second rider got on the bike. The only difference is the weaker rider will get tired sooner.

Alright. Repeating so I can get it... the weaker rider is NOT doing more work. Just getting tired faster.

The weaker rider is the smaller engine.

Okay.

Would it be a jump, then, to think fuel economy MAY increase, if the work is the same over smaller use of energy (does that make sense? A little jump.. stop me if I got it wrong.)
 
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Would it be a jump, then, to think fuel economy MAY increase, if the work is the same over smaller use of energy (does that make sense? A little jump.. stop me if I got it wrong.)
Fuel economy might not change much at constant cruising speed. The difference is, because you didn't remap the ECU, the ECU is pushing the same amount of fuel to the new (smaller) engine as it was to the old (bigger) engine. But the new (smaller) engine can't take in as much air as the old (bigger) engine could, so you end up with the wrong fuel-air mixture (running rich), which is not optimal.
 

JT20

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Fuel economy might not change much at constant cruising speed. The difference is, because you didn't remap the ECU, the ECU is pushing the same amount of fuel to the new (smaller) engine as it was to the old (bigger) engine. But the new (smaller) engine can't take in as much air as the old (bigger) engine could, so you end up with the wrong fuel-air mixture (running rich), which is not optimal.

So are you basically saying the fuel im saving is being wasted in combustion?

What about a possible ECU ST/LT Fuel Trim "Fuel cut"?
 

JHZR2

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Let’s start a Subaru thread if you want to talk Subaru. We can revisit the Infiniti when the time is right,
 

JT20

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Well, the J30 in the signature does have a stuck idler pulley. I can't turn it.

If I spray it with penetrating lube, and then try to turn it, could that un-stick it?
 

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Well, the J30 in the signature does have a stuck idler pulley. I can't turn it.

If I spray it with penetrating lube, and then try to turn it, could that un-stick it?
No. That means the bearing is pooched and you need to replace it. Is this the idler for the A/C? I assume it is, and would be the reason your belt broke.

Also, shouldn't this have been posted in the running thread for the car? This is also why we advised against you dumping money into stuff you don't need, because inevitably, there was going to be stuff you did need.
 

JT20

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No. That means the bearing is pooched and you need to replace it. Is this the idler for the A/C? I assume it is, and would be the reason your belt broke.

Also, shouldn't this have been posted in the running thread for the car? This is also why we advised against you dumping money into stuff you don't need, because inevitably, there was going to be stuff you did need.

Yes, it was the pulley under the AC compressor one and it would explain the snapped belt. So it can't be un-seized with spray...

How much I wonder is shop labor time on it? Money situation.. is improving.

Other thread got locked, reason given was Subaru discussion.
 
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Yes, it was the pulley under the AC compressor one and it would explain the snapped belt. So it can't be un-seized with spray...

How much I wonder is shop labor time on it? Money situation.. is improving.

Other thread got locked, reason given was Subaru discussion.

If it has stopped turning, it is because the bearing is damaged beyond repair. It can't be "un-seized with spray" Not even if you buy a case of spray.

Shop labor time will depend on the shop.
 
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R&R pulley consists of remove spindle nut, take pulley off, put new pulley on, replace nut and tighten belt. If you do this yourself you have to be careful to keep the three or 4 special washers and spacers in the right orientation and order when putting back together.

Officially the bearing is only sold complete with pulley, which might cost about $40 if still available, but it is almost certainly a generic 6200 series ball bearing that only costs a few dollars. Putting a new bearing in an old pulley would involve a few minutes with a press.
 

OVERKILL

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R&R pulley consists of remove spindle nut, take pulley off, put new pulley on, replace nut and tighten belt. If you do this yourself you have to be careful to keep the three or 4 special washers and spacers in the right orientation and order when putting back together.

Officially the bearing is only sold complete with pulley, which might cost about $40 if still available, but it is almost certainly a generic 6200 series ball bearing that only costs a few dollars. Putting a new bearing in an old pulley would involve a few minutes with a press.

Indeed, and the shop he dealt with for the Subaru may have a press and could save him a few bucks going that route.
 
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