intake whistle and low gas mileage?

You gotta Love these old VG30E/i powered beasts, raw truck DNA to the core.

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PattiM
Posts: 29
Joined: Thu Dec 06, 2018 2:03 pm

intake whistle and low gas mileage?

Postby PattiM » Thu Dec 06, 2018 2:08 pm

Hello! I'm a new Pathfinder owner and I'm glad I found this forum - I bought a 1992 pathfinder 4x4 for winter usage, and was wondering about the gas mileage. It's about 19 MPG - which seems a little low for a semi-modern 3 liter engine (trans in 2-hi). I got a tune-up from a local garage, and the mileage didn't change. There is an intake-manifold whistle which is related to the throttle position: It changes as the throttle opens, and goes away at over half-open. I replaced cracked tubing which I found - but the mileage didn't change. Is this normal (I saw on another forum that Nissan's have this issue maybe?)

Is 19 MPG about right for this car?

Also, what is a reasonable usable-RPM range for this engine? To cruise at 70 MPH takes the RPMs to about 3200 or so, which seems a tad high (although well below tachometer-indicated redline).

Thank You Very Much!
Patti

EDIT: About 175k miles and recently had timing belt and tensioner(s) replaced. Significant lifter noise which goes away after they fill with oil.


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smj999smj
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Postby smj999smj » Fri Dec 07, 2018 1:25 am

If you're getting 19 MPG, then you are doing great! EPA rating for that vehicle is 14 city/17 highway. Combined mileage is typically 15-16 MPG. Keep in mind that it's a fairly heavy vehicle pushed by an engine that is only rated around 160 HP and as far as being "modern-ish," the vehicle is over 25 years old (the VG engine was introduced into the US 35 years ago). It's a very reliable and durable engine (so long that people maintain it properly and change the timing belt at the recommended intervals), but power nor fuel mileage were never it's strong points. Even my 2006 Pathfinder, which has a 5-speed automatic trans compared to the 4-speed automatic used on the 92 Pathfinder, averages only around 17 MPG, which is typical for that vehicle. The 2018 Pathfinder with all wheel drive and which is more of a crossover compared to our full-framed Pathys only gets a combined mileage of around 22 MPG. As far as the whistling noise, it's hard to say without being able to hear it for myself and see the vehicle in person.

PattiM
Posts: 29
Joined: Thu Dec 06, 2018 2:03 pm

Postby PattiM » Fri Dec 07, 2018 10:21 am

Thank you very much! I'm just paranoid, maybe. As far as "modern," I was thinking mainly that the pathfinder engine is computer controlled? (I don't really know.) I think the mechanicals of the 4x4 design may be old-fashioned - I have trouble turning while backing up in 4-high (when the front wheels are turned) - it's almost like some differentials down there aren't doing their job very well. The car acts like it has brakes on - the more drag on the sharper turn (although that's only when I back up). It's a 5 speed with a transfer case. Is this engine throttle-body fuel injected?

It's good to hear that the mileage is OK - I was worried about the engine a tad. I bought this car knowing that the engines last a long time. Is it a good idea to visit the Nissan dealership mechanics for a car this age? I'm thinking about the whistle and the maze of aging rubber tubes in there - also odd suspension "clicks." (not clunks or knocks or heavy mechanical sounds)

Now that I think about it, it does one other odd thing. After the tune-up at a local mechanic, a couple of times it has acted like an engine cylinder was "missing" (rough running, loosing power) - then maybe two cylinders - then *poof* back to normal. Only a couple of times for a couple of minutes - and less often than once per month - but it didin't do that b4 the "tune up." It happened while the engine was warm once and once while the engine was cold. (I know that's almost no helpful information on the problem!)

Thanks for the reply on the gas mileage. Is there any information on what to watch out for on the chassis/suspension? I had all the ball joints and tie-rod ends replaced at 175k miles. The front CV joint rubber boots seem intact, and I don't hear any grinding from wheel bearings (I don't think any of that has been replaced).


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