mszilves

I find when the car is cold, it pulls like a champ, but when it warms up, it hesitates and really has a lack of power up to about 3000RPM. It always idles fine. To add to it, the problem is intermittent... I'd say about 80% of the time.

I have new plugs, new fuel filter, air filter, oil filter/synthetic, recently replaced left VTC, left exhaust studs. Two month old battery, alternator, starter.

The problem has been around for a while now, it's really annoying, as I typically don't rev my engine too high, so the lack of low end torque and power is really starting to bug me. Anyone have any ideas? Could it be the ignition coils?

Greeny

iTrader: (43)

Replace your knock sensor....

Pearl93VE

iTrader: (14)

Could a Knock sensor be the culprit of bad gas milage? I also notice on hot days the car just doesn't have that low end torque off the line like it does say... early in the morning or at night. I recently got my transmission replaced about 3000 miles ago and sometimes feel a surge, or sudden vibration coming from the front of the car when going up hills, or even sometimes when at a consistent speed. Could this be a faulty knock sensor?

Thanks in advance
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Greeny

iTrader: (43)

That sounds like maybe you needs a tune up..

91-Maxima-SE

Any advice on replacing the knock sensor on a VG? I know where it is and everything, but is there any easy way to get it out?

Pearl93VE

iTrader: (14)

94 VG

Just did a tune up less than a thousand Miles ago. Everything and then some. Oil Change, Cleaned EGR, Throttle Body, Custom CAI, New o2, All usual tune up parts including filters, plugs, and wires etc. Checked for exhaust leak found none. Seafoamed, Marvel Mystery Gas Additive. All same size tires, recent alignment job, new transmission. Running out of things that could be it here. Just can't find why I'm getting so poor of gas milage. Pulling my hair out trying to figure out it...
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VEvolution

Hey could a knock sensor still be bad if theres continuity in the plug? I know the ECU might not throw out codes..

How much MPG are you getting and whats your driving style?

Jeff92se

iTrader: (82)

O2 sensor?

Cliff Clavin

iTrader: (11)

first thing you should do is check for codes. This isn't a guarantee because sometimes a sensor could be bad and it still doesn't show up. It is a simple way to start. Dig through the stickies and you should be able to figure this out.

lack of power, especially when the car is warm is often the knock sensor. When my KS was going out, after about 45 minutes of driving, there was a noticeable decrease in power.

Jeff mentioned the o2 sensor, which usually hurts power and fuel economy.

hesitation on the VE engine is usually caused by coil packs. Either one or several might be cracked or internally malfunctioning.

mszilves

Thanks for all the good info guys... it does look like it's the knock sensor. I have disconnected it to test (I'm running 92 octane so I should be safe from knocking), and it does feel like a noticeable difference in power, especially in the low end. I'm gonna leave it disconnected for a couple of days just to make sure. If I do need to replace it, is it pretty easy, or do you need to take the intake manifold off (I really hope not)?

Jeff92se

iTrader: (82)

Upper and lower manifolds have to come off. You'll choke when you price out the lower manifold gaskets.

VEvolution

I heard it can still knock if you use the right gas

Pearl93VE

iTrader: (14)

...

Got a new o2 VERY short while ago, I'll probably take it to autozone or something and try to get it to throw some codes. Hmm.... Think I'm going to gut my catalytic converter as well...

Also, I don't drive very hard at all, pretty casual usually but I'll occasionally get on it if I'm merging or something. Gas Milage is around 270 to a tank city/highway mix.
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91-Maxima-SE

Ok, so I guess not then...

Greeny

iTrader: (43)

There is no easy way to get to it...It's a very small area to work in...


Unless you are sure it is bad,then don't mess with it...

92 Max

Here's a link to a good knock sensor replacement writeup. It shows what you're up against to replace this knock sensor. After reading this the lack of power might not be as bad as you first thought. http://www.4dsc.com/articles/drivetr...k_sensor.shtml

91-Maxima-SE

Ok, I do know its bad, but I was thinking of just getting another wiring harness and KS and zip-tying it to a stationary hose or something.
Thank you!

maximagician

what should a ve k.s read?mines 0.555 m ohms on a digital multimeter

mszilves

The knock sensor looks expensive to replace due to the labor involved. Anyone know a ballpark price to get this done at a shop?

Alex_V

Uh yea....dont! It will loose power and its really bad for the environment. Its wont gain you any power and its illegal. Just leave it as is unless its colgged. Only then should you gut it, but get a new one. I did on mine since it was clogged (smelled like rotten eggs) and Im definitly down on some low end power.

~Alex

Pearl93VE

iTrader: (14)

Well I'm just trying to figure out why I'm getting bad gas milage. Hmm, You lost some low end torque on it? Hmm... doesn't it just let the exhaust flow more freely?
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Greeny

iTrader: (43)

Gutting/removing the cat will NOT increase power at all,infact it will decrease power..Modern engines are designed to need some exhaust back pressure to perform at their best.....


You probably need a new o2 sensor and/or have a bad injector or 2...These problems are the leading cause of poor gas mileage for these cars....

Jeff92se

iTrader: (82)

Gutting cat = ricer exhaust sound + now you get to buy a new one to replace the one you just ruined.

ebaker

Is there a way to bypass the knock sensor? I remember something about using a 500K resistor.

internetautomar

iTrader: (30)

470k ,

ColombianMax

iTrader: (7)

hmm, I think I want to replace my KS..are there any write ups for that since I only saw the one for the VE?

VEvolution

Im pretty sure the idea is just about the same..

internetautomar

iTrader: (30)

the VG has it behind the rear exhaust manifold.

89blackse

iTrader: (2)

what?! are you serious. I was thinking of replacing that on my 89...

Greeny

iTrader: (43)

ColombianMax

iTrader: (7)

hmm, that doesnt seem to bad now does it?

Greeny

iTrader: (43)

Says the man with leaking tranny seals...