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Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 19670
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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05 altima 2.5 problem accelerating and winding out in

Customer Question

05 altima 2.5 problem accelerating and winding out in passing gear. Replaced maf, camshaft ps crankshaft ps knock sensor. Not a bad cat, cats. Timing advances erratically while driving, but not in park.
Submitted: 11 months ago.
Category: Nissan
Expert:  Jay replied 11 months ago.

Hello my name is ***** ***** thank you for your question.

Did you have codes for these parts you installed? Where did you get these parts? Also if you have codes, what are they?

Let me know..

Customer: replied 11 months ago.
No codes. I got the parts from and read something about the coolant sensor and disconnected it just to check and it ran a little bit better for a short time. Thanks
Expert:  Jay replied 11 months ago.

If you have no codes, the first thing I normally like to check is the air fuel trim readings. Do you have a scanner to check that?

Customer: replied 11 months ago.
I do. I have the torque app and a cheap obdii reader. I will report to you what it reads at idle and any other condition that will help.
Expert:  Jay replied 11 months ago.

Ok.. I am looking for Short Term Fuel Trim ( STFT ) readings

Customer: replied 11 months ago.
The readings seem erratic. At idle the range is from -1.6 to 8.2 percent.
Expert:  Jay replied 11 months ago.

Does it tend to bog and loose power? The fuel trim readings will jump around. That is normal. But they are boarder line lean.

Customer: replied 11 months ago.
It bogs when in drive, mostly on the freeway and a lack of power altogether. Unsafe on the freeway and the passing gear revs, but the care doesn't go any faster and seems to make the car bog more after it goes back into a high gear. Doesn't seem to have a problem in park without a load.
Expert:  Jay replied 11 months ago.

Do you have a K&N Air filter on the car? Also have you checked the Catt Converter?

Customer: replied 11 months ago.
Just a regular air filter. The exhaust manifold/first cat converter was just removed because of a hairline crack where the header pipes gather together. I noticed a strange sound when the car downshifted into passing gear and got it fixed immediately by an automotive welder. I examined the cat while it was off the engine and it looked intact. I have a mobile mechanic that I use that actually diagnosed another car that I had with a bad cat and he was there too to examine it. I had someone quickly push the accelerator while I was at end of the exhaust pipe and I didn't notice any delay from an obstruction. The manifold vacuum recovers quickly when from idle to 2500 rpm and back. I'm not trying to sound like a know it all. I have just been doing what I can to fix the car by researching what I can, but obviously I'm not that good at it. Is there a more positive method of identifying a bad catalytic converter?
Customer: replied 11 months ago.
Anything else I can try? I'm kinda desperate here.
Expert:  Jay replied 11 months ago.

Well, these catt converters tend to come apart on top. So normally you remove the upper 02 sensor and inspect the catt.

The only other thing is to try to drive with a fuel pressure gauge and see if fuel pressure is being affected when you try to accelerate. Did you try that yet?

Customer: replied 11 months ago.
No, I haven't. I think this engine needs a special hose and fitting to connect to the fuel line. I was just looking into that before I tried I have a small shop down the street and I will see if they can test the fuel pressure.thanks
Expert:  Jay replied 11 months ago.

OK.. Yes.. I have my own fuel pressure kit I use to check these cars. But it's a 500 dollar kit that does every car. So I would see if you can have the fuel pressure checked to see if that is your issue.

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