Tachometer problems with 2002 Nissan sentra ser spec v. HELP!

[N4LSpecV]

I just bought a 2002 Nissan Sentra Se-r Spec V and am having problems with the tach.I had it checked out by somebody at the Nissan dealer and they had never seen anything like it before.Sometimes the RPM's will go smoothly up to 3200 or so and then if i let off the throttle itll drop suddenly instead of going down smoothly, this will also happen if i accelerate quickly. Also itll tweak out and twitch kinda like a second hand on a clock.Has anyone had similar problems like this or have any idea how i can fix this or what to do???Any help would be great. Thanks!

[RED_DET]

Does the engine still run properly even though the tach is messing up? If so, I think its time for nissan to give you a new ECU. ECU is covered under Federal emissions warranty, 8y/80k miles.

[N4LSpecV]

Yeah engine runs perfect. As of now im shifting by sound of engine cuz i don't trust the tach 100%. It still works on occasions it will just twitch instead of run smooth. Engine is running fine though. Is the ECU/new engine warranty covered no matter what?? we bought it used so i'm not sure if the warranty would still be good?

Also does your 02 Spec V take a while to start up?? I'm thinking i need to fix my throttle body to get a more clean start up. Sometimes it'll start right up and others it'll chug for a few seconds then start...??

[nametakennow]

Check the battery terminals about that start. These things corrode the terminals like crazy.

Should still be covered, there were enough ECU problems that you might run into one of the recalls as well. Have them check the VIN and/or try the warranty route before you shell out for a new ECU.

[N4LSpecV]

So nametakennow you think if i was to bring it in to Nissan and have them check the VIN to see if there were any recalls on my car then try and do the engine warranty route would be my best bet on getting everything back up to normal?

The people who had the car before us put an aftermarket lower o2 sensor on and universal wiring harness...you think that would have anything at all to do with the rough start up or the tach problem for that matter? I'm new to the whole car thing and just recently getting into so I don't know much. Thanks.

[nametakennow]

What sort of aftermarket O2 sensor and harness? Seems odd. Did it have a header (you're going to want one anyway)?

Anyway, have a dealer run the VIN for recalls just to be sure, then see about getting the ECU replaced either under recall or under the 8/80 part of the warranty.

[N4LSpecV]

About the o2 sensor and harnes..I honestly have no clue. I do know that they used universal wires though because they are spliced together.

I'll try ang get the VIN into nissan asap. thanks for the pointers

[N4LSpecV]

And yeah we bought it with Fujita cold air intake nismo exhaust and headers. along with a sway bar.

[RED_DET]

You can buy universal o2 sensors where you actually have to rewire your plug onto the new o2 snesor. As far as the ECU goes, I finally got Nissan to do the right thing on my wifes car. The temp gauge stopped worked and didnt' work for a year. The gauge is run by the ECU. Then the vehicle started having hard starts, like you are experiencing. It finally got to the point, where one day it wouldn't start up at all. But would start with a different key. I called and talked to one of the techs and he said it sounded like the NATS(nissan antitheft system) was giving me some problems. He then mentioned ecu's were covered under 8yr/80k mile warranty, which no one ever told me about before. Took the vehicle over, told the service manager the problem and that I know all about the warranty and that the temp gauge was controlled by the ecu. He acted as if he had no clue about the warranty. About 45 mins later, I was told a new ecu was on order. This fixed the temp gauge and the starting issue.

[Sechsterlo]

And yeah we bought it with Fujita cold air intake nismo exhaust and headers. along with a sway bar.

Nismo header you say? W/ or W/out precat?

[N4LSpecV]

I'm not sure if it's NISMO header or not...how can I tell?

[Sechsterlo]

I'm not sure if it's NISMO header or not...how can I tell?

If its a Nismo header, there should be a Nismo logo stamped on it.

[N4LSpecV]

ohh. No they are not Nismo headers.Mine are more of a polished stainless steel look.

[blindsnyper]

ohh. No they are not Nismo headers.

IT is not a HEADER