engine feels like it's cutting on and off in 4th and 5th gear

[GasSavers_TomO]

Have you checked the base timing yet?

With the car off, insert a paperclip jumper in the service connector (the same one for checking codes) and start the car with the engine warmed up already. Check the timing via the timing mark (located on the lower timing cover) and a timing light, adjust as necessary.

[redEGG]

Not to be ignorant, but i'm not familiar with inserting a paperclip jumper in the service connector.
The mechanic that looked at my car, checked the diagnostics, and he said it had a code 48 (bad o2 sensor).
So I changed the o2, and it still has the same issues.
I dont have a computer diagnostic tool. I dont know how to check the timing, or where the timing mark/timing light is.... I dont know how to adjust it. Sorry for not having much knowledge about this. But the engine runs very smooth in idle, 1st, 2nd, and 3rd. It's just in 4-5th gears it jumps and feels like it's cutting in and out.

[GasSavers_Erik]

You can get the codes read again for free at many auto parts stores (Advance, auto zone etc).

It would be interesting to see if it is still setting the o2 sensor code even after replacement.

[bobc455]

Remember that the computer is very dumb. All it knows it that it doesn't like the signal from the O2 sensor, and there are MANY possible causes for that. Perhaps the O2 sensor is bad, but maybe you have leaking or blocked fuel injectors, or a leaky exhaust manifold gasket, a clogged fuel filter, or blah blah blah. If your mechanic diagnosed a bad O2 sensor purely on the basis of a code 48, without any other diagnosis, I would go demand my money back.

With 160k on the car, it wouldn't surprise me if your injectors are not flowing as they should. Injector service (or replacement) will frequently take a poorly-running engine and make seem brand new again (even on cars which do not "seem" to exhibit problems). Unfortunately it is usually difficult to diagnose the injectors without doing 99% of the work of replacing or cleaning the existing ones- the only real way to diagnose them is to remove the injectors from the vehicle and put them on a special flow bench which can pulse them at 5%, 50%, and 90% to see if they are flowing somewhat linearly. (At this point, it is simple to just clean the injectors and re-flow them.)

And I don't mean pouring a bottle of injector-cleaner in your gas tank...

I'm not saying that the injectors are definitely your problem, but I am saying that it is a possibility. You could also have EGR issues, PCV issues, a vacuum leak, a fuel-pressure problem, a bad fuel pump, low-quality gasoline (unlikely), a leak in your intake tract so that your MAF is not seeing 100% of the air, a bad TPS, a wiring issue, etc.

-Bob C.

[theholycow]

Originally Posted by Erik

You can get the codes read again for free at many auto parts stores (Advance, auto zone etc).

When you do, make sure they give you the code numbers. They like to just tell you what it might be so you'll buy that part, or tell you what the description of the code is, but many codes have shared descriptions. The code number is the important part.

[jadziasman]

I was getting a intermittent code 48 for about two years. I replaced the LAF sensor with a slightly used OEM Honda LAF last November. Have not seen another code 48 since. It seems the sluggish response time of old LAF sensors periodically triggers the code. I didn't notice a difference in drivability before or after the switch. BTW - the catalytic converter was as white as a televangelist's smile.

The LAF sensor for all its hype is still an emission control device. Remember when cars didn't have oxygen sensors? I do and I'm sure there are many here who do as well. My first car didn't even have a catalytic converter and used leaded gas. Those were the days (cough)!

[redEGG]

The advance auto parts by my house doesn't do cpu diagnostics or anything. They aren't allowed to go out and change wipers, batteries, or anything?
I guess they got sued or something.
Anyways, I've changed the spark plugs and wires, no difference!
I'm going to change the fuel pump and fuel filter tomorrow. I'll keep you guys posted. Hopefully this is the missing link. If not it's probably the fuel injectors, LAF, ????? I DONT KNOOOW. I'm going nuts...

[redEGG]

Im back,
So i took the VX to a popular honda shop here in Miami.
They diagnosed the issue to be the o2 sensor. I told them that I just put in a new one. They stood firm with their diagnosis, and told me that if I were to unplug the o2 sensor and drive it, it would drive normally.
So i listened to them, and it's true, I unplugged the o2 sensor, and the car is driving normal, no more jerking, losing power in 4/5th gear. So i returned the o2 sensor which i bought online, and i bought another one. Same problem when I plug the o2 sensor.
So now I'm really stuck. Could this be a wiring issue????
Or should I just buy the real deal honda o2 sensor?
help!?

[VetteOwner]

have you unplugged the battery since youve swapped sensors?

need to put the new sensor in, plug it in, disconnect the battery for at least 10 minutes (longer is better) then reconnect the battery.

you need to force the computer in its default mode so it can relearn all its sensors again.

[redEGG]

Yes, I've unplugged the battery before I even started working on the car.
Waited a few minutes, then started changing out the o2 sensor.
I have no clue what this could be, I'm thinking it's an electrical wiring issue.
Maybe a wire has gone bad?
I dont know how to troubleshoot wires though.