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My girlfriend has an 03 auto Neon. Recently I noticed while driving it that it seems to have a dead spot around 80 kilometers an hour. Sometimes it felt like I could put my foot to the floor before it would shift. It also seemed to work worse when the car was not at full operating temp.

At first I thought it was the transmission going, but someone said that if I gave it gas, it would puff black like it was really rich. The car does not have a CEL, and I just replaced the downstream 02 sensor a few months back. Could the other one be going?

I have not looked into it to much, but would it have anything to do with the TPS?

derek wrote:
I have not looked into it to much, but would it have anything to do with the TPS?

It could be TPS-related.... but since you replaced only one O2 sensor, you can't rule out that the other one needs replacing by now.

Have you checked for any stored codes by doing the "key dance" ?
Better yet, if you have access to a scanner, try that instead.

- Nick

No related codes. One I know of that I believe to be a failing gas cap.

No other suggestions?

derek wrote:No related codes. One I know of that I believe to be a failing gas cap.

No other suggestions?

I don't think that a failing gas cap would cause an overrich condition (not on a Neon, anyway.)
You may want to try replacing it anyway, just to see what happens.

While we're on the topic..... Check under the hood, and look for any obvious problems. (hoses, vaccum leaks)
Just a hunch....

- Nick

I agree with Nick.

Remember, do the cheap/easy stuff first

Good luck!

NickKo wrote:

derek wrote:No related codes. One I know of that I believe to be a failing gas cap.

No other suggestions?

I don't think that a failing gas cap would cause an overrich condition (not on a Neon, anyway.)

I just meant there was was other code that I believe is the gas cap, but I don't think this is related to the current problem.

She did just call me and tell me that her check engine klight is on now though so maybe so that will finally solve the problem.

P0128 so I don't think that has anything to do with the way the car is running either.

Unless the car always thinks it's cold and is dumping a shit tonne of fuel into it.

But now that I think about it, she did say it took awhile for her car to warm up the other day while going to work. So maybe that is exactly what is happening. I'lll replace the thermostat and see what happens.

derek wrote:P0128 so I don't think that has anything to do with the way the car is running either.

Unless the car always thinks it's cold and is dumping a shit tonne of fuel into it.

But now that I think about it, she did say it took awhile for her car to warm up the other day while going to work. So maybe that is exactly what is happening. I'lll replace the thermostat and see what happens.

SURE this could cause all your problems !!

Besides throwing off your engine temperature and causing it to run less efficently, it will also throw off the CTS (Coolant Temp Switch), which will cause the PCM to affect fuel trims, etc. .... and on it goes.

- Nick

Well, replaced the thermostat, spark plugs and checked the air filter. Seems to be running much better now, though I still feel it lacks a bit of power.

I used to work at a dealer so I think my next stop will be there to take a look at that other 02 sensor on the DRBIII.

Same code came back today.

derek wrote:Same came back today.

Did you take it to the dealer yet and have them take a look with the scanner ?

- Nick

P0171 showed up today. Finally. Going to replace that other 02 sensor and hope she's all done.

Replaced o2 sensor and erased codes today. Works good so far.

This car is a nightmare! P0128, P0420, P0441.

Car is intermitantly running cold again, but she hasn't noticed because it's summer. I doubt the thermostat has failed again, but might be worth a try.

(of your girlfriend)