Reader Question: I have a 2002 Jeep Grand Cherokee Laredo v-6. When I am idling at a light, my jeep has shut off about seven times. It starts right back up though.
When I am idling and sometimes while driving my car will rev up and the RPMs go up and then back down to normal. It feels like the jeep is trying to shut off but then the RPMs go way up to stop it from shutting off.
I went and put it on a computer at a local auto zone and the problem that came up was the throttle sensor. I also went and had a fuel injection cleaning at my local oil change place and when they were doing it, a bunch of white smoke came out of the tail pipe. I was told this was good that it meant the fuel injectors were very dirty.
I was hoping this would be the answer to my problem. However, unfortunately not, the next day it started acting up again.
My question is – do you think the bad throttle sensor could be causing the car to shut off like this? The part is US$75 and then I need to pay someone to install it so I am wondering if I should spend the money or it was suggested by a couple of people that I possibly could use a tune up, which I know is good to do anyways but I am trying to fix the problem at hand.
In addition, the check engine light has been on for a long time but when I read the manual initially, it said that this light came on and it meant I had put some bad gas in.
Please help me with any information you think I need!
Thanks so much,
If the check engine light is on, I would definitely spend US$75-100 to have your computer codes read by a real mechanic; not at Auto Zone…they are great for buying parts but not for diagnosing computer related problems.
You could very well have a TPS – Throttle Position Sensor problem, but this problem could be caused by many other issues as well, so before I guessed at a US$75 part I think I would have someone look into it further.
A dirty throttle body and idle speed motor can cause a common idle surging and dying at low speed complaint, which is part of the fuel injection system. Your local oil change guys may or may not have cleaned the throttle body and idle speed motor when they did the “fuel injector cleaning”.
Although a dirty throttle body and idle motor will cause dying and idle surge complaints like you mentioned it will usually not cause the check engine light to come on.
The check engine light is continually coming on due to a consistent problem your onboard computer is seeing when it performs its self-tests. One of the man emissions control sensors is usually the culprit of a yellow check engine light being on. A drop in fuel mileage and engine performance can sometimes accompany a yellow check engine light being on.
Needing a tune up could cause poor engine performance, but you did not mention anything about the engine running bad OFF idle so I do not think you need to get a tune up to correct this problem and I really doubt you have a “bad gas” problem.
Here is more about the throttle body and idle motor on my blog: