Check engine light ON

[demarpaint]

Originally Posted By: Vikas
Since all monitors are completed, it is best that you completely forget about this incident. Keep the new gas cap on.

- Vikas


If I did that then I wouldn't be a Bitog member, and a glutton for punishment. I had it out for a drive last night, no CEL and I'm down to 1/4 of a tank of gas. It has been about 2+ weeks since I cleared the code and replaced the gas cap, and about 6 weeks since I gassed it up. I'm thinking you are right and I should leave well enough alone, I will.

I'm just wondering if my infrequent refueling and the vehicle sitting idle for 1-2 weeks at a time could be part of the problem, or if the gas cap replacement nailed it. That thought enters my mind from time to time.

 

[Vikas]

Quote:

I'm just wondering if my infrequent refueling and the vehicle sitting idle for 1-2 weeks at a time could be part of the problem


I do not believe so i.e. it did not cause the CEL or the cap to go bad. In the past, inspection stations in Mass had a gizmo which used to be able to check your gas cap. If you have your regular mechanic with access to that, you could check your old gas cap and verify that it did not seal correctly.

Given that you were pressed for time (inspection and looming end of warranty) you did not have opportunity to re-oil the seal in the old cap and to try to see if that could have fixed the problem instead of having to buy a new cap.

I checked the manual for your scanner and it DOES support Mode $6 data! It is called non-continuous test and it is on page 57 of the scanner manual. If you are game, I will go through it and find out how to extract the information so that you can have something to be worried Seriously, you will have to help me to find the manufacturer's test id information over the web. Which model is this Liberty?

- Vikas

 

[demarpaint]

I'm game to learn anything I can! Thanks for the offer. It is an 08 Liberty 3.7L.

As I mentioned, prior to the Liberty my newest vehicle was a 95 Caprice, oh how I hated that car, LOL. My son had a 96 Blazer and the one time the CEL went on I took it to AAP, and had a miss in one of the cylinders. It was due for plugs, I changed them and that fixed it! So I'm new to the 96 and up technology, but learning fast, anything I can learn is always a plus.

You mentioned oiling up the gas cap? Is that something they do? I took it out of the package screwed on and made sure it clicked!

Thanks!

 

[Vikas]

The gas cap has a o-ring and I just make sure that it is still pliant and not cracking and then put dab of oil on it. I meant I would have tried that with the old one before springing for new but you did not have the time to mess around.

Do you have access to service manual for that vehicle? Did your scanner came with USB or serial cable so that it can be hooked up to a PC?

- Vikas

 

[demarpaint]

I don't have a service manual for the vehicle yet. I can hook the scanner up to the PC.

 

[Vikas]

Doing quick Google search did not get me the test id definitions for your car. Without them, this exercise will not yield any meaningful information.

The exercise consists of getting all the tests results from the scanner (page 57 of your scanner manual). Each test tells us the observed value and the manufacturer set limit and whether it is high limit or the low limit. The test fails if the observed value is outside the limit. If it succeeds but the observed value is very close to the limit, then you know that something is degrading. All those numbers are in hexadecimal format. You can use calculator on any Windows PC to convert them in to decimal and/or to get the difference between the observed value and the limit using the hex mode in the calculator.

The scanner unfortunately makes you go through each test one at a time. You can either write the relevant information on the piece of paper or hook up the scanner to PC to download the test results.

Suppose out of 30 odd tests, you found couple which were on the borderline. Now you need to find what those tests really meant. That is only possible if you can get the test definition from the service manual.

Since yours is a newer vehicle with CANbus your data might be standardized. This is what I found on the internet

===========================
The key difference between older Mode $06 and newer CAN Mode $06 data is that SAE further refined the definition, unit and scaling conversion process. For example, prior to the new standards, Toyota established TID $01 as Catalyst Monitor; however, Ford established TID $01 as Oxygen Sensor Monitor. This can make the process of converting the data confusing. The newer SAE standard recommends vehicle manufacturers utilize MID $21 through MID $24 for Catalyst Monitor data to be uniform.
================

So, when you have some free time, hook it up to the car and have some fun!

- Vikas

 

[demarpaint]

Thanks. I probably won't be doing it anytime soon, to many other projects. Thanks for the explaination!