O/T Any mechanics here?

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 8:32 am

Here's a long shot. I'm having some car troubles, and am looking for some help.

As some of you know; I'm a full time university student.... A broke university student! Tuition alone is $10,000, and it's killing me. School is 65km from where I live; therefore I drive about 130km a day commuting to and from classes.

I drive a 2003 Cavalier, which has been holding up great considering the mileage I have been putting on it. It's at roughly 160,000km right now. Ok now on the the problem:

Yesterday for the first time, I came to a stop at the lights, and the car started to shake. Not a lot; but a decent amount. The RPMs are about 600, which is normal, but the needle is now jumping up and down between about 550-650. the engine vibrations are coming at the same time as the rotary fluctuations; which is about 2-3 times a second. the Check engine light turned on; around the time the vibrations started. all symptoms disappear while driving, but become present again while idling. It acts the same in drive (with brake applied), neutral, and in park.

I started thinking that perhaps it's misfiring? not to sure though. As soon as I hit the gas; everything appears normal. There is no loss in power, or fuel efficiency. I used my trip odometer to measure how far i can go on a tank; and it is still pretty close to my average. There is no abnormal clicking, or grinding noises, but you can hear the engine winding up, and down slightly; and can visibly see the engine shaking to the auditory fluctuations.

So here is where I stand. I don't work during the school year, but work 80-90hours a week at a decent pay during the summers. I begin working late April, should get my first pay cheque around the beginning of May. I'm wondering if if this is a condition I can leave for a month... or do I have to bite the bullet, and put the repair on credit?

Second option, I am pretty handy, and have taken a few auto shop classes. I have a decent set of tools, and can borrow what I don't have. Although, I have never done a serious repair on my own car... or without supervision.

Here are my first thoughts on the problem:
- Dirty spark plugs
- Poor spark plug wires
- Problem with the distributor cap
- Dirty air filter
- Clogged fuel filter
- Clogged fuel lines
- Leaking cylinder (probably not since there is no serious power loss)
- Broken motor mount (probably not, since the vibrations are only while idling.)

That list looks a little intimidating to me; I'm not sure where to start. Can anyone rule any of those out for sure; or add to the list? any ideas where to start?

- Is this something I need to get to a qualified mechanic ASAP?
- Can it wait?
- What can I do myself?

Pydpiper · Post by **Pydpiper** » Tue Apr 01, 2008 8:42 am

If the check engine light goes out when you start moving again I would bet you are good for another month.. That light on GMs can be pretty picky, my old truck would turn that light on when my gas cap wasn't completely tight.
You can swing it in through a Midas or other place that do free computer checks, at least you will know what is wrong.
It could simply be your car for some reason has chosen not to idle correctly, that part of the computer can be reset fairly simply if you know the technique. My GM could reset the idle by holding down the brake, turning the key back and fourth 5 times then starting it and manually holding the gas pedal to 3500 rpm for one minute, bingo! It would correct it's self, I am betting your problem is as simple as that. You just need to find the reset combination for your idle.

Normous · Post by **Normous** » Tue Apr 01, 2008 8:44 am

I would first see if I could get/borrow a scan/diagnostic tool to produce a code fault regarding the check engine light. Maybe you could pay someone to do it. The code would let you know what the problem is regarding the check engine light. With that information you could hopefully fix the problem yourself. Good luck!!

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 8:45 am

Pydpiper wrote:If the check engine light goes out when you start moving again I would bet you are good for another month.. That light on GMs can be pretty picky, my old truck would turn that light on when my gas cap wasn't completely tight.
You can swing it in through a Midas or other place that do free computer checks, at least you will know what is wrong.
It could simply be your car for some reason has chosen not to idle correctly, that part of the computer can be reset fairly simply if you know the technique. My GM could reset the idle by holding down the brake, turning the key back and fourth 5 times then starting it and manually holding the gas pedal to 3500 rpm for one minute, bingo! It would correct it's self, I am betting your problem is as simple as that. You just need to find the reset combination for your idle.

Thanks for the quick reply Pydpiper. Since the first time the engine light turned on; it has not turned off. I will look online for the reset combo for my car.

I'll fill you in on how it turns out.

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 8:46 am

enormous wrote:I would first see if I could get/borrow a scan/diagnostic tool to produce a code fault regarding the check engine light. Maybe you could pay someone to do it. The code would let you know what the problem is regarding the check engine light. With that information you could hopefully fix the problem yourself. Good luck!!

Good point. I think I will bring it in to get a diagnosis.

Thanks Norm.

Pydpiper wrote: You can swing it in through a Midas or other place that do free computer checks, at least you will know what is wrong.

Maybe I'll give Midas a call.

Pydpiper · Post by **Pydpiper** » Tue Apr 01, 2008 9:03 am

Looking back I recall mine started doing the symptoms you are describing after the battery was ran dead thanks to my kids.. Did you by any chance have a dead battery recently? That can create havoc with those computers, And I have no doubt this is a computer related issue.
Try disconnecting the battery for a while, then try it again, it could very well be that simple.

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 9:14 am

Pydpiper wrote:Looking back I recall mine started doing the symptoms you are describing after the battery was ran dead thanks to my kids.. Did you by any chance have a dead battery recently? That can create havoc with those computers, And I have no doubt this is a computer related issue.
Try disconnecting the battery for a while, then try it again, it could very well be that simple.

Yes! Last week!

I left my lights on for 15 hours. came back and the car was dead. I found a nice young girl in the lot, but even after connecting the cars for 10 minutes, the car wouldn't start. I called a tow truck, and it started right away. I think her terminals were too oxidized to get a good contact.

I haven't been able to find the reset combo yet; but to be honest I am in class, secretly on the Excal forum on my laptop in the back corner of class.....

Pydpiper · Post by **Pydpiper** » Tue Apr 01, 2008 9:17 am

Here, I went and found my old thread.. This was from a Ford Mechanic, and it did fix my GM idle problem.

Idle Adaptive Strategy
I have been out of the loop for a few years now so I
am not sure this applies to the Chevy PCM...but try disconnecting the battery for 30 minutes...trickle charge it during this period...then disconnect charger
and reconnect battery...start engine and hold idle at 1000 rpm for 1 minute...then hold idle at 500 rpm for 1 minute...then drive normally in city traffic for 10 minutes.
The PCM should relearn how to idle...
This assumes your battery is ok of course...

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 9:23 am

Pydpiper wrote:Here, I went and found my old thread.. This was from a Ford Mechanic, and it did fix my GM idle problem.

Idle Adaptive Strategy
I have been out of the loop for a few years now so I
am not sure this applies to the Chevy PCM...but try disconnecting the battery for 30 minutes...trickle charge it during this period...then disconnect charger
and reconnect battery...start engine and hold idle at 1000 rpm for 1 minute...then hold idle at 500 rpm for 1 minute...then drive normally in city traffic for 10 minutes.
The PCM should relearn how to idle...
This assumes your battery is ok of course...

- Sorry; Whats a trickle charge?
- Do I disconnect the positive lead, then get a charger, and connect the charger to the disconnected lead?
- How do I idle it at 500RPM if it idles higher than that on it's own. is 600 close enough?

Sorry I know that was someone else's post, not your words... but maybe you can steer me the right way anyway.

Pydpiper · Post by **Pydpiper** » Tue Apr 01, 2008 9:26 am

Here is the thread
http://www.chevyavalanchefanclub.com/ca ... 115.0.html

Trickle charge is a slow charge, usually around 2 amps, not needed in your case. Yes, disconnect the positive for a half hour, then do the idle thing.. I would guess 600 is close enough, it is tough to do anyways.. I had a hell of a time with the 1000 RPM stage.

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 9:34 am

Ok... so the plan.

1) disconnect battery for 30 mins.
2) reconnect battery
3) start car
4) rev to 1000RPM for 1 minute
5) allow to drop to 600 RPM (no action needed, since the car idles around 600)
6) drive for 10 mins
7) cross my fingers

Correct?

Pydpiper · Post by **Pydpiper** » Tue Apr 01, 2008 9:39 am

Correct, however, you may find that the RPM's will drop to 500RPM after doing the 1000RPM part, so be prepared.
Good luck!
It wouldn't hurt to trickle charge the battery anyways, if you have access to a 12v 2amp charger.

Rage_A_Holic · Post by **Rage_A_Holic** » Tue Apr 01, 2008 9:45 am

Pydpiper wrote:Correct, however, you may find that the RPM's will drop to 500RPM after doing the 1000RPM part, so be prepared.
Good luck!
It wouldn't hurt to trickle charge the battery anyways, if you have access to a 12v 2amp charger.

Whats trickle charge?

- just connecting it to the battery charger? We have a charger in the garage, but I have never used, or looked at it.

- Do I disconnect the battery, and connect the charger to the exposed lead? or the battery terminal? or do I leave the leave connected to the battery?

Country · Post by **Country** » Tue Apr 01, 2008 9:45 am

You can buy a hand held analizer for less then what it would cost you to have someone read the code. Mine was under $100 and it doesnt just give you a code number but actually says what is wrong. I found this out the hard way after spending $125 to get a Exxon station to read it for me. Now I can not only read the problem but delete it as well.
I think someone else mentioned this but you can on some makes just disconnect the battery and then reconnect it to get the onboard computer to reboot.

Pydpiper · Post by **Pydpiper** » Tue Apr 01, 2008 9:56 am

The trickle charge is not necessary, but it wouldn't hurt.
It connects to the battery terminal.
"Trickle" just means a slow, low amperage charge opposed to slamming 40 amps into the battery, car batteries are no designed to take a fast charge, deep cycle are.
If your charger is about the size of a shoe box as many are then it is a trickle charger, a switch will let you alternate from 6 to 12 volts.
I would suggest skipping that stage, it seems to be confusing a fairly simple process.

Just do the disconnect and idle stuff... It will take a half hour and costs $0