SES Light Blinks and shakes when idle

[echoes85]

I have a '99 Grand Am 4-door 2.4L twin cam. This problem has occurred before, I had to change the spark plugs, spark plug boots, coils, and coil housing; it was VERY EXPENSIVE!!! This time I have already changed the coil housing, adn checked the codes and it read 3rd cylinder misfire, so i changed the 3rd spark plug, because I had changed the spark plugs 2 months ago. I cleared the codes, but after driving after all that, the shaking persists and the SES continues to blink after I try to accelerate adn then the Trac Off lights up a short while after. If anyone knows how to fix this please tell me because this is the only problem on the car that still stumps me.

[xeroinfinity]

I would say the misfire on cylinder 3 would be a injector pluged or dirty.
Try some Lucas Oil injector cleaner , or get the fuel system cleaned/flushed.
Some times cleaning the injectors helps.

Any other codes showing up?

Plugs should last way longer then 2 months unless you hav really bad emmisions/fuel system troubles.

[echoes85]

No other codes, but i'm going to switch the 3rd fuel injector with the second or first and run it for a while, if problem persists I would like to check the wires but am not sure how exactly to check if they are working properly. Would you have any idea how to check them without having to buy any expensive tool. I tried the fuel injector cleaner and drove it for about 20min., but the problem persisted.

[xeroinfinity]

If you switch them and the misfire moves to that cylinder then It would be the injector.

If your plugs and boots were just replaced then I wouldnt expect them to be bad for 50k miles +, especially with the 4cyl since thier are no wires involved.
Even cheapo parts would last at least that long.

But you can test the resistance with an ohm meter.
It will probly take more than 20minutes of driving to really see any benifets from the injector cleaners. Maybe even a couple tanks of fuel.

let me know how it goes!

[echoes85]

I changed the 3rd fuel injector with the 2nd and ran it for a while, but it the same trouble code came up "cylinder 3 misfire," so its not the fuel injector, I changed the sparkplug, the coil housing, the 3rd sparkplug, and the injector with the other one, the injector wires are working properly, I am begining to think that the problem is somewhere else.

When I got the new coil housing it didn't come with the boots, could the boots cause such a big problem.

The SES light blinks as soon as I accelerate past 25 miles and the TRAC OFF stays on right before the SES comes on.

[xeroinfinity]

Ok, when you swapped the injector, did you clear all the codes before you started the car?

If not it'll keep showing the misfire on 3, and still run like poop.

How long hav the plug, boots, coil paks all been on the car?

I'd start with the cheaper fixes tho, you could try new boots and see what you get.

[echoes85]

I did erase the codes, but the engine still sounded the same and after I drove it for a while the SES light came back on along with the Trac off light, as usual.

The boots and coil packs have been in there for about a year, but I haven't driven it for 50k since then, maybe 30k-35k tops.

I have a spare set of coil packs, but there in houston and im in Austin. Could an aging coil pack malfunction in one terminal and not on the other, woul like to know before I have my brother deliver them.

Thanks very much for the information, I know you have probably been asked these same questions before, but I just didn't have time to look through 100+ threads.

Again, thanks for your knowledge and patience.

[echoes85]

Ok This is what i've verified is not the problem:

Coil Housing
Sparkplugs
Boots
Fuel Injector
Injector wires

All that's left is the coil packs.

If that isn't the prblem, is there anything else that I could check because after the packs I have no idea where to go from there

[xeroinfinity]

Ya you can swap the coil modules around.
If you get them swapped and the trouble moves with the corresponding coil its probly bad.

Make sure all the connectors and stuff are clean and making good connections.
Kinda check over the boots for any cracks that might cause them to spark out.

Also it might not hurt to get the fuel lines blown/cleaned out.
Could also hav debrie in the fuel rail thats sticking in the injectors.

[echoes85]

I switched the coil packs and the misfire jumped to the 1st cylinder, and cleared on the 3rd.

To make sure, I switched them back and the misfire returned on the 3rd and cleared on the 1st.

I was wondering though, I read in one of the threads that one coil pack regulate 1st and 3rd/ and the other coil pack regulates 2nd and fourth. Is that a mistake or is something weird going on with my coil packs?

[xeroinfinity]

It was probly an older GA(or V6), tho someone might hav made an error

You can use an ohm meter to double check the coils primary and secondary resistance.
[+ - - ]
This being the plug on the coil(s) with the catch tab down.
-Primary resistance measured acrossed the "+" and each negative one at a time should be aprox 0.4 -0.8 ohms.
-Secondarry measured acrossed the coil towers.
The resistance acrossed them should be between 4k -8k ohms if it is not replace the coil.

[echoes85]

Thank you very much

It turned out being one of the coil packs, I just repalced the part and nothing lights up anymore, it only took a week and a lot of work.

I appreciate your input and letting me know other ways to check the parts in my car, this is a really great forum.

[xeroinfinity]

No prob !