01 GrandAm rough Idle

[butt3rfly]

I recently took a trip to South Texas and started having car probs. I took it to Advanced Auto and they did a diagnosis of " Ignition Misfire" they told me to replace the ignition coils, cover plugs and boots. I did so but it still does the same thing. It runs great when on the road. I have no problems with that. Just when I slow down to a stop it make loud noise and shakes. (sometimes it shuts off) what can it be? I'm tight on cash therefore a trip to the dealership is out of the question. !!

[xeroinfinity]

Welcome to AF!

After the repairs are made you usually need to clear them if they will.

If the codes dont clear, then you probly have injector troubles.
Or something alone those lines.

Try some Sea Foam or Lucas Oil injector cleaners with some premium fuel.
This would generaly clear up a small injector clog or dirty injectors.

Hope that helps.

[butt3rfly]

Originally Posted by xeroinfinity

Welcome to AF!

After the repairs are made you usually need to clear them if they will.

If the codes dont clear, then you probly have injector troubles.
Or something alone those lines.

Try some Sea Foam or Lucas Oil injector cleaners with some premium fuel.
This would generaly clear up a small injector clog or dirty injectors.

Hope that helps.

I put in some B-12 which is a fuel injector cleaner and have been putting in premium fuel. Do you think it maybe / could be fuel filter clog problem?

[xeroinfinity]

A clogged fuel filter wouldnt cause the misfires

But it wouldnt hurt to change the fuel filter,
as they should be changed regularly.

GM also recommends that you get your fuel system cleaned every so often,
which they charge around $200-300 for

I would also check your injector wiring at the harness,
and check the grounds for the injection system which is on the intake.
Sometimes these wires get breaks, sometimes the grounds get loose and cause misfires.

Good Hunting !

[butt3rfly]

Vehicle: 2001 PONTIAC GRAND AMEngine:
L4 2.4 Liter FI

HOW MANY INJECTORS DO I NEED TO HAVE REPLACED? IS IT EASY TO DO?

[butt3rfly]

Would You Know How To Remove/install The Injectors? Is It Easy To Get To ?

[xeroinfinity]

You have 4 injectors, but lets not jump to conclusions just yet.

We dont know if the injectors are truly bad without testing them.
Which you can rent or buy a "Noid light"
that will help you determine whether or not they are getting power and working.
Also the resistance acrossed the injectors terminals is 1.95-2.3 OHM's. This can be tested with a multimeter.

And no its not hard to replace them,
but its not easy without a manual,
As several things need removed to get to the fuel rail.

But first I would get the ignition control module(ICM) tested !
Test the injectors,
then Get your fuel pressure checked/tested !
It should be 41-47 psi.
This Deos require a fuel gauge adapter and hose
that will need installed in the fuel lines.

hope that helps

[Aki334]

Hello, no reason to worry, I had rough idle and I was thiniking very deep about what could be wrong with my Grand Am 97 3.1L, and I ended up replacing many good parts. Xeroinfinity is probably right. Start with injectors. I did use "Seafoam" and it did not help me. Believe or not I noticed that there could be something bad with my injectors because when I squeezed the return line after the fuel pressure regulator I noticed that engine would run better. Mabe your lines are all metal so you can not do it, but try using ATF oil instead of seafoam or anything else. I had one galon of used ATF oil in my garage so it was sitting there for some time because I was lazy to take it to Autozone, so yesterday my gas tank was almost empty so I put half of that galon into my gas tank so I can bring my gas level up, try to clean my injectors and burn that oil and get some good use out of it. ) And beleve me it finally worked. I have all the good toys to test engine Data streams, etc and now #3 and #4 cylinders are not misfiring any more.
My GA has only 28000 miles. WARNING: MAYBE ATF IS NOT SAFE TO USE IN GAS TANK. Many people use it to clean inside of the engine, why not use it in gas tank. ATF should noe harm any seals in fuel system since it was made for gasoline which I think is stronger on seals in this case. Now ATF for engine cleaning I would think twice, because if your engine has a lot of miles than it si probably sealed from inside from the oil, and if you put some ATF it will take that oil that was hardened and acting like a seal on some points of your engine block, and now you have a oil leak. I am just trying to help...

[Aki334]

If you do not have any codes, and your engine is idling rough it must be vacuum leak, injectors or maf sensor. As I can remember maf sensor sometimes can be bad and not show any codes, so the best way to test maf sensor is to tap it with your fingers and see if engine idle changes. If yes - replace maf. Usually if maf is bad, you will feell like your fuel filter is clogged or you are not getting any fuel for a sec or two then you will have DTC stored. Second test your coils take them off and measure secondary resistance it should be (5000-8000 ohms) or just switch coils. spakr plug wires should not have resistance greather than 30Kohms, and stick to original parts when buying new (D.... sparkplugs and wires) believe me.

[xeroinfinity]

I would not recomed what Aki334 said

Putting that old ATF,
or even new, is not good for the fuel system,
or the environment at all.

The junk thats in old ATF contains PCB's,
which causes birthdefects and other serous health problems.
And burning them just spews the crap into the air you breath.

So please, do screw with my air

[gmack221]

might not be a bad idea to clean your idle air controll motor (do not twist just clean with carb cleaner & clean out port on thoratle body), just a thought ....

[Aki334]

I agree with Xeroinfinity, but that is just a drop of water in an ocean comparing to other polutants around the world ex (big oil spills in the middle of ocean etc ) +I did not tell him to inhale his exhaust fumes , just to quickly clean his injectors. I did talk to my ASE Master Technician instructor, he sadi that ATF will not harm fuel system just as I said, but if it was engine oil that would be different story. But anyway, he does not have to use it. Another thing you can check is your EGR valve if it is stock open or cloged egr passage. Xeroinfinity do not get me wrong I take care of my hazardous waste but it is better to fix it faster than have him destroy his O2's and catalitic convertor after using all those different cleaning solvents and driving with bad cat and that bad egg smell and poluting air even more before buying new cat. Do the math hopefully we will help you solve it. If you need more details on certain sensors and how to test them just ask.

[Aki334]

this one is very rare, but how are your brakes (power booster)? Here is a quick test for that one - engine off, key off also pump your gas pedal 5-6 times, does it get hight and firm? - good, now keep firm pressure on your pedal and start your car - does your pedal go imediatelly to the floor? if not there is your problem. And as you said it happens only when you come to a stop. That one is kind of hard to replace (bolts are hard to see you will need to feel them with your fingers) but if there is something bad with booster, you will hear many times hissing vacuum sound under your dash, your braking ability will normally be reduced also. Look for leaking oil from your master cylinder on the booster, if that back end seal from master cylinder goes bad it will allow oil from master cylinder to enter your booster and make an opening in your vacuum diaphragm. Another good test is start your car in park and whille it is idling press your brake pedal 5-6 times and observe your rpm needle and listen to possible hissing sounds. If rpm starts to noticably jump up and down and if you have one of the symptoms described above my suggestion is to focus on that big black round thing in front of you (under the hood). IF YOU SEE OIL on your booster right where master cylinder is and if you do not have those symptoms REPLACE YOUR BOOSTER ANYWAY.