dexter_dennis

I have a grand am GT with around 165 k on it. I started noticing the problem about a month ago, no one of mechanics has any ideas. No codes are coming up neither do any lights go on. When i suddenly accelrate from start it goes till 6000 Rpm then switches to next gear and then the rpm starts just jumping to reach 5000 or 6000 and to change to next gear, car also jerks a little whith rpm jumps. I have new wires new sparkplugs new filtre new oil change ne fuel filtre. Any ideeass it is driving me crazyyyyy those jerks can it be the Leak in air system if yes how to check it ? THanks.

xeroinfinity

Could be the trans, has the fluid and filter been changed?

Could also be injector related like a clogged injector.
Have you tried any fuel treatment?
Might consider a professional fuel system cleaning.
You can be the Tool to do this from Napa for around $300, hooks to the shradder valve and cleans things very well !

On a vacum leak a visual inspection is the best way to locate. Listen for a whistling sound.
Also if you have a vacum leak the motor should idle faster then normal.

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1999 Grand Am SS 3.4 OHV

dexter_dennis

Trans Fluid and filtre was changed lik 20 K ago. So i hope it is not tranny. However sometimes car's RPM jumps when you start in it just goes from 500 to 1 k and you can really hear it, but if you press gas hard few times (while on park) get rpm past 3-4 k it dissapears and works perfectly, it is a mystery. As well while driving when RPM starts jumping if i let go gas and floor it it goes without hesistation and RPM doesnt jump

xeroinfinity

That would be your IAC making the rpms jump on start ups and could contribute to the other symptoms.

Here is a link for testing & replacing.
Usually a good cleaning can help.
Idle Air Control(IAC) Testing Replacing for 99+

Hope that's a fix

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1999 Grand Am SS 3.4 OHV

dexter_dennis

Tried it didnt work any other suggestions ? Thanks, funny thing is it doesnt do this on start up anymore.

dexter_dennis

I checked IAC Cleaned it tested all other possible sensors They show the ok voltage. Any ideas what could it possibly be, when car is on you can see theat the engine is not working stable. It shakes a little bit is it normal ???? When on neutral also if i floor it it jumps up and then drops down almost to 200 rpm you can here that the car is almost shutting off, but then jumps back to regular after few of those tricks. While driving around 2000 rpm (60-80 KM/h ) you can see rpms jumping a little bit but not alot but you can feel the car pulling forward with steps. PLEASEEEE HELPPPPPP Driving me nuts

xeroinfinity

Well from waht you describe now sounds more like an ignition system problem.
Plugs-wires, what brand and type were they ?

And with 165k, could possibly be your trans fluid & filter are stoped up.
Check out the "chugging" thread, same problems/symptoms you are experiancing.

Also if the car is in P or N and you floor the car it should not rev much past 3-4k rpms as the rev limiter will keep it from throwing a rod.

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1999 Grand Am SS 3.4 OHV

dexter_dennis

Wires are Nemihof or something like that bought from canadian tire. PLugs are boch platinum, the thing that i discovered one of my tips where the wire goes was rusted had to clean it.

dexter_dennis

Xero, i really appriciate your help thanks. My question is i heard a lot of stories about cloged CAT you think it is a possibility ? If yes is there a way to clean it out or check if it is bad ????? Thanks.

xeroinfinity

Those plugs are not very good.
GM does recomend the use of the AC Delco Iridium.
Pull one or two of the plugs and see how the end elctrode look, I bet some are already damaged.
Shouldne be rust on the wire(s) ends either

You could have a clogged Cat but I think thier would be several other symptoms.
And No it cant be cleaned because you cant get to the inside, and No you could not test it unless you have a machine to test the Co2o levels, or a pyrometer to see what the temps are of the Cat.

Some GA had a problem with the Catalist inside the Cat breaking into pieces, but I believe that was on the 01-02" models.

Hope that helps!

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1999 Grand Am SS 3.4 OHV