View Full Version : Car shakes when I start it up, stops shaking when I hit the gas
12-27-2010, 02:52 AM
Hi, I have a 2003 grand am GT V6 and I am having “shaking” problems. When I start the car up I notice sometimes it shakes, and continues to shake till the car reaches about 5 mph. Usually once I hit 5 MPH (again..usually) the shaking stops and the car runs normal. If the shaking doesn’t stop after slight acceleration I have to turn the engine off and turn it back on, then usually its fine again after I hit the gas. Its like it needs me to step on the gas a little in order to correct itself. If the car is cold usually it shakes more often, if the engine is still warm chances are when I start it up it will not shake.
I had this problem for a while, so a few months ago I replaced the spark plugs and also the spark plug harness and that solved it. I slowly noticed it starting to shake again about 1-2 months later, by now it shakes just as bad as it did before I changed the sparkplugs / sparkplug harness.
What spark plugs did you replace the existing plugs with?
Did you replace the spark plug wires onto the correct plug?
12-27-2010, 06:48 AM
Sparkplug "harness"? O.o
And yes, what plugs did you use? The LA1 is very picky with what plugs go into it.
12-27-2010, 09:36 AM
Hi, thanks for the replies. I used NKG iridium spark plugs (I researched them before I purchased, they seemed to have the best reviews).
I definitly matched the wires (aka harness lol) back to the sparkplugs correctly, I tripple checked. I also gapped all 6 plugs correctly before I installed them.
One thing I should mention is I did not put any grease or lube (or anything else) on the new plugs prior to the install. I purchased 5 new sparkplugs at autozone (they only had 5 in stock) and I asked them if they need any grease or anything and they told me no. I went home installed all 5 plugs then went to another autozone to pick up the 6th sparkplug (same type) and they asked me "do you want to buy the grease stuff to coat the sparkplug before you install"? (they probably used the exact name of the grease stuff but I dont know what it was). I told them no I dont want to buy it. The reason was because I had already installed the other 5 without it and they were such a pain to install the last thing I wanted to do is remove them again, coat them, then reinstall them.
Could that have anything to do with it?
12-27-2010, 11:17 AM
It does help for sure.
Sounds like you could have a faulty coil pack, or possibly a dying fuel injector if the motor still has a hiccup like that.
What's the mileage?
SES light on?
12-27-2010, 03:43 PM
Hi, to answer your questions my car has about 80k miles on it and the SES light did go on about 2 weeks ago. What happened is I put it in drive and hit the gas and the shaking did not stop. After about 20-30 seconds the check engine light came on. I pulled over and turned the car off and put it back on, the check engine light did not show up this time however. It did not shake after that ether (but it did warm up so it wasnt cold at that point- usually if its warm I dont have problems on startup)
The SES light did go on a few times before I changed the spark plugs, (I reset it by d/c the battery) but after I changed the spark plugs it seemed to run fine till a month later. So about two weeks after I noticed it acting a bit jumpy is when the SES light went on again.
I took it to auto zone today so they can read it with the scanner and they said there is a large evaporative emissions leak :-(
He said it could have to do with my gas cap but I always make sure I put it on real tight because a few years ago my SES light went on and they said it was an evaporative emissions leak (small leak I believe) and they said it can be my gas cap so ever since then I make sure I put it on tight. *a few years ago the problem went away on its own, it didnt shake or anything.
So I called my local repair shop today and they said they can do a smoke test for arround $100. I asked how much the average repair will cost and he said it really can be so many different things that he couldnt give an estimate without doing the smoke test first. He said its safe to drive for now so I told him if I cant come up with anything in the next few days I will bring it in for the smoke test.
So is there anything else I can try? Its just so odd to me that I changed the spark plugs and for a solid month it was running perfect. It was so bad before I did the spark plugs that I would have to start the car up, hit the gas, but eventually even that didnt stop the shakes, so I would stop turn the car off and back on again (it would work then). At that point I had to basically do that every time I started the car up cold. Right after I did the plugs it worked fine- not even one shake till a month later. Would it be worth it for me to take the plugs back out and grease them up or would that be a waste of time?
12-27-2010, 04:38 PM
The EVAP system runs off the car's vacuum, so I'd check for a leak at the manifold, and by the EGR. Bad vacuum can cause an erratic idle/sluggish acceleration.
Only an EVAP code was present?
12-27-2010, 07:23 PM
The grease wouldn't have anything to do w/ the car shaking. It's only there to help prevent the spark plugs from being so hard to remove next time.
12-27-2010, 10:19 PM
Hi, that was the only code he told me about- since he said it was a large leak maybe that was the first one he saw and said that must be the problem since its a large leak and didnt check for other codes. I can take it back for a scan tomorrow to check for others.
Thanks for clarifying what the grease is for- I was thinking that the grease would increase the contact of the metal or something.
I filled my gas tank today and as I was pumping the gas I was looking at the gas cap and I noticed it was pretty dirty. When I got back to work I took a microfiber cloth and sprayed some isopropyl on it and cleaned the sides of the gas cap (the threads) and wiped it dry then put the cap back on. I was thinking maybe the dust / dirt is preventing a good seal, maybe air was entering from there? I will find out tomorrow afternoon if it shakes when I start it up (or maybe tonight when i go home). With any luck that is what was causing it.
CHAOS- Interesting you should say that about the vac. Not sure if this has anything to do with it or not but if I remember righ back in 2006 or 2007 I was having a problem where the car made a whining noise on acceleration. If I remember right that was due to a vacume problem, but I may be getting that confused with another symptom- I have to see if I can locate paperwork. I do know I had a problem years ago and it involved the vac. They fixed it and the problem was resolved, I am 95% sure the problem was a high pitch whining sound on acceleration however. It never shook at all back then however.
12-28-2010, 12:26 PM
Vacuum leaks can definitely cause erratic idle problems and there are several places it could be leaking in the EVAP system. It could be a faulty gas cap (could be bad even if it's tight), but it could also be a loose connection at the charcoal canister (under the car in front of the gas tank) or at the EVAP solenoid (on the back of the engine by the EGR valve). I would have them check all those.
Good thing you got the code checked because that always makes it easier to diagnose the problem if it can point you to the general area. That is always the first thing you should do if you get an SES light.
02-18-2011, 03:57 PM
Well its been a few months since my last post, and just wanted to post an update because I think I fixed the problem myself! Best of all it was an extremley quick and easy repair (I believe).
Sure enough the day after I posted my last message (back in December) the car did the same thing (shook when I hit the gas alittle) and I had to turn the car off then back on again (and then it ran fine). I noticed it did not do this as often however. About a week after that, the shakes got even less common- by the 2nd week it seemed to be cured .
So what do I think was the magic fix? I could be off here but I have a feeling the solution was cleaning the gas cap threads! I used a lint free rag and some isopropyl to clean the groves in the plastic threadding and it seemed to fix itself shortly after that. I live in the northeast so there is lots of dirt and dust, I am guessing the dirt and dust prevented an airtight seal so air bubbles caused the misfiring, and it may have taken a few gas tank refillings before all the air bubbles were eliminated.
It ran great untill Feb. 13th, on that day I was driving to work and as I aprotched a T intersection some lady pulled her car out right infront of me. She apparently didnt wanna wait for me to pass before she turned. Needless to say nethere of us got much further then that intersection.
RIP CAR *2004-2011* :angel
Believe it or not I walked away without a scratch.
:-( truley a sad day however, especially right before V. day.
02-18-2011, 06:27 PM
wow that sux really bad the a similar thing happened to me except mine had about $8,000 under the hood so i bought another one cuz i liked it so much now im almost back to where i left off
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