help with rough idle!

gearbox · 06-05-2004

Ever since the new cylinder head went on, my idle has been really bad. The whole car shakes back and forth before I accelerate. I think it's due to the higher compression, but what can I do to try and fix it? I have a cam gear but don't know how to install it. Plus I don't want to make things worse adjusting it. So what else can I do to try and make it better? Thanks.

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Macfay · 06-05-2004

don't you have VAFCII? I guess you can go to dyno tune your car...I bet your air/fuel ratio are off...

btw...my AEM CamGear works fine for me, but you gotta remove the cover for the cam gear...do you have a regrind cam? if not, then I guess by adjusting the cam degree doesn't work as nice as a regrind cam(I don't have it either)...

gearbox · 06-05-2004

So would just the air/fuel cause the idle problem? I have stock cam and stock cam gear.

Havok2k1 · 06-05-2004

Sounds like timing is off or a vacuum leak...

gearbox · 06-05-2004

Hmmm. But it starts up perfect now and runs great. Only thing is once I let off the brake in drive (from a stop), I get the jerking back and forth before stepping on the gas. It's Kinda like pumping the pedal. So I think timing is fine, but how would I find out for sure? vacuum leak?

I'm also gonna spray some TB cleaner just in case.

luciferi · 06-05-2004

Since you had the head off, the timing belt be may a tooth off.

gearbox · 06-06-2004

It's still shaking pretty bad in drive while at idle. Then I press the gas and it's fine. How can I make sure the timing is right on? Also, would not enough fuel cause anything?

VTECTypeR · 06-06-2004

My moms altima had that problem and when they fixed it they replaced the whole head. So i dunno could the head be bad. I dunno if that was the only problem to fix it but it had the same problem, the engine kept shaking in park

gearbox · 06-06-2004

Well this shakes when the car is in drive and I let off the brake. So it's just barely moving forward by itself. Then it shakes alot.

Don't know if this matters, but I was driving it hard yesterday and I noticed it completely went away for the moment. Then today it's back again. Really confusing. What else would cause it? Maybe if it's not gonna cause anything bad, I just won't worry about it. I'm scared to go to the dealer cause they'll take one look at my intake and header and say that's what's wrong. Thanks for the replies--keep em coming

gearbox · 06-28-2004

Bump. Anyone else? I looked at the cam degree kit and it's way too complicated. I wonder if the dealer would be able to see if the timing is off. Don't even know if that's the cause. Would rough idle happen from the air/fuel being off? sparkplugs?

tinman · 06-28-2004

First: Check compression on each cylinder. That'll tell a lot more.

Check it both cold, and hot. Write it down and post the results.

tinman · 06-28-2004

Gearbox, I have been following your troubles for quite some time on this board. I have been rebuilding engines for quite some time. There are basic rules to this game, and you have to eliminate the causes for this in a systematic order. Tough to do on a forum.
But I'll keep an eye on this thread if I can help.

gearbox · 06-29-2004

Well I don't know much about this stuff. How do I check compression? I'm assuming a shop can do this test, but those are slim to none in this small town.

I had an idea to change my iridium ngk with regular copper to see if it helps.

orso · 06-29-2004

ok since we can not adjust the ignition timing on the 7thgen that is not the problem. maybe you should check the spark plugs to see if they are fouled. Find the person(s) that installed the head and make them double check the cam timing. if it is off then that could very well be causing your problem. your compression should be fine, but then again you never know. you can get a compression tester from any parts store. you will want the one with the long hose and screw fitting. then follow directions it is very easy. if that comes out ok then maybe you got a bad head job. hope you find the problem. good luck

gearbox · 06-29-2004

Thanks. Is it easy to check the cam timing to make sure it's correct, or should I just take it to the dealer. I'll look into checking the compression. Thanks guys.