1999 q45 shaking at idle

[squadone619]

Hi guys,

I just bought a 1999 q45 with 147,000 miles on it about a month ago. at first, it did this little jerk at idle, nothing too major. but recently, its been really bad. Its more of a violent shake but only when I'm in drive, not neutral or park. I searched and am thinking it might be a coil pack issue but i know its a very common problem with these motors. Can anyone point what some of the causes for this idle shake could be. I have not replaced the spark plugs yet. thanks in advance.

[Infinitiguy19]

Well you might be right to assume a coil pack because they usually fail and often.

If I were you I would read the FSM: http://Nicoclub.com/FSM/Q45 and look though it to see what would cause the shaking at idle, Coils, Injectors, Plugs, MAF.... are all possible causes but coils are the most possible cause because there a known problem.

Hope you have a warranty or know how to work on cars.

Good Luck and Welcome to NICO

[squadone619]

thanks paul. I'm okay at diy's, as long as its not to technical. the motor seems harder to work on compared to my 99 gs300. I'll check out the fsm and also was thinking of changing the plugs, cleaning the MAF sensor... just not a good beginning for me i guess!

[96Qowner]

Yes, it's probably one or more bad coils - very common issue for the Y33. The tough part is finding the bad one. If it's bad enough to throw a code, yer in luck. Here's the definitive thread on Y33 misfire issues:

y33 idle jerk / hesitation discussion (lets fix this!!)

[squadone619]

thanks Qowner! that's one of the threads I was reading up on and has lots of good info. That thread listed so many causes...its like a shot in the dark to find the cause. Unfortunately, its not throwing any codes so I'm kinda lost on where to start looking. appreciate the input as always.

allen

[96Qowner]

After all that discussion and argument, I think we've pretty much decided that coils are the problem. Sure, it could be other things, but probably not. Very few Y33 owners have reported MAF problems, so I doubt it's that, but as always, it's easy to pull the connector and check it out thoroughly - also the CAS connector.

You might try encouraging it to throw a code. Maybe put it under load, like a slow uphill climb in 4th, or something. It'll throw a code if it misfires so many times in so many seconds - an occasional misfire isn't enough.

But, we've also decided that when the first coil goes, more are coming. To save labor, you might consider replacing them all and being done with it for another 100K miles. Kinda spendy, but not outside routine maintenance cost - 2 cents per future mile, or so. Tires are more than 1 cent per mile, for instance.

[maxnix]

When one dose not know the maintenance history, one must replace all filters and fluids for a known baseline. Plugs also!