Last week, I had a really rough idle and shaking, so I took my Q to a local shop and then to the Infiniti dealer for diagnostics. The first shop said injector #3 was bad and the next day Infiniti said injectors #1 & #3 were bad.
Two days later I had the local, reputable shop replace all eight injectors. I also asked them to check for any other problems under the plenum such as bad wire harness, knock sensors, brittle hoses, and so on.
I picked the car up today and at start up I get a very rough idle and some shaking. The tech came out and played around with the idle. It smoothe out to the point of just a slight roughness in the idle. (atleast more roughness than I recall.)
They asked me to drive the car for a day or so and see what happens. The tech said the computer may be trying to adjust to the new injectore. (?)
I drove it for about 20 miles and let it sit for a couple of hours. Came back out and still had a little roughness to the idle, but in a few minute of driving it smoothed out. But, then after about another 15 miles of interstate driving the check engine light came on. I stopped at a gas station and when I resumed driving the check engine light did not reappear.
Any thoughts on what should have been done or check and what I might do at this point? As always, you comments will be appreciated.
Repalced Injectors and still getting rough idle
OUCH!
All that money and no perfection..
When under the plenum did u have them get plenum hoses and plugs too, as long as they were there?Or were both pretty new?
Did you get a <good> TB cleaning (dirty TB can cause uneven idle)?Also the idle adjust is not something for the non Q experts.Just fiddling with the idle adjust can cause more problems than it solves according to those who do this a lot (Q45tech).
It has happend to me once, when I replaced all 8 when (3 were bad one marginal) than one of the new injectors (!) was bad causing a noticabaly less than perfect idle.Injector ohmed out bad even tho new.Probably damaged during installation into my car.
Fred...
All that money and no perfection..
When under the plenum did u have them get plenum hoses and plugs too, as long as they were there?Or were both pretty new?
Did you get a <good> TB cleaning (dirty TB can cause uneven idle)?Also the idle adjust is not something for the non Q experts.Just fiddling with the idle adjust can cause more problems than it solves according to those who do this a lot (Q45tech).
It has happend to me once, when I replaced all 8 when (3 were bad one marginal) than one of the new injectors (!) was bad causing a noticabaly less than perfect idle.Injector ohmed out bad even tho new.Probably damaged during installation into my car.
Fred...
hobber,
TB cleaning is <always> recommended.Not doing it ,can cause problems, such as loss of power, dropped mpg and uneven idle.Also you <cannot> properly adjust the idle on a Q (or any modern car for that matter) with a TB that is less than clean.There are some very good posts from Q45tech on this issue here on the board somewhere covering this in detail.
Fred...
TB cleaning is <always> recommended.Not doing it ,can cause problems, such as loss of power, dropped mpg and uneven idle.Also you <cannot> properly adjust the idle on a Q (or any modern car for that matter) with a TB that is less than clean.There are some very good posts from Q45tech on this issue here on the board somewhere covering this in detail.
Fred...
Hobber, I don't have an answer but I have had a similar experiance. Last year, my engine shook and ran really rough below 3,000 RPM. I mean REALLY ROUGH, thought it was coming apart.
The problem was erratic and I could NEVER diagnose the problem. I checked the injectors, MAF Sensor, everything I could think of. All the service manual specified tests checked out fine. I thought maybe it was the coils, but never could pin anything down.
After 2 tanks of new gas and a quick road trip, the problem disappeared. Since it has not popped up again, I assumed it was bad gas. So, you may try a can of 44K and a roadtrip to see if that solves it.
The problem was erratic and I could NEVER diagnose the problem. I checked the injectors, MAF Sensor, everything I could think of. All the service manual specified tests checked out fine. I thought maybe it was the coils, but never could pin anything down.
After 2 tanks of new gas and a quick road trip, the problem disappeared. Since it has not popped up again, I assumed it was bad gas. So, you may try a can of 44K and a roadtrip to see if that solves it.
