Injector Replacement from GM Engineering

[Red Sky at Night]

Just a bit of a heads up. I had been noticing a slight shudder while my R/L sat idling. I took it in for service to my dealership and told them about it. I also had my diff replaced as a recall and while it was there they busted a panel on the car behind the left front wheel.

Because of their screw up they bent over backward to please me, so they hooked it to the computer to find the cause of the "shudder". NO CODES. They tested it for weeks and could not find a thing wrong but the shudder persisted. It was eventually discovered that the injectors were faulty. By this time the dealership had had the car for 3 1/2 weeks. GM was obviously aware of this problem because the replacement injectors did not come from the parts warehouse but rather, engineering. It took them another 1 1/2 weeks to get the injectors and install them. In total they had the car for over 5 weeks.

Anybody else had issues with their injectors or an unexplained shudder/tremble while the car idles that the dealer can't explain? Have them check your VIN number against engineering. It might be that simple.

The car works fine for now. Discouraging about the clumsy dealership and all the ongoing issues with a great little car.

Red Sky at Night.

[lostcause]

I get a little shudder when it's cold. Once it warms up for 45 seconds or so it's fine.

[sky in pdx]

Originally Posted by lostcause

I get a little shudder when it's cold. Once it warms up for 45 seconds or so it's fine.

Same thing happens to mine.

[snaponbob]

Originally Posted by lostcause

I get a little shudder when it's cold. Once it warms up for 45 seconds or so it's fine.

Mine had the cold shudder as well. It was produced in late August 2006. The TSB is 07-06-04-410B Date June 15, 2007, VIN breakpoint 7Y139741. This TSB calls for replacing the spark plugs with hotter plugs P/N 12617309.

Check you serial number and if you have a Redline you get some spark plugs. Did mine 8000 miles ago, all is still good.

[ceeker]

I have notice a little ruff idol after I sit for a few seconds. It's barely noticeable but it is there. It's kind of a random shudder at idol. If I increase idol just a touch with the gas pedal it goes away, almost like the idol needs turned up just a tad!

Have not noticed any performance problems or any delays during normal driving!

[Rail Jockey]

maybe I should come up and we can let our cars idle together and see who shudders first.

[Red Sky at Night]

The shudder would occur regardless of whether the car was warm or cold. It did not appear to affect the performance but seeing the dealership was so keen on making sure that they made up for the body damage, I thought I would mention it to them. They first noticed it on cylinder 4 and when they moved the injector to another cylinder, the shudder followed to that cylinder. Injector pressures are very high. At idle pressures were at 600psi. At rest just after the motor was turned off the injector pressures shot up to 1100psi. The dealer said that this was within spec.

Its running fine now but what started as a problem that I didn't think was originally worth mentioning turned out to be a serious problem.