sluggish Q45

[anton]

Sluggish Q45

Hello all- I'm back after a long period when my '94 Q45 behaved itself very well.However, a few weeks ago it developed a misfire which my dealer(DIS-Advantage Santa Monica Infinity) diagnosed as a couple of bad injectors. I was told that since it cost about a grand to get to them I should replace them all. Stupidly, I agreed and $3400 later I got the car back.Driving it home I realised that it was running rather poorly- Extremely sluggish acceleration at full throttle until 4000+ then as though a switch had been thrown, normal strong acceleration to redline. I took it to a friend's BMW shop and we gave it a quick look under the hood. All we could see was a couple of vac. hose clamps that had not been replaced correctly so I took it back in the morning.3 days later it was done and on driving it there was no change. I complained and the tech who worked on it went for a ride with me and said it seemed fine to him. He apologised for "leaving that vacuum line off" and he said there "were no codes showing a problem" therefore it was fixed. We drove another customer's car and it was marginally better than mine but nowhere near as quick as mine had been before the misfire developed.I left before I got violent.I haven't driven it much since then but I notice that it doesen't start like it used to- it sometimes cranks for 2-3 seconds before firing and the transmission shifts a little funny sometimes. They also replaced the "turbine sensor" and 2 other sensors.The tech was a pretty young guy and didn't leave me with a favorable impression. I had the feeling he didn't know the Q45 very well.Is it possible that a vacuum leak or transposed hoses could be causing this problem?I'm pretty good with old Ferraris and Fiat V8s but I don't know squat about modern cars and their systems.Help!Thanks,Anton

[90Q45blue]

A vacuum leak could be the culprit here but, since you're accelerating fine above 4k rpm's, I'd say it's probably your MAF (Mass Air Flow Sensor). Have the tech wiggle it around on idle and see if it makes a difference. A loose or bad MAF connection can cause considerable power loss to a car.

Nick

[fxjackso]

A bad MAF connection would throw you into a limp home mode, and you would not be able to get to 4000 rpm.

Ask your friend to check the fuel pressure. Do a search here for the procedure.

[DougQ45]

Drive it over the hill to Miller Infiniti in Van Nuys and INSIST on William Orellano. He is a master tech and can get it fixed. Your "young guy" probably doesn't know the car very well as you mentioned. If there are no codes he thinks its OK, which it obviously is not. Codes aren't always thrown for errors. Good luck.