A very frustrating idling problem

[Yimu]

Hey guys, thanx for the expert advices on my previews questions, it really helped me improved my car a lot more with the least amount of money.I changed a couple of injectors, all the hoses, knock sensors and the TPS like 3 weeks ago, the car had a very bad rough idle, died once and had black smoke coming out from the back. I realized it was the TPS(the old TPS was a good one but i had a spare one so just changed for fun, not a good idea)after i swithced back to the old TPS, the car ran much smoother and no black smoke anymore, idling was basically smooth. But there is one problem thats bothering me, after i start the engine, RPM would crank up to 1500 rev and directly drop to 500, and go up to 1200 again and drop back to 500, it flucuates for a couple times and the stays stable, it almost happens everytime i start the engine, after the rev is stable, it stays stable.Was wondering is this still a TPS problem or something else, seems like everything was good b4 i changed the injectors and stuff, if u gus have any ideas, plz let me know.

Thanx guys

[driverdriver]

What car ( year and model) is experiencing this?

[Yimu]

94 Infiniti Q45

[Yimu]

I realized this happend after i switched the TPS and i changed the oil, TPS is a bigger possiblity but is there a chance thats the oil? Since i saw the oil light on once for like 2 secondsthanx

[Q451990]

I don't think the oil and your idle issue are related. When did you see the oil light? If it was anytime after the initial start-up after the oil change I would be very concerned. The oil pressure sending unit isn't that sensitive - so when you see that light (other than right after an oil change) damage is being done!

In fact, I'm so anal about it that I pull the injector fuse after I change the oil and turn the engine over several times without starting it. That gets oil through the system so there's no "dry start"

Heath

[CrimsonQ]

Happened after changing oil?

change filter from top or bottom? (re: maf issue?)

[richardchen0530]

i assume the mechanic changed it from the bottom, what kinda MAF issue will occur with a oil change?plz advice

thanx

[96Qowner]

The MAF connector is especially troublesome on a Q45. It's easily disturbed when changing the oil filter from the top, or removing the air cleaner housing, contributing to idling and performance problems.

Here's a thread on the subject:

zerothread?id=161560