I have a 2001 aurora 3.5 L that when initially starting it rolls over for about 10 seconds before starting. After started the rpm’s are at 5k and as soon as you touch the gas it pegs out at 8k. If I shut it off immediately after starting and start again it starts immediately and rpms are fine. Occasionally it stalls out at stoplights. Is this the crankshaft positioning sensor or mass air flow sensor or something else?
Unlikely the crankshaft position sensor, possibly the MAF, but I think unlikely. Maybe the idle air control valve but it should not rev anywhere close to that high. Possible a dirty and stuck throttle plate but it is all a wild guess without data.
Data like; How many miles on the engine? Is the CEL on? What are the codes?
110,000 miles and cel is on but I don’t know what codes
Have the codes read and post them here. That will give much better suggestions .
The numbers I got from autozone are P0410 and P0385
I would look at replacing the IAC valve.
The first code is a secondary air injection problem. The valve may be stuck open intermittantly causing your rpm flare. Probably dirty, I’d replace it.
The second code is a crankshaft position sensor code. Either the sensor or the wiring. Check both. Replace it before it stops your car.
it is cable operated.
Just struck me… if it really pegs at “8k” that is 8000 rpm, this engine would float the vales and possibly blow up. Maybe you mean 800 RPM??? If so, that could very well be an IAC in addition to the AIR valve.
The hard starting and stalling are probably the crankshaft position sensor. The high RPMs are the IAC. Replace both and the issues will probably go away.
The other issue is just driving around with the check engine light on. This signals a problem that the onboard diagnostics have found so shouldn’t be ignored.