# Rough Idle



## CT_Nismo (Dec 25, 2005)

I have a 90 max that just received a new replacement fuel injector. The car runs fine at road speeds. But it exhibits a rough idle. Not enough to stall the car but very noticable. Any ideas?


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## DonaldHays (Jul 22, 2004)

All the basic items need to be done on the car if you haven’t already done them; here is the list to get started with.

(1)	Plugs and wires
(2)	Air filter
(3)	Fuel filter
(4)	Cap and rotor
(5)	Coolant system flush
(6)	Transmission service, if you have records of it being done before (otherwise if no records might risk killing the transmission if it hasn’t been kept up on service)
(7)	Flush the power steering and brake fluid as well also
(8)	Clean the air box out if there is any loose debris in it, will get stuck to the air filter and will in turn make the car run weird
(9)	Run some “GOOD fuel injection cleaner thru it” not the cheap 99 cent stuff that’s almost water.

Once you get that stuff done if it hasn’t been done, you should see a big difference from how the car runs now. 

If none of the list above helps or seems to help, start checking the vacuum lines for leaks, check the pcv valve, have a fuel pressure test ran on the car (fuel pump going bad maybe, but should be at higher speeds if that’s the case and not at lower speeds)

What’s the mileage as well?

This should get you started looking in the correct direction, you might check for the vacuum leaks first, but if you don’t have the records and know when the above services was done, then do them, also don’t forget the timing belt service every 60k, I have my belt, water pump and belt tensioner replaced every time, never know when you get a poor quality part and will leak water before 60k and then you have a snapped belt and no more motor)

Let us know more history on the car as well so we can help better also for future references 
Donnie H.


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## CT_Nismo (Dec 25, 2005)

The history of this car is that I have owned it since day one. My habits are to take care of my autos although I will not take it into a dealer as the cost can get too high.

The only thing I have not done is change out the ignititon wires. Would that make a difference in idle.

Another question: I know about the timing belt change. Do you follow 60k miles interval or the time (4 years?) interval. Thanks.

The car has 104k miles.


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## internetautomart (Mar 8, 2004)

both.
though the mileage appears to be more important , I wouldn't bet my engine on it


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