Does your Z rev high right after a cold start?

[PerfectApex]

Shortly after I added the Stillen dual cold air intake system to my 07 Z, my rpms go to 2000 right after starting when COLD. After driving only a few blocks the rpm settles down to normal range. Any starts when warm are normal. This same thing happened on my 06 Mustang after adding a CAI system. I am assuming the computer is sensing the CAI system and causing a higher rpm at cold starts. The hassle for a dealer check is that the car would have to be left over night to create a cold start in the morning for the tech to diagnose. If you have had this same problem and corrected it, please let me know how. Please no amateur guessers though. Thanks.

[oc350z]

I bought an new 08 last week and had a Nismo cat back installed prior to delivery. It is doing the same thing your car is doing, 2000RPM upon a cold start and goes to normal idle within a couple of minutes.

I'll call the dealer to see what they say and advise further.

[oc350z]

I bought an new 08 last week and had a Nismo cat back installed prior to delivery. It is doing the same thing your car is doing, 2000RPM upon a cold start and goes to normal idle within a couple of minutes.

I'll call the dealer to see what they say and advise further.

I just talked with the dealer and the master tech advised that it is normal for a new Z to rev between 1800 - 2100RPMs upon a cold start and then go to a lower idle after a few minutes.

I'm going to take it in on Monday to have them check the computer per his suggestion. He further advised that it would not be necessary to leave it overnight to replicate the issue since the computer settings will show if all is normal whether the engine is cold or hot.

I'll advise futher after they do the computer check.

[samej82]

yah it's normal i think... mine does the same..

[PerfectApex]

I appreciate your replys but why is this normal (as you state) when I never had the problem prior to adding the CAI and exhaust system? It seems like ALL after market stuff is JUNK and only degredates the cars reliability. Also it is NOT good for any engine to rev excessively high during a cold start. When I trade this in too I will NEVER add another after market piece of Shi: again to the new car.

[samej82]

Hmm good point.

My 07 Z revs to 1800 rpm or so even before I installed the Fujita SRIs... It'll hold there for a minute or so then drop down to regular idle at 600 rpms or so.

My 01 Sentra, with the SR20DE motor does the same thing on a cold start-up and then drops the idle down, and that has the OEM intake on it.

In my opinion it is because of the engine oil. I'm sure you're well aware that oil viscosity is thicker when it's cold than when it's warmed up. I guess the increased rpms on cold start is ensure there's adequate oil flow, into the cylinder. Next time your Z is starting cold take a look at the oil pressure gauge, you should see it pegged to the right. At least thats what happens to me in my Z.

Cars in itself are bad investments, that continue to depreciate in it's value, save for some special cases. Aftermarket component never really increase the monetary value of your vehicle, and if you think about it, it just speeds up the depreciation while you increase the cost of ownership for the car.

[Q45tech]

By DESIGN cold cranked cars rev to light the precats and cats faster........trade off to reduce emissions faster............trade 1st 90secs for less over first 10 minutes.Function of coolant temperature..................solved by installing external coolant heater and keeping car in heated garage.

[PerfectApex]

By DESIGN cold cranked cars rev to light the precats and cats faster........trade off to reduce emissions faster............trade 1st 90secs for less over first 10 minutes.Function of coolant temperature..................solved by installing external coolant heater and keeping car in heated garage.

Sounds good, so why then did my new Z only do this shortly AFTER I installed the CAI around 1500 miles? When I bought the car with 7 miles on it until 1500 miles, the car started normally with rpms around 800, even when cold. My new Mustang did the same thing but only after installing a CAI and other mods.

[samej82]

Sounds good, so why then did my new Z only do this shortly AFTER I installed the CAI around 1500 miles? When I bought the car with 7 miles on it until 1500 miles, the car started normally with rpms around 800, even when cold. My new Mustang did the same thing but only after installing a CAI and other mods.

I guess for you only to be sure it's the CAI causing it would be to replace the oem intakes and cold start the motor. I'm not sure what the difference would be if any though, since when you installed your CAI you installed it with the OEM MAF sensor, and the connected the crankcase vac line to the intake piping... right?

[PerfectApex]

I guess for you only to be sure it's the CAI causing it would be to replace the oem intakes and cold start the motor. I'm not sure what the difference would be if any though, since when you installed your CAI you installed it with the OEM MAF sensor, and the connected the crankcase vac line to the intake piping... right?

Thats a good idea but a hassle. And yes to your question. I might call Stillen where I got the CAI and ask them about this but doubt I would get an honest answer. Sales 101. Thanks for your input on this.

[oc350z]

I just talked with the dealer and the master tech advised that it is normal for a new Z to rev between 1800 - 2100RPMs upon a cold start and then go to a lower idle after a few minutes.

I'm going to take it in on Monday to have them check the computer per his suggestion. He further advised that it would not be necessary to leave it overnight to replicate the issue since the computer settings will show if all is normal whether the engine is cold or hot.

I'll advise futher after they do the computer check.

I went to my dealer this AM where the tech checked the computer and all was normal. Not being a believer, I asked if we could start a couple of 08 6 speed Z's that were cold. I started two myself and they both reved to 2k for a minute or so before they went to normal idle as mine does.

The tech further advised that the fast idle control is at the cats and a cat back exhaust would have no effect.

Maybe...... the reason it didn't do it until now on your car could be related to colder weather in your area causing it to go to fast idle upon start up. By the way, new Mustang GT's do the same thing at cold start as do Corvettes, the two other cars I checked out before I bought the Z.

Enjoy your car.

[Sympathy For The Devil]

An old adage in materials science says: "materials are like people; it is the defects that make them interesting".

My current 07' "Z" cold start 1100-1700 depending on outdoor tempMy old 87 "Z" (for 15 years) cold start 800-1500 depending on outdoor temp.

Both- retained a "normal idle" after 3-5 minutes after the allowance to regain normal operating temp of the materials that make a combustion engine a combustion engine.

[PerfectApex]

[QUOTE=oc350z][/QUOTE] oc350z, thanks a bunch for posting all this info. This is the type of reply I was looking for. Very thorough and informative. Just cant figure out why my 07 did not do this til after 1500 miles or so. Thanks again.