About a week ago I had the spark plugs replaced and also 1 ignition coil. When I got my car back the idle was running too high, 1000-1200 rpm. I took it back but after 4 hours the mechanic said he couldn't get it to reset the idle. He told me to take it to the dealer and have them reset it and he would pay for it. I took it to the dealer but after 4 tries they said they couldn't get it to reset and told me it was probably a vacuum leak or bad throttle body. So I go back to the original mechanic who assures me that he's checked for leaks and cleaned the throttle body.
So I try the reset by disconnecting the battery and pumping the brakes. It seems to have lowered the idle to around 1000 rpm, but it's still too high. I only left the battery disconnected for about 5 minutes, is that not long enough? Any ideas?
2003 Touring 6 speed

 

https://my350z.com/forum/engine-and-...procedure.html

would be the first thing I would try

 

^^ yup, he probably touched the throttle plate and threw the thing out of calibration.

 

I've tried that and it didn't work.

 

So how do I get the throttle plate re-calibrated?

 

by completing the steps in the reset link posted for you.
YOU MUST USE A WATCH W SECOND HANDS OR FIGURES.

It has to be dead on.

3 seconds, 7 seconds, more than 20 seconds all that good stuff.

 

I tried that procedure and it didn't work. I was very careful with the timing. Any other ideas?

 

Just joined your post late. Sorry.

Do you have any CEL codes?

I recently had a high idle that was not able to be set, after a new TB and MAF sensor the problem still existed.

Replacing the ECU fixed everything. I have an 03' with 90K on it. Mostly stock.

 

It keeps throwing code 507, idle air. I can erase the code but after driving it for a short while it goes on again.

 

I had the same code, P0507, but the idle was around 1100-1200. The tech tried to set the idle after replacing the throttle body, but couldn't. Not even with a computer. Several attempts were made with the 3 procedures recommended after a TB install for air volume and idle with no luck. The idle is controlled by an actuator in the throttle body, so start there. You may have to replace the TB, and the ECU.

The problem is, if your TB is bad it will damage the ECU over time.

The tech tried a reflash on my ECU first, but no luck. You should be able to find a new TB for $175 and a used ECU for like $300. Programming it will cost you another $200 though.

I'm not sure how a new coil and spark plugs would cause this problem, but who knows. Z's are pretty finicky.... You didn't do anything else recently to the car? Or clean the TB?

Let me know how it goes.

 

I went back to the original mechanic and he finally got the idle reset. He said it wouldn't reset until he pulled 3 ign. coil wires and it dropped down to around 600 rpm. Then he was able to run the procedure and the reset worked. Sounds strange but it's working good now.

 

I forgot to mention that trick! I'm glad it worked out. My new ECU and install was $500! It's running great now though...

 

replaced uppper plenums (oem-polished), took t.b. off w/out unhooking batt. cleaned butterfly etc...high idle, did relearns about 4 times, still came back, 1100rpm steady idle..P0507s....checked for leaks, gaskets, etc....frustrating bc i got idle down a couple hundred rpms....
answer for me...unhooked batt. last night for about a total of 14hrs, baby is back now, took round block to about 110mph...feels good, no rough idle etc.........well, im gona drive it all day tday an chk for sure, but it is a night/day diff from when i had prob...pretty sure shes fixed......GL to anyone who has this prob, id do the battery unplug overnight first before

 

^Hoping its fixed

 

ive been driving it all day, rolling w a buddy w a supercharged Porsche a little....I've put some miles on her, i think its resolved now. Id def say if u didnt unplug batt before u unplug TB harness, id try the overnight batt unplug for sure. Idk if that even works if u uunplug before, just from what ive read anyways. GL to anyone. Its def frustrating. Sure feels ggood knowing that its "RIGHT" now.