RPM dip while in neutral?

fuct · 05-21-2013, 01:12 PM

Ok after 3 years of ownership Ive finally made a thread about my RPM's that dip once i put the car in neutral at stop lights.

heres the situation:

car is at normal operating temps. AC is on but not blasting. Weather outside is hot and humid. im driving along like normal and come up to a stop light. i stop at the light and put the car in neutral while i wait for the light to change. as im waiting there my RPM's will dip from the normal 750 to just under 500 and go right back to 750.......

is this normal?

ive recently had my fuel pump changed out after it quit working on me a few months ago. the dipping RPM's happened before and after the fuel pump change so i dont believe it is fuel pump related. during the fuel pump change i also put in a brand new battery. also i cleaned out and re oiled my K&N air filters around that time too. (i made sure not to over oil and i cleaned the MAF sensors with electrical cleaner a week after the filters were cleaned just in case they were dirty)

any one have any ideas?

wheee! · 05-21-2013, 01:18 PM

Manual or automatic trans?

fuct · 05-21-2013, 01:22 PM

Quote:

Originally Posted by wheee!

Manual or automatic trans?

manual

wheee! · 05-21-2013, 01:42 PM

I have seen this happen at different times with my manual too, but never thought much about it... more or less a self check/correction...

Mitco39 · 05-21-2013, 01:52 PM

AC kicking in and out is my guess. Mine does it. Even though the AC is on it will cycle. Back in my truck racing days we had to pull the AC fuse to keep it from coming on (even when it is off on the dash) and I would bet the same is true for these cars.

KeVoH · 05-21-2013, 02:09 PM

I have the same issue.. Many people told me that it could be a vac leak, but I couldn't find anything. Sub'd for answers.

My Z info : Manual Base/Sport, Mods : CBE and CAI.

Mitco39 · 05-21-2013, 02:12 PM

Try pulling the AC clutch relay and see if it stops. Easy way to eliminate that possibility.

fuct · 05-21-2013, 02:20 PM

hmm thx guys for the answers so far!

stewarts2008 · 06-20-2013, 06:41 PM

i had this on my mustang too. It happens with some tunes. I spent days trying to track down vacuum and boost leaks and found nothing. Are you running a tune? stock tune? Maybe unplug battery for a while and let it learn idle again?

red2010z · 06-20-2013, 06:46 PM

I had this happen I took my sensors out of my CAI and cleaned them and everything after that was gravy.

edub370 · 06-21-2013, 09:16 AM

same thing happens on my car. rpm's dip about 300 or so for a second or 2 then the car recovers. mine has done it with the ac off as well. only noticed it after i was tuned

JARblue · 06-21-2013, 09:27 AM

I had the same experience as edub in that it started after I got a tune: idle RPM is around 700 but occasionally dips below 500.

I'm going to clean my throttle bodies at some point this summer and see if that makes a difference. Some people claim they have smoother idles after cleaning them.

05-21-2013, 01:12 PM	#1 (permalink)
fuct A True Z Fanatic Join Date: May 2009 Location: Sugar Land Posts: 3,692 Drives: 97' Ranger :) Rep Power: 24	RPM dip while in neutral? Ok after 3 years of ownership Ive finally made a thread about my RPM's that dip once i put the car in neutral at stop lights. heres the situation: car is at normal operating temps. AC is on but not blasting. Weather outside is hot and humid. im driving along like normal and come up to a stop light. i stop at the light and put the car in neutral while i wait for the light to change. as im waiting there my RPM's will dip from the normal 750 to just under 500 and go right back to 750....... is this normal? ive recently had my fuel pump changed out after it quit working on me a few months ago. the dipping RPM's happened before and after the fuel pump change so i dont believe it is fuel pump related. during the fuel pump change i also put in a brand new battery. also i cleaned out and re oiled my K&N air filters around that time too. (i made sure not to over oil and i cleaned the MAF sensors with electrical cleaner a week after the filters were cleaned just in case they were dirty) any one have any ideas? Last edited by fuct; 05-21-2013 at 01:18 PM.

05-21-2013, 01:18 PM	#2 (permalink)
wheee! A True Z Fanatic Join Date: Sep 2009 Location: Mod Capital of Canada Age: 58 Posts: 7,354 Drives: cars. lots of cars. Rep Power: 40182	Manual or automatic trans? __________________ H&R / Stillen / Berk / HKS / Swift / Michelin / UpRev / SPC / Amuse Rep / Seibon / Fringe XVO / TWM / more... My Journal

05-21-2013, 01:42 PM	#4 (permalink)
wheee! A True Z Fanatic Join Date: Sep 2009 Location: Mod Capital of Canada Age: 58 Posts: 7,354 Drives: cars. lots of cars. Rep Power: 40182	I have seen this happen at different times with my manual too, but never thought much about it... more or less a self check/correction... __________________ H&R / Stillen / Berk / HKS / Swift / Michelin / UpRev / SPC / Amuse Rep / Seibon / Fringe XVO / TWM / more... My Journal

05-21-2013, 01:52 PM	#5 (permalink)
Mitco39 A True Z Fanatic Join Date: Aug 2012 Location: Edmonton Alberta Canada Posts: 2,089 Drives: 40th 370z Rep Power: 132	AC kicking in and out is my guess. Mine does it. Even though the AC is on it will cycle. Back in my truck racing days we had to pull the AC fuse to keep it from coming on (even when it is off on the dash) and I would bet the same is true for these cars. __________________ 2007 Chevy Duramax - EFILive Tuned By Me 2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her My Build --> http://www.the370z.com/members-370z-...39s-build.html

05-21-2013, 02:12 PM	#7 (permalink)
Mitco39 A True Z Fanatic Join Date: Aug 2012 Location: Edmonton Alberta Canada Posts: 2,089 Drives: 40th 370z Rep Power: 132	Try pulling the AC clutch relay and see if it stops. Easy way to eliminate that possibility. SouthArk370Z likes this. __________________ 2007 Chevy Duramax - EFILive Tuned By Me 2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her My Build --> http://www.the370z.com/members-370z-...39s-build.html

05-21-2013, 02:09 PM	#6 (permalink)
KeVoH Base Member Join Date: Jan 2012 Location: Puerto Rico Posts: 239 Drives: 11 Nissan 370Z SP M6 Rep Power: 14	I have the same issue.. Many people told me that it could be a vac leak, but I couldn't find anything. Sub'd for answers. My Z info : Manual Base/Sport, Mods : CBE and CAI.

05-21-2013, 02:20 PM	#8 (permalink)
fuct A True Z Fanatic Join Date: May 2009 Location: Sugar Land Posts: 3,692 Drives: 97' Ranger :) Rep Power: 24	hmm thx guys for the answers so far!

06-20-2013, 06:41 PM	#9 (permalink)
stewarts2008 Base Member Join Date: Jun 2012 Location: Memphis, TN Posts: 24 Drives: 2010 370z Rep Power: 13	i had this on my mustang too. It happens with some tunes. I spent days trying to track down vacuum and boost leaks and found nothing. Are you running a tune? stock tune? Maybe unplug battery for a while and let it learn idle again? __________________ 2010 370z Touring \| K&N Typhoon 2013 Mustang 5.0 \| 650 rwhp (sold) 2011 Mustang V6 \| 270 rwhp (sold)

06-20-2013, 06:46 PM	#10 (permalink)
red2010z Track Member Join Date: Apr 2013 Location: Texas/North Carolina Age: 39 Posts: 587 Drives: '10 Red B/S/M Rep Power: 14	I had this happen I took my sensors out of my CAI and cleaned them and everything after that was gravy. __________________ AGENCY K&N SWIFT CSF EVO-R VOSSEN MICHELIN Z1 JVC ZENCLOSURE JLW3 JVC

06-21-2013, 09:16 AM	#11 (permalink)
edub370 A True Z Fanatic Join Date: May 2011 Location: KCMO Posts: 3,458 Drives: 09 370z S/T 6MT Rep Power: 20	same thing happens on my car. rpm's dip about 300 or so for a second or 2 then the car recovers. mine has done it with the ac off as well. only noticed it after i was tuned __________________ 09 370Z ST 6MT//Injen CAI//Greddy CBE//TP//TSW's//Swifts//Stillen lip//Whiteline sways 326whp/268tq

06-21-2013, 09:27 AM	#12 (permalink)
JARblue A True Z Fanatic Join Date: Mar 2011 Location: Austin, TX Age: 44 Posts: 36,450 Drives: 11 Z34, 98 E36 M3 Rep Power: 2684441	I had the same experience as edub in that it started after I got a tune: idle RPM is around 700 but occasionally dips below 500. I'm going to clean my throttle bodies at some point this summer and see if that makes a difference. Some people claim they have smoother idles after cleaning them. __________________ 2011 370Z 6MT Sport Gun Metallic \| ARC \| CJM \| Ecutek \| FI \| Fujimura \| R2C \| SPL \| Stillen \| TWM \| Z1 \| ZSpeed \|

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