Severe Idle dips, HELP!!!
Apr 21, 2012, 09:50 AM
#1
Severe Idle dips, HELP!!!
Here is a vid I took awhile ago and its been doing this for prolly 6-8 months now at least. I know I am a base lancer but I am posting this here because I have not had any luck in my forums plus I am turboed using a tephra 9170715 (close maybe?) V7 rom. Also I am using an evo 8 turbo, evo 9 full intake (fmic, maf, piping, bov), I have been turboed for going on 3 years now and never had an idle (within reason considering) issue until this. There was no changes to my tune for quite sometime when this occured any ideas would be wonderful thanks
http://www.youtube.com/watch?v=mPiOx...uzV4kurGn2xZ8=
http://www.youtube.com/watch?v=mPiOx...uzV4kurGn2xZ8=
Last edited by 03lances; Apr 21, 2012 at 09:56 AM.
May 2, 2012, 04:09 PM
#3
Bump it up. No one has any ideas for me to try? I have done plenty to try to fix this. Put it this way i thought it would be easier to wait for suggestions and tell you if I have tried it instead of listing every single thing I have done in order to solve this. I have several logs trying to figure this out so I anyone is feeling froggy and wants to look them over I would be very thankful.
May 5, 2012, 12:04 AM
#6
Anybody have any thoughts on a Crank Sensor causing this? Its one of the few sensors I havent pulled, cleaned, or replaced. I will also throw out there that this ONLY happens after the vehicle is fully warmed up. It has never done this cold. Not only that the more of a "workout" I give the engine generally the worse the dips are when I come back to idle leading me to think heat is the dominant factor here.
May 5, 2012, 12:03 PM
#7
Never tought about that. I bought my car used and had to rebuilt the engine and transmission.
Engine wise the only remaing parts were block, accessories, head casting and valves, intake manifold, crank, cam, oil, knock and MAF sensors. Already changed both O2 and the issue is the same. My voltage when cold ranges from 13.9 to 14.0, and when hot drops do 13.6 and sometimes get as low as 12.8, making the engine trumble and stall. Couldn´t find a ground issue.
The ECU controls the alternator charging voltage. It´s just a guess but the problem could be on the ECU too.
Engine wise the only remaing parts were block, accessories, head casting and valves, intake manifold, crank, cam, oil, knock and MAF sensors. Already changed both O2 and the issue is the same. My voltage when cold ranges from 13.9 to 14.0, and when hot drops do 13.6 and sometimes get as low as 12.8, making the engine trumble and stall. Couldn´t find a ground issue.
The ECU controls the alternator charging voltage. It´s just a guess but the problem could be on the ECU too.
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May 6, 2012, 05:48 PM
#8
Thats a good point it could be the ecu itself. Im really leaning towards the crank sensor though since I've eliminated almost everything else. Anybody know if evoscan 2.8 correctly logs crank signal? Mine seems sporadic. It will have long periods of 1 then long periods of 0?? I've noticed though most of the time when it dips there is a change in the signal.
May 7, 2012, 09:59 AM
#10
Pretty sure load has an effect on this as well. I have these dips but of course when Im moving it does not dip in rpms or misfire or anything (under a load). Moreover though if the a/c clutch is engaged putting a load on the engine at idle it will not dip EVER. As soon as the a/c clutch disengages it will dip. Any thoughts or things I can try relating to this? Probably going to be a couple weeks until I can pull out my crank sensor. My garage currently has another rig I am working on in there, waiting to hear back from the tranny shop on that.
May 7, 2012, 03:41 PM
#11
Doesn't really sound like a crank sensor to me as putting a load wouldn't change anything with how the sensor reads, just a sensor reading off of a tone wheel. Have you checked base timing? Make sure you have no vacuum leaks as well, Try cleaning your iacv as well or swap in a known good one. you can also pull a plug and ground against the engine block and see if when it dips are you losing spark.
May 7, 2012, 04:09 PM
#12
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try checking the idle servo control ISC.
Does it stall when you turn on the AC?
Does it stumble on cold starts? On cold starts, does the idle raise to it's normal level or stay below 1000rpm?
if you answered yes to any or all of these questions, then you have a dirty or failing ISC.
Does it stall when you turn on the AC?
Does it stumble on cold starts? On cold starts, does the idle raise to it's normal level or stay below 1000rpm?
if you answered yes to any or all of these questions, then you have a dirty or failing ISC.
May 7, 2012, 09:45 PM
#14
Doesn't really sound like a crank sensor to me as putting a load wouldn't change anything with how the sensor reads, just a sensor reading off of a tone wheel. Have you checked base timing? Make sure you have no vacuum leaks as well, Try cleaning your iacv as well or swap in a known good one. you can also pull a plug and ground against the engine block and see if when it dips are you losing spark.
try checking the idle servo control ISC.
Does it stall when you turn on the AC?
Nope I have the a/c idle adjusted well no issues
Does it stumble on cold starts? On cold starts, does the idle raise to it's normal level or stay below 1000rpm?
Cold starts it fires right up not a hint of stumbling and hits around 1500 and slowly drops as it warms up
if you answered yes to any or all of these questions, then you have a dirty or failing ISC.
Does it stall when you turn on the AC?
Nope I have the a/c idle adjusted well no issues
Does it stumble on cold starts? On cold starts, does the idle raise to it's normal level or stay below 1000rpm?
Cold starts it fires right up not a hint of stumbling and hits around 1500 and slowly drops as it warms up
if you answered yes to any or all of these questions, then you have a dirty or failing ISC.
.Thanks alot guys for the input so far I am dying to get this resolved
May 7, 2012, 10:13 PM
#15
Heard ya, its pain in butt. I had similar idle issue with my previous car (350z SC). I tried everything i can do and end up took it to shop...they found i had clogged hfc, replaced with tp & removed utec and retuned with stock ecu and problem gone.