Jump to content
SAU Community

Effect Of Too Much Ignition Timing At Idle?

Rolls

By Rolls,
in Engines & Forced Induction

 Share

Recommended Posts

Rolls Grand Master

Rolls

Posted
Posted

I was wondering what would happen if your timing was 30 degrees at idle instead of the 15 base degrees?

I had an issue where on cold start the ECU (rb20det r32) would pull timing back to maximum retard making the car horrible to drive in cold weather. Pete from nistune adjusted the cold start ignition trim map to make them all 20s instead of 5 or something to fix my horrible cold start retard that made it undriveable, anyway my idle ignition is 30 degrees now when cold and slowly lowers to 15 degrees.

Now I am chasing around a weird idle problem where sometimes my car idles great and other times terribly and I am just curious what too much ignition timing at idle would do? I don't believe it is the issue but I'd like to just make sure.

I plan to get my own license and tweak things in the near future but for now I want to rule out a mechanical problem.

Would this make it harder for the AAC/ECU to control the idle speed due to more ignition?

Could an admin merge these two topics?

http://www.skylinesaustralia.com/forums/topic/401709-weird-idle-problem/page__pid__6399112__st__40#entry6399112

Also how does the nissan ECU control idle speed, as I unplugged my AAC and there was no change in idle speed, is it done via ignition/injector pulse or a combination of all 3?

Thanks.

GTSBoy Grand Master

GTSBoy

Posted
Posted

Idle speed if ONLY controlled by the AAC. It is of course AFFECTED by timing and mixture, but the only deliberate control is from AAC opening and closing. If you can pull yours without it affecting idle at all, then it is probably not working at all. And in fact, this would be one of the reasons for you having a crappy idle.

rob82 Mentor

rob82

Posted
Posted

Idle speed if ONLY controlled by the AAC. It is of course AFFECTED by timing and mixture, but the only deliberate control is from AAC opening and closing. If you can pull yours without it affecting idle at all, then it is probably not working at all. And in fact, this would be one of the reasons for you having a crappy idle.

Could just mean that it's close to the desired idle speed. If you increase the commanded idle speed you should see the aac duty increase.

Good luck finding the cold start retard - I think it's a static number in some ecu's.

ARTZ Grand Master

ARTZ

Posted
Posted

My AAC has been playing funny buggers too..has been cleaned..

If it's plugged in,(brown plug,purple is just ac isn't it?) it starts and idles fine, then soon as I drive it and stop, idle will bounce between 1500-2000...

Unplug it and idles (about 900rpm) and runs fine but of course now cold start is no good.. Have been just plugging it back in when cold to start it, which of course is annoying..

So quite obviously an AAC issue..not sure if it's mechanical or electric though..

Also not sure is it worth replacing AAC or just block it off and tune for cold start accordingly, or even considering just putting a switch inline to turn it off and on as needed..

I know it Probably doesn't help you much Rolls..just thought I'd throw it in here.. :)

GTScotT Grand Master

GTScotT

Posted
Posted

Mine originally had the same symptoms as yours ARTZ, Jez was able to play with some idle settings to fix it.

Later when I changed cams it came back.

I now leave the AAC unplugged and touch the throttle as I turn the key. Once its on (even when cold) it runs fine. It is annoying though, the car should run like magic (never has). Ill get all that fixed when the new motor is finished.

ARTZ Grand Master

ARTZ

Posted
Posted

If I try to start cold ( it has been very cold here lately) with it unplugged it won't idle..If I give it a heap of gas when I start it it may keep running..but starting at 3000rpm isn't a great idea...

It does run like magic if I plug it in and start it and it runs like magic when I unplug it and drive it..def something wrong with need another AAC to try, or just piss it off all together..

Rolls Grand Master

Rolls

Posted
  • Author
Posted

Good luck finding the cold start retard - I think it's a static number in some ecu's.

Oh Ive already found it, we zerod it all out and my car no longer drives like a sack of shit when cold. It is a 2d map from 0-2800 rpm, was pulling timing back to maximum retard when cold however I think now it is adding timing.

simpletool Mentor

simpletool

Posted
Posted (edited)

Idle speed is controlled by AAC only when hot.

Seems to be controlled with a combo of all 3 when cold (mine runs 35° timing at 20° C coolant for a 1100rpm idle).

For adjusting the idle my screw is about one full turn inside flush - something for you to go on. For cleaning it I found the Nulon upper engine cleaner works GREAT.

Edited by simpletool
rob82 Mentor

rob82

Posted
Posted

Idle speed is controlled by AAC only when hot.

Seems to be controlled with a combo of all 3 when cold (mine runs 35° timing at 20° C coolant for a 1100rpm idle).

For adjusting the idle my screw is about one full turn inside flush - something for you to go on. For cleaning it I found the Nulon upper engine cleaner works GREAT.

R33 are a different story. They have delta rpm ignition control which will add/subtract timing to control the idle speed.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
    • perry_r33
      R34 GTR Vspec Garage Sale - All must go!

      By perry_r33 · Posted

      Pm sent 
    • Robot
      Skyline v36 350GT sedan hunting on idle

      By Robot · Posted

      Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • GabsReDeal
      R32 GTS (RB20DE) Injectors Replacement

      By GabsReDeal · Posted

      After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
×
×
  • Create New...