_Matt

Nissan v8 idles high until turned off and on

Recommended Posts

52 minutes ago, Grotty said:

not a stepper motor, did you test on the bench after cleaning it?

No I didn’t, but I did change the throttle body to a whole different unit which included another idle valve. The new one looked to be in better condition on the inside. Would of thought there would of been a slight difference on how it runs after changing the TB, if the issue was somewhat related to that. 
Will pull it off and check though. I will also check what voltage it’s receiving during different times. 

Share this post


Link to post
Share on other sites

Have swapped in another ecu and it has made no change. Have also had the idle valve unplugged for a while and it is better, sits somewhere around 600-800rpm pretty much all the time now. Just doesn’t like starting when cold that much. 
Blocking off the idle valve inlet kills the engine, so I assume that means no air is coming from anywhere else.
Voltage from the ecu to the idle valve solenoid is 12v and decreases when revving, which is weird because it should be 6-7v when cold and 7-10v when hot. 
Had a thought the temp sensor could be bad but that is outputting the correct voltage. 
No idea what else to check!

Share this post


Link to post
Share on other sites

Try putting the MAF in a longer pipe if you can. Or even just try rotating it relative to the bend after it.

MAF turbulence is a real ball buster and idle/low load is where it makes the most trouble.

See if you can borrow a factory airbox to test fit even if just for idling.

Share this post


Link to post
Share on other sites
1 hour ago, Roman said:

Try putting the MAF in a longer pipe if you can. Or even just try rotating it relative to the bend after it.

MAF turbulence is a real ball buster and idle/low load is where it makes the most trouble.

See if you can borrow a factory airbox to test fit even if just for idling.

Cool thanks, will check it out tomorrow! There is a slight pie cut bend right before the airflow meter, so maybe that’s causing an issue

  • Like 1

Share this post


Link to post
Share on other sites
22 hours ago, thegreatestben said:

@Roman was it you who made that air flow straightener years ago out of party straws?

Nah not me. But I had an absolute wanker of a time by not having the right MAF housing. The factory airbox made more power than anything else I had tried and car ran heaps better. Not because it was magic, just kept the MAF getting the right signal.

Which reminds me @_Matt with a MAF remember its expecting all air to be metered from the maf, if you have setup a catch can it can act like a partial air bypass which can stuff things up too.

Share this post


Link to post
Share on other sites
18 minutes ago, Roman said:

Which reminds me @_Matt with a MAF remember its expecting all air to be metered from the maf, if you have setup a catch can it can act like a partial air bypass which can stuff things up too.

Thanks, no catch can or anything that bypasses the afm. 
Gave the afm and pod filter a clean and rotated the afm around 90° so the sensor is upright. Maybe made a slight difference, will see what happens in the next couple of drives. The signal from the afm was pretty consistent at 1.08v at idle. The pages from a manual say it should be approx 1.1v. 
Another thing is when I give it a little rev with the icv plugged in, it will drop down to about 1000-1200rpm and then take a few seconds to drop further to 800rpm. With it unplugged it goes straight down to 800rpm. Unsure if that’s related in some way?

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.