Author Topic: Idle wandering like crazy v7 ej207  (Read 1376 times)

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Offline Mason

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Idle wandering like crazy v7 ej207
« on: September 28, 2018, 08:30:37 pm »
Hey guys, I have a tune date booked for the forester and this issue popped up today. Only here because I don't want this to effect tuning

Started it with a semi warm engine (operating temperature, then parked for an hour and started again). The idle bounced between 400 to 1200rpm. Zero shuttering, it was actually very smooth and consistent and was almost constantly reving up and down.

I shut it down, let it sit for a bit and fired it up, no change. I limped it home. Nothing funny happened on the drive and it didn't happen while stopped at lights after I started driving. This happened once before about a month ago, but it was parked for a few days and it didn't happen again until today.

Details:
While warm the car idles at 400rpm like a dart.
While cold it idles at 1200 rpm like a dart
Iacv recently cleaned and gaskets replaced
MAF recently cleaned
Boost and vaccuum leaks recently fixed
 Tune needs updating due to changing of the dp and fmic. Car runs slightly rich right now.

With the temps and rpm ranges it almost seems like it is kicking from high idle to low idle repeatedly. Any thoughts on this? Things I should check?

Offline diamondedge

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Re: Idle wandering like crazy v7 ej207
« Reply #1 on: September 28, 2018, 11:42:18 pm »
Water temp sensor maybe? What's the temp needle doing?

400 is pretty low for warm. Should be more like 600-750.

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Offline Mason

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Re: Idle wandering like crazy v7 ej207
« Reply #2 on: September 28, 2018, 11:55:57 pm »
Water temp sensor maybe? What's the temp needle doing?

400 is pretty low for warm. Should be more like 600-750.

Nothing unusual with the temps guage. Fired up just under operating Temp and raised normally until fully warm.

I know that is super low, but usually it doesn't even give a blip while idling warm. Even my 2014 STI at 30xxx would wander slightly between the 600-700rpm range.

Could it be the tune? This only came up after doing that work, and I don't believe it idled that low when I purchased it.

I might try replacing the pcv as it's probably about time, and doing an idle relearn

Offline gf8wrx

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Re: Idle wandering like crazy v7 ej207
« Reply #3 on: September 29, 2018, 02:24:12 pm »
Have you tried resetting the ECU? I have had a 20g for 4 years and I notice when the weather changes from winter to spring and fall to winter my car idle hunts on cold start ups, and usually does this for 1-4 weeks then disappears as weather starts to become more winter like or more spring like. I've never had a issue other than when the seasons switch. I never really looked into it but I haven't had a major problem arise from it as of yet.

Offline scApegoAt

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Re: Idle wandering like crazy v7 ej207
« Reply #4 on: October 04, 2018, 11:27:59 am »
My v8 207 did something similar.  Check the tension on the throttle cables.  It should have just a bit of slack, no tension.  The ECU seems to have trouble compensating for a non-zero throttle position at idle.
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Offline Mason

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Re: Idle wandering like crazy v7 ej207
« Reply #5 on: October 04, 2018, 01:27:31 pm »
On this topic again with idling issues  >:( misread my rpm gauge, it idles at 700. Throttle body is completely closed. Little bit of slack on the cable. Haven't had time to reset ecu since last post and have only driven it once.

On that drive something even more strange happened.

 Drove around running errands for an hour and everything was okay until It sat at idle for maybe 5 minutes. Started to drive it and when the clutch was disengaged the car would Rev up 200-300 rpm and not fall until put into gear eg: disengage clutch at 3300 to shift from first to second, revs would climb to 3500 and stay there until clutch was engaged again. This made for some jankie gear shifts and did this 1-6 gear. Most of the drive home was highway and when I got back into town the car stopped doing this.

It has also developed a bad starting habit of not wanting to. Usually I let the guages swipe, wait a second, turn over, and it starts within the first couple cranks.

Once and a while on cold starts it will not catch 'properly'. It will crank for a little bit longer and then it will start slow and roughly. Once it is idling it is normal except the mentioned incidents. It use to do this when I first purchased it. I changed the fuel pump and it went away until until recently.


Offline darthekai

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Re: Idle wandering like crazy v7 ej207
« Reply #6 on: October 04, 2018, 02:26:01 pm »
Sounds like its a cable throttle not drive by wire, is it maybe sticking? When the idle hangs, try mashing the gas and letting off super quick and see if it changes.
This may effect startup as well, as its more difficult to start if youre letting too much air in.

This could also be caused by a boost/vac leak

My car has a hunting idle on cold starts as well all the time (not super relevant because standalong), its just trying to seek the target RPM but its overshooting. it cycles 3 or 4 times in about 2 seconds and then settles in.
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Offline Mason

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Re: Idle wandering like crazy v7 ej207
« Reply #7 on: October 04, 2018, 03:29:29 pm »
It previously had a few vacuum and boost leaks that were corrected and the idle never really did this.

It is Drive by cable. I did put the gas in while in neutral rolling and the rmps raised slowly and fell slowly back where they started (3500rpm) until back in gear. Throttle response was back to normal while in gear.

Again all this went back to normal after driving on the highway for a bit. If I get some time I'll clean and lube that cable and do an ecu relean. All that's free and we can go from there.

Some other thoughts are:

Fuel pressure regulator
Fuel check valve
Running double fuel filters (one in tank, one under hood)
A vac/boost leak that popped up recently

Offline darthekai

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Re: Idle wandering like crazy v7 ej207
« Reply #8 on: October 04, 2018, 04:12:37 pm »
Yeah could be pressures too high because of fpr but with dual filters I don't imagine it's super likely?

Try the free stuff, could be a learned timing trim but hard to imagine it would kick rpms up to 3k+...
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Offline Mason

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Re: Idle wandering like crazy v7 ej207
« Reply #9 on: October 04, 2018, 04:35:48 pm »
Yeah could be pressures too high because of fpr but with dual filters I don't imagine it's super likely?

Try the free stuff, could be a learned timing trim but hard to imagine it would kick rpms up to 3k+...

Doesn't kick up that high, just won't drop down unless iit was in gear driving??

The filter in tank I'd just one of those bag fliters like in this picture
https://www.amazon.ca/AEM-50-1215-E85-Compatible-Tank-320lph/dp/B016MWXRK4/ref=asc_df_B016MWXRK4/?tag=googlemobshop-20&linkCode=df0&hvadid=292925829318&hvpos=1o1&hvnetw=g&hvrand=6201341619282446497&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9001291&hvtargid=pla-494932870715&psc=1