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Thread: Rough, Unstable and sometimes high idle!

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2014-01-06 20:22:04
Rough, Unstable and sometimes high idle!
So i've been working with John on resolving this issue for sometime and have tried a number of things to resolve the problem.

I've tore down the intake manifold, cleaned the IACV and replaced all gaskets with new OEM ones

Checked for Vacuum leaks

Verified timing while in timing mode with Nemu SA and adjusted to 15* BTDC by setting to the second to last mark on the crank with timing gun

The only thing I have not done is block off my IACV to see if this fixes the problem to determine if it's a faulty IACV.

The problem I have had was a high idle, around 12-1300 rpm when my target was set at 1000 rpm.

Took fresh logs, now my idle is around where it should be but the car is running lean around 15-16 afr!

Here is the latest log i've taken:


Last edited by Jybfan04 on 2014-01-06 at 20-30-12.
2014-01-06 20:35:17
Sorry not able to check your logs at work. Have you verified the coolant temp sensor and maf are reading accurately/stable? I run leaner at idle

2014-01-06 20:57:53
The Coolant temp sensor appears to be fine, as the idle will drop from 2k rpms to close to the target RPM as the ECT temps drop.

Maf appears to be reading accurately/stable is there a way to test this?
2014-01-06 21:29:09
ok so you got the idle issue resolved? have you tried adjusting the screw on the iacv while the cars in timing mode?

as for the leaner afr, if it remains that way just adjust the cells in the map where it idles till you get the right afr..

winters the best time to set idle afr imo, the reason is the engine starts so cold you get to actually adjust most of the cells in the ECT trim table..

but first i like to set the afr while warm, say at night or last drive of the day, then the next am it'll be nice and cold.. i then adjust the ect trim table to further assist the afr so that it blends nicely from startup till its fully warm.
2014-01-06 21:42:14
I've been touching my car sooo sporadically that I wasn't sure if it was resolved or not...

But it appears that the high idle issue isn't a problem as much as it running lean now..

Before, I was testing to see if the high idle issue went away after disabling closed loop and it did but it would have lean afr's...

In closed loop, afr's were around 14.3-7 but high idle...

Closed loop disabled afr's were around 15-16 sitting around 1k which is what the target idle is set too..

I took a log on Friday and it was with closed loop enabled but my afr's were a little lean...

It idles kind of smooth but i'm sure it would smooth out with richer afr's...

So I wanted some direction in should I put it in timing mode and adjust IACV again or just richen out the fuel table cells where map trace sits?
2014-01-06 22:03:59
turn closed loop off an just tune the fuel map where its idling
2014-01-06 22:27:05
First problem I noticed is your final ignition is all over the place. Second, your ecu is not seeing neutral and therefore is not setting idle timing, this is related to your final ignition issue. Also, your knock voltages are really low on cylinder 2, 3, and 4. Another problem I am seeing is your idle error is set pretty low and your low idle error ignition map is causing your final ignition to be out of wack. Give me a few minutes and I will upload a new TCD for you to try. Your TPS voltage is also slightly high, it may not seem like it matters, but the idle recovery uses tps voltage to set idle timing.

Ive had all the problem you have had.
Last edited by ebinkerd on 2014-01-06 at 22-28-10.
2014-01-06 22:55:13
Thanks Lynch and Ebinkerd I gotta check that out!
2014-01-06 22:59:27
One thing before I put this new TCD together, is your PNP switch working? This is the switch on the transmission that tells the ecu is it in gear.
Last edited by ebinkerd on 2014-01-06 at 23-07-59.
2014-01-06 23:01:30
Psp is power steering you mean neutral switch
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