loping idle

[thevork]

p.s. I am just curious as to why the engine will speed up when I open the bov, not to revive any idiotic comments from earlier, but i am just curious

i tried to explain that in a post on the first page. I really think this is the case. if not people, please correct me.

Personally I think that the effect of opening the bov manually is that there is more unmetered air coming in and for a few seconds the idle rpm rises until the ecu compensates and brings it back down.

hope it makes sense...

 

[gotsomegetsome]

Sorry I am replying to this so late, Ive been away at school.

I fixed the vacuum leaks at the throttle body. Basically recirculated it back to the accordian pipe like stock settings. Re-did the wiring on the AFM just to make sure that my ground voltage was correct.

About the same thing is happening. Upon startup, engine idles fine. Once engine is warmed up, idle slows down to about 650 - 700 and AFR jumps to about 20. If I rich up the ARF using the SAFC2 to a value of 16 or even 18%, the engine starts to run way better. The only other leak that I can think of having about be at the BOV, but its brand new.


old thread: http://www.supramania.com/forums/showthread.php?t=102625&highlight=lean+at+idle&page=5

thanks guys

p.s. tryin to get this baby runnin so I can drive her daily, then sell my other car and buy a big honkin diesel truck

 

[3p141592654]

Could you provide the following info (I've put in what I could find from the previous posts):
1) AFM freq, AFR, and RPM at idle with BOV shut. (34-40Hz, 20:1, 650-700)
2) AFM freq, AFR and RPM at idle with BOV open. (?, ? ?)

Also measure Vf under those conditions.

 

[gotsomegetsome]

Could you provide the following info (I've put in what I could find from the previous posts):
1) AFM freq, AFR, and RPM at idle with BOV shut. (34-40Hz, 20:1, 650-700)
2) AFM freq, AFR and RPM at idle with BOV open. (?, ? ?)

Also measure Vf under those conditions.

Open:

AFR: ~15-16
RPM at idle ~750-800
I didnt look at afm freq just now because it was very difficult to do this with no help.

 

[3p141592654]

Would expect the opposite. It should run leaner with the BOV vented since unmetered air is entering the engine.

Is your intake stock? 40Hz is high for idle. Is there a filter on the end of the AFM?

 

[gotsomegetsome]

Would expect the opposite. It should run leaner with the BOV vented since unmetered air is entering the engine.

Is your intake stock? 40Hz is high for idle. Is there a filter on the end of the AFM?

No my intake is completely not stock. Turbo is stock ct26, rest is 2.5" aluminum 6061T pipes, silicone couplers. All tightened and checked. Unless there is a boost leak that is small enough that I did not detect it, then I dont know what to say. There is a filter at my AFM but it is a high flow filter.

and there is an a2w intercooler. but its a basic setup: filter-> afm-> piping-> turbo-> piping, intercooler, piping, throttle. etc

 

[kotu100]

im still gonna lean toward a small leak in the intake tract somewhere after the AFM.
that would make the car run leaner at idle cuz some air would make it into the engine unmetered causing a lean condition. do you still have the stock accordion hose going to the turbo? these can get cracked and cause a vac leak.
Another thing that could cause the problem is the AFM itself, whether it be bad electronics (maybe someone tried to clean it) or maybe the plug.
have someone sit in the car and watch your Kar numbers on the safc, while you go and wiggle the AFM plug.
good luck!

 

[3p141592654]

Given the AFM is reading more air than typical, I think we can rule out an intake leak, especially since introducing one (with the BOV) improves the idle.

Do you have a fan shroud on? Air buffeting the AFM can cause it to give unreliable readings, especially at idle, although the filter usually is enough to mitigate this.

By the way, did you check for codes as someone asked earlier and what is Vf doing?

 

[gotsomegetsome]

In that case I'm gonna get some stuff to replace that accordian hose. Its been nothing but trouble and not a pretty sight.

And no I took off the fan shroud because it was cracked.

Given the AFM is reading more air than typical, I think we can rule out an intake leak, especially since introducing one (with the BOV) improves the idle.

Do you have a fan shroud on? Air buffeting the AFM can cause it to give unreliable readings, especially at idle, although the filter usually is enough to mitigate this.

By the way, did you check for codes as someone asked earlier and what is Vf doing?