rb25 idle problem running rich

[lazyeyes13]

My 91 s13 with a s1 rb25 is running very rich. It has a greddy intake, a fmic, a q45 throttle body, and a walbro 255 pump. When I first start it up the idle is fine, then I will rev it up and when the rpms come back down the idle will get very low, almost die (sometimes does die), and then just fluctuates from really low to normal idle. Anyone have any idea why its doing that???

[lazyeyes13]

anyone????

[Largekid]

Does your BOV release to atmosphere? I betting thats the issue, or there is a vacuum leak somewhere.

[lazyeyes13]

No I'm pretty sure my bov is recirculated...theres a hose coming off of it running back to the intake manifold (greedy)

When I rev the engine up and it comes back down it has trouble catching itself, I have to feather the gas to keep it running... and whenever it does this is runs really rich (black smoke coming from exhaust)

Im going to double check timing and adjust the idle and hopefully that'll do it!!

Any other suggestions guys??? Any help is greatly appreciated!!!

[Darius]

No I'm pretty sure my bov is recirculated...theres a hose coming off of it running back to the intake manifold (greedy)

When I rev the engine up and it comes back down it has trouble catching itself, I have to feather the gas to keep it running... and whenever it does this is runs really rich (black smoke coming from exhaust)

Im going to double check timing and adjust the idle and hopefully that'll do it!!

Any other suggestions guys??? Any help is greatly appreciated!!!

Check the IACV underneath the intake manifold. The screw on it should be screwed all the way in and backed out about 1/2 turn. Also, it sounds like the system is not air tight so you should do a pressure test on your piping to make sure there isn't a vacuum/boost leak.

There should not be a hose running from the BOV to the intake manifold unless you are talking about the boost reference line. The BOV should recirculate back to the turbo intake pipe downstream of the MAF sensor.

[lazyeyes13]

Isn't there a certain procedure for adjusting the IACV? I think I read somewhere you have to get it to operating temp, unplug TPS, then set it
Does that sound right?
Also I was reading the fsm and it was saying something about and idle set screw on the ecu too??

And for the bov, I'm not sure what the line running to the intake manifold is for..
I'll post some pics of it

I'm in the process of rewiring my cooling fans, so whenever I get that done I'll set the IACV and check for leaks

[Darius]

No, that's for setting the timing. Warm engine and TPS unplugged. The screw is a peak air inlet adjustment and a valve modulates inside the IACV to fine tune the air being let into the engine. If the screw is open too far, the valve won't be able to pinch down enough and the idle will surge up and down. Screw is turned in too far and it probably won't stay running after starting.

I'm 99% sure there is not an idle control set screw on the ECU.

Pics of the BOV would be helpful.

[lazyeyes13]

Oh ok and yeah I'll take some pics and post them here soon

[USMCgetsome]

darius bro i'm surprised you forgot you can adjust idle by that potentiometer on the ecu that helps check the codes/errors on the ecu. Check the fsm it tell you how to adjust it from that screw as well. but mostly set on iacv.

[lazyeyes13]

/Users/rb25det_collin/Pictures/iPhoto Library.photolibrary/Previews/2014/04/01/20140401-205310/00bmYk46TdajOzbgS+ymiQ/IMG_3128.jpg

/Users/rb25det_collin/Pictures/iPhoto Library.photolibrary/Previews/2014/04/01/20140401-205310/Q7rhMIQ0SB+Gffi+kKrGIA/IMG_3129.jpg

/Users/rb25det_collin/Pictures/iPhoto Library.photolibrary/Previews/2014/04/01/20140401-205310/OlFNMmwbRFOWgcqUcDV3kQ/IMG_3131.jpg

theres some pics of the bov and the rubber hose I was talking about runs to the back side of the intake manifold near the iacv

how should it be setup properly??

[lazyeyes13]

well dang haha let me actually upload those pics..

[Darius]

darius bro i'm surprised you forgot you can adjust idle by that potentiometer on the ecu that helps check the codes/errors on the ecu. Check the fsm it tell you how to adjust it from that screw as well. but mostly set on iacv.

Ha! You learn something new each day. I never had to adjust my idle on the stock ECU. The knob was always turned all the way left and the IACV screw adjustment was set per the FSM so it didn't need any further tweaking. After reading the FSM, it sounds like the knob on the ECU is more for fine tuning with maximum adjustment of up to 250 rpm by turning it 3/4 turn to the right.

[lazyeyes13]

Hey Darius could I get your email or something so I can send you those pics?