westcoaststyle

B18C1 swap with unchipped P72 ECU.

I lowered my fuel pressure to try to get it to quit running rich and now (even after I've raised the pressure back up) when it's cold it idles way down to like 600RPMs and then back up to like 1800RPMs and back and forth - sometimes it even dies.

Even when it's at running temp. it still pulses in the idle from 7/800RPMs to 1200 RPMs.

Even stranger, sometimes after I've been driving the car for about 15-20 minutes it all of a sudden starts running super lean - so lean that it doesn't even show up on my air/fuel meter. When I'm cruising the power fades..... and catches back up.... and fades.... you get the idea.

If I turn the car off and back on, it's fixed. HELLLLPPP!!!!

I've thought vacuum, but I've checked them all... only thing I can think of could be a sensor.

Thanks!

1stGenCRXer

To me that sounds like either air in the coolant, or a fuel pickup/delivery problem.

westcoaststyle

if it were a fuel pickup/delivery problem what would I do to fix that? new fuel pump? I've been meaning to get one since I'm still running the D15B7 one on the B18C1...

1stGenCRXer

Yeah, new fuel pump and fuel filters, especially if that was on your list anyways it couldn't hurt. Do you have any way of monitoring fuel pressure while it does this fluctuation?

westcoaststyle

I guess I could look. I have the B&M in-bay gauge so when I first start it I could look at it. I'm running 40PSI when it's at normal op. temp. and I know stock GSR is 36 PSI, but I'm at 9.5:1 instead of 10:1.

Also, I have a brand new AEM filter, rail, Venom injectors, and B&M fpr.

westcoaststyle

bled the coolant today.. but doesn't seem to have made a diff...

westcoaststyle

still need some feedback....

inspyral

Make sure your TPS, IACV, and MAP plugs aren't interchanged. If you're sure they aren't, try cleaning out the IACV. If you have access to another Honda IACV that you know is working properly, swap it in and see if it solves the fluctuating idle. Of course you would have to make sure you don't have any vac leaks or air in your cooling system before tinkering with the IACV.

westcoaststyle

Where is the IACV? Got a pic? I'll look in my book and see if I can figure it out. I've checked my vacuum lines and it just started doing this so I don't think that I could have the plugs interchanged...

Thanks for the info man, I knew I could count on you.

inspyral

The IACV is on the back of the intake manifold. It has coolant lines running to it and a round plug that looks like the TPS and MAP sensor plugs.

It's #8 in this pic:

You can clean out the mesh screen filter with some carb/intake cleaner if it's dirty.