DC2 with B18C F.I. leans out.

I have a 94 DC2 motorized with a B18C and turbo.

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The car sat all winter with a half tank of 92 octane...while i added the HKS BOV, AEM FPR, and other mods. Driving it today, I noticed the A/F ration leans out after getting off the throttle, then returns back to about 14.0 while cruising. The A/F is around 10.5 or 11 while at idle. I also notice that after going from gear to neutral at a redlight, the RPM fluctuates from 100 to 1000 before coming to a normal idle. Sometimes it has died. I think the vacuum also changes from -19 to -15. I've checked all around for vacuum leaks. I'm going to get a spray bottle tomorrow and check really good again under the hood.

I've bled the coolant system using the bleeder valve
Checked my MAP sensor
Checked for vacuum leaks
Added octane booster and fuel cleaner along with a half tank of 92

I'll be getting a compression tester tomorrow to get numbers and will post them after.


Anyone else have any other suggestions as to what or how to fix either the leaning out or the RPM roaming at closed throttle before I go to get a tune the first week of May?

It's only at 10.5-11? Do you have a base map?

I would have to check the A/F numbers but it's something like that. I have the map from last year's tune. I think I remember seeing an option in my smanager for basemap by Honda engine.

Get that vacuum check done, maybe you have an intake or TB gasket leaking in vacuum but it holds at less vacuum and WOT.

Last year's tune needs to have IAT corrections for cold weather. Bump up the idle speed with the idle screw on the throttle body and youll be fine until your tune appt.

Your car's going to lean out when your off the throttle because the injectors stop firing.

Since last tune I have changed the BOV, fixed vacuum leaks, switched to a different B18C, installed the FPR, and hondata 4-Bar MAP sensor. With all this, is the car safe to drive...150 miles to my tuning guy or should I just rent a car dolley...which I want to avoid.

The FPR needs to be set to the same fuel pressure as before. And absolutely not with the MAP sensor. But you can switch out the MAP sensor on site. The other stuff is minor.