yeahd00dshaun

Hey guys just did my first swap recently. I put a b20b into my crx. I've got it running and it seems to be hesitant and misfiring or back firing from 2k to 3k rpms. It just suddenly stops and you can feel it pull a little harder as soon as it hits 3k. This is happening while just driving the car normally. When its a WOT I can still notice it but it also vibrates and shakes between 2.5k and 3k rpms in 1st, 2nd, and 3rd gear. Almost like a bad alignment but it only happens between "said" rpms. After 3k rpms it feels normal and vibrations go away. It does not vibrate when in 4th or 5th gear under heavy accelleration but still has the hesitation and misfire or back fire.

I also noticed that it smells almost like its running rich, but I can't quite determine what the smell is. I am using a test pipe instead of a cat, could this cause the exhaust fumes to smell funny? I seem to use more fuel now but I expected that because the b20 doesn't get as good mpg's as the d16.
Not sure if its related to my problem but just something i noticed.

I am using a stock b20b fuel map on a chipped p28 and I have no codes at all.

So this is what I've done so far.
-clean IACV and FITV (had rough idle)
-checked for vacuum leaks
-checked mechanical and ignition timing (both are good)
-checked plugs (looked dark white or greyish)

Things to do
-Compression/Leakdown test
-check fuel pressure
-tune up (I did not change plugs,cap,fuel filter, etc.)
-Listen to Honda Guru's

SpeedOFsmell

take a video of this thing, sounds really odd.

m4xwellmurd3r

try new spark plug wires if you havent already. I had a horrible misfire caused by my wires arcing between each other

And I only missed at lower rpms. At abover maybe 3k it cleared up

blackeg

leak it down too. not to anticipate the worst but those motors have a tendency to burn up exhaust valves and that could make it run crappy in the low rpm.

also some b20 maps ive seen have lots of timing around 2700 rpm which is odd because the motor has a need for fuel right there. the ls/b18b timing map may be better suited just saying

EddyNN

Hi guys, just registered.
I was wondering if Shaun ever found the cause of this issue.
I am experiencing the same problem, while running a similar setup.
US B20B in a 91 EF. Running P28 with a stock CRV fuel map.
B16 fuel rail and FPR.DA LS Intake manifold. DC 4-2-1 headers, 2.25in piping with test pipe.

When I did the swap I put in a new Honda IACV which is still running fine.
I ran stock b18b map before, change to b20 map made the engine run smoother across rpm range, and reduced the hesitation effect around the 2900RPM. But the problem persists.
I noticed this happens only after the car has warmed up. I found out after oversleeping a few times and taking off after only a minute or so of warm-up time, it behaved just fine until it warmed up completely.

In an effort to isolate the problem I did the following:
Checked mechanical and electronic timing.
Changed fuel filter.
Changed ignition wires and spark plugs.
While doing other maintenance I also changed out the distributor housing, rotor and cap(all Honda OEM).
To fix a slightly bouncy idle while warming up I did FITV delete.

I noticed this effect is stronger when the gas tank is below 1/4. But it still happens when it's full, so not sure about that one.
I considered changing the FPR to the one the 98 CRV uses(slightly higher pressure I hear) but haven't done so yet, something more important always comes up for me to spend my free coin.

And one last note, a long time honda/toyota dealer mechanic suggested I install a cat, but I considered it a pricey attempt at a fix since I don't need it for smog check (will never pass anyway).

EddyNN

I know this is a long-dead thread but I figured a followup would help people with this, or similar issues. I fixed my hesitation problem by changing out my O2 sensor with a good quality Denso unit.

The computer was not throwing a code for O2 but I had read that O2 sensor could cause this and not throw the code.
So before spending the money I tested the resistance on sensor's heater circuit and it was way below the service range(it was below 5 Ohms, and it's supposed to be between 10 and 40 ohms. The replacement unit had 15 Ohms resistance.)

If anyone wants to know where I got my bad O2 sensor that was less than a year old(and never worked right), I got it from Rywire.