on my honda crx b16a1 edm 1991

my engine on idle and if i press on the gas fluctuates 200/300 RPM

COLD don't fluctuates
hot engine fluctuates 30 seconds after starts running ( the first 30s when is hot don't fluctuates )

I've done:

-IACV-
clean 2 times, i close the IACV and engine still fluctuates

-FITV-
clean 2 times, i close the FITV and engine still fluctuates

-vacuum system-
the vacuum system was verified with proper gun, and check the tubes, tube are like new
check with proper smoke equipment (smoke will emerge on leaks)
test it with carburettor cleaner

-PCV valvule-
replace for a new one from HONDA

-TPS-
tested 3 - all tuned to 0.45v open , 4.55V closed

-TB-
clean and tested 2

-IAT-
temperature sensor admission was clean

-Bleeding Air In Cooling System-
done several times

-ECU-
tested 2 stock ECUs

-injectors-
4 hours ultrasonic cleaning

-LAMBDA
installed new two o2 sensors DENSO DOX-0125

-valve lash
in 0.15mm
ex 0.20mm

-ignition timing
15 deg.

-engine timing
its ok ( set properly )

-cams are proper alignment

-compression check
cylinder 4 - 11.5
cylinder 3 - 12.5
cylinder 2 - 11.5
cylinder 1 - 12.5

-spark plug wires-
3 sets tested (2 used, 1 new NGK)

-spark plug-
tested 2 sets (NGK BKR6E-11 - 5304 Denso Iridium IK20)

TESTS with STRANGE results

if i unplug the TPS, engine dont fluctuates
if i unplug a spak cable (any one) and plug again engine stop fluctuating
if i unplug the TWO o2 sensors or remove it on REPRO engine dont fluctuates




what more can i do ?






i decide to change my ecu pw0-x00(obd0) to obd1
so, i made this changes.

-b18c4 exhaust manifold
-p28 ecu (chipped with p30 map)
-td-86u dizzy with obd1 plugs
-4 wires o2 sensor

and now with o2 sensor enable i dont have fluctuating idle

THANKS TO ALL !!! for helping

 

What kind of gauge cluster is that?

 

do you have more pictures of your car?

 

S2000 ap1 cluster

 

did this today, and didn't solve my idle problem

-valve lash
in 0.15mm
ex 0.20mm

-ignition timing
15 deg.

-engine timing
its ok ( set properly )

-cams are proper alignment

-compression check
cylinder 4 - 11.5
cylinder 3 - 12.5
cylinder 2 - 11.5
cylinder 1 - 12.5

 

Was the car originally DPFI and converted to MPFI when the B16 and the B16 has never ran properly?

 

my car é CRX EE8 1991, come with b16a1 from factory,

i did not change nothing

 

my ecu is obd0 pw0-x00

 

Did you check if there are leaks in your intake manifold and your throttle body gaskets? However if you unplug the tps and it stops fluctuating that may indicate something in the tps sensor itself. You can pull out the tps sensor from the throttle body and see if the tps gasket is all worn out. You can try to clean out the old gasket off the sensor and throttle body and use a little honda bond or another gasket to see if that helps

 

-the vacuum system was verified with proper gun, and check the tubes, tube are like new
-check with proper smoke equipment (smoke will emerge on leaks)
-test it with carburettor cleaner

i have no leaks

i tried 3 TPS... 2 used ans one NEW

 

i made other approach...

i decide to disable the first oxygen sensor on the ECU ( on BRE )

idle problem solve, with 1st o2 sensor DISABLE and 2nd O2 ENABLE

(i think thats why the idle start after 30s, because is when ECU starts making adjusts on AFR)

do i have the 1st o2 sensor defective ?
my ECU gives me NO errors

is normal to have a defective sensor with no ECU error ?
could be a exhaust manifold leak ? a leak on 1st o2 sensor hole ?

just cleaning solves the problem ?

EDIT:
find out that the second o2 sensor had the wire cut, i replace the second o2 sensor but didnt fix my fluctuation

 

Just some questions to consider:

Have you removed the aluminum shroud to check under the manifold to check for leaks or cracks?
Does your exhaust manifold make a complete seal?
Have you tried taking a wire brush to the manifold and the side of the engine where it comes together?

 

the first 2 questions is what i'm gonna to see next, i'm just waiting for a o2 senser #1 to test

i didnt understood the " Have you tried taking a wire brush to the manifold and the side of the engine where it comes together "

 

Sorry for the confusion. I was referring to cleaning the mating surfaces - of the exhaust manifold and side of the engine - off really well and making sure a tight seal is made.

The manifold side (where the gasket goes) looks quite rusty. Maybe it is not making a seal. Probably a stupid question, but do you use a gasket with it?

 

my exhaust manifold is stock with stock gasket

next Saturday (day 7) i will test other o2 senser , and will look that manifold side

 

replace the second o2 sensor (for a used one), and didnt solve my problem

and i removed the aluminum shroud to check under the manifold to check for leaks or cracks, and nothing

 

Does it only fluctuate when idling or does it do this when you press on the gas to hold it around maybe 1,000 or so RPM?

I know some of these things you already checked

- vacuum leak
- vacuum leak in hose going to MAP sensor or MAP sensor faulty
- Main O2 sensor
- IACV is dirty or faulty
- FITV needs to be opened, cleaned, tightened up, and thoroughly checked

Skip to about 2:00 for 2 things many people miss

 

Your first post requires the addition of car information. If this information is missing, I'll close your thread. Edit your first post.

 

done, sorry

 

find out that the second o2 sensor had the wire cut, i replace the second o2 sensor but didnt fix my fluctuation
if i unplug or disable on repro the two o2 sensors my engine don't fluctuates

does fluctuates when i press the gas at 1500rpm or 2000rpm ..... fluctuates a little less, but fluctuates

- vacuum leak
(checked several times with proper gun, and with a machine that pumps smoke to the IM and checked with carburettor cleaner)

- vacuum leak in hose going to MAP sensor or MAP sensor faulty
(my smoke from muffler is white, bad MAP equals to black smoke, right ?)

- Main O2 sensor
(didnt done this, i will check the voltage like the manual says to check)

- IACV is dirty or faulty
(clean 2 times, i think is working good i ear the "click" when closes, and on the first video i close the IACV hole and still fluctuates)

- FITV needs to be opened, cleaned, tightened up, and thoroughly checked
(done this 2 times, cleaned and tightened up, and i close the FITV and still fluctuates )

 

here a video testing the o2 sensors voltage

 

You have white smoke coming out your exhaust?
That's usually a sign of water getting into your combustion chamber from a blown headgasket.
When you did your compression check, did you remove one spark plug, test the cylinder, replace spark plug? Or did you remove all the plugs, test all cylinders, replace all plugs?

White could also be too much fuel. The smoke usually has a blue tint to it, but not always.

Problems with the PCV system can give you idle issues that act like a vacuum leak. Use an Honda OEM PCV if you decide to change it out. Aftermarket versions are not built as well.

 

dont remember, i think was remove all the plugs, test all cylinders, replace all plugs

my PCV valvule is new, forgot to mention that, its OEM from HONDA

i will see my smoke... and see if is WHITE or BLUE

thanks a lot for the TIPS

 

Good if you removed all plugs. Some headgaskets fail in between cylinders so if you don't pull all the plugs you end up reading the pressure from the adjacent cylinder.

 

any more things to do ????