Help Plz - D16Y1 Running so rich the engine floods

[lil vito]

Hi guys,
First post, but i have lurked for a while before registering...

Anyways, a little background on my problem.

Have a 1994/5 Honda Civic Vti with a D16Y1 engine.
(I believe the D16Y1 is almost identical to the D16Z6 after reading the service manual end to end)

About a week ago, started having some major issues with it.

2 main problems are:

1) Erratic Idle - up and down between 400 and 1500 RPM

2) Runs extremely rich - if running from a cold start, will spit fuel out the exhaust after a minute or two of running, along with black smoke, at which point the engine starts to really struggle, until it finally dies. (I believe at this point the engine is flooded as I then need to leave the engine off for 10-20 minutes before it will fire again)

The check engine light does not come on, and the ecu has no stored error codes.
I can confirm the ecu is working correctly, as I disconnected the IACV sensor, then attempted a start, which then caused the ECU to report a fault with the IACV.

Essentially, I cant keep it running for more than 3 or 4 minutes.

Approximately 6 weeks ago, i took it to an exhaust shop, to have a 2" exhaust fitted, from the cat back. (Still has an oem cat, awaiting me getting funds together for a high flow.)

----------------------------------------

I think I have solved the first problem (Erratic idle)
I removed the Throttle body and IACV completely, and cleaned them thoroughly with TB Cleaner.
I removed the Fast Idle Valve (FITV), dismantled it, and cleaned it thoroughly also.

After putting everything back together, the idle is around 800rpm, and holding steady with no accessories, and a touch over 1000 with the aircon and headlights on.
There is also less smoke from the exhaust, but still spits fuel after a minute or so.

But the car is still running just as rich, and stalls out just as quick as before.

I cannot find any vacuum issues.

I can hear the injectors ticking, so i don't think they are sticking.
All cylinders appear to be firing fine, so I believe I have a good spark in each one.
(Plugs are about 7 or 8 months old, and have done about 10,0000kms.)

At this point, I think I have it narrowed down to the O2 sensor, or the LAF Sensor.
Normally, I would just look at the O2 sensor, but with the exhaust being put on recently, I'm not sure whether the LAF Sensor is something I should be looking at.

Oh, the car also was overheating about 8 weeks ago. I replaced the thermostat, changed and bled the coolant, and the car ran beautifully again.


Can anyone here offer me any advice as to whether I am on the right track, and where some of you more experienced guys would go from here?

[trism]

lil vito,

Have you simply gotten under the car to check the O2 sensor is plugged in, and no wires are damaged?

Sounds like thatd be the most likely cause going of the information youve already provided.

I wish you lick,

Regards,

Sean

[lil vito]

OMG Sean...
You know what?
I haven't....

Woulda thought that would be the first thing I would check....

Will be doing so shortly, and if that is all it is, I will be feeling rather stupid i think.... :$

Heres hoping it is that easy

[trism]

Likewise.

Also, my name is Matt, not Sean.

I'm being a troll.

Lolololol.

Seriously but, I hope its that simple also.

[lil vito]

Oh... i meant to say Matt... honest... :P

[ECU-MAN]

your test you mention in your first post doe snot rule out the ECU being faulty

I would start by testing the ECT sensor and the IAT Sensor. then check the injector duty of each injector. You will also want to confirm you leads are OK with a multimeter

the Oxygen Sensor has no effect at start up or until it has reachec operating temperature.

[MrJDMCivic]

its either your injector is jammed, "does happen" or your ecu has got a bad capacitor and its causing erratic functions. replace ecu with another and retest. the d16 engines normally are bullet proof from fail and from what your describing it would take a serious fault to cause it. the other possibility is your fuel pressure reg is faulty/disconnected vac, that to could cause issues, i'd start with the ecu.

[lil vito]

Ok guys, thanks for the suggestions....
Got it sorted now...

Turns out the o-ring under the map sensor had deteriorated enough to let air in to the map sensor.
This had the effect of telling the ecu that the throttle was wide open, so it was sending a tonne of fuel to the cylinders....

Couldn't actually see any difference between the new and old o-ring, but the car sure can tell the difference....

Upside to all the work I did, is that the car is now running better than she ever has.

Thanks again for the advice fellas

[FAITHLESS]

Very interesting. Glad to see you sorted it out.