mabus013

Ok, I have a 91 Civic hatch with the D15B2/four speed manual combo. A few weeks ago, it started running really rough and was belching moisture from the exhaust. I took the bus for a week or so, and then tried driving the car around - I found I could limp it around town as long as I heel-and-toed the brake and gas at stoplights to keep the engine from stalling. It needs a little prod of the throttle at startup to catch, but it will every time. Hot, it's more of a struggle to start up, but it can be done.

I started trouble shooting, and I found out that the #4 cylinder isn't firing. I replaced the cap, rotor, and wires, but it didn't help a lick. Tried replacing the plugs (NGKs), no luck. Checked the spark for that cylinder against the valve cover, and it's sparking away. There's absolutely not one iota of difference when the #4 wire is disconnected. There's no oil in the coolant or vice versa, and the moisture doesn't seem to be present anymore.

The car did have a problem burning oil (bad valve guide seals) but it hasn't been a problem at all - just add a quart every 75-100 miles depending on driving conditions and don't worry about it. More frequent plug changes, sure, but it beat replacing the D15 with another one from Nippon Motors - I'm trying to save for a ZC swap.

I thought that maybe the air filter was clogged (it wasn't , but I checked it without the filter box attached and it didn't help), or that the cat was maybe caked with oil - it wasn't, but I ran it without the exhaust attached (cat-back - the exhaust manifold up to the cat was still attached) and no improvement. Oil consumption seems pretty much unchanged, but my mileage has gone down a lot and there's the smell of unburnt fuel, especially at startup.

Interestingly enough, the car has gotten better the more I drive it - the idle has smoothed out somewhat in the last few days ands startups are easier, and it doesn't want to die at lights, but there's still barely enough power to drive with (between the way it runs and sounds, and the lack of power, I can close my eyes and pretend I'm driving my old Beetle! NOT good!).

I'm trying to avoid paying for a diagnostic check, and thus I'm putting this out there in the hopes that someone else has encountered the problem and knows what to do. I'd try to run the on-board diagnostic, but aside from once on the highway (it'll actually do 60-65 on a flat run fairly smoothly) the 'check engine' light hasn't come on! Great engine monitoring on this model, Honda, you've really outdone yourself...runs on three cylinders, but according to the computer, everything's a-ok!

If anyone would like to help a poor mo-fo out, I'd be much obliged.

Thanks,
M13

DUNK_Performanc

Sounds like alot yu got there, hmmm i have seen engines that have evolved hair line cracks in the intake wall , especially on the #4. the thermostat and water through is right there. Also the gasket where the intake meets the cylinder head, have yu checked around there? There are coolant channels near the 4 cyliner and if the intake gasket is bad near the water passage that resides near that area a little water /coolant will seep into cylinder 4 keeping it frum idling and or running properlly. have yu checked yur coolant latelly? If the car never runs hot and is down a bit or so of coolant then maybe its going sumwhere huh? I would investigate the intake manifold gasket area and around the thermostat housing as it conjoines in that area.

qtiger

Unplug all spark plug wires from the plugs, leaving them connected to the distributor. Wrap them thoroughly in rags and get them as far away from the engine as you can.

Remove your fuel rail from the intake manifold, keeping the injectors and supply/return lines in place. Set it atop yet more rags, and have a friend crank the engine while you watch the injectors. I'm guessing the results will be... fascinating.



By the way, in referring to cylinder #4 are you counting from right to left or left to right?

DUNK_Performanc

BUT that does not say much but to take off the intake and remover the plug wires, why not just UN-PLUG the electrical connector to the DISTRIBUTOR?I hope yu dont think hell see much that way, maybe hell see his intake gasket is bad and is seeping coolant into intake port #4? Besides that the piston will be drawing air into the cylinder frum that port wut will he see?Id like to kno.

qtiger

He can't unplug the distributor because all the sensors the ECU uses to determine fueling are in the distributor and the injectors won't pulse without them.


He'll be actually watching the injectors spray fuel, and I'm guessing that cyl #4 is pulsing intermittantly or not at all.

DUNK_Performanc

Yu could have said that frum the start , there is more to say about that but.....

mabus013

Problem: the D15B2 is throttle body injected, not sequential injected like the D16's. Now, I could pull one or the other injectors and see if they're just pouring fuel down the intake.

Yesterday, while trying to get it to hot start, I removed the intake piping from the box above the throttle body, and was greeted by a creeping cloud of gas vapor. Curious, I removed the four screws holding the top of the 'box' on, and more vapor was coming in via the vacuum hose attached to the #1 side of the intake manifold. With the increased fuel consumption, the raw gas smell, the #4 spark plug that's wet with fuel, etc, something is making this thing run extremely rich.

I've been thinking it could very well be the O2 sensor - it might be caked with deposits from the burnt oil, or just be very old. I looked at it today and it seems like it's been there for a long, long time. Of course, one or more of the injectors could be faulty as well. Maybe the CPU, but it runs fine otherwise, so I'm not inclined to think that that's the case.

Ideas? Sorry, I know this isn't exactly as exciting as troubleshooting a new B16A swap or anything, but I'm just trying to get my po' ass to work until I can afford a ZC swap. Any further ideas? Trying to avoid having some greasy mofo adjust a screw or something and then talk me into some retarded repair that wasn't even necessary. I appreciate it, believe me.

Thanks,
M13

DUNK_Performanc

Thanks sum1 who knew wut i was thinking, i didnt want to jump the gun since I am in thailand but ive been to my cousin shop in the USA and i did seem to think that it was throttle body injected. So it still fals back to wut i said about the intake gasket.

DUNK_Performanc

its running rich yu say? Yu might want to remove the throttle injector unit and check the pre heat screen under it. Some have pre heat screens under the TBI unit and some dont, see if any of the gaskets are cracked around it, also, one of the injectors can be bad , instead of pulsing it could be just open and dumping fuel, ill get back when i have more ideas. Its midnight now , have to go home.

qtiger

Ah, I didn't pay attention to the engine model. Well I'd still do the same thing and see what the injectors do, one could be stuck open, etc.