steeltoe

here goes:

I have a 91 civic 1.5L all stock.

I changed the head gasket because the the original had 120k miles and was leaking oil/low compression. I went with the D16Y8 head gasket and dropped in a rebuilt D15B2 head that also had it's surface milled. I do not have a D16Y8 head just the head gasket from 96-00. torqued it down with arp studs. while I was at it I did the mpfi swap and got the wiring harness through a reputable ebay seller with 15+ years honda wiring experience and 1500 and counting 100% positive feedback - all from selling wires. the camshaft is from the 1.5L and so is the camshaft sprocket. It was NOT upgraded to the d16A6 camshaft. compression test shows between 180 and 185 in all four cylinders. tested with hot motor and wide open throttle cranked over 5-7x's.

the car starts fine and idles except that it runs super duper rich...I had brand new ngk spark plugs in there and within a couple of minutes they are all black with carbon. took them out several times while trying to find the problem - cleaned them and installed - and again just as filthy dirty within a minute of running. while it idles there is black soot spewing out of the muffler and from the rear the idle sounds bad/not right/off/lumpy. when I rev the motor a lot of smoke comes out the tailpipe..mostly whitish in color but definitely smells like fuel not coolant. I have read after googling that excessive fuel can give out white smoke not black. the excess fuel burns when it touches the exhaust manifold if you're really running that rich.

what I have done:

I have tested the injectors and the ohm readings were in spec..think it was 2.5 I even swapped out all four injectors with another used set and again all of those had good ohm readings as well.

I rechecked the wiring only on the parts that I was to do per the instructions that came with the wire swap... I even tried reversing all the pre labeled wires just incase they were accidentally labeled wrong but it ran worse when I did that. they were labeled correctly the first time.

I swapped out the ecu with another pm6 ecu - note that neither one was confirmed working 100% since I bought one from ebay and another with the mpfi swap from a reputable long time member from these boards. both ecu's gave a code 16

I installed a brand new oem main relay

I swapped out the fuel pressure regulator with another untested used one. when I pull the vacuum hose off of the fpr while idling there is no fuel smell indicating it's good. a broken/leaking fpr diaphragm would spill fuel into the vacuum hose and into the intake making you run rich. these things last forever so I hear and what are the chances of having two bad ones. I did not check the fuel pressure because I don't have the pressure tester although I can go buy one and have it tested.

I checked and rechecked my timing belt. I even took the crank pulley off to see if there where other timing marks on the oil pump to go by. apparently (also verified by oem repair manual and haynes) there are no timing marks for this motor other that the TDC mark on the crank pulley and the marks on the camshaft sprocket that you line up (on 1.5L motors) with the top edge of the head. TDC on cylinder one is definitely on the compression stroke..verified by taking the valve cover off and seen the intake valves open first then piston came up. at that point it lines up with the TDC pointer on the timing cover(the only way to check TDC on this motor).

I swapped out the injector resistor box with another one...both tested good with the ohm meter and were within spec between 5-7 ohms. tested terminal A to the other terminals one by one as per manual.

I removed the fuel rail and had it turned upwards with the injectors facing up as I cranked it. they all fire except it's very difficult to tell in what order because they fire so fast. I do have to say that it was not a mist of fuel and not sure if it should be. it was more like a heavy thick spray of fuel that almost seems like way too much but I can not verify what a normal spray is supposed to look like. this was the case with all 8 injectors ( I swapped out 4 with a different used set and did the same test.)

I do have to say that I did not set timing yet because when I turn the distributor either all the way to the left or right it has very little effect and still runs super rich. with that in mind I flirted with the belt by moving it one tooth towards the rear of the car but still no change. I returned it again to where it was. I did not move it one tooth towards the front of the car.

what I'm thinking of now is that since the D15B2 head was milled and the D16Y8 head gasket is half as think as the recommended metal head gasket replacement for half the price - maybe the reduced height in head and gasket combined is messing with my timing... but why the code 16?

the distributor is that from a d16A6...new oem rotor and spark plug wires plus spark plugs.
could the spark not be strong enough and not fully igniting the fuel hinting at a failing coil? the motor does run.

I was suggested that the motor is not getting air and the fuel/air mixture is bad. I have a new clean k&n filter...no blockage in the intake tubing all the way to the throttle body...

I have all brand new vacuum hoses and coolant lines and they are all connected where they should be.

I have a brand new PVC valve as well.

I need ideas and suggestions. perhaps getting an ecu, injectors from a known well running source may be next but not a clue who what or where to get one yet. don't know anyone with a civic of this year.

I hate to post new topics. I usually learn and figure things out by searching here and anywhere but this one has got me stumped and so I'm asking for your help. two minds are better than one.

thanks for any advice

paeEFsedan

have you checked your iat? cuz it sounds like the same thing that my friends car was doing an he had the wrong clip at the iat...

sh!ft

iat or o2 sensor is my assumption. you have to remember that you are running the Y8 HEAD and not the oem one. so your computer needs to be changed to the y8 specs as well as the o2 sensor as well.

just my .02

steeltoe

I just edited my post...it did sound like I had a Y8 head ..but it's not. It's the D15B2 original head with the Y8 head gasket only. the 96-00 head gasket is supposed to be the same as the 92-95 one for half the price..that's what I read up on and went with. it just may be not as thick as the 92-95 gasket from what I've read also.

I thought about the o2 sensor but wouldn't that throw a different code? I believe it's a code 1.

I'll look into the iat per you and the previous poster



thx for the info

sh!ft

are you running straight pipe? is your o2 even hooked up?

gringo7718

He actually has a rebuilt D15B2 (block and milled head) with a Y8 head gasket.

I had to re-read it a few times myself.



Anyways, Steeltoe you mentioned that you set the mechanical engine timing. But did you use a timing light and adjust the timing at the distributor?

Code 16 - Probably not a leaky injector since you swapped them out. I would look at the wiring to the resistor box and injectors for continuity from sensor plugs to appropriate location on ECU. Remember to check the grounds for continuity to ground as well.

You mentioned changing the coil...give it a try, it cant hurt.

Basically you confirmed the fuel delivery system is working and working quite well. I would look at sensors that influence the ECU to dumping that much fuel. -timing, and air density measuring devices- I would check the MAP sensor (and vacuum hose if applicable), O2 sensor wiring, IAT sensor, and Coolant Temp sensor. These sensors have a huge impact on A/F ratio.