I have a 1.5L d15b2 with a 90' SI head, MPFI, stock headers and exsaust, all stock. Heres the problem. The a/f gauge says its running lean, the ecu flashs number 1 . But the more gas I add the more it bucks etc. ( via VAFC ). I runs better if I cut fuel, even though the a/f gauge and the ecu says its running lean. So I replaced the O2 sensor. Not the problem.. I figured the injectors may be screwed, so of course I added talon turbo 450cc injectors, with out ANY adjustment of the VAFC it still says lean... It is CRAZY that it says lean with those already HUGE injectors !! So it has to be a sensor OR SOMETHING !!! ANY ideas at all ??

 

did you change your fuel pump, if you had the d15b2 that has dual point, i think that engine uses significantly lower fuel pressure than a mpfi setup, and your injectors on top of that..
just a thought

anyone else?

 

I agree with him, but i don't think you'd need to change your fuel pump (although you might want to) but I was thinking more along the lines that the fuel pressure would be different. I'd try a Adj. Fuel Pressure Regulator.

 

Here is another spin.... The DX head worked, and didn't run lean when removed... And if you've ever changed a head or replaced a head gasket you know the entire intake is removed, but all the fuel injection stuff isn't moved at all... The MPFI actully ran rich, with the DPFI fuel pump. I ran a 75 shot of zex so I never leaned it out with the VAFC, unless I didn't have the bottle in the car... I also have a in-car fuel presure gauge which reads the same at idle and WOT, as it did before... Crazy !!! Is there anything "special" you have to do to an O2 sensor ( beside not touch the sensor part ) when installing it ?? sounds stupid, but I'm stumped...

 

isn't the SI head going to make the car require more fuel? if so then if the fuel pressure guage is reading the same as it was with the DX head, and you aren't sending anymore fuel to the motor than with the DX head on, it SHOULD be running lean since the SI head requires more fuel, and if it's setup for the DX head it's not getting that fuel it needs...just a thought

 

does it stay lean during idle or always lean when ur driving. my gauge read lean too but mostly on idle.

 

so you're only basing the fact that it runs lean on your air/fuel gauge? If it reads lean all the time and never moves, sounds to me like the wire is shorted to ground.

 

it shouldnt run lean unless ur driving and let off the gas with mine i give it gas it goes rich and stays there....i have a d16y7 head on my d15b1 so im pretty close to the same setup...i would try a new o2 sensor with a diff fuel pressure regulator it may have took a **** try and see wut ur pressure reads...does ur car bog at all???

 

your gauge probably sucks, get an exhaust temp.

 

I told one of my friends today, I think it might be the O2 sensor wire was grounding out somewhere. I'd like to put this idea to the test, and run a new wire straight from the O2 to the ecu, but I don't know which pin on the ecu is the O2 wire can anyone tell me or tell me where I could find out.?? I tried sticking a test light to the O2 sensor wire, while giving the test light power, but it didn't light up... nor did it light up when I gave the test light a ground and touched it to the O2 sensor wire, so I want to run a whole new wire...

And a NA car running lean with 450cc injectors, that's insane, its not a fuel presure to low prob...


[Modified by 89dxhunchback, 9:35 AM 7/8/2002]

 

forget the A/F gauge, mine broke after 2 months...(1)check your plugs! look for metal shavings( if your rich it will have **** caked on your plugs kinda tar like) your plugs should look almost new if your running right(2) pound it, listen for ping( almost detonation)(3) check your timing it can cause no. 1&2 if its not adjusted properly....NEVER base anything on those A/F gauges those things are bullshit they read lean when your AC fan turns on GOod luck and I hope any o f this info helps you...

ps reading your sparkplugs is a pretty accurate backyard way of tuning!


[Modified by b18t4_crx, 12:32 AM 7/8/2002]

 

There is cam alignment issues between the D15 & D16, when swapping parts between blocks. I just wonder if thats not part of the over all problem...

Get that checked into first, before trying to da anything else... BTDT

 

also wut color is ur o2 sensor when u changed it out?? thats another way to tell if ur lean or rich but there is no reason to even use the 450s and as for it not being a fpr how can u tell if u dont know wut pressure ur running when i did the mpfi swap i actually had a bad regulator and caused it to run lean also no one could figure it out i had to do trial and error and finally i took a fpr off my b18 and then it ran nice as ****

 

also wut map sensor are u running the pm6 or the old one still

 

I have heard a few times that you are supposed to use the cam pulley off of the dx when you put the si head on your dx. I'm almost positive this is true...

 

Test your Fuel Pressure Regulator it might be going. Also what ecu are you using? I'll let you know what pin to connect the guage to.

 

Sweet, I never thought of the Map sensor !! I'm using the PM6... The cam pulley from every civic 88 to at least 95 has the same cam pulley, but just for peice of mind, when I got the head it didn't have a cam pulley on it so I did use the DX one.... I like the MAP idea... But I think my buddy used his HF MAP on his supercharged SI swap.... Anyway, yes, I am using the same MAP.... And thank you to everone for your ideas...

I've never heard of the DX and SI have the 1/2 tooth off problem, but its not like I've done it before either...

I see what your saying about the FPR, it is after the guage, so your right, who knows... The ONLY reason I put the 450cc's in is b/c I thought the injectors were bad,, and thought is was stupid to buy new honda ones, after spending $100 bucks on talon ones...

There is a $5, "go buy yourself a few beers" , reward ( via paypal only ) to the person that figures it out... ( I know, $5 sucks, but I'm moving in a month, I need a bigger yard to put car in, and a car port so I can work on them in the rain )...


[Modified by 89dxhunchback, 10:14 PM 7/8/2002]

 

The O2 sensor pin is C16. It's basically the right lower corner on the ecu.