Black spark plugs in my JDM ITR motor!! running rich!! Help
ok.. I read all the past forums on "running rich," but help me out...
93 civic coupe, 96 JDM ITR block, b16a head, Skunk2 (stage 2 cams, intake manifold, springs, valves, retainers, ECU, exhaust.), VAFC, Headers, AEM cold air, AEM cam gears, RC 310 injectors..

just put the motor in, breaking it in still. Everything is sweet except that it is running rich. The spark plugs are black. No liquid fuel on the plugs, just really black. Exhaust gas smells really strong.. Fuel pressure at 40psi, VAFC is not set yet.. Waiting to break in the engine, then perform valve adjustment, then dyno.
Autometer A/F gauge is rich at idle and at WOT. goes stoich when I am cruising and put in neutral

 

First off......why would you know that your A/F is rich at WOT when you are breaking the engine in?

SET THE VAFC. It not being set is what is making you run rich. Also, check your timing.

 

Well i think the reason your running rich at idle an WOT is because of the ECU you have(by saying ECU makes me think you upgraded it)And the 310 injectors...i think for what you have all you need is 270cc or 280cc...I think 310cc are good for 12+ compression and bigger cams then Skunk2 stage 2s..

The only way to get the Fuel down is with the FPR set that at 38psi or just leave it at 40psi and play with the VAFC,between 500-1000 RPMs...lean it out a little...Its ok for it to goto Stoich when your cruising around...and its kinda ok for it to goto rich at WOT...(not full rich but as long as its in the rich part)

And getting on it WOT isnt helping it break in....

Thanks
Ross

 

you can change the fuel pressure to maby 38 to 35, clean plugs or get new and check after 20- 30 min drive in different conditions like wot and idle and crusing. if still black lower a little more. if you see white smoke out of exhaust when wot with a load on the car then you went too low.

 

im running skunk2 ecu... I only ran in WOT a little... k..
is the air/fuel gauge supposed to be on full rich at idle?? i have 11.4 compression.. my psi is at 40 now.. should I lower it a little more?

 

Ok....The skunk2 programe is richer then the mugen programe....
Skunk2 propgrame is for stage3 cams and higher compression...than 11.4..
And no its not good to be rich at idle...Like i said in my last post play with the VAFC at idle..Lean it out....and look at the air/fuel gauge and it should drop to lean.
drop the FP at 38psi.....

You are going to wash the rings out if you cant get it leaner at the bottom...Or any where....
So try what you can to get it to work right...


Thanks
Ross

 

Oh you dont need 310cc injectors for what you have.....Get 270-280cc

That will work good..

Lets put it this way...I had 12.5 compression and ran on 92octane...pulled 230hp on a motor dyno and i was going to 8700 rpms and i had 240cc injectors,stock fuel rail,stock FPR and had no problems.....So really all you need is your stock injectors......with what you have...


Thanks
Ross

 

It's those injectors... You don't need 310's on a stock JDM ITR motor.. My friends CRVTEC runs those with 12.5:1 basically like allmotrb18c1... You should be able to trim them out with your VAFC... With 12.5:1 compression and an ITR ECU and VAFC on his CRVTEC +4 on top end was enough to have it running perfect. Try goin negative on bottom end and top end....

 

wash the rings out? would you mind explaining this a little? I recently put a rebuilt b17a into my car (stock except for p30 pistons, 10.9:1). I've been running rich ever since i put the motor in (about 2500 miles ago). The rear bumper gets covered in black soot from it running so rich. Other than the pistons everything is stock...so i don't know why i'm running so rich. Is this going to hurt my motor?

thanks
colin

 

Ok lets see....ok you have a cyl..with oil on it and thats what the rings slide on...If you are running rich the gas will clean off the walls and take the oil off and then you have metal to metal..that will eat the rings away..after time you will have no rings...thats called washing the rings or wall...the oil keeps the rings from hitting the metal to metal(kinda)..And makes it run better...if you have gas then thats not a good lubricant...Oil is........

Thanks
Ross

 

I'm in the same boat. I run all the way rich on my autometer a/f guage at WOT. I raced my friends 240sx and he was like "Once that big black cloud came out of your exhaust you were gone!" Presumably when I hit VTEC.. I have a stock B18C1 other than P73 ITR pistons. Anyone know how I can lean it out a bit at WOT?

 

i think the last 10 post can help you out on that...
You can get a FPR or some kind of a fuel controler...

Thanks
Ross

 

ross, thanks for the explanation, makes complete and total sense. Any idea how immediate of a problem this is? Like i said the motor is pretty much brand new, and now after reading some posts here i'm getting scared about ring life due to my rich mixture.

I just spent awhile reading over all the past posts about running rich and i haven't really learned anything new. I'm completely stumped as to what is going on. My mechanic says the O2 sensor is fine, and thats what i had originally thought was the problem. I guess i'm going to have to check over all the wiring for my obd1 conversion

thanks again ross.

 

I apologize, I went off on a bit of a rant and didn't really state my problem/question. My fuel seems decent at idle, decent under accelleration etc, it's only rich at WOT. If I drop to 38PSI, will it not be lean udner normal conditions and normal at WOT? Probably an ignorant question, but I'm not well versed in matters of fuel.

 

Teal,

Your a/f under anything other than WOT is ultimately controlled by your O2 sensor and other emissions control devices for environmental reasons. Since most people call upon WOT rarely (mooowahahahhaa), the feds don't care so much about being rich up there. If you lean your pressure out with your FPR, your computer will richen the mixture back to stoich under partial load and idle, but your WOT will be fine. Try it and see.

Thanks,
Nick

 

try this...put the FPR at 38 and see what it does...if its ok at 8k and it doesnt detonate and no black smoke then keep it there..But if it sound funny and it doesnt go any where(the car)..get off the gas and put it back the way it was....The only thing i can think of for that problem is getting a VAFC or a SACF....for the top end fuel adjustment...and no it will not lean out on normal conditions....with your set up. the ITR pistons and a GSR head you have 10.8 compression(unless you mild the head...)(thats with the USDM pistons)If you have the JDM pistons you have 11.3 p73...And sometime at WOT its ok to see black smoke...

And you dont have to apologize....I do for bieng an ***..So im sorry...
I like helping people with real questions....

Thanks
Ross