high compression motor done(need help)!!!

[Swift]

hey guys,

I turned to this board and my home forum for help on this.

I just got done assembling the first high compression C35A motor for my legend. I calculated it should be running 10.5:1. It starts and idles but very rough, i add octane booster etc just in case and there is NO check engine light..........I am also running my stock NGK plugs and do not know if i need colder ones???

So i theorize not getting enough fuel or air...or to much...right?


I have figured out i am running to rich somehow. If i spray some carb cleaner on idle it almost dies...

When i hit the gas a little bit it stumbles bad!! I have not taken it up to 3 grand yet and i have not moved it since i didnt install my CV shafts yet.

I am in uncharted territory but need some help on what my possibilities are etc.

Thanks guys!

ben

PS- I am very tired.

 

[nsxtcy85]

you have an exact list of what you changed internaly? Cams? and what not.

 

[HYPERTUNE]

If all you have done is up the comp to 10.5, the engine should run fine. It sounds like the cam timing might be out?

I just noticed custom intake manifold in your sig. Have you checked for air leaks? Do you have the map sensor hooked up properly? Any black smoke from exhaust?

 

[Swift]

C35 with high compression pistons
gasket matched heads with type 2 cams
custom intake manifold with shortened intake runners
bored TB
intake

3.5 fuel rails with stock regulator, using cleaned/flowed type 2 injectors.

running a chipped ECU which i ruled out already.

I know the cams could be somewhat at fault MAYBE but there is no way it is this rich. (running like crap)

 

[Swift]

^ thanks

yeah a type 2 cam i believe has more duration with slightly more lift than a type 1.

the stock cams have far more lift but less duration


People have ran stock C35 with type 2 cams..


So the question is would bumping the compression result in the cam profile not matching? causing me to run rich?

i have experience with that at all to be honest

 

[Swift]

no black exhaust and one slight vacuum leak on back side for the brake boost line and that is it.

I hooked up all vacuum lines needed an in correct place(quite a task)

it is not throwing ANY codes at all either??

 

[Swift]

well figured out some of the problem...or most.

was running rich so i swapped back to my stock rails and old injectors(partial clogged...) and threw in a slightly leaner chip and bingo she runs! Not good by any means still but i have to buy a FPR for the other rails and my freshly cleaned injectors.

I will be giving Momin at Elite a call quickly !

thanks guys.

 

[DDozier]

well figured out some of the problem...or most.

was running rich so i swapped back to my stock rails and old injectors(partial clogged...) and threw in a slightly leaner chip and bingo she runs! Not good by any means still but i have to buy a FPR for the other rails and my freshly cleaned injectors.

I will be giving Momin at Elite a call quickly !

thanks guys.

On your new intake did you move the injector locations or change the distance from the injector to the valve by more than say 10%, if so you could have an injector timing error, in other words the injector could be opening and closing correctly but not in time with the intake valves. The result on AFR would be unpredictable. If your injectors are in the stock locations then you can through this idea out the window.

Dave

I am betting on cam timing issues, did you index your new cams, or change the deck heights of the heads either with gasket thickness or decking the block or heads.

would love to see some pics when you get everything done, I sold my 92 coupe to get the NSX, I still love the old coupes though.

 

[Swift]

you will not believe this....

While i was messing with something else i accidently ripped out a vacuum line...for the MAP sensor...but it gets better...in my hurry..i hooked it up to a a VIS line or something and it was creating a worse possible scenario...so i was running rich...

then..tonight..that line melted through..and my engine was in limp mode.

jeez. 1 little line...and all that trouble

she runs decent now..just got to get it tuned.

thanks for all the help.