ok i recently rebuilt my ITR with CTR pistons, everything was speced out to ensure proper fitment, With the engine back in the car and everything wired right, the car has what seems to be a slight misfire at between 1500-2000 rpms. Replaced plugs, distributor, cap, and rotor, upon buildup. I am stumped towards what could be causing this, just curious if anyone has had a problem with this when replacing the pistons for high compression units, having a problem with a stock ignition system not being able to spark the fuel properly.
BTW engine mods are as follows
USDM ITR block
CTR pistons
all honda bearings and rings
factory head gasket
all arp fasteners
JDM ITR head
CTR cams
inline pro cam gears
ferrea valvetrain
spoon 70mm throttle body
Fuel system upgrades include hondata s100, rc 310's, walbro fuel pump.
anyone with any ideas would be greatly appreciated, i am seriously stumped beyond believe and with work dont have to the time to mess with it much longer
thanks

 

Sounds like a tuning, and timing problem. My car does the same thing sometimes. And before the timing was messed with i had detonation in that same range.

Not a big deal it seems, try tuning.

EDIT: I have those pistons as well. The high compression needs tuning.

 

ummm do you have anything to TUNE the car with?? if you are running on just a stock computer its going to run like ****.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RTW Ryan &raquo;</TD></TR><TR><TD CLASS="quote">ummm do you have anything to TUNE the car with?? if you are running on just a stock computer its going to run like ****. </TD></TR></TABLE>


yea stock Ecu will not run the caR on those pistons and cams.

 

yeah the car is running a hondata s100 unit, rc 310 injectors and a walbro fuel pump, the only problem about tuning right now is that the motor has less than 200 miles on it since rebuild, so putting it on a dyno isn't really an option, any ideas to possibly fix it without tuning, anyone think a stronger ignition system would help clear it up???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dc r-spec &raquo;</TD></TR><TR><TD CLASS="quote">yeah the car is running a hondata s100 unit, rc 310 injectors and a walbro fuel pump, the only problem about tuning right now is that the motor has less than 200 miles on it since rebuild, so putting it on a dyno isn't really an option, any ideas to possibly fix it without tuning, anyone think a stronger ignition system would help clear it up???
</TD></TR></TABLE>


you can do a preliminary tune now. Just tuned it modistly for now. I am rnning rc 310's same pistons, basically fully built. You NEED tuning with your mods. YOu probably have a huge dip in torque right now where it sputters or whatever.

 

throw it on the dyno, it will be fine. many people throw their cars on the dyno before driving a single mile. thats what I did.

 

yup..tune it a ur good to go..

 

thanks for the help guys appreciate it

 

ummm u realize with the compression u now have with those pistons you can't really run pump gas.

 

i understand about the pump gas aspect, right now i have about half about half a tank of 93 and a few gallons of 101 mixed in, the only reason i am not thinking that it is fuel is because the engine surge/misfire happens at 1500-2000 rpms then after that is clears up and acts normal, the misfire almost feels like a camming vibration at idle, however before i pulled the engine out and rebuilt it, it did not have that problem
any info is good

 

First of all, the compression isn't going to be all that high (relatively speaking). You'll have absolutely no problems running this set-up on pump gas assuming the tuning is decent.

When you say hesitation... under what throttle angle does this happen (10% throttle, 50%, 100%???)

Does this happen when the engine is warm, cold, or both?

What heat range spark plugs are you running? (#6, #7, #8)

What base map did you start with on the Hondata? Was it corrected for the larger injectors?

Need more info in order to help you out...

Get a wide band on that thing immediately and make sure the A/F is decent at idle and part throttle. Last thing you want is to run super rich on a new motor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmspoonitr &raquo;</TD></TR><TR><TD CLASS="quote">ummm u realize with the compression u now have with those pistons you can't really run pump gas. </TD></TR></TABLE>

yes he can.. Like i said my caR is probably dam close to his compression speaking. My car detonates with aggressive tuning, and now its set waay back because i recently got my head rebuilt.

All you have to do to run pump gas is

A. retard timing or
B. Dont floor it until you get passed about 3k rpms then your good to go without any detonation.

Thats what i had to do when mine was detonating.