K7-1Ktrevor

finally got my car back together after about 2 months now and Im working on getting it tuned. but I am running into problems else ware.

heres the deal:
ls vtec, eagle rods, wiseco pistons
B16 head
RC 750cc injectors
GM 3 bar map sensor
chipped on uberdata.

motor idles just fine now, I had a vac leak at the throttle body when we were trying to tune it so Idle afr's are probably all out of wack. the main problem I have is that under light throttle cruising the car will cut fuel to the injectors and cause it to buck. also under boost in the lower gears it will richen up so much that the car just falls on its face. in 4th and 5th it seems to do just fine... this makes me think it might have something to do with the map sensor...


things it might be:
TPS
IACV
crappy chip burn on uberdata? tried a base map on chrome too
map sensor?

Im working on narrowing it down right now, but I don't know how to test things to figure out what is the problem, I really don't wanna throw money at it by just buying parts that it might be.

since I have fixed the idle/ vac leak, the bucking is noticeably less. but It is still very annoying and makes the drivability of the car pretty crappy.

any help will be greatly appreciated.

pictures of my build for fun

K7-1Ktrevor

forgot to add. not running any o2 sensors
it was chipped to delete that in the tuning software.

K7-1Ktrevor

any 1??

93egSLEEPER

have you done tuning at all? just because it has been "chipped" for no O2 sensor doesnt mean it has been tuned for no O2 sensor. that will throw off all of your air related ratio and sensor issues. any CEL's?

K7-1Ktrevor

Im running 750's... its tuned at wot. and some partial throttle tuning, but my tuner quit on me due to the bucking...


adjusted the TPS to.45v at closed and its about 4.40 volts at wide open, this helped a ton with how it would cut out in certain gears when I would get on it.

still bucks. its at very light light throttle cruising that you feel it. it is much better then it was when I first started looking for problems...


thought for sure it was the tps that was causing this... turns out the search continues... : (

any idears?

K7-1Ktrevor

no one has any ideas?

HiProfile

First of all, if you fixed the vac leak after your tuner touched your car, you need to get it retuned. The turbo will be pushing more air in per psi, and all afr's will be screwed up (vac too). Not to say I told you so, but this is one reason O2 sensors are still used by 'weekend cars' on this website, it greatly reduces light throttle issues. In my experience, Honda motors will idle OK up to and past 19:1 AFR's. They will not accellerate on the road above 16:1, and sometimes bucking results.

It could also be your MAP sensor has issues. GM 3bars aren't made by only 1 manufacturer, many 3rd parties do and GM lets them puts their name on it. You should have your tuner check the datalogs for idle & "key on, engine off" for both sensors, back to back. GM 3bars sometimes suck at vacuum, and could be telling Uberdata that its running much higher vac - and entering decel fuel cut.

K7-1Ktrevor

I figured the rest of my problems are gonna be in the tune. I just wanna eliminate any possible issues that are gonna cost me more money when tuning.

BTW, love your sig
" NA = acronym for 'lost potential' "