beseman

So i swapped my old LS longblock bc it was old and had been boosted for lots of miles with a b20 from hmotors. I swapped the long block over and put back 99% of what was in there with the LS, including the old LS intake manifold and same turbo set up.

My problem is when the engine is at idle and I press the gas it kind of bogs down and looses rpms and jolts the engine pretty hard then the rpms shoot up to where they should be. My boost gauge reads a hard vaccum spike when this happens. I adjusted the throttle cable around and that is not the problem. Could this be happening bc the computer is still tuned for the old LS motor and the new b20 is not timed correctly? Any help would be appreciated.

steven_highet

Definatly sounds like a Throttle Tip In fuel problem. Advance the dizzy slightly and see if it makes a dif. If it does put it back to how it was and get it tuned!!

beseman

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by steven_highet &raquo;</TD></TR><TR><TD CLASS="quote">Definatly sounds like a Throttle Tip In fuel problem. </TD></TR></TABLE>

sorry for my ignorance, but could you elaborate on what a "Throttle Tip In fuel problem" could be.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by steven_highet &raquo;</TD></TR><TR><TD CLASS="quote"> If it does put it back to how it was and get it tuned!!</TD></TR></TABLE>

im deffinately not driving it until i get it tuned, dont worry. I had to drive it home from my friends' place to my own house and i drove way under boost.

steven_highet

You are pretty smart! Someone who says im not driving it till i get it tuned has the right attitude towards making things last!!

"Throttle tip in" is a % value which is used to add or trim fuel when the throttle is suddenly pushed to 100%. Like when you shift gears and get straight back on it, it allows the ECU to compensate for that sudden fuel dump. Normally only adjusted 1 -5% nothing major.

Well if you gonna get it tuned I wonted worry about it. Any compatent tuner will remedy the problem for you!

good Luck!!

beseman

ok, so the throttle tip in is an adjustment that has to be made by the tuner with whatever program he is using?

I want to get everything on this engine running properly b4 i take it to my tuner bc he charges a lot for doing work during a tuning session

steven_highet

One more thing it could be is your timing might be off. Double check and make sure the crank is at TDC and your cam gears are lined up correctly!!