I just got my LS/VTEC swap done a few days ago, and whenever u get on the throttle from 1000 rpms to 4000 rpms it stumbles the whole way and the car lurches... then at 4000 it smoothes out... then VTEC kicks in at 4800 and it doesn't accelerater HARDER it accelerates WORSE.

I changed plugs to some less-abused ones. Same type of plug though. Same problem too. Maybe with 11.5:1 compression I need a different type of plug???
I don't get it though because at 4000 rpms it feels great, then vtec hits and it feels like crap.

Also, if u rev it up from idle... If u just lightly press the gas it goes up like normal, but if u floor it, the car almost dies and it sounds like crap... almost like a misfire but the rotor is new and the cap isn't that worn... but maybe I'm blind lol.

Anybody got a clue?

Harry

 

Erm let me guess Please dun flame me if i'm wrong :naughty:

It should be your ECU air/fuel ratio for the different RPM is screwed up guess its time for some dyno tuning

I should be wrong cause i'm a very beginner :thumbup:

 

forgot to say the problem should be arise from using an ECU from the previous engine on your new LS/Vtec block so the air/fuel map is screwed :dunno:

 

1. I hope your motor is completely broken in before you start pushing it that hard.
2. Is your cam timing correct?
3. Is your ignition timing correct?
4. What plugs are you using now, and how do they look when you pull them out?

 

Well 4000 rpms isn't that high... besides, if I don't get it up to 4 grand b4 I shift I'm driving like my grandmother... SLOOOOOWWW.

Cam timing is right.... but I don't have a timing light with an adjustable dial so it's at "TDC" which would be 16 degrees if I had an adjustable light from what I understand.

harry

 

... And the plugs are bosch plats... they look alright, one set looked like they had been run really lean... but that was before I got the swap done...
Then the other set just looks like normal.

Should I get some "cold plugs" ???

And about the ECU... it's a p28 with a skunk2 chip in it.

Harry

 

Plugs: Switch to NGK copper, it's a better conductor, and go to a series 7 plug, it is a colder heat range and therefore will burn hotter. That 16 degrees is your ignition timing, which is regulated by the position the distributor is in, if too low of timing the car will be very sluggish. Kinda sounds like your problem.

 

okay... so maybe advance it a couple degrees then?

Harry

 

You put your ignition timing at TDC? The white mark on the crank pulley? That's wayyyy retarded(in the timing sense .) You need to line up the pointer on the block with either the red mark(stock timing) or one of the brown marks on either side of it(+/- 2 degrees.) You don't need an adjustable timing light to set stock ignition timing, or for +2 advance or -2 retard.

 

http://www.c-speedracing.com/howto/timing/timing.html

for B18C: