Hello my friend and i just built a ls vtec b18a1 bottom and b17 head the problem he is having is that the engine bogs and sounds like it misfires/backfires when you stomp on the gas or trying to accelerate quickly if you slowly roll onto the throttle it also bogs and misfires but you can actually pick up speed we are using the stock p61 ecu so it should be fine but what could be causing this? he currently has a check engine light because of no knock sensor the light comes on after 5 min of driving it and can be cleared if you switch off the ignition and fire it up again and that lasts about another 5 min of driving what could be causing this? the car ran great with the same head setup but on a b17 block till it spun a bearing.
sort of sounds like this but less rumble and dosen't pick up the rpms
http://youtube.com/watch?v=j8t0tud1Qh8

 

check all your fuel injectors.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crazyguy &raquo;</TD></TR><TR><TD CLASS="quote">check all your fuel injectors.</TD></TR></TABLE>



Clogged injectors cause that kind of problems...

also check the timing and maybe inspect the rotor, cap, cables and sparkplugs... just to be sure...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EK45VTi &raquo;</TD></TR><TR><TD CLASS="quote">



Clogged injectors cause that kind of problems...

also check the timing and maybe inspect the rotor, cap, cables and sparkplugs... just to be sure...</TD></TR></TABLE>

I never knew injectors could go "bad" or hadn't seen it happen until this past year. I've seen this problem with fuel injectors, low fuel pressure i.e clogged fuel filter or fuel pump filter, or even a distributor coil and ignitor going bad. Wires will usually cause a miss even at idle when bad. Also the knock sensor cel is going to cause the ecu to run in limp mode and turn the vtec function off in the ecu. Is the ecu even turning vtec on before the cel comes on? I would highly doubt it, but i'm not positive. Fix that problem first, get a knock sensor installed.

You can also tell if an ignitor is going bad by a tach that jumps around and doesn't operate smoothly. And I've taken the filters out of the injectors before because they were so clogged and it fixed a horrible bog. check fuel pressure and timing too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EK45VTi &raquo;</TD></TR><TR><TD CLASS="quote">
also check the timing</TD></TR></TABLE>

I would check that one FIRST since you just mounted that head onto that block and driving with off-time for any period of time can mess up the motor.

 

did u cut the wire to the distributor if you did it might be bad connectin i also had a problem like that befor the check engin light comes on after 5 min and when u park it will miss fire it self to mine was the ecu i think it burnt out

 

check that the tps and map connectors aren't switched.

 

I have that same probably right now and it caused me not to go to the track today

Narrowed it down to a bad fuel pump. Guess pushing 60psi out of a 255lph is asking for alot

 

Vtec works before and after the cel light comes on it runs the same also

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Luserkid &raquo;</TD></TR><TR><TD CLASS="quote">I have that same probably right: </TD></TR></TABLE> same here

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Luserkid &raquo;</TD></TR><TR><TD CLASS="quote">Narrowed it down to a bad fuel pump. : </TD></TR></TABLE> is there a way to test a stock fuel pump?