b20 vtec problem

[Aleks]

Hi people

I have a b20 vtec running a s300 hondata its been running sweet since about last week when i warm it up in the morning it idles fine for 5 mins then idle drops and sounds like its running on 3 cylinders then turns off i start it up give it a rev and is fine sometimes it jolts while driving seems like its not getting enough fuel and another issue is it hits vtec at 6300 rpm any help would be much appreciated


Thanks in advance

[hmetro24]

did you tune the car?

[Aleks]

Yeah cars been tuned

[hmetro24]

seems u have vacuum leak. Vtec engagement point should not, it ecu controlled, I would check tunes again.

[Aleks]

Its been running fine for about two months now and all of a sudden its started bogging heaps like if i drive at 100km in 5th car pulls back and feels like its running out of fuel then picks back up to normal ... i started it this morning and it idled at 400rpm sounded like a rotor was running real rough then goes back to normal keeps cutting in and out . How do i tell if it has a vacuum leak ?

[hmetro24]

What was Vtec engagement point before. do some tests could also be bad plugs, plugs lead, dizzy, injectors, low cylinder compression. Start the car, let it idle, start pulling plugs lead 1 at a time, if when u pull a lead and nothing change(idle, engine sound, engine stall) , could be bad plug lead or plug, or cylinder. Do the same for injectors, unplug 1 at a time, Same as before.
As for vaccum leak, get urself spray carburetor, start the car, and spray around vaccum lines, intake manifold... if car stall or idle drop, than it's vaccum leak.
Also do a compression test

[dougie_504]

Speak to your tuner mate. They will know best.

[Aleks]

Cars all good good now running alot better got a new set of leads and plugs thanks for your help mate appreciate it