Hi all I really need some help I have just fitted a B18C into my EK Civic (formally a 1600 non vtec) and seem to have a huge flat spot in the low rev range (way way flatter than the 1600) and I don't know why, as it seems to be ok when the vtec cuts in around 6000rpm.
I thought it could be because it was running 91 petrol, but I ran it for about 20 - 30mins tonight on 96 and there was no change. It has new plugs and the timing seems ok.
The only other thing I can think of is that the fuel pump isn't big enough (didn't change it when I changed the motor), but this doesn't explain why it seems to go ok in the higher rev range.

Any help would be apperciated as I'm lost.

 

Ignition timing could be off.
To much retard will make the motor very slugish.

 

Thanks for that, I'll give it a go on Monday and see how I get on. (although I think the timing is OK, but it can't hurt to double check).

 

I have now narrowed it down a bit as it runs fine when it is cold and the choke is on, but then it warms up a little and the choke goes off and I start having the "dead" problem (the only bit I don't understand is when it is in "Vtec mode", above 6000rpm all seems good).

It just has all the symptoms of being starved of fuel down low but why is it ok at higher revs, looks like it may have to be a trip to Honda (not something I'm really too happy doing here in Invers).

 

um, what is a choke?

(i know what a choke is, but why are you using that word when referring to a PGM-FI B18C?)

t..

 

Maybe "choke" is a old word, its the thing that comes on & makes the car rev higher when you first turn it on in the morning when its cold

 

understood

you really havent given us much to go on, what is a 'flat spot'? does it just feel gutless below a certain RPM?

what size exhaust are you running? you say it is OK when it is still warming up (this should take 5 to 10 minutes...)

did you change the timing belt? maybe it is off a tooth?

t..

 

It is basically dead or gutless once its warmed up until the vtec cuts in then it seems to go fine (when in vtec mode only). The exhaust is a 2 1/4 inch, its one that Honda NZ had made as an aftermarket exhaust to try to get younger people interested in new civics (I believe they did quite a bit of testing before they put this out). Yes we did change the timing belt if it was a tooth out wouldn't it be "flat" all the time?. Thanks for the help so far.

 

The problem is sorted now, it was the timing, (it must have moved since it was first set).

Thank you all for your help