Flat spot with d15b7 EG civic

Hi,
My 1995 EG d15b7 Honda civic (not modified in any way) has a flat spot
between 2000rpm and 4000rpm. I have tried new plugs, new fuel and air
filters, checked timing, new plugs, different plug gap, fuel cleaners
and better petrol, checked resistance on leads and cleaned the
distributor cap and button but the problem does not go away. Does
anyone have any ideas on what it might be or how to diagnose it.

Regards,
Mike

 

automatic? [don't presume that "d15b7 tells us enough.] if so, it's
the egr valve and passages clogged. also check the transmission fluid
is not over-full and that the kick-down cable is adjusted properly.


as a separate issue, do not "clean" the distributor cap and button:

1. unless you've taken the essential precaution of wearing gloves,
sweaty fingers can leave salty residues on them which attracts moisture
and causes spark leakage. same applies to plugs and leads.

2. if the cap is aftermarket and has brass contacts, oxide product can
be conductive and you're simply smearing it around. replace with oem
honda cap with all aluminum contacts which doesn't have this problem.

 

It's a 5 speed manual not an auto and the cap is oem.

 

was the timing belt changed recently? belt may be off a tooth. if the
distributor is not centered to get it timed, that's the tell-tale.

 

Yes the timing belt was changed recently but the problem was there
before the change. I am pretty sure that the crank and the cam were
lined up at TDC as I dis the timing belt change.

 

pedantically speaking, the important thing is that they're lined up
/after/. did you follow the checking procedure outlined in the factory
honda manual? haynes manuals are notoriously awful. loose belts jump
teeth too, so even if timed before, they can be out later. again, check
the ignition timing and confirm that the distributor is close to center.

beyond that, you'll need to be more specific with diagnosis rather than
this "hopefully lucky" guesswork stuff. a compression test might be in
order for instance.

 

My 96 EX 5 speed had a similar sort of flat spot, even before the belt
was changed. Which made it kind of a PITA when I was Auto-Xing. I
don't know if it was specifically that, but after the O2 sensor was
changed (via a CARB ordered recall) it "went away". Problem is, there
were several other changes at the same time.
--

- dillon I am not invalid

Toby (Tri-Umph That's the Sweet Truth)
March 1998 - June 2010
What a dog. What a dog!

 

Hi Mike

Sounds like a "Vacumm" issue. Check for any leaks.

 

Hi guys,
Thanks for the tips. This now give me a starting point at what to look
at.