Honda Car Forum

1992 Accord 5 spd has 'classic' EGR symptoms.

When warm, engine stutters slighty at low revs, smooths out by ~2.5K
Car runs smoothly when cold.

But...

Just this evening I discovered that Car still stutters even when EGR
valve vacuum line is disconected. The EGR system may not be to blame (??!)


Observations:
-------------

-General

Check Engine light goes on after ~20 min of driving, sooner on a warm
engine. Code '12' indicates EGR issues. No other codes.

A few Weeks ago, I pulled two of the EGR port plugs (Cyl 1 and 3,
neither transfer port) and found crusty but free flowing passages. Will
pull the others this weekend, just to be sure.



-EGR valve pulled, poked and prodded. (1 week ago)

Valve smoothly opens under vacuum, (As I recall, it was fully open by
about 7mmHG. Will test again to get more accurate numbers.)

Diaphragm does not appear to leak.

Diaphragm and valve plunger move smoothy. (There was a tiny bit of
carbon build-up on the plunger that caused slight drag. Cleaning it
hasn't changed anything that I can detect.)

Valve seals reasonably well when closed - blowing on the output port, I
couldn't detect appreciable flow at zero lift.

The valve spring seems 'OK.' I didn't measure lifting force, but it
seemed progressive and 'reasonable.'

Measuring the valve's electrical resistance, there appear to be two
complimentary outputs. As the valve is lifted, one resistance drops
from ~5K ohms, and the other rises from ~1K to ~3K (the second numbers
may not be terribly accurate - I observed that they changed and wasn't
paying enough attention to the actual values.)



- Vacuum meter tied into system, car driven. (Tonight)

When monitoring the vacuum control line, the EGR solenoid output (Vacuum
line 16 pressure) varies from 0 to a maximum of ~3mmHG. No more.
Vacuum rises as engine revs build, then drops abruptly to (near) zero.

When check engine light comes on, all solenoid activity ceases.

As mentioned above, the car stutters (as before) even with the EGR valve
actuation line disconnected/plugged.

~3 mmHg applied to egr valve stalls the car from idle.

I haven't yet fiddled with the control solenoid or constant vaccum
control valve.



Any thoughts or advice?

Thanks

-Greg

Greg Campbell wrote:
> 1992 Accord 5 spd has 'classic' EGR symptoms.
>
> When warm, engine stutters slighty at low revs, smooths out by ~2.5K
> Car runs smoothly when cold.
>
> But...
>
> Just this evening I discovered that Car still stutters even when EGR
> valve vacuum line is disconected. The EGR system may not be to blame (??!)
>
>
> Observations:
> -------------
>
> -General
>
> Check Engine light goes on after ~20 min of driving, sooner on a warm
> engine. Code '12' indicates EGR issues. No other codes.
>
> A few Weeks ago, I pulled two of the EGR port plugs (Cyl 1 and 3,
> neither transfer port) and found crusty but free flowing passages. Will
> pull the others this weekend, just to be sure.
>
>
>
> -EGR valve pulled, poked and prodded. (1 week ago)
>
> Valve smoothly opens under vacuum, (As I recall, it was fully open by
> about 7mmHG. Will test again to get more accurate numbers.)
>
> Diaphragm does not appear to leak.
>
> Diaphragm and valve plunger move smoothy. (There was a tiny bit of
> carbon build-up on the plunger that caused slight drag. Cleaning it
> hasn't changed anything that I can detect.)
>
> Valve seals reasonably well when closed - blowing on the output port, I
> couldn't detect appreciable flow at zero lift.
>
> The valve spring seems 'OK.' I didn't measure lifting force, but it
> seemed progressive and 'reasonable.'
>
> Measuring the valve's electrical resistance, there appear to be two
> complimentary outputs. As the valve is lifted, one resistance drops
> from ~5K ohms, and the other rises from ~1K to ~3K (the second numbers
> may not be terribly accurate - I observed that they changed and wasn't
> paying enough attention to the actual values.)
>
>
>
> - Vacuum meter tied into system, car driven. (Tonight)
>
> When monitoring the vacuum control line, the EGR solenoid output (Vacuum
> line 16 pressure) varies from 0 to a maximum of ~3mmHG. No more. Vacuum
> rises as engine revs build, then drops abruptly to (near) zero.
>
> When check engine light comes on, all solenoid activity ceases.
>
> As mentioned above, the car stutters (as before) even with the EGR valve
> actuation line disconnected/plugged.
>
> ~3 mmHg applied to egr valve stalls the car from idle.
>
> I haven't yet fiddled with the control solenoid or constant vaccum
> control valve.
>
>
>
> Any thoughts or advice?
>
> Thanks
>
> -Greg
>
>
the valve feeds a series of orifices in the manifold. where these
connect to the main manifold pipes, these are relatively small diameter
and tend to clog. can't remember the ages for transition, but older
ones have the orifice drilling hole welded closed, later ones have them
plugged with a blank that can be removed for cleaning. dealers carry
resealing blanks. if you have the later ones, google this group for how
to do it - there's a downloadable pdf out there somewhere. if they're
welded, you can drill them out, but blanking then becomes an issue. if
the manifolds are compatible, the ideal solution is get a later model
year manifold with removable plugs from a junk yard.