Re: Debugging a Funny PGM-FI EACV Problem ('89 1.5)
 

andrew m. boardman wrote:
> Oops. This is pretty old news at this point, but better late than never.
> (I found many a similar problems in the archives, but there was never any
> followup once it got fixed; perhaps this will help someone down the line...)
>
> jim beam wrote:
>> andrew m. boardman wrote:
>>> I've got a friend coming by with a multi-channel digital recorder this
>>> weekend; we'll wire up *all* the ECU inputs plus the EACV control and see
>>> what corresponds to the EACV getting thrown open.
>> wow, that's serious stuff! i love toys like that. keep us posted on
>> how it goes.
>
> Sadly, "how it went" involved my friend's nice laptop blowing up, so I
> don't have any lovely eight-color graphs of engine sensors over time to
> put on the web.
>
> We did, however, find the problem: it was the throttle angle sensor after
> all. The reason we didn't catch it the first time is that the arm had
> shorted to the +5 side, but the resistance readings between the ground
> side and the arm (which is what we checked) were perfect. Electrically,
> this didn't raise any error with the ECU because everything that was
> being reported was within spec, but it was all compressed into the upper
> part of the range of valid TAS readings. Thus, the ECU thinks I've
> always got the throttle way open and opens up the EACV and dumps in lots
> of extra gas to suit.
>
>> regarding throttle angle sensor replacement, it's actually quite easy.
>> if you're skilled, you can even remove it without removing the whole
>> throttle body.
>
> Indeed! It was a bit of a lousy angle, but I got in there with a Dremel
> and it took only moments. I'm at a loss as to why Honda doesn't consider
> this a replacable part.
>
> Sadly, the bottom end of the engine started falling apart after another
> few thousand miles, but I'm not completely unhappy with getting 380k out
> of it. (One owner since new, no real work beyond the occasional valve
> check and oil changes every 8k or so.) The same throttle body is on the
> new engine and is working perfectly. (I may get around to posting
> pictures of what the bottom end looked like once I have it apart; while I
> went for a new engine I've saved the old one.)

great followup andrew - closing the loop on problem solution is a
wonderful thing to anyone searching the archives. also, i note the fact
that you're standard transmission, not auto. i suspect that shifting
wears the tps a lot more on the sticks than the autos.

shame on the old motor - what replacement did you use? jdm?

Re: Debugging a Funny PGM-FI EACV Problem ('89 1.5)
 

andrew m. boardman wrote:
> Oops. This is pretty old news at this point, but better late than never.
> (I found many a similar problems in the archives, but there was never any
> followup once it got fixed; perhaps this will help someone down the line...)
>
> jim beam wrote:
>> andrew m. boardman wrote:
>>> I've got a friend coming by with a multi-channel digital recorder this
>>> weekend; we'll wire up *all* the ECU inputs plus the EACV control and see
>>> what corresponds to the EACV getting thrown open.
>> wow, that's serious stuff! i love toys like that. keep us posted on
>> how it goes.
>
> Sadly, "how it went" involved my friend's nice laptop blowing up, so I
> don't have any lovely eight-color graphs of engine sensors over time to
> put on the web.
>
> We did, however, find the problem: it was the throttle angle sensor after
> all. The reason we didn't catch it the first time is that the arm had
> shorted to the +5 side, but the resistance readings between the ground
> side and the arm (which is what we checked) were perfect. Electrically,
> this didn't raise any error with the ECU because everything that was
> being reported was within spec, but it was all compressed into the upper
> part of the range of valid TAS readings. Thus, the ECU thinks I've
> always got the throttle way open and opens up the EACV and dumps in lots
> of extra gas to suit.
>
>> regarding throttle angle sensor replacement, it's actually quite easy.
>> if you're skilled, you can even remove it without removing the whole
>> throttle body.
>
> Indeed! It was a bit of a lousy angle, but I got in there with a Dremel
> and it took only moments. I'm at a loss as to why Honda doesn't consider
> this a replacable part.
>
> Sadly, the bottom end of the engine started falling apart after another
> few thousand miles, but I'm not completely unhappy with getting 380k out
> of it. (One owner since new, no real work beyond the occasional valve
> check and oil changes every 8k or so.) The same throttle body is on the
> new engine and is working perfectly. (I may get around to posting
> pictures of what the bottom end looked like once I have it apart; while I
> went for a new engine I've saved the old one.)

great followup andrew - closing the loop on problem solution is a
wonderful thing to anyone searching the archives. also, i note the fact
that you're standard transmission, not auto. i suspect that shifting
wears the tps a lot more on the sticks than the autos.

shame on the old motor - what replacement did you use? jdm?