daisycivic1.6

I have spent many hours trying to diagnose the main issue I currently have in my 1997 Civic HX Vtec-E.

Check engine light is one. EGR valve low-flow (or some such terminology). It has been cleaned with brake clean multiple times without solving the problem. I checked the EGR valve for proper operation by grounding the negative pin on the valve itself to battery ground. Then running a jumper wire from battery positive to the positive pin on the EGR valve connector, and a "click" is heard. This indicates that it is actually working. I then checked the power (pink) wire from the harness with a DVOM, looking for battery voltage. 6.04V is measured...i checked the ground wire by putting the negative probe on the black wire, and the positive probe on battery positive. Reads 12.3V. I traced the pink wire all the way to the computer, then finally cracked open the computer and found no breaks anywhere in that circuit. The component i traced the pink wire back to (in the computer) is a circuit protector from unwanted spikes in the voltage. Could this be linked to my coil? (Below) If not, why in the world am i not getting battery voltage at that connector like the manual says i should??

Also, tachometer works, however it will sometimes reads at 5000rpm when idling. It will however increase or decrease like it should as i go faster or slower or downshift. This fluctuates between proper function and all the way pegged straight down or anywhere in between.

Could both be linked? If so, could my coil be going out and causing a spike in both circuits??

Thank you very very much for taking the time to read my novel.

ezone

That's the definition for a P0401 code.

The passage between the EGR valve and the intake manifold is clogged with carbon buildup. Clean it out.

Remove #11 and #12 to access the EGR distribution area.

daisycivic1.6

Hey thanks alot i'll give that a shot.

ezone

I was at lunch earlier and only had a minute to type.


You probably need to lift out the fuel injector rail (with the injectors and hoses still attached, as complete as possible) to reach the EGR distribution plate.

#11 is the distribution plate, there is a bunch of snakelike passages cut into that piece that all need cleaned of carbon buildup, scrape off the fat metal gasket #12 and poke out each hole, and there is a single hole in each intake runner that needs cleaned (poked out)....

I use a gasket scraper and various drill bits to get the majority of the crud out.

There will be a LOT of carbon, you will make a big mess so do it over a trash can or something if possible. The stuff will get everywhere.


This is considered "periodic maintenance".

daisycivic1.6

I was able to open it up with the fuel rail still in (not fun). But when I looked in I noticed that the cavity that was exposed contained no carbon, in fact it had motor oil pooled up in there. Is the space you are talking about below this part?

ezone

It isn't motor oil, it should be carbon.

You may have gotten it wet and gooey with cleaners when you tried to use brake-cleaner on it?




Follow or trace out all of the ports and passages between the EGR valve (larger hole) and the intake manifold (one smaller hole in each runner). There is or was blockage(s) or restriction(s) causing the low flow code.


2 tests you can do once you put the plate back on:

Remove the EGR valve and run the engine--the vacuum leak should make the engine run rapidly to 2000 RPM and surge repeatedly. (If no, then it is still clogged)

Reinstall valve, run the engine, manually activate valve (like you described in the first post) to fully opened position. Engine should stumble severely or die..

daisycivic1.6

Okay great. Thank you very much for your advice! I will attempt at getting all this done in the near future.

daisycivic1.6

Oh, another quick thing. When I shut the motor off, there is some sort back pressure that is slowly released coming out of the intake. More precisely it is coming out of the small hole just before the plate in the throttle body. Is this due to the clogging also?

ezone

Lasts about one second after you shut it off? Normal.
Pressures are equalizing between 14.7 PSI atmospheric and 20" vacuum in the intake from a running engine.

daisycivic1.6

Oh thats normal? Okay fresh i'll stop trying to fix it! Thanks again bud.