Civic VX - Leaking EGR Valve problem

[djenyc]

Did some more testing this morning on 92 Civic - Blocked off PCV line, vacuum booster line, charcoal canister line - went for a test drive - no change, idling is still rough.

Tried pulling IACV plug to check base idle on 92 Civic and it would not run unless I pressed on the throttle. Not sure what this is all about, I tried the same thing on 94 VX yesterday and it ran on its own.

Checked timing on 92 VX - about right, but the engine kept revving, so it was tough to check accurately.

Next I've made a steel block-off plate for the EGR valve and installed it on 92 Civic - went for a test drive and there was no change, so may be EGR is fine, or at least there is something else that's causing rough idle.

[djenyc]

Did some more troubleshooting on 92 VX:

- Removed throttle body/manifold and cleaned up carbon deposit, used new gaskets and some rtv sealant - test drove the car - no change.

- Swapped fuel injectors with a spare engine - test drove the car - no change.

- Swapped distributor with a spare engine - test drove the car - no change.

- Played with timing and was able to get the car to stop revving at idle with timing severely retarded, but when the bad symptom came back so I set timing back to where it was.

- Checked base idle with IACV connector disconnected - Idle was not steady, but stayed at around 370-420 RPM, which is within the spec. I also pulled off a small vacuum line and saw rpm increase - fluctuating between ~ 700-1000 rpm.

I noticed that sometimes the car will run fine, and idle steady at around 650 rpm, but most of the time it's revving up and down between 900-1300rpm, or idling steady at 1100 rpm.

Next I'll probably take it to a shop or start looking for a replacement engine, unless somebody has an idea on what else to try.

Thanks
Ross

[GasSavers_Erik]

IMHO- If creating a vacuum leak with the IACV disconnected sends the idle up above factory specs, then it seems like you didn't have a vacuum leak to begin with.

How about a compression test? Perhaps poor compression in one or two cylinders is giving the bad idle.

No need for a rebuild if the motor has good compression. Check it when the motor is warm/hot.

Remember to hold the throttle wide open and have all the plugs out when testing each cylinder.

The other issue might be a bad cam lobe- if one valve wasn't opening as far as the others, it could give unstable running. If its a flattened intake lobe this may show up on your compression test.

How about the timing- when you used the timing light was it nice and steady? or did the position on the pulley when the light came on seem to jump around randomly? I know you tested two distributors, but maybe both of them have worn internals.

What about fuel pump pressure?- if your pump pressure was unsteady, I would think this would affect mixture.

If the computer was adjusting the mix incorrectly (bad 02 sensor) or if the O2 sensor was slow to respond to changes in the mix, maybe that could cause it (grasping at straws now)

[djenyc]

Erik, I did compression check on '94 Civic and it had 197 psi in all 4 cylinder, didn't check '92 (both cars have the same idle problem). When I checked timing on '92 VX with engine idling steady, timing was steady, when engine started revving up and down, timing shifted a little. Don't know about fuel pressure. Might give it another shot next weekend.

For now I dropped the car off at a local shop, hopefully they'll figure it out. At this point I've probably spent 5 weekends troubleshooting that stupid thing, so I won't feel to bad about the bill

[djenyc]

Got the car back from the shop. The guy said he replaced MAP sensor o-ring and cleaned up some carbon deposit. A couple hours of labor, no parts, came out to $140 total.

[GasSavers_Erik]

Wow- congrats. Well- the answer will be here for any others with the same problem in the future.

$140 is much better than a rebuild!

[GasSavers_TomO]

This is good to know.

Last month or two I had been randomly throwing a code for MAP sensor, but my vacuum gauge showed that the levels of vacuum were where they were supposed to be. I ended up swapping out the MAP sensor and cleaned the O-ring for it as well as cleaned out the MAP passage in the throttle body. Haven't had an issue with it since.

[Carlos-gomez]

Hey there i need help so bad i cant get my car to pass smog i have done everything new o2 sensor, new cat, cleaned the egr valve and intake manifold and still cant pass have fail smog 5 times please help thanks

Originally Posted by TomO

This is good to know.

Last month or two I had been randomly throwing a code for MAP sensor, but my vacuum gauge showed that the levels of vacuum were where they were supposed to be. I ended up swapping out the MAP sensor and cleaned the O-ring for it as well as cleaned out the MAP passage in the throttle body. Haven't had an issue with it since.