Why isn't my EGR throwing a code, civic vx help!

[steffen707]

Hey guys, i swapped a 92 vx d15z1 motor into my 96 hatch. I had the complete donor car and swapped over everything including the black box on the firewall that includes the EGR control solenoid valve, and the cvc valve. I've studied the shop manual over and over the EGR system info is on pages 11-134 to 11-139.

The problem i'm having is that the system isn't working but doesn't throw a code. I've checked the egr with a vacuum pump and it operates, i've tested all the wires and they all run to the right spots. My check engine light does come on when you turn the car on, so i know the light isn't burned out. I've also used 2 different 49 state "lean burn" p07-A00 ecus.

I've driven the car with a vacuum pump connected to the egr and have applied and taken away vacuum to the EGR to activate it.

Some might ask, well with no check engine light what are you complaining about. I've driven the car for over a year and get 45-48mpg on average which is pretty good, but I wonder if the EGR was operating properly if I would get better gas mileage or not.

The main reason why I know something is wrong, is because I don't even have the black box hooked up now, have driven over 7,000 miles, city, highway for 4 hours at a time) and never once did I get a check engine light.

Does the EGR help give better gas mileage, or is it strictly an emmissions thing?

[cbaber]

If you are getting 48 mpg then obviously nothing is wrong. The egr is for emissions but can effect fuel economy. Before I put in a new motor I had a CEL for the egr that I didn't know about (bulb had been pulled) and my mpg was around 32 instead of the normal 38. I swapped the motor before having the chance to see if the egr was causing the losses or if it was because of the bad cylinder.

[drmiller100]

your question caused me to go do some research.

the 'net claims that only manual transmission engines had EGR's, and then only some models.

perhaps there are no wires in the harness for the egr wires? the trouble codes are pretty rudimentary - it might not detect the fact it is unplugged.

[brucepick]

Sorry, I can't guess why you have no CEL. Lucky you!

I've read that Honda's lean burn setup uses the EGR to feed exhaust gas back into the intake during lean burn. Clogged EGR passages in the intake path or in the EGR itself will reduce your lean burn capability, or eliminate it entirely.

So yes, it's for emissions. So are your cylinders and the intake and yada yada yada. But the EGR figures significantly in the lean burn system so you do want it working.

See the "Garage" link at top of this page, go there and do a search on Civic VX to see what other VX drivers are getting. From what I remember, they will do better than 50 mpg without mods if everything is working right.

[turbothrush]

Originally Posted by steffen707

Does the EGR help give better gas mileage, or is it strictly an emmissions thing?

I've got a MPGuino in my vx and I'll try to get an answer for you tomorrow.Since I am pretty sure it only works during cruise I'll do a few runs at 50 mph in leanburn with and without egr.

When I got my car the egr was frozen solid and no code.

[jonEmetro]

In theory the EGR does improve mileage by partially filling the cylinders with exhaust which is inert. Less oxygen means less gasoline burnt. This also means we have to open the throttle a little more to get the same power thus reducing pumping losses.

Attach a vacuum gauge to the vacuum hose going to the EGR valve and drive using less than half throttle and see if the vacuum solenoid is providing vacuum to the valve. The ECM will need to see warm coolant temp, vehicle speed & proper MAP sensor voltage before it will activate the solenoid.

[cbaber]

I thought the actual EGR valve was mounted next to the valve cover on the head with only a connector coming from it? The ports are machined into the head, and these can get clogged up which was the case with my old engine getting the CEL. Have you tried to disconnect this part of the EGR system?

[user removed]

Wasn't the VX OBD1 and the 96 and later OBD2?

regards
Mech

[02ws6]

Yep.. Can only assume that his state doesn't do inspections.. If the car is running, he's already converted to OBD1.

The EGR having a malfunction could very well be the case..

I just wanted to ask if you had the EGR control solenoid "black box" hooked up properly all the way back to the ECU. It aint gonna do anything without that piece.. There's also a nice detailed diagram on hooking this bad boy up..

[turbothrush]

Originally Posted by turbothrush

I've got a MPGuino in my vx and I'll try to get an answer for you tomorrow.Since I am pretty sure it only works during cruise I'll do a few runs at 50 mph in leanburn with and without egr.

When I got my car the egr was frozen solid and no code.

Well it turns out my egr valve is leaking at the point where the lift sensor attaches to the valve so no test today. I am going to try and fix it to do the test as a new one is over $200 at Majestic.

Just in case anyone is interested even without a working egr my vx has no code and goes in leanburn no problem at all.