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

[steffen707]

Originally Posted by 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.

Well the ecu i'm using does have egr control in it. You are right that the car i have the motor in didn't have EGR, but i've added all the necessary wiring to connect the egr, and the black box to the ecu, and i've tested all the pins.

I'm just baffled that I can completely unplug the egr and the black box and it never throws a code. i'm wondering if perhaps i have a bad ecu, somebody swapped the ecu case, (which i highly doubt because the vx ecu is only useful to vx owners, you can't modify it for hondata like the EX ecus, ect.).

While some have said, hey, 48mpg sounds like it is working, i'm curious if the egr system was working properly, would i get even more than 48mpg, or would I get less.

[steffen707]

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.

That would be awesome, I really appreciate any help you can give.

[steffen707]

Originally Posted by 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.

I have tried exactly what you said and there is no vacuum.

I've even driven the car with the vacuum pump hooked to the egr to manually actuate it myself and it certainly does put exhaust into the engine. if i put enough vacuum to the EGR it will choke the motor off enough that it shuts off. So I know the EGR can work, but doesn't seem to ever get actuated by the ecu.

Could it be the car never gets up to high enough temp? And yes i've driven 4 hours straight with the car on the highway, so it "should" have gotten up to temp before.

[steffen707]

Originally Posted by 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..

My state does inspections but not near where i live, the vx engine is obd1, and my car is obd2a. i used an obd2a engine harness to obd1 conversion harness. I do have the EGR control solenoid "black box" hooked up properly all the way back to the ecu. I've tested each wire and compared it to the shop manual diagrams. I've even gone through all the trouble shooting steps in the manual and it seems to check out.

It has been about 6 months since I did my thorough checking, i think maybe i'll test everything again.

I have an mpguino and even with the egr unplugged the car still goes into lean burn mode. I just wonder if it would get better gas mileage with the egr working.

[steffen707]

LMAO. Yesterday I was trying some stuff while driving. I realized that under certain road conditions, my car prefers 70mph than 65. I think its because i can still be in lean burn mode, 70mph in 5th gear the tach was just under 3000. Its not great, but about 51mpg.

Similarly if I go 65mph the car gets like 55-59mpg, but often keeps dropping out of lean burn because i can't maintain the speed.

WELL the reason why this is significant, is because today I was on the highway and tried cruising in 4th gear at 70mph. After a mile or so the check engine light came on.

I came home and checked it, CODE 12 EGR VALVE ERROR. Aparently my ECU is working.

The funny thing is that so many people have read how crucial the "egr black box" is to a vx d15z1 swap, when in reality, it hardly ever gets activated. I have only seen this error once in over a year doing something I would never normally do as I almost always cruise in 5th gear. So the EGR system rarely gets used.

I'm about to go back outside and drive around until I can mimick the 4th gear condition that caused the CEL12 and then re-hook up the EGR with the vacuum gauge to see if the EGR system is working.

[brucepick]

I also had low speed lean burn problems, and occasional but repeating CEL's re. the EGR. Things have been much better since Jan. 17; read below.

Try Marvel Mystery Oil (MMO) in your fuel, 4 oz per 10 gallons of gas, per the bottle instructions. And 10% of sump capacity in your oil (MMO bottle says 20% but I used 10%). I think it's the MMO in the gas that does the trick, for my car anyway.

Till this past January, my HX would only allow lean burn down to about 61mph. It was that way for over 3 years / 70K miles, including after I had the head rebuilt professionally. Occasionally I'd see LB between 46-61 mph but sometimes only a few seconds, sometimes a few miles. Then no more. But other Honda lean burn drivers reported LB down to about 45ish mph. I found it frustrating.

One day this winter I added MMO as above, in the sump and the tank. Boom! Lean burn came back. Now it holds LB down to about 45-46 mph, as long as I pay attention to the amount of MMO in the fuel.

Then I refilled the tank and didn't think to add MMO with the new fuel. Low speed lean burn went away. Pulled over, added it, low speed LB came back. I've had good results using between 2-4 oz per 10 gal gas. I'm tending towards 3 or 4 oz but I haven't completely settled my scheme yet.

My current tank isn't visible in the gas log yet. Low speed LB is working again, and my nice LRR Michelin snow tires are back on the car, and MPG is back up around 52-53 so far for the tank.

Working this since Jan, I've seen low speed LB go away about 2/3 way through the tank. Deduced that MMO is heavier than gasoline, is gradually settling to bottom of tank and gets sucked up by fuel pump. Gradually reduces the concentration. I'm testing adding an ounce or so about half way through the tank to compensate.

See my gas log. See notes on low speed lean burn for the Jan. 17 and Jan. 27 2012 fillups.

You'll need a funnel with about 10-12 inches of hose or tubing. And a rag to wipe the funnel.

[steffen707]

So i went out and drove 70mph on the highway in 4th again and the check engine light came back on. I hooked the EGR back up and I hooked up my vacuum gauge to the EGR and went 70mph in 4th again and low and behold every so often it sees vacuum when the black box activates the EGR. I was also able to see the egr work when you cruise in 2nd or 3rd gear at a high rpm.

As I expected though, through normal driving when I always coast in 5th gear I never saw vacuum on the egr, leading me to believe that the EGR rarely is used on the d15z1.

[steffen707]

Originally Posted by brucepick

I also had low speed lean burn problems, and occasional but repeating CEL's re. the EGR. Things have been much better since Jan. 17; read below.

Try Marvel Mystery Oil (MMO) in your fuel, 4 oz per 10 gallons of gas, per the bottle instructions. And 10% of sump capacity in your oil (MMO bottle says 20% but I used 10%). I think it's the MMO in the gas that does the trick, for my car anyway.

Till this past January, my HX would only allow lean burn down to about 61mph. It was that way for over 3 years / 70K miles, including after I had the head rebuilt professionally. Occasionally I'd see LB between 46-61 mph but sometimes only a few seconds, sometimes a few miles. Then no more. But other Honda lean burn drivers reported LB down to about 45ish mph. I found it frustrating.

One day this winter I added MMO as above, in the sump and the tank. Boom! Lean burn came back. Now it holds LB down to about 45-46 mph, as long as I pay attention to the amount of MMO in the fuel.

Then I refilled the tank and didn't think to add MMO with the new fuel. Low speed lean burn went away. Pulled over, added it, low speed LB came back. I've had good results using between 2-4 oz per 10 gal gas. I'm tending towards 3 or 4 oz but I haven't completely settled my scheme yet.

My current tank isn't visible in the gas log yet. Low speed LB is working again, and my nice LRR Michelin snow tires are back on the car, and MPG is back up around 52-53 so far for the tank.

Working this since Jan, I've seen low speed LB go away about 2/3 way through the tank. Deduced that MMO is heavier than gasoline, is gradually settling to bottom of tank and gets sucked up by fuel pump. Gradually reduces the concentration. I'm testing adding an ounce or so about half way through the tank to compensate.

See my gas log. See notes on low speed lean burn for the Jan. 17 and Jan. 27 2012 fillups.

You'll need a funnel with about 10-12 inches of hose or tubing. And a rag to wipe the funnel.

I don't have problems getting lean burn at most speads under 60mph, the only times I have problems is trying to maintain lean burn at 65mph with slight hills. I don't think this is the engine running poorly, but rather a heavier, less aerodynamic vehicle that I put the d15z1 into.

I'll have to look into that MMO though. I've got 210,000 miles on my engine. I'm sure it can use some help.

[turbothrush]

Originally Posted by steffen707

So i went out and drove 70mph on the highway in 4th again and the check engine light came back on. I hooked the EGR back up and I hooked up my vacuum gauge to the EGR and went 70mph in 4th again and low and behold every so often it sees vacuum when the black box activates the EGR. I was also able to see the egr work when you cruise in 2nd or 3rd gear at a high rpm.

As I expected though, through normal driving when I always coast in 5th gear I never saw vacuum on the egr, leading me to believe that the EGR rarely is used on the d15z1.

Wow Steffen Excellent work !! I fixed the leak on the egr valve on my vx and I will now go through the tests in the manual to make sure the system tests out. Then I will drive like in your example and we will see if a totally stock vx does the same thing.

Maybe someone else with a vx could do it also. Hx might be different but would still be cool to know if leanburn cruise uses ANY egr at all.
.

[steffen707]

Yeah just try crusing around at 3500-4000rpm in any gear. I noticed the vacuum on the egr hose occured more often when you accelerated a bit like from 65-70mph in 4th gear and then let off the throttle to enter into lean burn. It would then show up.

Its funny though because in 5th gear doing the same thing it wouldn't do it. Not even once with my car. And I drove around for 30 miles on the highway testing it.