Hey everyone,

After running my car with the EGR ports plugged for over two years, I've gained enough might to dig back in and try to figure of my EGR stumble once again.

I ran a test yesterday with the PDU. Engine running, EGR commanded on, and held the RPMs at about 2000. Engine was sputtering and sounded like crap, overall. I was expecting that.

I wasn't expecting this:


You can see the smoke rising up from behind the engine. It was VERY hot back there. I took a closer look and the smoke appeared to be coming from the EGR pipe, right around where the woven fabric heat protector ended. Could this just be residual oil burning off from the tube after a couple years of not heating up to EGR temps?

Would a bad EGR pipe would allow un-metered excess air to enter the intake through the EGR adapter? Wouldn't that cause mixture problems even with the EGR off too? The car seems to run okay, as long as the EGR valve isn't opening. How would you guys check it? Also, what would need to be done to replace it? Raising the rear of the engine up?

Thanks,
Nick

 

IIRC it is a bit of a PIA to remove but once both ends are released I think you can jiggle it up and out of there

Of course when I removed it I'd already dismantled quite a lot of the ancillaries so maybe that's why I was able to get it out??

What about finding this theoretical hole/split and welding it in situ? No?

Good luck with it

Larry

 

Thanks, Larry. I suppose a fix could be done in place and you're absolutely correct, this is a theoretical hole or split. I'm not sure how to test to see.

If there was a split then there would be a vacuum leak there which I could potentially test with propane or carb cleaner or some other fluid that would raise or decrease engine speed.

I wish I had a smoke machine, it would make this a quick process. Fill the intake and see where the smoke leaks out.

As I've said, this smoke could certainly be from residual oil burning off with the heat. I didn't try running the EGR for very long to see if the smoke would stop at some point. Maybe I need a long drive with the EGR enabled first, to see. If it's oil burning then I'm back to square one.

Nick

 

the schematic EGR line,
it may help you

Best regards

 

Hi Nick,

I can't tell from the video and I know this wouldn't help explain your apparent EGR issues, but is it possible the smoke is from oil leaking from the half-moon rubber seals at the rear end of the cam cover or the cam cover gasket itself?

Cheers,

Don

 

Thanks guys.

I did drive the car on the highway for about 20 minutes with the EGR enabled, and I didn't see or smell smoke after testing the EGR with the hood open back home afterwards. I guess it might've just been residual oil from a valve cover leak.

I thought I was onto something here! Now its back to where I started...

I should ask while I'm here: Is there supposed to be some sort of vacuum restrictor or delay valve in the EGR valve vacuum supply?

Nick

 

The EGR valve does not use vacuum alone but back pressure from the exhaust also.

Lift the EGR diaphragm with your fingers under the edges and the engine should idle ROUGH!!!!!!

The EGR temp sensor (thermocouple) will see a rise in temp at the intake when the EGR is commanded OPEN.

If the temp sensor does NOT see the rise it will set the FF39.

The pipe gets clogged with carbon and results in NO FLOW!!!

You nee to download S91_AJ6 4.0 Engine Management.pdf from the interweb.

I uploaded a copy to various forums a decade ago and Gus should have it on his site.

The document has all the info on the engine management for your car.

bob

 

Thanks Bob,

All of that checks out. When lifting the EGR valve by hand or by running the EGR test with the PDU, the car will actually stall unless I manually open the throttle. Even with the engine at 2000 RPM and the EGR test running, the engine still stumbles and runs rough. With the EGR vacuum hose connected and driving down the highway, I can also feel the very slight stumbling of the engine. This does not happen with the EGR vacuum hose plugged. Is this normal behavior?

I have not had any other FF code set other than FF39 when the vacuum hose is plugged. I have cleaned the EGR adapter port which had a small amount of buildup, but nothing remotely close to a blockage.

I'm trying to determine if I have an EGR system issue or another issue which is only made apparent when the exhaust gasses are being introduced. And thanks for the EMS manual, I actually have a print copy.

I know EGR operation and monitoring takes place over a specific envelope on an RPM x Engine Load graph. I've swapped the Air Flow Meter to see if maybe it was faulty, causing the EGR to be commanded at too low an engine load, causing my stumbling. No results there.




Thanks again,
Nick

 

I've got some good news when it comes to the EGR issue with my 92 Sovereign. For those who don't know, I get engine surging and stumbling at low road speeds any time the engine RPM is brought above 1000 RPM (EGR is enabled at this point), especially when decelerating to a stop light or traveling in heavy traffic. I've been chasing solutions for years with no success, throwing hundreds and hundreds of dollars in parts at the car.

My first stopgap solution was to plug the EGR solenoid valve output and disable the EGR valve entirely, which works great... Aside from tripping the Check Engine light and setting Fuel Fail 39 every few days.

My next solution was to install a resistor across the EGR temperature sensor plug to trick the car's ECU into thinking the sensor is actually seeing "EGR flow," thereby keeping the Check Engine light off. This doesn't really sit right with me, though, and I'd rather all the Emissions Controls are working properly and automatically, especially during emissions testing.

My most recent fix was to remove the trick resistor across the wiring, putting it back to stock, and installing an old-school vacuum delay valve between the EGR valve and the solenoid. These are hard to find these days, and I was only able to get my hands on a 3-second delay unit. This helps to ignore the EGR signal for a few seconds, and has reduced the stumbling greatly, unless I'm in traffic or traveling at a steady, slow speed at 1000-1300 RPM for more than 3 seconds. (Above this engine speed, the stumbling goes away).

It's a small, waterproof digital timer circuit. I will set it to a 30-second or 1-minute delay. This will essentially disable EGR during slow-speed driving. Each time the engine speed drops below 1000 RPM, the signal from the ECU is cut and the timer will reset. This will allow me to keep EGR function at highway speeds, where stumbling isn't an issue. It will install between the car's harness and the EGR vacuum solenoid, using the solenoid power to trigger the timer, and passing it through to the solenoid once the programmed timer has elapsed.

I plan on picking up the EV1 pigtails to give me a plug-and-play solution.




-Nick

 

Hi Nick!

I merged your post with your original thread so all the posts will be together.

In the past I've ordered EV1 connectors from DIYAutoTune at around $6 each, but I happened to come across this company that lists the EV1 connector pigtails at $1.66 each:

https://www.delcity.net/store/Fuel-I...kaAvRwEALw_wcB

Cheers,

Don