A story from a newbie shade tree mechanic... Me.

My 2000 Silhouette Premier with a 3400 engine was sending a P1404 lean code so I had my work cut out for me. P1404 code refers to the EGR valve being open when it should not be, and from what I read online, removing & cleaning the EGR valve would probably fix the problem.

In order to get a wrench on the bolts, I had to rock the engine forward. This was my first time doing this so I have tips for newbies like me.
1. Follow the instructions in the Haynes Manual & BLOCK the rear wheels!
2. Don't do this on an incline or decline. (I was fortunate the bolt on the driver's side engine strut was very difficult to dislodge, so I started investigating as to why. Decline & wheels not blocked.)

Ok, first I removed the antifreeze overflow tank and the support stucture it was mounted to. Even though the book says nothing about this, trust me, it helps.

Then I disconnected the accelerator & speed control cables. Piece of cake.

Then I removed the air cleaner duct & air cleaner. It was then that I discovered my air filter had not been installed properly & debris was passing under it. Bought new air filter. Then, while it was off, I decided to inspect the Mass Airflow Sensor & discovered the screen was 2/3rds blocked.

I used brake cleaner to clean it out real good, but after speaking with those in the know (after the project was completed), the next time I will spend the extra few bucks to use a spray cleaner designed specifically for cleaning Mass Airflow Sensors. I was told brake cleaner can be too harsh and damage the sensor, so I was lucky.

After finally suceeding at rocking the engine forward, I still had a dickens of a time getting my socket & ratchet on the EGR bolts because they are on the firewall side of the engine so I ran & bought 2 each 1/4" & 3/8" universal joints for my ratchet set. Without these I was going nowhere. After I just about had the EGR unbolted, I noticed the metal exhaust tube running into the back of the EGR, so I had to retighten the EGR bolts (still a dickens) in order to get a wrench on the exhaust tube bolt & get some leverage w/o breaking the EGR bolts. Then I again removed the EGR bolts & it finally came out.

I was lucky in that the gasket came out in one piece & I didn't have to try to scrape it clean. But I did plan to use the new gasket I had already bought just to be on the safe side. Just to make screwing the bolts back in easier I sprayed them down with PB Blaster (WD40 will work too) & set them aside on a rag. I also sprayed a spritz of PB in the female threads for ease of reassembly.

Next I inspected the EGR valve, and yes, it did have some carbon on it, but the condition didn't seem too bad. I had read horror stories where the ports were nearly clogged & or the exhaust tube was nearly clogged with carbon. Mine was not like this. Please note that there is no vacuum port on this particular EGR valve so I could NOT properly inspect the valve seat. I didn't want to spend hours online trying to find which wires opened the valve, so I proceeded as described below.

For this next step you really need safety glasses as the cleaner can come out of the same port it enters, and just as violently. Trust me on this, I know from experience, but I WAS wearing safety glasses. I used Carburator cleaner & cleaned the ports on the EGR making sure to NOT spray anywhere near the electrical connections or near the pump itself. I also used a very small screwdriver & test scraped carbon & didn't get much better results, so carb cleaner was all I used.

Then I set out & put it all back together which worked as long as I held my mouth just the right way for each step.

Finally I took it for a drive. It seemed peppier on takoff & basic acceleration with no hesitations at all.

All this said, if you get a P1404 code on your Silhouette with a 3400 engine I would recommend checking to make sure your intake air filter is properly seated & that the Mass Airflow Sensor is clean & debris free. If they aren't, replace the filter & clean the Mass Airflow Sensor, put it back together, clear the code & test it. The EGR is difficult at best to remove & clean. Plus it costs over $100 to replace.

What I think happened:
Mass Airflow Sensor was restricted in front of the actual sensors so it leaned the fuel to match the air it thought it was getting. The oxygen sensor(s) was detecting more oxygen in the exhaust telling it that it was running lean. The lean condition indicated a possible EGR valve sticking open, thus the P1404 code.

Had I taken this to a shop they probably never would have looked at the air filter or the Mass Airflow Sensor. They probably would have charged 2-3 hrs labor + a new EGR & replaced a part that was just fine, & I would have had the same codes show up while driving home.

I hope this helps someone else.

Referee

 

Nice write up!!!!

 

Very good writeup, thanks! I learned to check the filter first from you, thanks again.