Parts Diagram For 2012 Suburban Intake Manifold

Joined Dec 29, 2014

6 Posts

Discussion Starter · #1 · Dec 29, 2014

Hello, I'm new to this forum and hoping for some help. I am not a mechanic, but know my way around engines and like to wrench.

The Story

I have a completely stock 2001 Silverado with the 5.3L and was getting codes P0171 and P0174 lean bank 1 and 2 during the winter. I read that the intake manifold gaskets are a common issue with these motors because the ethanol in gas eats away the OEM plastic gaskets. The truck ran and idled fine but was getting bad gas mileage so I decided to change them because I have a 45 mile drive to work. I replaced them with the metal Felpro gaskets and torqued everything down to factory specs this weekend. I cleaned the surfaces well, vacuumed all the dirt and crud away from the ports, everything came apart and went together pretty easy.

Summary of the Problem

Replaced intake manifold gaskets with Felpro gaskets, now it is idling very rough, still has the P0171 and P0174 codes, and will stall on occasion. The truck will run and drive smooth when you get going, but will run rough when my foot is off the gas at a stop.

What I have tried to fix it
- Checked, double checked, triple checked all electric and vacuum lines. I even removed the whole manifold again to make sure the gaskets were seated and nothing fell in between.
- Checked the gaskets were sealed by spraying the edges with brake cleaner. Doesn't seem to change the RPMs, but hard to tell 100% bc it won't idle steady.
- Cleaned my MAF sensor with MAF cleaner
- Cleaned my MAP sensor
- Cleaned my throttle body
- Cleaned my IAC valve
- Cleaned my PCV valve
- Replaced EGR gasket and O-ring that goes into the manifold (came with Felpro gasket kit)
- Double checked all of the clamps on my intake are tight.

Any suggestions and help are appreciated!

Planning on having a friend sit in my truck to keep the RPMs around 1000-1500 while I spray around the intake when I get home from work.

Joined Dec 29, 2014

6 Posts

Discussion Starter · #2 · Dec 30, 2014

Checked the intake with carb cleaner again yesterday and I think there is a slight leak. It seems to idle rougher when its cold and better when the engine is to temp. Planning on getting new intake bolts in hopes that the new rubber seals will help torque it down a little better. If that doesn't fix it completely, everything is coming apart and checking to make sure the plastic intake isn't warped.

Joined Sep 29, 2014

89 Posts

Do you have your own obd 2 scan tool? If so I would hook it up and look at your readings for the maf, map, tps, 02 sensors and check your fuel trims. If you search the Internet you should be able to find directions on how to troubleshoot each and what readings should look like.

Joined Dec 29, 2014

6 Posts

Discussion Starter · #4 · Jan 6, 2015

I just have a cheap OBD2 bluetooth dongle and the Dash Command iPhone app so it doesn't tell me very much info.

Next I tried to fix...
-GM intake bolts - didn't change anything
-Dorman Intake Manifold - the original intake was a little warped but still idled rough

The solution
I could hear a hissing noise from the passenger side of the motor which i originally thought was the intake manifold gasket again. It turned out to be from the

EGR Valve

. I confirmed this was the problem by closing off the EGR hole on the the Dorman Intake Manifold with a cap that came with the new intake and it idled fine and didn't throw any check engine codes. The EGR tube under the valve was cracked from flexing it to get the Intake Manifold off. That was it.

Joined Dec 29, 2014

6 Posts

Discussion Starter · #5 · Jan 7, 2015

Figure I might as well give a review of the Dorman Intake Manifold for anyone who might have to replace their OEM manifold.

I got it from Advanced Auto Parts when they had a 20% off online special, so I paid $280 with tax (regularly $330 +tax). The part number is 615-183 and they fit the 4.8L, 5.3L, and 6.0L. I was happy with the quality, installation instructions, fitment, and would recommend it. It came with new intake bolts, throttle body studs, all other studs and bolts needed (need to reuse the original throttle body nuts and top wiring harness bracket nut), fuel injector O-rings, and has built in gaskets for the throttle body and intake ports so you don't need to buy new ones (they are replaceable still too). It looked slightly larger to me like the ports might flow better, but I haven't really noticed any difference in power, however, I don't really beat on my truck much. The MAP sensor was also moved from the top to the back of the manifold. I have no real complaints.

Here are some pictures and descriptions of the differences...

Original GM Intake Manifold Side (with fuel rail installed)

Dorman Intake Manifold Side

Comparison of the back (GM left, Dorman right)

Comparison of the front (GM left, Dorman right)

Original GM Intake Bottom with Felpro Steel Gasket

Dorman Intake Bottom with built in Gaskets around individual ports.

GM Intake Bolts on Left vs Dorman Bolts on Right

Original GM MAP Sensor Location

Dorman MAP Sensor Location

Joined Nov 9, 2014

13 Posts

Thanks for the review, I priced a oem intake manifold once and it was over $500! That was not from the dealer either. if I understand correctly your original code was from a bad intake manifold gasket?

Joined Dec 29, 2014

6 Posts

Discussion Starter · #7 · Jan 7, 2015

I am not sure if the original codes were from the intake manifold gasket or if the EGR tube already had a leak. I learned a lot in the last week or two after taking it apart over and over, so if I were to do it again, I would first check...

If P0171 and P0174 lean bank 1 and bank 2 codes

1. Spray carb or brake cleaner around the edge of the intake manifold to check the gaskets on each side.
2. Also spray around other components to check for vacuum leaks. (EGR valve and tubes, PCV valve, MAP sensor, throttle body, intake tube, etc).
3. Disconnect and clean MAP and MAF sensors with MAF cleaner as well as IAC valve
4. Test sensors and valves to see if any need to be replaced. (MAF, MAP, EGR, PCV, IAC, TPS)
Probably other stuff I am for forgetting or don't know about.

If rough idle (I also got P0300, with P0171, P0174 codes)

1. Check the fuel pressure regulator on the drivers side fuel rail by pulling the vacuum line off. (It is bad if wet with fuel)
2. Check EGR valve is working properly, gasket is good, and the tubes don't have a leak with carb cleaner.
Again there is probably other things to check so feel free to add if want.

Joined Dec 29, 2014

6 Posts

Discussion Starter · #8 · Jan 9, 2015

This is what my EGR valve tube looked like. It was cracked under the valve on tube going to the intake.