Red97LT1

Just got the car back yesterday from having a new engine installed.I had new wires,plugs.opti,injectors,etc replaced while my mechanic was at it. It runs fine,but I am getting these codes today.

I checked for leaks,but really don't hear anything. I'm going to replace the PCV valve tomorrow just to see if that does anything since it's cheap and an easy replacement.

I also checked my fuel pressure at here's what I got...

Primed 38psi
Idle 32psi
Removed FPR hose(WOT) 42psi

Do those numbers look ok?Could a bad Fuel Pump cause the error codes? Anything else to check?

I have no problem taking it back to my mechanic to fix it,but I just got it back and I don't want to have to put it back in the shop.

Injuneer

Fuel pressures look OK. GM spec for no vacuum is 43.5psi, but accept 41-47psi. The pressure should drop proportional to intake manifold vacuum, and a 10psi drop is a bit high, indicating a stock cam.

Did you check the fuel pressure with the car out on the road, engine under load? You want to make sure it's not running low on fuel supply when you are WOT/5,000+
RPM.

Is the engine basically stock, and did the mechanic install the correct 24 #/HR injectors?

Was the MAF sensor replaced? Is it facing in the correct direction?

Is the rubber inlet elbow torn?

Did you check for vacuum leaks - it would have to be a large one and affect both banks of the engine? How about areas like the throttle body gaskets, injector lower o-rings, vacuum ports for the HVAC, EGR, Opti vent, AIR vent, PCV system, power brake booster, EVAP purge?

Red97LT1

Yes


Update: I replaced the PVC and the P0171 code went away. P0174 was still there. I took apart the air intake and cleaned the MAF sensor and then I noticed that where the connections to the air filter has some openings where it looked like they were actually crushing in instead of sealing around the plastic connectors.I fixed it the best I could and took it for a test drive.

I drove for about 10-15 miles and my scanner doesn't show any codes,it's still checking the H02 sensor before it gives an all green on my scan tool. Could the MAF in conjuction with the areas where air was probably getting in around the connectors cause the P0174 code?

I'm ordering a CAI kit anyways,so if so that will take care of the sealing problem around the stock air intake.

I'm going to go take another drive later to see what happens.

Injuneer

Did you check for vacuum leaks using something like starting fluid, or only visual?

Air leaking at the connection on the inlet (air filter) side of the MAF sensor isn't going to throw the air measurement off, just admit dirty air. Only leaks after the sensor cause a lean condition that the PCM has to correct. CAI isn't going to change anything that would cause it to run lean.

Leaks like the connectors after the MAF sensor will affect both banks of the engine equally - leaks on one side of the engine only affect one bank.

P0171 and P0174 are the same code, for each bank of the engine. The codes sets when there is a massive error on the A/F calculation, requiring corrections in the area of almost +22%.

Just because the code went away on one side of the engine doesn't necessarily mean you found the problem. It may mean that there was a minor correction that reduced the fuel correction to +21% (code sets at 21.9%).

Might be time for a full scan, using GaryDoug's OBD-2 scanning software.

Free OBD2 scanner software - Firebird Nation

Red97LT1

I may have found out the problem. I took off the 90 degree elbow that attaches to the TB and the bottom part had been push up inside the elbow and wasn't around the bottom part of the TB,so basically there was a big gap on the bottom.but the top part was screwed down tight. I drove another 10-15 miles without any P0171 or P0174 codes........but on the way back I got a P0410 code. Seems to be the Secondary Air Injection System.Any ideas as to what to check there?

Injuneer

Is all the plumbing hooked up for the AIR system?

Red97LT1

Yes. I hear the pump running(used a jumper), but I don't feel any air. So I either have a bad pump or a bad check valve. I checked it with the check valve on, so I'm going to remove it and see if I get any air.

Injuneer

The diagnostic is based solely on air flow - cycles the pump and looks for the expected change in the O2 sensor readings. Check for a hole in one of the rubber components/hoses.

Red97LT1

Removed the hose from the pump and air was gushing out,so it not the pump. Hooked up the a check valve(attached to outlet hose) that has a vacuum line on it and no air. I can push the inside of the check valve with the end of a socket wrench fairly easy,so I'm not sure it the check valve?

There is a vacuum line that runs from the bottom of the check valve that wasn't hooked to anything when I removed it. I can push in on the check valve and put my finger over the tip of the vacuum line and the check valve stays open,I remove my finger and it closes. Any ideas as to where that line goes? Is this my problem?

Red97LT1

Here's the part that I am referring to.It looks like a check valve with a vacuum line attached to it.

Red97LT1

I'm wondering if the vacuum lines were hooked back up correctly. There appears to be two solenoids,one up top near the TB and the other lower on the block.

The upper solenoid has one line going to the intake and the other going to that lower solenoid.
The lower one has a little blue oval check valve that doesn't have anything attached to it. Could that be where the loose vacuum line is suppose to go to create some sort of vacuum to open and close that valve?

GaryDoug

Maybe this will help:
http://shbox.com/1/air_pump_recall.jpg

By the way, what is the loose electrical connector in the photos (with the purple seal)?

Red97LT1

Its a solenoid with two air connectors and an electrical connector that goes to the air pump.

Injuneer

The big black, round device is a shutoff valve, to prevent exhaust from reaching the AIR pump when it isn't running. The smaller solenoid controls the vacuum from the side of the intake manifold to the shutoff valve, to open and close it. Make sure you have the connectors for the solenoid, and the purge valve shown in the Shoebox diagram attached to the correct locations. If the [edit] bleed [edit] valve is open, or the shutoff valve is shut, there will not be any flow into the manifolds.

The "check valves" are the black metal, somewhat conical pieces in the line, up by the attachment to the [edit]exhaust[edit] manifold.

http://shbox.com/1/diverters.jpg

Red97LT1

Are you referring to the bleed valve? I don't see a purge in the diagram. So the upper solenoid near the TB should have one hose going to the manifold and then the hose from the shutoff valve goes to the other side? I'll check it when I get home, but I believe that there is a hose that goes from that solenoid to the bleed/purge? valve down below.