Outlawc4

I have a 97 with a super charger. I am getting a p0174. Code. With in driving the car 1-2 miles. At most. I pulled air filter and cleaned it. And I got a aftermarket mass flow. So I swapped it. Looked over vacuum lines all look good. Drove it twice in heat of day. And again with in first mile light comes on. I checked all my super charger tubes. And found one loose. So I tightened it. Last night in cool of night I took it out put 15 miles with no issues. Went on this morning to take it to get inspection. And with in 2 blocks light came on. Same code. Reset. Again with in mile back on. Why whe. It's cool out. No code. When it's hot. It set code quick. Any ideas?

Bill Curlee

LEAN ISSUE!


There are several possible causes and you stated that you addressed some of them. Examine the info below:

Possible causes

- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection

What does this mean?

Tech notes

If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.
The P0174 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate.



If it were My C5,, I would do the following:


Find a way to Scan the PCM and look at to following LIVE SENSOR DATA:

Front O2 Sensor output. Once the O2 sensor is at PROPER temp, The sensor output SHOULD go high to low high to low, high to low ect... during the idle or steady state RPM The low reading should be around 100 Millivolts and then swing high to around 800 millivolts.

IF,,,, the O2 sensor output is not changing correctly,,, the sensor is BAD. If you change ONE,,, you should change them both.

Before you mess with the O2 sensors, turn the ignition switch ON. About 5 mins later, Carefully,,,, feel the body of the O2 sensor (Metal Part that screws into the exhaust pipe/manifold.)
It should be HOT to the touch. It can get VERY HOT so be careful. Both should be similar temps.


The Intake Air Temp Sensor should read pretty close to ambient air temps. May be a little bit higher when the engine compartment (under hood temps) are high.


Try this also:

(Vacuum / intake air leak) Spray some starting fluid around EVERY intake air joint from the MAF to the intake manifold gaskets. If you hear the engine RPM differ when you spray it in one area, you have found a LEAK that needs to be repaired. Any UNMETERED air entering the engine, can cause this issue. Also spray the PCV piping and fittings. Especially the piping behind the intake manifold.

Please post the results..


BC

Outlawc4

Any idea what the valve is on right side of photo. It's Tee off the vacuum line running along fuel rail. There a broke line on it. I have flipped up. But see no where it goes

Bill Curlee

Well,,, theres a Fuel pressure regulator and gage and attached to that is a fuel pressure sensor OR a low fuel pressure cut out switch.. Cant tell by looking at it.

What fuel pressure are you running as indicated by that gage????

BC

Outlawc4

It's 55psi at idle. And raises 1:1 with boost

This part I circled. Line broke I turned up. Can't find where it went. I put a cap on it. And put 10 miles on it. No light.

Outlawc4

Found 2 vacuum lines cracked. Replaced them. Still getting 174 code. I replaced my 02 senders. Just to make sure. Now I'm getting p0171 p0174 p1153 This car is killing me

Bill Curlee

Well,,,,,,, That tells me that you are having an issue with the connections that you made at the O2 sensor OR something in the O2 Sensor circuit is wrong. Have you checked the O2 sensor Heater fuse??

Look at the O2 sensor connectors and make sure that the female pins are not spread apart and or deformed, the wires are in good shape. The connector is in a crappy place and take lots of abuse.

O2 Sensor Schematic:



Bill

Outlawc4

Ok. I'll check fuse. Figured I would pull the 02 and take back exchange for another. They are new Bosch sensors. Thought I might have got a bad one

Bill Curlee

Rereading your post and looking at the DTCs,, The new sensors are just confirming that you have LEAN CONDITIONS. There working better.

Something is causing not enough fuel or too much AIR into the cylinders.

Again,, look for a vacuum leak, manifold seating sealing issues, air ducting between the MAF and TB loose etc...

Bill