Hey guys, I just bought a 96 Camaro Z28. Im new to the Camaro world and already loving it. But unfortunately its got some issues. When I first hooked the scan tool up to the car I got all kinds of trouble codes, I think about 5. The guy I bought it from said that some work had just been done to it and didnt know if all the codes had been erased. So I erased them to see what would come back up. P0400 comes up every time and P0174 comes up occasionally. Ive been reading alot of other posts and people say the EGR valve is vacuum controlled and the exhaust plays a major factor. It has stock manifolds and the cat but no muffler at all. I also read that the EGR malfunction could lead to the P0174 code, bank 2 lean. Is that true? What bugs me the most is that the car acts like it doesnt want to start most of the time. Its cranks just fine but acts like its not getting enough fuel to start. Sometime it does and sometimes it doesnt. Im not sure if thats linked with the EGR code or not. My scan tool reads live data but im not too sure what im looking at. Any help would greatly be appreciated, especially with the starting problem. Thanks

 

You say it starts sometimes. When it does start, does it idle ok? Does it drive ok? Suggest you get a fuel pressure gauge if you don't already have one.

Common problem with this vehicle is the check ball in the fuel sending unit. It is supposed to hold pressure in the fuel system so it starts quick the next time. Many MANY folks have a problem that the check ball leaks fuel back toward the tank. So the next time it's started after sitting for a while, is it has to crank excessively before starting. Maybe you have this problem but haven't waited long enough for the fuel to pressurize to over come this problem. Hard to tell from your post. Here's a way to tell if that is a problem.

Turn Key On Engine Off. This powers up the fuel pump for a couple of seconds. Then turn the key off. Then KOEO again for a few seconds. Then off. Repeat this process for about 5 or 6 times. Then finally try to start it. If it fires up quickly, you pretty much proved the check ball is a problem. Incidentally, the fuel gauge would show the pressure dropping in the fuel system as a result of the defective check ball.

With regard to the EGR problem, your answer to the idle will determine what type of problem you have with the EGR. If the EGR had anything to do with the starting, it would probably cause the idle to be very bad. Therefore, if the idle is smooth, the EGR probably had nothing to do with the no start problem.

Capish?

 

P0400 means the MAP sensor reading does not change the way the PCM expects it to, when the EGR vacuum solenoid is cycled. Could be:
-EGR vacuum solenoid stuck
-EGR vacuum hose(s) cracked or disconnected
-EGR valve stuck in one position
-EGR passages in manifold plugged
-EGR pintle dirty
-EGR valve vacuum leak
-EGR riser tube from ex. manifold to intake manifold leaking
-Insufficient back-pressure on exhaust system.

You have to systematically eliminate all those possibilities. Start by testing the vacuum system with a vacuum pump to insure there are no leaks. While doing the vacuum test, activate the EGR vacuum solenoid to see if its working. That would eliminate several of the above possibilities.

For P0174 to set, the long term fuel corrections have to be adding an AVERAGE of more than 21% extra fuel to bank 2 (passenger side). If you have access to a scanner or scan software, observe both the bank 1 and bank 2 long term fuel corrections in as many cells as possible. That will tell you if it really is a lean condition affecting only one bank of the engine, or if the bank 1 readings are also close to setting the code for bank 1 (P0171). That will tell you if you have to look at things that affect both banks (low fuel pressure, leaks in the intake system after the MAF sensor, etc.), or if you have to look for things that only affect bank 2 (exhaust leak, misfires, incorrect valve adjustment, faulty O2 sensor or wiring, etc.)

If you don't have a way to check the long term fuel trims, start by checking the fuel pressure. Hard starting and lean conditions could be caused by low pressure.

 

The car will start every time but 95% of the time it cranks for a few seconds and then starts. Once it is started the car runs great and idles relatively smooth. Its not smooth as silk but it doesn't act like its going to cut off. When I try to start it, I let the pump run for a few seconds before I crank it so hopefully it builds enough pressure. Sometimes, rarely, it will fire right up without hesitation. I will try cutting the ignition on 5 or 6 times like you said to see if that helps.

As for the EGR system, the car has no muffler. So im figuring that the lack of back pressure is causing that, at least thats what alot of people say causes it.

Thanks alot for the quick replies and any more info is always appreciated!!

I just tried the KOEO 6 times and it still had hesitation. Im not sure where the check ball is located but the guy I bought it from said he just replaced the fuel pump unit.

 

If not fuel related, then an ignition tune up is on the agenda. Including plugs wires cap and rotor.

 

Thanks speedy. Tune up it is. If that doesn't fix it do you have any other ideas?