1996CamaroZ28

Hi I just bought a 94 Camaro z28 with a 96 LT1 engine. Anyways the car starts right up and idles OK, just smells like its running VERY rich, also it is getting gas into the oil. I hooked it up to a Snap on Modis scanner and pulled the codes. I don't remember the code numbers since I didn't write them down but I will tomorrow. I remember it was an O2 bank 2 sensor 1 code and also 2 CKP codes, both said Learn "A" in them. At Idle I am getting 4.78 volts BARO reading and 100 kPa( 29.53 inches of mercury ), 1.57 volts MAP reading and 40 kPa. ST Trim 1 at the time(clsd loop) was -4, ST Trim 2 was 0, LT Trim 1 was 14, LT Trim 2 was 9. Everthing to me seems normal to me but the Spark Advance readings which was, at idle, -23/-28. Any ideas what could be causing it to run like crap when I step into it and to why it seems to be running rich. Any help is appreciated, thanks. BTW I work at the shop where the car is now so I can do any tests you need me to do

agchoset

iTrader: (1)

Check the vacuum line coming off the top of the fuel pressure regulator (located at the rear of the intake manifold). If it's wet with fuel, then you've got a faulty fuel pressure regulator. Could cause the signs you are describing.

1996CamaroZ28

I will try that tomorrow. I will also take a couple freeze frame pictures and get the code numbers.

1996CamaroZ28

By the way I did not mention this but the car has a lack of power throughout the RPM range when I step into it. I can definitely tell there is something not right. It smells terrible ( not like a clogged cat, like gas ), has very poor performance and sounds like ****. Sounds good at idle though

ahritchie

iTrader: (1)

The coolant temp sensor on the waterpump will cause a very rich condition if it fails, it will tell the PCM it is -40 degrees all the time; or you may need to replace the O2 sensors, or possibly the MAF...diagnose the issue first though. Gut that cat to eliminate the possibility It'll sound way better, add about 10 hp, and best of all....FREE! I believe your year model has O2's behind the cat that would need tuned out of the PCM however, but is pretty easy to do.

Oh yea, are you absolutely sure it's firing on all 8? It may just need a tuneup...

1996CamaroZ28

Okay I finished the spark plug and wire change, also put a new crank sensor in( it was cheap since I get it at cost ). I replaced the Summit MAF with an OEM one too. Car idles fine, but still hesitates/pops, never gets smooth when I step on it. Also ran the Modis again and the same codes P0335 and P0336 were there. I'm thinking my Optispark is on its way its out. I think I can use the modis to scope the signal coming from the distrbutor, maybe see if its being disrupted. Its either that or maybe I'll test fuel pressure and see if the pump is going out. I have a pump ready to go if thats they case.

leadfoot4

iTrader: (1)

Did you check what was told to you about the vacuum line and the coolant sensor? If not, you're by-passing two potential causes of your problem, only to throw more parts/$$$ at the car.

ahritchie

iTrader: (1)

^ What he said, I don't know what kind of scanner is needed, but a GM dealership can definitely be able to tell you what the coolant temp sensor is reading.

1996CamaroZ28

Snap on Modis is a 10k scanner, it can read anything. I took the vacuum line off the regulator and it was dry. Coolant temperature was reading correctly. I ordered an opti and water pump. Hopefully will solve the problem.

1996CamaroZ28

Okay well still having an issue. I've done a new Opti (From the dealer), plugs and wires ( ac delco double platinum ), new fuel pump ( had one in my other Camaro shell that was brand new ). The car runs and drives great but when I step down on it fully it will down shift then sputter very bad and go up in RPMs very slowly all the way to the redline. I don't mind throwing money at the car honestly, this is why I went ahead and put an opti in it. I'm thinking I will do the ignition coil and module next and see where I stand.

ahritchie

iTrader: (1)

Did you gut the cat yet or put on a test pipe at least? They DO go bad cause S L O W acceleration under load, it literally chokes the engine....mine when bad once (when I had one ) and I couldn't pull on a chick in a 3.8 Camaro LOL. You can't really tell by sound alone other than it's a bit quieter than a functioning cat. How many miles on this car?

1996CamaroZ28

The car is super loud, even with the cats.. I'm not sure on the mileage of the motor because its a 94 car with a 96 motor in it. If I use a temperature gun to check the temp of the exhaust before and after the cats what should I see if they are working properly? I'm trying to stay away from pulling the exhaust since every bolt is rusted and not breaking one will be next to impossible. Once I replace the Ignition coil and module, if that has no effect I will just go ahead and buy pacesetter longtubes and just get rid of the cats all together.

ahritchie

iTrader: (1)

No idea what temp exhaust should be.....I've only heard of testing cats by putting on a test pipe, or as I keep suggesting, a big flathead screwdriver/chisel and a BFH! 10 free hp! What's not to like? If you have a shop, just spray down the bolts overnight with some rust penetrant, and use a impact wrench; or saw the exhaust off and clamp it back.

ahritchie

iTrader: (1)

I stand corrected: http://www.3geez.com/forum/technical...converter.html

1996CamaroZ28

Have not had a chance to check the temperatures of the cats yet, but I did run a fuel pressure test. Pressure with the system prime is 40psi, Driving conditions are anywhere between 39-42psi, WOT doesn't really increase the psi at all, just stays around 40psi. When the vacuum line is pulled from the regulator, pressure bumps up to 46psi. New fuel pump and fuel filter, vacuum side of the regulator is dry. Also checked the Ohms between the post and the prongs in the connector on the coil. All three tested at 5.53 kOhms. Grabbed another from my old car and it tested all three at 6.60 kOhms.

1996CamaroZ28

I gutted the cats and had no change. I tested the new optispark. My Modis says the Hi res signal going to the PCM should read between 4.0khz and 4.5khz at idle and go up as RPM is increased. When I tested it, it read around the 2.35khz range at idle and increased as RPM increased. Would the low khz reading at idle cause my problems when the car gets over 4,000 RPMS?

Huntr1117

iTrader: (18)

I would check the front 02 sensors. My car was kinda running like that when I put on LT headers and old O2 sensors. Replaced the 02s and the problem went away.