New to me Vette...1st mod
 

I am swapping the exhaust on the 1990 vette I just picked up.

I am swapping out the front cats for a straight thru Y pipe. This will go into a HI Flow resonator and into another Y and finally to the exhaust. Everything is MAGNAFLOW, Stainless Steel.

I hope to have significant improvement in both sound and power. I am keeping a resonator in an attempt to eliminate possible drone. The shop is making me a pipe to swap it in and out if I like.

Y pipe
http://content.mamotorworks.com/img300/fr971.jpg

Pipes
http://content.mamotorworks.com/img300/fr6904.jpg

That will nicely open up your much restricted exhaust system.

Now match that with cut lid & K&N, bump fuel pressure a tad and you should see/feel a nice power boost.

Running great. But my check engine light is on. I retained all sensors.
Could it be the oil in the new pipes? They really stink.

Pull some codes and see what they tell you.
http://www.corvettephotographs.com/c4vettes/codes.htm
There is a good chance that the Oxygen sensor got screwed up/broken/banged up on the install or was never even hooked up at all.

Code 32. EGR valve failure. I assume this is the tube that goes to the mid cat/resonator. It is attached. Could this be due to a high flow cat?

Any harm being done??

I don't think this is going to see significant power seeing as you still have the stock exhaust manifolds and no tune.

Drove today for 15-20 minutes with no code. Weird. I will keep and eye on it.

Concerning the power, seems a little more snappy. Throttle response seems better. Could just be the exhaust note.

From what I have read, most of the chips for the L98 are worthless.??????:confused:

The guys who helped me out said freeing up the pipes and removing the cats is good for about 20-25 HP. May get another 20 by installing headers. I think those are a bit high but I am happy with it now. At least it sounds like a vette should.

EGR isn't always going to show. I believe it has to have certain conditions to activate. Been too long since I had to deal with it.

Most likely it is a placebo effect.

Mist any chip off the shel is worthless. Either get it tuned using Datalogging or a dyno.

Using those calculations, I'd have 2000 HP. I don't think headers and exhaust alone is going to net you 50 HP. Toss in a dyno tune after you do an intake and you probably would

how exactly does a tune work on an L98??

They programs the ECM with different values from factory to optimize the system in place. They strap it onto a dyno and tweak the entire program to utilize what you have. The other way is to hook up a laptop and record what the ECM sees and tune it remotely.

so they re-program the chip while its in the car.....

no, it's not done that way
the chip gets pulled out andis modified on a chip burner witha laptop and program

The EGR code is set when the ECM sends a signal to the EGR solenoid to open the EGR valve. THe sensor on the EGR pipe then (supposedly) gets hot, generating a resistance change that the computer sees and interprets as the pipe getting hot, ergo, the EGR valve is open, and exhaust gasses are flowing, heating up the pipe.

I have an 86 with an 89 right hand exhaust manifold. THe 89 manifold has the bolt-on type of EGR tube that you have. I loosened the two bolts out by the outside edge of the rocker cover on the exhaust, and slipped a thin piece of aluminum in there and i tightened the bolts, effectively turning off the EGR.
The interesting thing here is that the sensor on the pipe apparently gets hot enough that the code never gets set.
A few years ago, the connector became disloged from the EGR solenoid and that threw a code. THe pipe that never gets hot doesn't.
I saw an 89 corvette at a car show once that the guy installed a blanking plate on the right EGR pipe, drilled a hole in it, and installed the EGR sensor right in the blanking plate. I asked him about it, and he said it worked for all intents and purposes. I.E. no codes.