new guy needs help with his 88

[Ralph Schroeder]

P.S. Z51 is the heavy duty Suspension I own a 1988 Corvette

 

[shakey]

oh well guess I got excited to quick. Failed emissions.
High Carbon MON. level and REAL high NOX levels. Probably bad EGR valve at least. How hard are they to replace? I was searching it and coming up with lots of hits but no times or Degree of difficulty. Thanks
: (

 

[69MyWay]

oh well guess I got excited to quick. Failed emissions.
High Carbon MON. level and REAL high NOX levels. Probably bad EGR valve at least. How hard are they to replace? I was searching it and coming up with lots of hits but no times or Degree of difficulty. Thanks
: (

It is really a pain because it is in the center of the intake under the upper plenum.

If you have never done it before, make sure you have a good assortment of torx style sockets, and plenty of antiseize lubricant to apply during the reinstall.

You will need a new gasket set, and be prepared to examine all of your underside vacuum lines and make repairs as needed/replacement of those as well.

Take your time, and you will be fine.

I would imagine it would take about four hours for a first timer.

 

[vigman]

Depending on skill & tools

I agree with Chris....

But if your and OLD DOG 1 hr but there some tricks.

1) Do not lose the clips for the throttle linkage

2) There is a breather line at the rear of the plenum( drivers side )..need a flare wrench.

3) GOOD torx wrenches...not CHEAPOS!

4) I had to cut down a wrench to get to one of the EGR bolts... the one closest to the head is a bear!

5) Get your gasket set FIRST!!!!!

6) Get an assistant.

7) While your down there.. do the IAC cleaning.


It's not bad...just take your time.


Vig!

 

[shakey]

YOU GUYS TRUELY ARE AWESOME.

When I got home I looked at the sheet of paper that kinda helps you when you fail emissions. My mechanic was too swamped to put the car on a code scanner and help to pinpoint anything but said next week he will start it. (prior commitment)
Anyway Like I mentioned it failed NOx ,Carbon Mono, and it barely passed the 3rd gas ( can't remember name).
Anyway this sheet kinda gives clues as to what each gas is caused by. First thing for the NOx is the EGR but after further review (L.) The EGR is not listed as a problem for the other 2.
However the cat convertor is listed under all 3 columns as a problem child. Now it got me thinking 100,000 miles hmmm. Maybe
I will replace the exhaust with a nice high flow cat, and a couple of new Flowmaster mufflers. ( I like Flowmasters as they are on my Blazer as well as my Expedtion).
Do I also have to( or want to) change the small convertors near the manifolds or are they more like resonators?

I went out last night and bought plugs,wires, cap +rotor, new K+N air filter,fuel filter and a PCV valve too, so much for fishing this weekend. L

 

[vigman]

The two " resonators"

Are PRE-CATS and change em out as well...

because if you change the MAIN cat and not the front ones.. then a few weeks later if either of the pre cats starts to go.. it will clog the main cat... and you will HATE yourself!


Vig!

 

[shakey]

Over the weekend I installed a K+N air filter, new Bosch 4 plugs,
new cap and rotor and some new 8 mm wires. She is running really strong, plus her idle is a little higher.

I will be putting a new exhaust on this week. It has mufflers that are kind of just inside the pipe. They are some kind of trap or baffle system. There are no actual mufflers just pipe. So I will replace it all. I will put on a high flow cat.
Those pre cats are they needed? Can they be replaced with high flow as well or just eliminated?

 

[shakey]

exhaust update.

Well as it turns out the pre cats had been removed already.
The main cat was empty. Gee wonder why she was failing emissions.
So we wound up putting I believe a 93 system on the car. She has true duals and we put high flow cats 1 on either side
will take her back in for retest tomorrow.