Darkshot

iTrader: (4)

I just picked up a 91 Z28 (L98, G92, J65, N10, the works) for $700 from somebody who didn't know what they had. 154,000 miles and it hasn't been registered in a couple years, but I was able to drive it home and everything. I'm going to try and get it through smog but I want to make sure I get it in tip top shape before. It's failed miserably in the past (I found the VIRs in the glove box). I'm done the usual cap, rotor, wires, and fuel filter, and I'm gonna do the plugs, O2 sensor, and new cats after I do a Seafoam treatment.

I want to make sure the EGR system is working at it's best. Will I need to pull the base? Or will I be able to clean out all the buildup just removing the plenum and runners? Any other recommendations on making sure this thing blows clean the first time around? This is my third thirdgen but my first TPI motor. Will I get any benefit from completely dismantling the whole TPI system and cleaning it, or a waste of time? I could do it cheap (just the cost of gaskets) and my labor is free.

Mathius

I'm not sure there IS a fix for an EGR. Maybe someone else can chime in and correct me. Maybe they're rebuildable. Eventually if its bad AFAIK it will need replaced.

However, I do know a guy who told me that you can take an EGR off and clean it out with carb/throttle body cleaner and it will pass emissions a few extra times by doing that, but he said the most times it'll work is 3X and then you have to replace it.

He said it also worked if your car was throwing a code for the EGR.

I have never tried this however. An EGR is under $100 and you have to have it by law where I'm at, so I usually just bite the bullet.

Mathius

BC GTA

To replace the EGR valve you will need to at least remove the plenum. You do not need to remove the runners and certainly not the intake manifold. If the runners and the base are really dirty now would be a good time to remove them and clean them. Also, look into porting work at this time. When you go this far it is a good idea to check for vacuum leaks before you remove everything especially the throttle body butterfly shaft. You will need all new gaskets for whatever you take off.

So, I had my EGR valve cleaned in the parts washer but found out not much later it was not working properly. If it has many miles on it, or you do not know how many miles it has on it, or you suspect it is failing I think it is a false economy to try and wash it to get by. Also, at this time there is a temperature thermostat near the EGR valve and the same above applies to it. You have gone to all the trouble of buying new gaskets and tearing everything apart and putting it back together again only to have the EGR valve fail completely a few months later. Not worth it!

The wires that go to the EGR valve and temperature thermostat may become brittle so look at them as well. If you have gone this far other things to consider are new fuel injectors and adjustable fuel pressure regulator if you have any suspicions about them. Also, now is the time to clean everything very well and do any polishing or painting of parts to make it all look good.

Darkshot

iTrader: (4)

I'm actually not too concerned with the valve itself. My question is really about the channels and making sure they are cleaned out. Can I get to the whole channel without removing the base?

tinymay

Yep... I just went thru that. After you remove the EGR and plenum runners, the passage is uncovered and you may run a brush thru it to get the carbon out. Shop vac the exhaust inlet too. Lots of crud in mine but scrubbed it, washed the valve and reinstalled. Working okay, so far.

paulo57509

Take a look at the emissions test results. Why did the car fail? High HC and/or high NOx?

rgarcia63

Don't forget to clean out the TB as well.