Back on the Road: Formula VS Smog Check - Epilogue

A lot can happen in 5 months...

Back in December when I posted my last entry to this blog I wasn't sure what my future held.  All I had was hope and a belief that if I didn't give up things would eventually work out.

Which is exactly how I approached getting the Formula back on the road.

I'm not especially religious but I do believe the old adage that the good Lord doesn't give you anything you can't handle.

December is a pretty long time between posts but I haven't posted anything about the Formula since October of 2015!  That's because, well, honestly there was nothing to post about.

That changed recently.  I picked up some work in March which improved my fortunes.  Now the Formula was always at the top of my priority list but it became even more so as the weeks wore on and it became apparent that what I was driving to work was not ideal for the purpose.  

The Formula needed to be back on the road...Fast!

Of course that meant getting rid of the demons that had kept it chained to the garage for 2 years.  

Recall that we had already dealt with the Fuel Pressure regulator, EGR, got a new intake elbow and ran a few tanks of the proper octane fuel.  Sadly it wasn't enough.

The emissions testing results from 2015 while less than helpful at diagnosing the problem still pointed to a likely culprit.  A high HC reading, that's raw fuel.  High CO?  sloppy ignition system.  High NOx?  Combustion chamber temps too high.  All of them too high?  That points to a bad catalytic converter plain and simple.  

Lot's of things can go wrong with modern emissions control systems on cars but the symptoms would show up long before a failing smog test.  As in the car literally wouldn't run if you could get it to start at all if it was anything but the Cat.

1995 was an interesting year for auto makers.  It was the last year before they formally adopted the new ODB2 standard in emissions controls.  20 years later it's a pain in the ass.  For example, the Formula has a diagnostic port identical to an OBD2 connector but it isn't.  It's OBD1 which means you have a lot fewer codes to help point you in the direction of what's wrong.  Not to mention finding a scan tool that you can actually plug into it!

Still, there are basic emission codes that can be set if something was really going wrong and luckily none of them were set.  Although that's not definitive either since OBD1 has a far shallower pool of data to draw from.  That means things have to be really going sideways before you get any information out of that port.  By that time the code probably doesn't mean much to you.  

So...

Fast forward to the solution to my problem and we open on me in the parking lot of Mesa Muffler early on a Saturday morning.  


For less than $200 I was able to drive out with a new catalytic converter an hour later.  I immediately took the car out on the freeway to warm up the converter and then held my breath and got off on the exit that led to the emissions testing station.

As I pulled into the station, took my ticket and waited in a long line for my turn at the indignity of an Arizona emissions test my time had finally come.

I pulled up onto the rollers, turned off the car and dutifully retired to a cramped booth while the technician did his best to ruin my day...

He didn't.   At the end of it all I actually shook his hand and thanked him!  The Formula was finally legal after 2 years and all it took was a catalytic converter....



Oh yeah, and a MAP sensor, EGR, Fuel Pressure Regulator, Intake Elbow...

I documented the whole thing in the video below.  I'd have liked to get more of the actual test but I was rather forcefully discouraged by the technician.  

There was still work to do before the Formula started commuting duty, however.

We needed tires, badly.  We also needed a new belt tensioner pulley and weirdly a new gear for the headlight pop-up motor.  

So what's left?

I still need to deal with the fuel injectors as at least one is still leaking.  I still need to fix the headliner, get the hatch repainted.  All the normal stuff that a 20+ year old car would need.

In case you're interested, I've also included  a few videos below of the new tires and how I fixed the headlight motor.  I've been posting regular videos of my adventures with the Formula on my YouTube channel.  Check it out as I tend to update it more than this blog...obviously.

More as it happens!  

Formula Vs. Smog Check: EGR sadness

Last time I pretty much laid out my dilemma.   20 year old car, Emissions testing Nazis, questioning my life choices...

So I won't rehash it here.  It's a problem anyone with a car roughly the same vintage as their parent's high school diploma knows well.

This time we're going to attack the root cause of our NOx failure at the emissions testing station.  If you recall, the standard for a 95 Formula in Arizona is 2.00 and I managed to crush the scales at 5.99.

There are two primary emissions systems that contribute to this failure.  The first is the EGR or Exhaust Gas Recirculation valve and the second is the Catalytic Converter.

As I see it, the Catalytic converter is a secondary emissions component.  Meant to clean up whatever the other primary systems left behind.  There are exceptions such as certain vehicles that eliminate the EGR altogether and incorporate similar functionality within the intake system of the engine itself. 

But most of us with older cars will still have to deal with the tried and true EGR valve.  Considering it's exposed to constant exhaust heat, depends on a seal made of rubber and failure of said seal negates its function you're going to have to deal with it at some point.

The good news is that at least on mid 90's GM F Body cars ( 93-97 Firebird/Camaro) with an LT1 V8 the diagnosis and replacement is straightforward.

I should clarify here.  Diagnosis is easy, replacement would be easy if you could somehow wrest the engine out of the car in under 5 minutes.

That's not going to happen in a 4th generation F Body.

But enough of that...

The EGR's function is to circulate exhaust gases back into the combustion chamber to cool it down.  

Combustion temperatures above 2500F cause NOx, a noxious gas that creates excess ozone and irritates respiratory ailments among other things.

So the emissions Nazis are gunning for you if your car exceeds their standards.

On the 4th Gen F body LT1 (V8) cars the EGR is located on the back of the intake manifold in pretty much the most inaccessible location GM could come up with. 

Now if Camaros or Firebirds had hoods that tilted forward ( like the same vintage Corvettes do) it would be no big deal.  Thing is, these cars are cursed with about a foot of bodywork hanging over the engine.  Thank that 60 degree windshield for that one.

Still, you can deal with the EGR and the Fuel pressure regulator as well ( since it's in the same location) so long as you're willing to lay across the front of the car to get to them.

Which is what I had to do to replace mine. 

But we're jumping ahead here. 

Before we start turning wrenches we need to figure out if we need to.

Assuming the rest of your emissions components are working within specification, high NOx generally only comes from the aforementioned high combustion temperatures caused by a bad CAT or EGR valve.

The simplest test for a bad EGR is to stick a vacuum pump on the vacuum port on top of the EGR and give a few pumps.  If it doesn't hold vacuum it's junk, no exceptions.  The EGR relies on a flexible diaphragm that moves in and out as vacuum is applied to it. 

That diaphragm operates a rod ( pintle ) that allows a measured amount of exhaust gas to recirculate in the combustion chamber which helps cool it down and decrease NOx emissions.

If that pintle doesn't move then NOx can run rampant.

The other reason the EGR system can fail is if the EGR passages in the manifold become clogged up.   If the exhaust gas can't get to the combustion chamber it can't cool it down.

It can also cause the engine to run too lean ( too much air not enough fuel ) which can increase HC emissions as well.

Vacuum leaks can contribute to high HC and NOx as well and a torn diaphragm in a 3 inch disk is a pretty big leak.

So now we know the problem, the solution is pretty simple. 

Replace the valve...

While you're at it, check out the EGR passages and clean them out if they're full of crud( as best you can considering where the EGR is.)

Removal is easy, 2 (1/2 inch) nuts on a couple of studs.  Of course getting to them requires draping yourself across the front of the car but once you get positioned, it's not so bad.  I'd also recommend the use of an offset boxed end wrench since the bolts are partially shrouded by the EGR "disc."

Pop it off, remove the gasket, clean up the mating surfaces ( there's likely to be a sticky film left by the old gasket) and clean out the EGR passage of any carbon build up.  Then just bolt the new one on, torque the bolts down and reconnect the EGR vacuum line and you're done!

Really not much more to it. 

Below is a video that outlines the diagnosis and testing procedures.