NOx, Arizona and the emissions Racket!

The Firebird Project - New Front Shocks...and more!

 

Once again we come to a crossroads.  

Fix it or ditch it. 

Is it good money after bad or is it an investment in the future.  Only you can answer that but if you extend your best foot forward every time at least you can be confident that you didn't cheat the process.

So it went with the latest project on the Formula.  Do we ignore obvious problems and just stick to the original plan or do we dig a little deeper and see if we can't advance toward our ultimate goal.

The desired result was to replace the front shocks, that was going to happen regardless.  However, experience has taught me that we weren't going to get away that easily.  The end result was not so much a surprise as an inevitability.

In the videos below you'll learn what it takes to tackle this project as well as learn about what you should be watching for.

Remember, you're dealing with a primary safety system here.  Shortcuts only invite disaster.

I'm hopeful the following is helpful in your project!

The Formula Project: Back under the hood

 

It's been close to 4 years since I brought the Formula home.  4 years and 18000 miles later it's been a tale of love.  But not that sweet unconditional love beaming from your dog's eyes when she looks up at you.  No, no, no.  This is the kind of love that demands all of your attention, a few pounds of flesh and most of the contents of your wallet if you don't put the brakes on every once in awhile.

Love hurts....

One way or another it always does.

Considering my ownership of this family heirloom began with $500 worth of parts and the front of the engine in pieces within 24 hours of delivery the tone was set.

BUT!

Opportunities abound if your eyes are open.  Which led to a new YouTube channel and more relevant content in this blog.

I've been busy trying to make a living doing something other than turning a wrench or saving somebody's server so time's short and so is the money.  That means projects fall into 2 camps; Things I want to do to the Formula and things I HAVE to do.

Seems there's lots of things I've HAD to do in the past 6 months.  Luckily, every one of them has been documented with a video.

Speaking of which, the 3 videos below show what I've been up to.  To sum it up: The car doesn't sound like an old rocking chair anymore, the transmission stopped hitting the floorboards and starts easier now that the PCM has some clue as to what the engine termperature is.

Check it out!

Formula Vs. Smog Check: Testing Fuel Pressure and the MAP sensor

On this page are a couple of videos showing you the results of my Fuel Pressure Leak-down test and how to test a MAP sensor on an LT1 V8.  These are two important tests when you've got an emissions problem especially if the car is running rich.  

The fuel rail will bleed off some pressure over time but not all of it in a few minutes!  Anything more than a couple of PSI drop after a few hours means there's a leak in the system somewhere.  

It's important to mention that if at all possible, you really want to isolate the individual components of the fuel system when troubleshooting.  If you're testing the fuel rail and you don't know the condition of the fuel pressure regulator, for example, then ideally you'd want to block off any return lines to the tank so you don't confuse a bad fuel pressure regulator with say a stuck check ball in the fuel pump. 

If that's not possible then you're only going to get a general idea that there's a problem.  In which case you'll have to take into account other factors.  In my case I know the Fuel Pressure regulator is good ( brand new ) so I'm fairly confident that any pressure loss seen at the rail is going to be isolated to a component of that rail.  Note that all of this testing is done with the engine off.  With the engine running other factors like the Fuel Pump, Injector pulse time and engine vacuum come into play which can mask a basic fuel pressure problem.  

Incidentally, you won't see it in the video but the way to isolate the fuel system to check for what part is causing you the headaches involves either pinching off the return lines or installing a shutoff valve.  I don't have the valve and I'm not about to start pinching anything made of plastic that's been baking under the hood of a car for 20 years.   So I didn't do that test but a rich mixture is more likely to be a fuel injector than a check ball in a fuel pump at the back of the car.  I was more interested in seeing if there was a drop in pressure in general.  

Once I can afford a new set of Injector O-rings I'll be pulling the injectors out, priming the rail and seeing which one(s) are leaking.

As for the MAP sensor testing, well, it's always the first thing blamed right behind the O2 sensor when an engine is running to rich or lean.  That makes sense since those sensors as well as the MAF (Mass Air Flow) provide critical data to the engine's PCM to adjust the mixture rate.  There are others like the Coolant Temperature sensor, Throttle Position Sensor and others but basic emissions troubleshooting will have us starting at the MAP sensor since it's usually the easiest one to access and check.  

The MAP sensor's job is basically to read engine vacuum and send a signal back to the PCM.  With an LT1 the PCM takes that vacuum value and compares it with the Air flow data from the MAF to see if the two values complement each other.  That allows the PCM to make more minute adjustments to the fuel mixture for performance and emissions.  It's also a sanity check for each sensor since the failure of one can be compensated for by the other.  Either one can provide enough data to allow the engine to continue to run but not as efficiently.

Some cars only have a MAP sensor but LT1's are a bit of a wild animal when it comes to tailpipe emissions. Getting the engine into emissions compliance takes a lot more data points than your average grocery-getter especially with high compression that lends itself to problems with NOx and CO issues.

So if you ever wondered why there's so many wires under your hood, now you know....

For me this is all kind of a reference exercise but for  you it might be instructional.  Enjoy!


Fuel Pressure testing...

Checking the Manifold Absolute Pressure Sensor (MAP)

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.

Rear Transmission Mount on my 1995 Formula

Yesterday I received my new Transmission mount from RockAuto.  I got it because it's the first thing I thought of when I heard a very noticeable "Thud" from the floorboard when I gave it a little more gas than normal.

Now I wasn't completely sure that was the problem but for $8 it was cheap enough to give it a shot.  Well, it turned out it was indeed the problem.  The telltale sign that your LT1 F-body (93-97 model year) has this issue is a noticeable THUMP in the floorboards that comes from the rear console area when you nail the throttle and a general looseness in the rear end.  When the mount is bad it causes the torque arm that runs to the rear differential to rise with the tranny making the rear end even more squirrelly.

Mine was completely shot as you can see from the video.  

It's a simple enough procedure.

1. Raise the car to a convenient work height

2. Grab a jack and support the transmission. 

3. Remove the mount to crossmember nut (5.8)

4. Remove the trans crossmember (4 bolts, 2 per side)

5. Unbolt the old mount from the transmission (13MM socket)

6. Install the new mount to the transmission, flat side facing the rear of the car

7. Re-install crossmember, If the stud doesn't go through the hole you likely have the mount on backwards

8. Lower the jack holding the transmission up.

9. Re-install the bolt and washer on the tranny mount stud that's poking through the crossmember.

10. Get your crap out from under the car and lower it down.

11. You're done, go take a test drive.

Note, I've included a section in the video showing the part numbers for the transmission crossmember for these cars.  If you have to go on a junkyard hunt they'll be helpful.

The stamping on mine are:

10198323

10198347-C

LT1-MD8/M30

Hope this helps!

Enjoy the Vid!

The Optispark distributor, the best and worst idea GM ever had

Ever get that sinking feeling? 

Gearheads do, all the time.  For many it's almost like ESP.  We just know something's off even if we can't quite put or finger on it.  Maybe it's subtle.  The occasional misfiring ignition, a hard start condition or maybe the not so subtle hint that's something gone wrong when your car just stops.

Any of those symptoms can indicate a problem with the ignition system but when it's a car equipped with the GM Optispark optical distributor you're going to be questioning the "excellence" in the "GM mark of excellence"

What's an Optispark?

The Optispark is a unique ignition system found primarily on GM's venerated LT1, LT4 and L99 V8's from 1992 to 1997.  This was the second generation of the GM small block V8 motor and the first major design change since 1955.  Unlike its predecessors, the Optispark distributor is an optically triggered ignition system much like those seen in high performance and race vehicles. 

Optisparks showed up in everything from Corvettes to Cadlillac Fleetwoods and they all have the same design flaw.  That being, putting it in the absolute worst place you could possibly locate a component sensitive to heat, moisture and oil contamination.

Put yourself in the following scenario.  Imagine having a job where you were forced to work next to a blast furnace every day with the threat of a huge water pipe bursting over your head.

That's pretty much the life of an Optispark distributor.  Buried deep under belts, hoses, pulleys and a water pump, the unit can be barely seen and hard to service. Replacement is always a major undertaking involving the removal of the aforementioned bits and pieces as well as assorted brackets, wiring harnesses and other assemblies depending on the vehicle being serviced.

So just what's different about an Optispark?

Other than the look of it, not much really.  It's still a distributor that requires a rotor, Ignition module and coil to provide spark to the spark plugs at the right time.  The primary difference is that timing is determined via an optical signal instead of the position of a reluctor or cam follower.  Normal distributors usually have shaft with a rotor on one end and a gear on the other that meshes with its counterpart on the camshaft.

Where the only indication of incorrect timing on a regular distributor is a poorly running engine, the Optispark ignition provides feedback to the engine's PCM.  Using data from other sensors at its disposal, the PCM can then adjust the ignition timing to optimize engine operation.  

It utilizes an optical pickup assembly that reads a thin rotating disk with two rows of perforations punched into it.  One row is comprised of 360 slots on the outer ring with another row of 4 cutouts of differing size on the inner ring corresponding to 90 degrees of engine rotation.  The disk rides on a bearing assembly mounted into a base plate that engages with the timing assembly on the front of the engine.  As the engine rotates the optical pickup reads the position of the disc and reports that information back to the PCM where it can adjust the ignition timing according to current conditions. The major components of the distributor are fairly simple consisting of:

• ·         A cap
• ·         Rotor
• ·         Plastic separator
• ·         Metal separator
• ·         Optical pick up assembly
• ·         Timing wheel
• ·         Wheel support disc
• ·         Bearing assembly
• ·         The man body or base plate

Aside from some sealing gaskets and the wiring harness there's not much more to it.

Depending on the year of the engine, the distributor engages the crankshaft timing gear with either a splined shaft or on later engines (95+) a large bearing resembling a hockey puck with cutouts to engage a pin on the engine's timing gear.  An issue with condensation and ozone buildup in earlier models of the Optispark (92-94) caused premature failure.  GM redesigned the distributor for later models in an attempt to eliminate the issue.  The easiest way to tell the difference between the two is the presence (or absence) or two rubber hoses connected to the distributor.  One is connected to vacuum while the other usually connects to the intake ducting of the engine.

The Optispark distributor allows for both fine and coarse tuning of the engine timing and has a certain amount of redundancy because of the presence of those two timing rings.  Should something short of catastrophic failure (which usually happens anyway) interfere with either timing signal, the engine can continue to run at reduced power levels.  It usually sets a code in the engine's PCM that will trigger the Service engine light. 

Most common codes are:

P0372 - Loss of the high resolution timing signal ( not reading any of the 360 slots) 
* 92 to 95 engines will set an OBD1 code of 36

P1371 - Loss of low resolution signal ( Not reading the 4 cutouts) 
* 92 to 95 engines will set an OBD1 code of 16


The design allows finer control of the timing by reading not just what cylinder is firing in relation to mechanical engine timing ( what valves are open, where the pistons are in their stroke etc.) but exactly what degree in rotation the engine is currently in.  In this way the Engine's control computer or PCM knows exactly where the timing sequence was in relation to a specific condition and how long it lasted.  For example, If a condition such as a misfiring plug were indicated, the PCM would be able to either correct the condition or set a trouble code.

Sounds great, so what can go wrong?

Oh wow, let me count the ways...

I remember when optical pickup distributors were cutting edge.  Using light to time an engine might as well have been rocket science to most shade tree mechanics. 

Usually, optically based ignition systems are among the most accurate and reliable ignition systems available.  Even modern so-called "Distributor less" ignitions use "flying magnet" or Hall effect sensors that operate similarly to optical triggered ignition systems but use magnetism instead of light to determine timing.

BUT...

Unlike most ignition systems that are generally designed to keep the most sensitive components away from harm the Optispark stands in stark contrast.

It sits low on the front of the engine between the water pump and crankshaft pulley and sandwiched between a rats nest of cooling hoses, brackets and engine accessories.  It's at just the right height to get drowned by the undercarriage spray at the local car wash and sit's below a notoriously leaky water pump.  Lest we forget seals for both the distributor to timing cover and water pump shaft whose inevitable failure are sure to coat the Optispark in a greasy mess. 

There's usually some degree of warpage on most Optispark distributor caps which allows gaps in the seal between cap and distributor.  That makes it even easier for infiltration of water and oil.

Then there's the issue of varying quality of replacements.  I've yet to find any source for replacement of just the optical pickup assembly which is the most critical component of the Optispark.  That means failure of it requires replacement of the whole distributor.  With prices ranging from $50 for a unit guaranteed to leave you stranded to $900 for a GM aftermarket unit that may be no better you could go broke before you found a reliable source.  Nothing like doing the same job two or three times before you finally get one that works.

We've talked a lot about failure of the Distributor itself but don't forget about the wiring.  Mid 90's wiring harnesses tended toward the flimsy and after 2 decades they can get a bit crispy.  It's always good policy to check the wiring  before going to all the trouble and expense of replacing an Optispark only to find out a $20 Distributor harness would have fixed the problem. 

A good source for troubleshooting Optispark ignition issues can be found at SHBOX.com.  While focused on 93-97 Camaro and Firebird models the troubleshooting steps will work on LT1's installed on other models.  If you have one of these engines, this is a bookmark you'll use often.

http://shbox.com/1/4th_gen_tech2.html

So if you've made it this far you'd probably like to know how to fix your Optispark problems.  Aside from the link above we'll leave that topic for the next article.