Seems the Formula has gotten all the attention but I have 2 project cars and the other one wanted some attention.
How did I know?
Well, I was a bit dense. Any car guy with a project will tell you that it's sometimes a game of denial. We simply can't accept that something we already fixed may need attention again.
So it goes with my shocks. I had changed them but it had been so long that I didn't realize just how many miles they've soaked up holding up the front end of 4000 pound car.
So it was with the El Camino. Now I should know better having changed the transmission 3 times, carburetor at least 5 times not to mention a myriad of other things.
But the shocks, I thought they had plenty of time left.
Well, truth be told the shocks were one of the first things I ever replaced on the El Camino which puts the timeframe somewhere around 1992. Before the engine change, before the new paint job and of course before 80,000 miles had passed under the third set of tires.
Yeah, it was time. More accurately, it was overdue.
The signs were there just not obvious to my rose colored perspective.
The front end sat too low, so low in fact that I could no longer get a jack under the front of the car.
Hard stops became a bit scary with the car diving to one side or the other.
Then the handling... Any imperfection in the road caused varied degrees of drama.
Yes, time to do something. So I did and the video below shows the adventure. Take a look.
What does it really mean to do a tune-up on your car? Regardless of what you may drive, if it has an internal combustion engine it's going to need 3 things: Fuel, Air and Spark. When most people think tune-up they think ignition system ( SPARK ) At least with a gasoline powered vehicle. Yes Diesel's are different but it's still Fuel, Air and BOOM!. We're going to be dealing with the BOOM! in your gas powered engine today. I'll show you the basics and try to answer the how and why's in the video below.
No need for a lot of verbiage. This is the conclusion of the carb rebuild series featuring the Carter AFB. The Second video picks up where the first left off and shows you how to reassemble the Carter AFB carb and covers important topics like how to set float level, float drop, and initial setup. There's also a bonus section on testing the fuel pump.
So enjoy and if you learned something, let me know! I'm here to help!
Old cars break stuff, it's a fact of life. Sometimes, however, it's not obvious that something's broke. It's more subtle.
Hard starting, a loss of power or just that feeling like you're dragging an anchor behind you. You'll get where you're going but it won't be as much fun getting there.
When everything else has been checked and you've got symptoms like the ones above it might be worth a look at your vacuum advance unit on your distributor.
Most points and early HEI ( non computer controlled) units will have them and when they go bad you usually don't get any notice.
There's two easy tests that don't involve anything but pulling the vacuum hose off the carburetor (because chances are you don't have fuel injection) and see what happens.
Get the engine to operating temperature and then pop the hose off the vacuum advance unit. If the idle speed drops you know the unit is probably good. If nothing happens it's probably bad.
Time for the next test.
Get a vacuum pump like a mighty vac hooked up to the vacuum advance unit and give a few squeezes. Whether the engine is running or not, you should see some vacuum reading on the pump's vacuum gauge. If the engine is running you may hear the engine speed up as well.
If you don't get either of those things and you know the pump is hooked up and working right then you've got a bad vacuum advance.
Trolling the automotive forums most people will tell you it's an easy fix. You pop the distributor cap, remove a couple of bolts and wiggle the old one free. Of course it gets more complicated if your distributor is hard to access and it's even worse when the engine is hot. Yeah, you can probably change it in 5 minutes if you yanked the distributor out but that's usually an even bigger pain than dealing with it in the car if your setup is anything like mine.
I made the video below because nobody was ever going to read the 1000 words it would take to describe a 15 minute job.
So have at it and check off another little project on your classic car "to-do" list.
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)
You get your registration renewal and in big block letters
you see, "EMISSIONS TEST REQUIRED."
So you dutifully prepare to waste half a day sitting in your
car inhaling exhaust fumes from the 30 other people ahead of you similarly
afflicted.
So it was with my Formula.
If you've kept up with this blog you already know the car's
been an adventure having suffered more breakdowns in the 2 years I've had it
than the last 5 cars I've owned combined.
Not that I'm surprised. It's led
a long life of commuting and road trips that have ticked off over 165,000 miles
in its 20 years.
So things are gonna break.
I've been down this road before and the truth is that you're either in
it for the long haul or destined to wave goodbye as it's dragged off to the
scrap yard.
I was pondering the latter after suffering the indignity of
the car failing almost every emissions standard except the gas cap.
Things are still tight and the last thing I needed was
another dip into my wallet. As it is I'm
living on ramen noodles!
So armed with my failing report card I began my latest
adventure.
The car failed on all the readings, CO, HC and NOx. I've been suspecting the catalytic converter
was failing but these readings went far beyond anything a single emissions
component could cause.
The CO readings were slightly above the acceptable standard
but HC was almost 2x. HC means unburned
fuel is leaving the exhaust pipe (rich.) CO is also considered to be a condition of an overly rich fuel mixture but usually caused by weak spark not completely burning the fuel. Remember we're dealing with chemistry here. While CO and HC being high both indicate an engine being over-fueled (rich) they aren't the same thing. HC is unburned gasoline showing up in the exhaust stream. It hasn't been chemically changed by the combustion process. CO is an overly rich condition as well but the difference is that it has been partially changed by the combustion process. A weak ignition, compression loss in a cylinder, anything that interferes with the combustion process can cause this reading to go high. If HC is a raw steak, CO is that same steak but partially cooked. Neither is edible. I've had carbureted vehicles that ran lean but produced a high CO reading. That seems contradictory but taken with the accompanying Low HC it made some sense. The other component I failed to mention was that the reading only went high at high speed but was normal at idle. That meant there was a problem with my ignition system not keeping up with the fuel being delivered. It's an example of the value of looking past initial readings and the importance of collecting all the information. If I'd just taken the high CO at face value I'd be led to believe I had a fuel problem instead of an ignition problem. Which ultimately turned out to be the case. When computer controls get involved things get even more interesting. The output from the O2, MAP, MAF and other sensors play an important role in keeping that ideal fuel ratio of 14.7 to 1. Any failure of those measurements could effectively lie to the engine management computer and cause a response that makes it run inefficiently. For example, a rich running engine with sensors telling it it's lean could literately flood the engine with even more fuel.
HC and CO aside, however, the worst failure was the NOx readings. It was almost 3x the standard. NOx readings
indicate how efficiently the engine is at using fuel. High readings usually mean the engine is
running too lean and heating up the
combustion chamber. But even a rich running engine (like mine) can make this reading go high if upstream sensors are getting bad information. It's kind of the canary in the coal mine since it's more of an overall indicator of the combustion process than just the HC or CO readings alone. Causes could be an
overheating engine (which can happen from
idling too long in that damned line) and/or a failing EGR ( Exhaust Gas
Recirculation) valve. The EGR is
designed to force some spent exhaust back through the combustion chamber to
cool it down thus removing the conditions for the gas to form. If your EGR fails you lose
that effect.
The other component that can affect NOx is the catalytic
converter whose primary job is to clean up any leftover NOx before it leaves
the tailpipe.
So now we have some idea of the problem, time for the
solution.
The Formula has always had a slightly rough idle which I
attributed to mileage and age. Thing is,
with a completely new ignition system and no evidence of a compression problem
on the cylinders, something else had to be in play.
Looking at the test results and noting that the car has been
experiencing long starts intermittently it was time to dig deeper.
I looked at the 2 most likely culprits that could cause both
an excess of fuel and high combustion chamber temps.
That led me to checks for vacuum leaks (which can make high
NOx worse) and fuel pressure. I began
by hooking up a fuel pressure gauge to the port on the fuel rail and watched
the pressure over time. What I noticed
was a slow drop just barely noticeable but it was there. I then pulled the vacuum line off the fuel
pressure regulator (FPR) and connected a vacuum pump to the fitting on the
regulator. It mimicked the result I saw
with the Fuel pressure gauge, a slow bleed off but of vacuum not fuel. The final test was to take a whiff of the
vacuum line that connected to the regulator.
Damning evidence, the telltale smell of gas where there
should be none. Gas fumes present in the
FPR vacuum line indicate a ruptured internal diaphragm which compromises fuel
metering and allows fuel into places it shouldn't be.
So I needed a new FPR.
That should help with the high HC readings but what about the NOx and
CO?
The EGR valve on the Formula (and the FPR for that matter) is
in an almost inaccessible area under the foot or so of bodywork that supports
the windshield above. Still I have my
tricks and I was able to do some preliminary testing of the EGR valve itself.
Testing an EGR without the car running is pretty
straightforward. The first test is to
try to move the internal EGR diaphragm assembly by hand. If it moves freely then you know the EGR valve
itself isn't frozen.
This first test it passed.
On to the next test...
I connected my vacuum pump again and proceeded to give a few
pumps.
Nothing, absolutely nothing...
It was like attaching the vacuum pump to a straw which told
me the internal diaphragm was ruptured.
Being a vacuum controlled valve no vacuum means it's broke.
The final test required the engine to be running.
With the engine idling I again moved the internal EGR
assembly and the engine sputtered and died.
That's exactly what it should do and told me that the internal passages
were clear enough to work with a properly functioning valve.
OK, so now I know I have 2 problems that are causing me all
this grief with the emissions Nazis. A
bit of research and some shopping found me a deal on both parts ( thanks
Amazon.com )
Thing is, even with a deal I was going to be out a C-note I
couldn't really afford but I couldn't afford to be without the car either.
Once more we fast forward to today and the first of my parts
showed up. The FPR. I did a little more research to see how much
of a pain it was going to be and if I was going to need more parts.
I made the decision that I had what I needed and if I
didn't... Well, I was going to need more parts anyway so there was really nothing
to lose.
Instead of recounting the whole process of replacing the FPR
I made a video. I'll just touch on the
major points you need to know.
Safety is always a primary concern so make sure you do the
following before attempting the repair.
Disconnect the negative battery cable - Sparks and gas
are meant for combustion chambers, not garages.
Depressurize the fuel system - A faceful of gasoline or
worse spread all over the engine is not only annoying but dangerous.
The minute you open the fuel system gas is going to come
out - make sure you've got rags or something handy to catch the fuel that's
going to leak out the minute you pop off the fuel line and/or FPR
Once you've done all that keep the following in mind while
you perform the repair...
Take your time - Better to do the job right the first
time than wonder because you rushed through it.
Be organized - keep track of all the bits and pieces that
you take off. Nothing's worse than a 45
minute job taking 3 hours because you lost a screw you can't replace.
Follow directions - Use a manual or do some research on
the Internet before you do anything.
You're not inventing the wheel here and chances are someone's done it
before and wrote it down or posted it somewhere.
Use the right tools - For instance the retainer bolt for the fuel line clip that you must remove is a T-25 (Torx) the FPR retaining bolt is a T-27. The T-25 kind of fits but you risk stripping the head of the bolt and ruining your day
Check your work - make sure you've got everything back where it needs to be. #2 makes this a whole lot easier
So with that I'm going to close Part 1 and invite you to
come along with me as I replace the FPR on my Formula in the video below.
Next time, we'll cover the EGR and see how that goes..
