Saturday, January 25, 2020

#ChelseaTheCivic, Part 6-- Race Car Fuel Injector Cleaning Benefits

"Modern" Fuel Injectors

Fuel injectors are tiny valves that feed gasoline into the intake runners or directly into the cylinder of an internal combustion engine.  On some cars, injectors can open and close (one cycle) 50 times per second at engine speeds in excess of 6,000 RPMs.

As wisely stated by Super Street Magazine, fuel injectors are the analogous equivalent to the beating heart in the human body.  These devices can cycle as much as 562,500,000 times in a a typical 200,000-mile Japanese car, and as a result are subject to significant abuse and damage over time.  Needless to say, these components are very important.

An extreme example of a plugged injector.

Use and Abuse

Due to their location, injectors are exposed to unburned hydrocarbons such as gasoline and engine oil, byproducts of hydrocarbon combustion such as soot, and other contaminants.  Heat, vibration, and constant cycling between open and closed states exacerbate the negative affect these contaminants have on injector health.

Another extreme example of a plugged injector

Poor injector health can have a plethora of negative side-effects.  On commuter cars, most people don't get concerned until their car doesn't idle properly or hesitates under load.  These can be side effects of fouled injectors causing inadequate fuel delivery to one or more cylinders.

However, most of our race cars are running in good enough condition that they do not stutter under load or hesitate at idle (at least as a result of poor injector health).  Injectors are important in this context because in racing, the concern is always, "how do we get MORE SPEED!?"

Spencer, Kallie, Dame, and Ken saying "MUST GO FASTER!!!"

But why would clean fuel injectors give us more speed?  Let's cover the basics first...

The Basics of Fuel Delivery in Modern Cars

Fuel delivery to the engine is controlled in a negative feedback loop where the air-to-fuel ratio (AFR) is first measured in the exhaust stream.  The car's computer (ECU) reads the air-to-fuel ratio, and it knows whether there is too much (rich) or too little (lean) fuel going into the engine based on the reading.  Knowing the AFR, the ECU can alter the amount of fuel going to the engine by increasing or decreasing "fuel trim" as detailed below:

When the AFR number is too high, there is a larger portion of air in the exhaust stream, suggesting that fuel delivery is inadequate-- the computer will then tell the injectors to let more fuel into the engine (increasing trim).

When the AFR number is too low, there is less air and more fuel in the exhaust stream, suggesting that fuel delivery is in excess-- the computer will then tell the injectors to let less fuel into the engine (decreasing trim).

Diagram of closed-loop engine operation.

In a naturally aspirated car, an air to fuel ratio of 14.7 is optimal at idle, but under heavy load the optimal ratio varies from ~12-13 depending on application. 

Consequences of high or low AFRs

An engine that runs on the lean side may make more power than an engine that runs a little rich under load.  As a result, some tuners will install adjustable fuel pressure regulators (FPRs) to lower the pressure upstream of the injectors, which will lower the volume of fuel delivered to the cylinders.  For example, on my stock Integra LS motor, AFR at wide open throttle (WOT) was about 12.1:1.  To get more power out of the car, I tuned this to somewhere near 13.3:1.

AEM AFR gauge

So, why not starve even more fuel if leaning out a car will increase power?  Adding more fuel than is needed for optimal power levels means there is more cooling provided to the cylinder in the form of unburned gasoline.  Manufacturers typically want to make their engines last a very long time, so to improve reliability, stock engines typically run a little rich under load.

When a car is leaned out, the cylinder temperatures will be higher, increasing the risk of pre-detonation (fuel combusts too soon before top-dead-center) and damage to the engine.

Diagram of effects of lean engine operation from Laskey Racing

An engine that runs too rich is no good either, as excessive fuel (a solvent) can wash away oil which lubricates the piston-to-cylinder interface and prevents damage and scoring.

The spark plugs can sometimes indicate whether your motor is too rich or too lean

Bad Injectors Are Bad Mkay?

Most engines in sports cars have more than one cylinder.  Ideally, AFR would be measured at each individual cylinder and fuel trim would be changed at each individual injector accordingly.  However, this would increase complexity and cost-- so manufacturers choose to measure AFR in a point downstream of all four cylinders.

Most cars made after 1996 have a two O2 sensors at the catalytic converter.

This means that if one cylinder is burning lean due to a fouled injector while the rest of the cylinders are burning optimally, the computer may not know that there is a significant issue present and may only slightly increase fuel delivery.  Additionally, fuel delivery will be increased to ALL of the injectors which will make the cylinders with healthy AFRs now run rich and the cylinder with a lean AFR run closer to optimal.

What This Means for Racers

So why not install an aftermarket ECU that can measure AFR at all four cylinders in this example and tune it to deliver the optimal fuel volume?  Well, in some club racing classes such as Honda Challenge H4 (HC4) and Spec Miata (SM), it is illegal to run an aftermarket ECU (as of 2020).

So, these racers must find other means to insure the health of their engine and increase their horsepower.  As mentioned above, fuel pressure regulator tuning is a popular technique used to increase horsepower without ECU tuning.  Remember that to make more horsepower using this technique, one must lean out fuel delivery as much as safely possible while the car is operating at WOT.

But how much is "safe?"  In a thread on the Forum, members discussed the benefits of fuel injector cleaning.  One member states that a customer of theirs blew up their motor while on the dyno due to leaning out the car too much.  They sent the injectors out to be serviced and they discovered that one of the injectors was bad.

So, as detailed above, it's very important to know the health of your injectors and to ensure they're as clean as possible before extracting the most power you can out of your engine via FPR tuning.

Decisions, Decisions...

So, you now know how important it is to have clean fuel injectors.  But what should you do?  If you're racing, there are five options that come to mind:

1.) If your car runs, you can send it
2.) You can buy aftermarket OEM replacements
3.) You can do "parts bin tuning"
4.) You can try and clean your OEM injectors on your own
5.) Or, you can have your OEM cores cleaned by a professional shop

Cheap, "OEM" re-manufactured injectors from eBay

Here's why you may want to or not want to choose one of those options above:

Option #1: Send it

Aside from being a funny thing to say, and something people say to appear cool and laid back/chill, "sending it" could be what's right for you.  The other options I mentioned above are not free and do require time and effort-- whether you're researching the best aftermarket replacement to buy, service shop to choose, or DIY method for cleaning.

Additionally, as I mentioned above, most race cars I've seen in lower power classes such as HC4 and SM run perfectly fine with their stock AFRs, offering reliable, fun track time.

When building a race car or tuning one, it's important to attack the low hanging fruit first.  If your suspension or brakes are not up to par and you're on a budget-- save your money and tackle those items first.

Option #2: Aftermarket or OEM Replacements

The beauty of running an older track car like a Honda or a Miata is that there are usually huge, supportive communities and a vast supply of aftermarket parts-- fuel injectors included.

If you go on eBay and look for a set of stock Integra LS injectors, a set of aftermarket re-mans usually go for about $40 with free shipping.  This is an extremely low cost and as a result it is an attractive option.  Amazon even sells cheap, aftermarket replacements for about $45 with one-day shipping!

Cheap "Catinbow" Injectors

The downside of cheap, aftermarket injectors, however, is a lack of specs regarding flow pattern, flow volume, or how closely they adhere to OEM requirements.  Sure, your Catinbow injectors might be 45 dollars shipped in a day with Jeff Bezos' extremely convenient Amazon service, but do you know how well they're made?

As documented on, not only is the proper flow rate or pressure important, but so is the spray pattern of an injector.  OEMs pay PhDs a lot of money to determine optimal intake runner design and cylinder head geometry to ensure the best cooling, atomization, and combustion efficiency.  In fact, my rule-of-thumb for most mods on my own race car is to keep as much as I can OEM while still building a competitive car per the rules.

But what about OEM replacements?  They have the right specs and you can be sure that they're going to give you the best performance.

Except, you forgot to consider the drawbacks of owning an old track car-- such as dealing with OEM-discontinued parts.  Even if you can find a set of new injectors for a 20-year-old car, they will likely be costly.  For example, a set of injectors for a 1998 Acura Integra LS (06164-P72-010) goes for about $170.

Fancy but Expensive Injectors

Option #3: Parts Bin Racing

In spec classes, especially, parts bin tuning is a very popular way to make your car incrementally faster.  Parts bin tuning consists of buying multiple used components that you'd like to test and installing them one by one and recording the results.

There are tales of some dedicated SM race shops, for example, buying about 10 old Miata ECUs and trying each one on the dyno to see which one makes the most power.  Another tale is of SE30 racers that buy multiple used MAFs and test each one for the most power on a dyno.

In this instance, we're talking about parts bin tuning with fuel injectors, which was outlined in an article by another fellow H4 racer, Rob Krider of Double Nickel Nine (DNN) Racing.  In Rob's article, he was provided access to an injector flow tester and cleaner.  He then tested multiple injectors that he found at a local scrap yard and picked the most evenly matched and highest flowing ones to use on his race car.  Results proved successful as he made more power on the dyno.

Rob Krider of DNN on the dyno

This technique is probably the most optimal for a class such as mine, HC4.  However, it requires access to a plentiful amount of spares, it requires money for testing the spares on an injector cleaner/flow tester, and it requires dyno time.

As a result, parts bin tuning is usually very expensive.  Therefore, I did not choose this method.

Option #4: Do it Yourself!!!

To my readers' surprise, I actually didn't choose to tackle a project as a DIY for once.  Yes, it's likely the cheapest route, but it takes the most time and results can vary distinctly.

For example, Super Street tested fuel system cleaners on a 210-k mile Acura Integra (DC4) and 190-k mile Mazda RX7 (FC3S).  The results were disappointing.  The injectors on the Integra didn't clean up at all after using Pro-Gard Fuel System Cleaner and not much improvement was noted in the RX7 either.


Sure, there are probably better, more thorough ways to clean injectors on your own-- and I have done these in the past.  But they take a lot of time and can be unsafe in some instances.

For example, I once attached a vacuum tube to the inlet of an injector needing cleaning, filled the tube with acetone, hooked up a tire air compressor to the vacuum tube, and then created a power supply using an old wall outlet adapter (AC-to-DC) and some wire crimpers.  Exposed electrical leads and a volatile solvent?  Yeah, I think not...

Option #5: Make Someone Else Do it!!!

Ahh yes, Capitalist America's favorite solution to most problems people face-- if you can't do something, just give someone money to do it for you.  Always works right?

Stupid stock photo because pictures

For this option, you'll need to research the company that is the best for you.  Make sure whoever cleans your injectors provides you with a flow sheet of before and after cleaning results, make sure they provide some assessment of flow pattern quality, and make sure their turnaround time meets your needs.  This all takes time and is a drawback for this option.

Prices for these services are also somewhat high and can range from ~$75 to $100 not including shipping, but when all is said and done, it's cheaper than a new set of OEM injectors, a little more expensive than a set of knock-offs, and the results are more promising than a DIY project.

In case you were wondering-- yes, this is the route I chose for my Civic.

Mr. Injector

The OEM Keihin fuel injectors on my race car were in service for over 170,000 miles and were over 20-years-old.  They weren't leaking and the car was running well.  I also had tuned the car with a fuel pressure regulator on a dyno earlier in the season and it made some extra horsepower.  Yet, I still figured now was a good time to finally have them serviced.

Crusty and Old Injectors

I chose a shop out of Illinois called Mr. Injector after being referred to them by my good friend Alex who is the owner of #TrashTeg and also has been building cars for a long time now.

The Mr. Injector Logo

Bill has been operating his business for over 25 years and it shows.  Turnaround time was less than a week in total, communication was timely, and the finished product looked and performed extremely well.

Can't believe these are the same injectors I sent out!

More pics

More pics again...

A Picture of my son, Pidgey, standing next to a Jolly Rancher and  serviced injector

Along with my new injectors, I received installation instructions to prevent damage to the seals and I received the flow test results from before and after cleaning.  While all of the injectors were (apparently) out-performing the manufacturer-specified 244 cc/min, the flow they were delivering was highly varied.  After cleaning, they all flowed at 260 cc/min.  The biggest improvement in flow was 6% at one injector.

Flow test results from Mr. Injector

A nice bar graph of before and after results

Concluding Remarks

Would I go to Mr. Injector again?  Yes.  I've seen his work put to the test in my buddy's builds and his work was fast and of high quality.  I'm looking forward to installing these on my car and I'm glad I haven't ran into any issues at the lean AFR I'm currently running on my Honda Challenge H4 car.  Maybe I can lean it out even more now!

Thanks for nerding out over injectors with me, readers.  Until next time, have fun and take it easy.

Tuesday, December 10, 2019

EJ2 Track Rat Starts a YouTube Channel!

Over the course of this off-season (at least in the Northeast), you can expect EJ2 Track Rat to be doing some new and innovative things.  For example, EJ2 Track Rat was recently featured on Garage Heroes in Trainings' Podcast.

Working on the Capri
The Garage Heroes in Training Being Garage Heroes

Well, EJ2 Track Rat has created its own YouTube channel with its first video.  The video is already gaining traction as a popular video among the high performance driving and racing community.  

It is entitled "5 Things You're Doing Wrong in HPDE and Track Days"

EJ2 Track Rat's First YouTube Video

When you get a chance, take a look.  There's some great information on common mistakes made by drivers at all levels in the sport.  Feel free to like, subscribe, and comment on the video, or leave your opinions on this blog post!

Thanks for reading.

Wednesday, November 27, 2019

EJ2 Track Rat Does a Podcast!

Recently, EJ2 Track Rat was featured on a podcast hosted by "Garage Heroes in Training," a group of endurance racing individuals not that different from EJ2 Track Rat.  

Their goal, as is EJ2 Track Rat's, is to get people into the sport, promoting racing at a cheap cost while they currently run several cars in HPDE and LeMons.  Bill, Vicki, Alan, and Jennifer are just some members of this crew.

Some of the Garage Heroes in Training Squad with Randy Pobst

Take a look at the podcast below and thanks for reading, as always:

Sunday, November 24, 2019

#ChelseaTheCivic, Part 5-- Off-Season Engine Health Assessment


Racing puts a lot of stress on a car.  In addition to the lateral and longitudinal Gs subjecting the chassis, structural suspension components, and bushings to stress, cars get crashed, transmissions break, driveline components break, and shocks wear out.  Oh yeah, and engines get abused too, I guess.

Ant working on Alex's #TrashTeg

For example:

After living in a 1998 Acura Integra for 170,000 miles, my B18B1 was transplanted into a 1993 Honda Civic DX for racing duty.  

Denise the D Series Integra, Donor to Chelsea the Civic

While in the Civic, it experienced a couple of money shifts, I found some metal shavings in the oil a couple of times (not sure from where), I lost a radiator cap and pegged my coolant temperature in a qualifying session, and toward the end of this season, it began smoking more than usual, and halfway through the season, I also did a fuel pressure regulator tune which doesn't increase longevity.  

The motor did still run great, getting me a podium at The 2019 NASA Champs and a win for my last race of the season.  However, with all of that abuse, I figured it would be a good idea to get an overall idea of the motor's health.

Engine Bay of Chelsea the Civic

Compression Test

The first test I wanted to do on the Civic was a compression test.  So, I borrowed a compression tester, and some other tools-- including a leakdown tester and an air compressor from my friend Anthony, an H2 racer, and went to town.

Ant's Car

A compression test is used to read the max pressure each cylinder can produce when the engine is cranked over.  Compression tests are useful for determining the general health of the motor.  Max pressures are recorded for each cylinder and then they are compared.  If one cylinder is down on compression relative to the other cylinders, you know that there is a problem at this cylinder.

Compression Testing a VTEC Honda Motor

If you do find a cylinder low on compression relative to its siblings, it could be caused by a variety of factors.  There could be a burned valve, bad ring, scored cylinder, cracked piston, cracked or warped cylinder head, or more.  To figure out where to begin troubleshooting a cylinder low on compression, we do a leakdown test-- this will be discussed later in this post.

Photo by Viken Photography

I decided to do the test on a cold motor with the cylinder "dry" and with the cylinder "wet."  The definitions of a dry and wet test are shown below:

A dry compression test is done with the engine in its normal operating condition.  It can be done with the engine cold or hot.  I chose to do it cold due to time constraints and because I ran into some issues when trying to do it hot (the pressure gauge broke).

A wet compression test is done to see how well the oil ring is sealing between the piston and the piston wall.  It is called a wet compression test because a small amount of oil is added to the cylinder and the compression test is then conducted.

Wet Vs Dry Compresion Test Diagram from

Dry Compression Test

While performing the dry compression test, I made a mistake while taking compression readings on cylinder #1.  The connector for the pressure gauge was slightly loose and this likely threw off the reading.  During analysis, I will treat this reading as an outlier and assume that the average compression for cylinder 1 is actually 155.

With this being said, two things became apparent after reviewing the data:

1.) Cylinders 2 and 3 were lower on compression than cylinders 1 and 4.  Since I overheated my engine halfway through the season, it's possible that the head gasket partially failed in between cylinders, allowing for cylinder-to-cylinder leakage.

2.) Cylinder 3 was the lowest on compression of the three.  While performing further diagnostics, this cylinder will receive more attention than its sibling cylinders.

The table below shows the data from this test:

Dry Compression Test on an Acura Integra B18B1 Motor with Two Race Seasons and 170k Street Miles

Wet Compression Test

Next, I performed a wet compression test.  I added two caps of 5w-30 Pennzoil Platinum Synthetic Oil to cylinder one to start.  After attaching my pressure gauge for the first test and cranking the motor over, it became immediately apparent that two caps of oil was too much.  Wet compression at cylinder 1 came back at >300 PSI....

A "Windowed" Engine Block (Pic from

So, for cylinders 2, 3, and 4, I added only ONE cap of oil, using the same oil, and achieved more realistic results.  After performing the wet compression test, it was apparent that cylinder 4 had the highest wet compression and cylinder 2 had the lowest wet compression.  Perhaps the piston rings at cylinder 4 were in better condition than cylinders 2 and 3.
Wet Compression Test of a B18B1

After some consideration, I'm not sure that the wet compression test provides as much value as the dry compression test because there are too many variables in the test, such as:

1.) The exact amount of oil added to each cylinder (an oil cap is not most accurate way to add)

2.) Where the oil lands on top of the piston when it's injected into the cylinder

3.) When the oil is injected vs. when the compression test is taken (more time allows more oil to seep past rings)

4.) And more...

I think performing a dry test cold and a dry test hot would give a better subjective overview of how the engine is performing.

Leakdown test

As mentioned above, a leakdown test is used to determine WHY a cylinder may be down on compression relative to another cylinder.  A good DIY for the beginner on this process is shown in the video below:

Eric the Car Guy Makes Some Great DIY Videos

To do the leakdown test, I wanted the motor to be at running temperature to ensure the valves and valve seats were fully sealing inside of the cylinder.  I also wanted to ensure any residual oil from the wet compression test was out of the engine.  

I Ran the Civic for 15 Minutes After it Stopped Smoking

I set the air supply from my air compressor to 60 PSIG and began conducting the leakdown test, recording the leakage pressure to get a percentage leakdown for each cylinder.  I did this test twice for each cylinder.

Let's take a look at the leak down percentages below:

Leakdown Percentages for a B18B1 at Running temperature

There are four test results that show nearly 100% leakby and four tests that show realistic leakby values for a motor that doesn't run like a bag of rocks.  I treated the high readings as outliers because they didn't make sense for a motor that runs as well as mine does.  Additionally, I've seen excessive leakby on engines where the cams were still installed in the past.

With the cams still installed, slack in the timing belt, stiction between residual oil, cams, roller-rockers, pistons, and cylinders becomes a factor in ensuring the valves fully seat when the piston is rotated to TDC.  So, I took the best reading for each cylinder and used that to calculate a leakdown percentage.  

Interestingly, cylinders 3 and 4 had the worst leakdown percentages of the four cylinders, but only by 2%.  Recall that cylinders 1 and 4 had the highest compression readings of the four cylinders and cylinder 3 had the lowest compression reading.

Me and Dame Racing at Watkins Glen (Pic: Windshadow Studios)

To determine where the leakage is coming from, for each test, I listened to see if I could hear air hissing out of the throttle body (which would imply intake valve leakage), air leaking out of the exhaust (implying exhaust valve leakage), and air leaking out of the valve cover (which would suggest piston-to-cylinder leakby).

Below is a table showing where air leakage was heard for each successful test-- that is, I ignore the tests with erroneously high leakby values:

B18B1 Leakdown Test Observations

In all tests, it is apparent that leakage for each cylinder was due primarily to leakage between the valves and valve seats, which is to be expected from a motor with 170,000 street miles.  Additionally, I did hear some air hissing out of adjacent cylinders when conducting leakdown tests on the middle cylinders-- which corroborates suspicions of head gasket failure.

Oil Analysis

Oil is used to lubricate any rotating and reciprocating components in the engine, such as the crankshaft and bearings, connecting rods and bearings, piston-to-cylinder surfaces, camshafts and journals, and roller-rocker surfaces (to name a few).  Lubrication for these components is necessary because they are constantly creating friction during normal engine operation.

If adequate lubrication is not present in the engine, affected components will fail and metal bits from them will end up in the oil, in addition to other contaminants.

VTEC Valvetrains See Even More Heat and Friction Than Their Non-VTEC Counterparts

Metal isn't the only thing that shows up in engine oil when the engine is not running optimally, however.  A sample may show that an engine is running too hot as evidenced by degradation of additives or carbon chains in the oil.  A sample may also show that the engine has excessive blowby or incomplete combustion as evidenced by unburned fuel or sulfates and nitrates which have dissolved into the oil.

So, we sample the oil to get an additional snapshot of engine health from a different perspective.

Oil analysis isn't guaranteed to identify a failing engine.  For example, a healthy running engine that experiences a brief transient where a bearing is partially wiped at the crank may have a relatively healthy oil analysis, but a large, insoluble piece of bearing may be present in the oil.  This happens frequently in heavy industry with steam turbines, for example.

However, health assessments are broad and take into account many factors...we want to analyze the "big picture" and avoid relying on only one test to determine if our engine is healthy or not.

The Big Picture (A Cool and Good Stock Photo)

So, after performing my compression and leakdown test, I decided I'd send the oil to Blackstone Laboratories for analysis.  Blackstone laboratories is based out of the Midwest.  They will send you a sampling kit for free and all you have to do is pull a sample of oil and send it back to them.

A Blackstone Laboratories Oil Sample Kit

In the sample kit, they have a questionnaire that asks about the car's use, any important info like engine swaps or mods, and the age/mileage on the oil.  They have experience analyzing many types of cars from daily drivers to race cars.  They even have experience in analyzing hydraulic fluid or fluid from industrial machinery.

Within two weeks, I had my oil drained, collected, mailed, and sampled by Blackstone.  Their analysis stated that my motor was in healthy condition with wear parameters below or in-line with expected values for most motors similar to mine.  Take a look at the results below:

Blackstone-Provided Comments on Engine Health

They provide an extensive data sheet showing wear particles found in the oil with average values for comparison purposes.  The table below shows this:

Elements Found in Oil

Lastly, they provide a table on values such as percentage anti-freeze and viscosity of the oil:

Additional Oil Information


After discussing results from the tests above with champion level racing drivers and builders in the amateur motorsports community and after analyzing the results on my own accord, it became apparent that the motor was in good health.

Wear material in the oil was low, suggesting the engine did not have significant degradation due to a lack of lubrication anywhere in the rotating/reciprocating assembly.  Leakdown wasn't exceptionally high, and any leakdown present in the engine was most likely due to valve-to-seat leakage, and not bottom end leakage which would require an extensive rebuild.

The head gasket was a likely contributor for high leakdown % on cylinder 3 and also for lower compression numbers on cylinders 2 and 3.  This was likely the result of damage from pegging my coolant gauge high during a qualifying session at the beginning of the season in 2019 at NJMP Thunderbolt.

Me and Ken Racing at Thunderbolt (Pic: Windshadow Studios)

Overall my B18B1 is in good condition.  I know that I can likely run this motor for another season with no issues.  This knowledge will allow me to focus my efforts on other upgrades to improve the car's speed, such as suspension and brakes.

Thanks all for reading.  I hope this post was informative and interesting.