Understanding induction systems

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How to help your customers

Understanding induction systems on

naturally aspirated engines & turbo-equipped engines

By Bill Fulton

FIGURES COURTESY OF BILL FULTON YYou have heard it said before that the internal combustion engine is basically an air pump. The internal combustion engine has never been 100% efficient, but recent technology has improved the engine on a major basis with the addition of intake runner control systems, variable valve timing systems and turbo and turboequipped engines. Before we look at these systems, let’s go back and review the fundamentals. The first rule is to

Figure 1: A clogged converter on Bank 2 would impede those cylinders’ ability to breathe and would result in negative fuel trim values. The bank with a good converter will show double-digit fuel trim positive numbers.

Figure 2: With increased rpm the PCM would allow butterflies to open and direct air to the short intake runners, increasing engine breathing.

determine what type electronic fuel injection (EFI) at wide open throttle (WOT) conditions. Another system the engine is using. The most popular sys-method is to simply multiply the liter size of the tem is the mass air flow (MAF) equipped engines. engine times 40. For example, a 4.0 liter engine For example, let’s say during a cruise condition should pull a minimum 160 grams per second at the MAF is reporting 56 grams per second on an WOT and 5,000 rpm. When capturing scan data 8 cylinder engine. The powertrain control mod-during this test, be sure to lock the transmission in ule (PCM) would assume that each cylinder on its low gear to avoid getting a speeding ticket and by intake stroke would pull 7 grams per second. This all means use the record mode on the scan tool and formula would only apply to engines with equal keep your eyes on the road. The “times 40” rule aplength intake runners sometimes referred to as plies to engines with fixed valve timing. On engines tuned intake runners on a tuned port engine. Each where both the intake and exhaust cam timing is intake runner has the same length and inside diam-varied, these engines breathe better, so multiply the eter. A clogged converter on Bank 2 would impede liter size of the engine times 50. These formulas will those cylinders’ ability to breathe and would cause only apply to naturally aspirated engines. negative fuel trim values on that bank, whereas the Some auto makers are on the turbo band wagon bank with the good converter will be drawing the to improve the volumetric efficiency of the engine major volume of air and its fuel trim numbers will and thus increase the horsepower and torque ratgo double digit positive (see Figure 1). ing of the engine. On these turbo-equipped en-

Some late model GM and Ford systems are us-gines I have taken the liter size of the engines times ing a hybrid type EFI system whereas both a MAF 80 at 5,000 rpm during WOT conditions. For exand MAP sensor are used. To check if the engine is ample a 2.0 liter 4 cylinder engine at WOT condibreathing properly and the MAF sensor is working tions at 5,000 rpm will pull upwards of 160 grams properly, we can use the calculated load value on per second. Later on we will be monitoring the the scan tool. For those of you who live in elevaturbo boost sensor on these engines. tion below 1,000 feet above sea level you should MAF EFI systems are very sensitive to vacuum see a minimum 80% calculated load at 5,000 rpm leaks and or false air leaks. Positive fuel trim values

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Figure 5: The technician had the advantage in that the problem occurred after a previous shop had replaced the IMRC unit.

at idle when manifold vacuum is strongest while type of approach is being used on most late model normal fuel trim values under road load condi-GM and Ford systems. GM systems use the minitions point to a vacuum leak. Negative fuel trim mum of 80% calculated load at WOT and 5,000 values at idle coupled with double digit positive rpm to determine the engine’s ability to breathe infuel trim values under road load conditions point stead of using the MAF grams per second formula to an air measurement error which usually indi-we talked about earlier. GM hybrid EFI systems do cates a bad MAF sensor. not use the MAF input to calculate the load but in-

All manufacturers except Chrysler have gone to stead uses the MAP input, rpm and throttle angle the MAF-type EFI systems.to calculate the load. In the mid-1990s, Ford and

The Speed Density-type EFI systems used on Chrysler began using Split Intake systems. What Chrysler systems rely on MAP sensor inputs, rpm this allows is to improve the engine low load perand throttle angle to calculate the load. Anything formance and enhance the engine breathing ability that creates low manifold vacuum will shift the at higher engine rpms. The first engine we will talk MAP values high and create a rich condition and about is the 3.8L and the 4.0L Split Port engines as cause negative fuel trim values under road load well as the 5.4L Triton engine. conditions, such as a restricted exhaust or retarded valve timing. The Speed Density EFI systems have Split Port/Triton engines the quickest throttle response while the MAF-type Tuned intake systems have been around for at systems have the edge on fuel economy and emis-least 20 years. This means that all intake runners sion control. have the same length and inside diameter. In the

A combination of both type systems is known late 1990s, Ford released engines with dual intake as hybrid-type EFI systems that use both the MAF runners on the 3.8L split port engines and the 4.0L sensor combined with a MAP sensor. GM first used engines as well as the 5.4L Triton engine. this system in 1986 on its 3800 V-6 engine. This During normal low road load conditions a

Figure 6: A look at the turbo. Exhaust gas spools up the impellers which in turn rev up the compressor. The compressor draws in fresh air and forces pressurized air into the charge air cooler and then into the intake system.

longer intake runner was used. As the air flow en-haust and or retarded valve timing. The technician tered the open intake valve on the piston’s intake had checked for good enrichment previously and stroke, good manifold vacuum was sustained. found it was OK. When the intake valve closed the air flow abruptly Having prior knowledge that a previous shop stopped and actually began a bounce back in the had replaced the intake runner control unit, he opposite direction. If the larger intake runner was then took the truck for a test drive and recorded at the proper length, by the time the piston came the throttle position sensor (TPS), rpm and intake back around to its intake stroke the bounce back manifold runner control functions (see Figure 3). of air flow actually increased the engine’s ability to On the left side of the screen the TPS is closed breathe during normal road load conditions.and the engine is at idle. Note that the position of

When the throttle was increased and the engine the intake manifold runner control (IMRC) inrpm reached higher rpm the PCM would energize dicates open. Note that when the throttle is coman electric motor that was connected to butterflies manded open and rpm increases the IMRC goes that would open and direct air to the short intake from open to closed. This appears to be the exact runners which reduces intake restriction and in-opposite of how the system was supposed to opercreases the engine’s ability to breath at higher rpms ate. The technician removed the intake manifold to (see Figure 2). discover the flapper doors were in the open posi-

Lets’ look at a case study from a 5.4L Ford F-150 tion for the short intake runners when they should with a lack of power complaint. This engine is have been closed. equipped with an intake manifold runner control A careful inspection revealed that the rods consystem. We all know that a lack of power complaint necting the IMRC motor to the flapper doors were can be due to lack of enrichment, a clogged exreversed.

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Figure 7: The PCM duty cycle controls the boost solenoid.

Let’s now take a look at data after the repair somewhat. Looking at the innards of a turbo, we (see Figure 4). Note that at idle the IMRC is in the have the turbo impellers and the compressor conclosed position. As the throttle is opened and rpm nected by a shaft (see Figure 6). The exhaust gases increases, note that the position of the IMRC went spool up the turbo impellers which in turn rev up from closed to open. The lack of power problem the compressor. The compressor draws in fresh air was diagnosed properly. The short intake runners and forces pressurized air into the charge air cooler reduce the air intake restriction and thus improve then on into the intake system. This pressurized air the volumetric efficiency of the engine. There is generates a lot of heat. The air is pumped into the a feed back signal to the PCM from the IMRC as air charge cooler where it is cooled and now more to the position of flapper doors and likely would condensed. Any air leak between the compressor have been detected by using the key on engine off and the air intake will result in an under boost con(KOEO) self test. dition and a lack of power complaint. These turbos

The technician had the advantage that the spin in excess of 100,000 rpm. problem occurred after a previous shop had reAn oil pressure supply line keeps the bronze placed the IMRC unit (see Figure 5).bearings lubricated. A lack of oil pressure to these

Turbo-equipped engines are getting more pop-bearings will destroy the unit. Customers who igular and more powerful. For one example, Honda nore oil change intervals or use the wrong oil will offers a 1.5L turbo engine that cranks out 174 hp ultimately pay the price. The American Petroleum @ 6,000 rpm with 16.5 psi of turbo boost. Twenty-Institute (API) and the Society of Automotive Enfive percent of the vehicles built since 2014 are tur-gineers (SAE) have designated turbo-approved oil bo-equipped engines. The early turbo-equipped to prevent the oil from coking up from turbo heat engines were plagued with a turbo lag symptom, and clogging the oil supply to these critical bearwhereas during low rpm conditions when exhaust ings. GF5 is the new designation of oil that prevents flow was low the turbine speed was low resulting in the oil thermal breakdown. little to no boost. In addition, synthetic-based oil has superior

Recent engineering changes have improved that flow characteristics and better protection against

Figure 8: An example of a 3.5L Ford V6 twin turbo Ecoboost engine. The system is designed to improve throttle response while limiting turbo lag.

thermal breakdown. Oil pressure is known to leak Most modern day turbo-equipped engines have a into the compressor chamber causing oil con-limited boost of around 16 psi. We will be monisumption. If a visual inspection on the compressor toring this boost value with the scan tool later on. side of the turbo unit indicates oil or a film of oil Note Figure 7 where the PCM duty cycle controls this should be conclusive to a worn out turbo unit. the boost solenoid.

Cheap or clogged air filters create an under As the duty cycle command increases, the soboost condition. The wastegates are designed to lenoid bleeds off the boost pressure to the atmodump off excessive boost under high rpm condi-sphere. When the max boost pressure is reached, tions. The wastegates are normally spring loaded the PCM turns off the boost pressure control soclosed and opened or controlled by boost pressure. lenoid and boost pressure opens the wastegate to

Figure 16: An over-boost condition. The APP is requesting WOT. Note to the left of the cursor we momentarily have WOT from the TPS. dump off boost. The PCM uses inputs such as opened. There are some common reasons for unMAP, IAT, ECT and knock sensor inputs to more der boost (note Figure 9). There are also common accurately control boost pressure. reasons for over boost (see Figure 10).

One of the early complaints on turbo equipped There are 2.0L Ford turbo engines wherein the engines was a audible whooshing sound whenever wastegate is normally open and closed with vacthe throttle was released after acceleration. This uum (see Figure 11). This system allows for more sound came from the excessive boost pressure that accurate wastegate control under all engine operhad nowhere to go and be dumped off. The engineers ating loads. Note that there is an external vacuum have solved that by incorporating a by pass valve. pump to supply a vacuum to the wastegate and to

In Figure 8 is an example of a 3.5L Ford V-6 the brake booster. Since turbo-equipped engines Twin Turbo Ecoboost engine. Note that there are don’t generate vacuum under boost conditions, separate turbos, one for each bank. The idea here many systems with a brake booster will have an is to improve throttle response while limiting external vacuum pump. turbo lag. The wastegate control solenoid is duty The by pass valves are designed to dump off cycle controlled by the PCM. The higher the duty boost pressure once the throttle is released and are cycles, the more boost pressure is bled off from the normally closed and opened with vacuum. wastegate and boost pressure increases. When the Figure 12 shows an intake manifold from a PCM turns off the boost control solenoid, exces-1.4L GM engine with the vacuum reservoir atsive boost pressure overcomes the spring in the tached. The vacuum is used to open the by pass wastegate and the wastegate opens dumping off valve during decel conditions to dump off boost boost pressure. pressure. The by pass valve solenoid is con-

A two stage Mighty Vac would be needed to trolled by the PCM to open and direct vacuum ensure the wastegate can hold vacuum and then to the by pass valve. This vacuum signal opens switching to pressure to confirm that the wastegate the by pass valve and dumps off the boost pres-

Figure 17: Recorded scan data from the problem vehicle. The APP is requesting 98% throttle. The MAP is indicating 21 psi, or 6 psi above atmospheric.

sure. These vacuum valves are known to leak the MAP value reads 12.3 psi above atmosphere. thus causing an under boost condition. The The PCM electrically backed off the throttle from PCM electrically monitors the control circuit to a over-boost condition. The problem here was a the by pass solenoid. faulty boost sensor.

Figure 12A shows a turbo unit from a GM 1.4L Let’s look at a lack of power complaint on a 2014 engine. The only serviceable unit is the wastegate Ford 2.0L with a P0299 under-boost code. The first control solenoid. Figure 13 shows the vacuum thing to look up is the code set criteria. The PCM control to the by pass valve. Figure 14 shows an must see more than 4 psi difference between the acexploded view of a by pass valve. The PCM will tual pressure and the desired boost pressure for more ground-side control the solenoid to send vacuum than 5 seconds. This sounds as if it is a very reliable to the by pass valve to open it to dump turbo boost. code. We talked about this engine briefly before.

Let’s look at a normal turbo-equipped engine As you may recall, the wastegate is controlled during WOT acceleration and monitor for good by vacuum and is spring loaded open and closed by boost (note Figure 15). Note the APP and TPS vacuum. The PCM controls the wastegate control indicate WOT. The top parameter indicates the solenoid with a ground side controlled duty cycle amount of boost which indicates 26 psi which is signal. Refer to Figure 11. Let’s capture some scan 11 psi above atmospheric. In another example, let’s data from this problem vehicle. Note the recorded look at an over-boost condition in Figure 16. The scan data in Figure 17. The APP is requesting 98% APP is requesting WOT. Note to the left of the curthrottle. sor we momentarily got WOT from the TPS. Note The MAP is indicating 21 psi or 6 psi above that the boost pressure sensor indicates 38.5 psi atmospheric. The rpm is at 4,100 rpm. The turbo which is 23.5 psi above atmospheric pressure. Note charger boost sensor reads 21 psi. The desired tur-

Figure 18: Scan data with a new turbo. The APP is requesting 98% throttle. The rpm is at 5,800. The turbo charge boost sensor (TCBP) indicates 27 psi. Desired boost pressure is nearly the same at 26 psi. Note that the duty cycle command to the wastegate control solenoid is at 58%.

bo boost value is 31 psi. There is a 10 psi difference Well, that’s it for this round. In closing, thank between actual boost pressure and desired boost you for your commitment to this industry. ■ pressure. The PCM has ramped up the duty cycle command to the wastegate control solenoid in an effort to increase boost. There are no intake air Bill Fulton is the author of Mitchell leaks and the air filter is not clogged. 1’s Advanced Engine Performance

The first thing to suspect is a wastegate that may Diagnostics and Advanced Engine not be sealing or a worn out turbo. To check the waDiagnostics manuals. He is also the stegate, the turbo unit must be removed. The wasteauthor of several lab scope and drivability gate is spring loaded opened and closed with vacumanuals such as Ford, Toyota, GM and Chrysler um from the wastegate control solenoid. Applying OBD I and OBD II systems, Fuel System Testing, vacuum to the wastegate with a Mighty Vac unit many other training manuals in addition to his own indicated that the wastegate would not fully close. 101 Lab Scope Testing Tips. He is a certified Master The wastegate is not serviceable, which means that Technician with over 30 years of training and R&D the entire turbo unit needs to be replaced. experience. He has instructed for Mitchell 1, Precision

Let’s look at the scan data with the new turbo Tune, OTC, O’Reilly Auto Parts, BWD, JD Byrider, unit in Figure 18. The APP is requesting 98% throtSnap-on Vetronix and Standard Ignition programs. tle. The rpm is at 5,800. The turbo charge boost You may have also seen Fulton in many Lightning sensor (TCBP) indicates 27 psi. The desired turbo Bolt Training videos and DVDs and read his articles in boost pressure is nearly the same at 26 psi. Note the many auto service magazines. He currently owns and duty cycle command to the wastegate control soleoperates Ohio Automotive Technology, which is an noid at 58%. automotive repair and research development center.

COMMUNITY CONSCIOUS

CoAuto applies a unique approach to business

CCoAuto is an extremely successful repair operation located in Reno, Nev. CoAuto’s motto is Community Conscious Car Care . As co-owner Vinnie Lucido noted, “Our initial ambition was to provide a location to allow people to work on their own vehicles. Due to severe insurance liability concerns, that simply didn’t work. My brother Anthony and I then decided to open the shop in 2014, staffed by the two of us. Eventually it has grown into three ASE technicians, two service advisors and an in-house bookkeeper. We’ve been growing by leaps and bounds ever since our opening. Our initial facility featured only 2,000 square feet, and today we’ve expanded to a new facility with 7,000 square feet. Ours was the first shop in Reno to be ‘Blue Seal certified’ by ASE. In our first year of operation, gross sales were at $360,000. Today, we’ve increased that to $1.5 million.” Aside from operating a successful business, the shop’s primary thrust is to provide services to the local community, a philosophy termed “commuby the Veterans Resource Center of Nevada. “It is an honor to provide reliable transportation for men and women who served our country.” 2. High School Internship Program. “CoAuto invites local high school students to visit the shop and shadow our technicians. We mentor and chalALL PHOTOS COURTESY OF COAUTO Brothers Vinnie (left) and Anthony Lucido are the owners of CoAuto in Reno, Nev.

nity conscious.” Toward that end, CoAuto estab-lenge them to see if auto repair is a possible career lished a five-program platform that sets their shop path. Our future relies on the youth of our local apart: community.” 1. Car Giveaway Program. CoAuto gives away 3. Community Education Program. “CoAuto one car per year to a local veteran in need, chosen offers classes and workshops in the field of automotive education, maintenance and basic automotive knowledge. We empower our community to make educated and confident repair decisions. Classes are held quarterly at a cost of $40 with a $20 CoAuto cash rebate on their next service.” 4. Local Art Display Program. “CoAuto exhibits artwork in the customer waiting room, showcasing local talent, which gives our creative community more opportunity for promotion. CoAuto does not collect commissions for the sale of any art. We simply enjoy giving our artists more exposure.”

5. Reverse Your Carbon Footprint Program.

“CoAuto partners with the Arbor Day Foundation and plants one tree with every oil change we perform. Our hope is to provide a little more oxygen for our universe and reverse our carbon footprint. “As a result of our commitment to the com-The shop logo is predominantly munity,” noted Vinnie, “we’ve been lucky enough displayed in a professional manner.

It’s no wonder that the shop won first place The service area is extremely clean in ASA’s “Best Waiting Area” contest. and well-lit. The wall murals provide an The customer accommodations are eclectic and visually stimulating work absolutely off-the-charts spectacular. environment for the technicians.

to have achieved a number of awards and recogni-What do customers want/expect from your shop? tion. We won the Vision award in 2018 for facility An extraordinary experience. Excellent client care, of the year, Nevada Business magazine presented and top-notch auto repair, in a clean and profesus with a family-owned business award, and the sional environment. mayor of Reno gave us our own special day in recognition of our community service, called CoAuto What is your approach to technician training? Day, on October 11 of each year. This was quite an Eighty hours of training per year is required, about honor for us. Our most recent award was winning 20 hours per quarter. We took the whole crew to first place in ASA’s ‘Best Waiting Area’ contest, for Seattle for ATE and as owners we are always workour ‘Art Gallery meets Auto Repair’ entry.”ing on our leadership skills and attending many other industry training seminars.

Does your shop offer general automotive repair or do you tend to specialize in specific makes or How does ASP benefit your business?

types of repairs?CoAuto technicians use the Tech Tips columns We specialize in pre-purchase inspections and — there are always fun ideas there and good, edumaintenance services. Our second specialty is di-cational technical stuff. TSBs can be helpful when agnostics.trying to keep up on the newest bulletins that come out. ■

What is your business philosophy?

We love to build relationships through good con-COAUTO ‘COMMUNITY versation and relating to the needs of our clients. CoAuto builds relationships at multiple net-CONSCIOUS CAR CARE’ working events like BNI, Rotary Club, Western Reno, Nevada Industrial Nevada, Toastmasters, Chamber of Owner(s) .......Brothers, Vinnie & Anthony Lucido Commerce, etc. CoAuto prides itself on creating Business founded ........................................ 2014 a beautiful atmosphere, a fun work culture and a Number of bays .......... 5 x 2-post, 1 x 4 post and one-of-a-kind auto repair experience. 3 open floor bays = 9 total Number of certified technicians .............. 3 total. Where do you buy your parts?2 are ASE masters, 1 is working Factory Motor Parts, WorldPac, and dealerships. toward his master certification Shop size ................ currently 5,250 square feet, What influences your parts buying decisions? growing to 7,000 (taking the Rank from 0 to 3, with 0 having no influence and “last bay in the building in 3 having the greatest influence.August. We own the building.”)

Price...............................................1Number of vehicles serviced per month ....... 200

Brand name recognition ...........3Hourly labor rate .................................... $140.38

Promotion in racing ..................0Average job ticket price ..... Approximately $667

Perceived quality .........................3Gross profit .......................... Approximately 58%

Availability/time ........................ 2Average spent on tools

Other (describe): We are constantly reading and equipment annually ........................ $12,000 and researching to stay informed regarding newly Vehicle makes serviced......... Al 1996 and newer introduced parts, tools and equipment and procedomestic, European, dures. Asian, 1-ton and below