This section is for LS based engines swapped into another vehicle or ANY LS powered vehicle with more than bolt on modifications (like upgrades to cam, heads, turbo, supercharger, nitrous, etc.)

☐ Completing this checklist is going to take some time and may require you to spend some money. We will gladly assist you through email and (if we have time) over the phone with anything in this section AFTER you have paid and scheduled your dyno tune.

☐ If you used low quality parts and your installer was cheap/inexperienced (nothing wrong with that, it’s just the reality of the situation) then it’s probably going to cost you more time and money to get it ready for dyno tuning.  If you don’t want to mess with all of this, you can buy our $2,250 LS ENGINE SWAP/LS ENGINE UPGRADE STARTER PACKAGE. This is not meant to finish your build. This is for the last few technical things needed to get the shakedown on the vehicle completed so it ready for tuning. We provide 10 hours of labor and up to $500 in parts as well as all the tools and equipment needed to get your LS swapped or upgraded vehicle ready for tuning on the street, on the dyno, and just overall going strong. The dyno tuning is not included in this price, that is additional.

Typical examples of things we take care of in this package include identifying and replacing bad O2 sensors, upgrading fuel injectors, MAF sensors, finding and fixing vacuum leaks, exhaust leaks, wiring harness issues, eFan issues, coolant leaks, performing a leakdown test, and diagnosing fuel system issues related to pressure and flow.

Want to save some money? Great! Keep reading and get to work

Don’t get discouraged. This is next level stuff. Figuring this out on your own will literally save you thousands, but you’re going to have to spend some time on it. If you have problems here, you’re going to have to do your own research and learn more on how various sensors function to get the problem sorted out.

☐ Buy a scan tool that can read live data (if you don’t have one already). You will need this to check codes and confirm certain sensors are working properly. The Autel AL319 is about $30 on Amazon and the Hyper Tough HT300 is $40 at Walmart. They will get the job done. For something a bit nicer, the Zurich ZR8 for $100 from Harbor Freight is a decent choice.

☐ Plug in your scanner. Make sure the scanner turns on. If it does not turn on something is wrong. The OBD port always has 12 volts (pin 16 at the bottom right when looking at the vehicle’s OBD connector). Find the issue and fix it. Probably a fuse. Might be a ground. The vehicle’s OBD pins 4 and/or 5 should be grounded.

☐ After your scanner comes on, turn the vehicle key on but don’t start the engine. Try to connect to the car’s ECU. If it won’t connect, find and fix the problem (probably wiring). 

Once connected, read and clear/erase all the trouble codes. 

Now start the vehicle. 

Then read/check the codes again to see if any came back. 

Make a note of any code that says current, active, or pending (like literally write them down on some paper or take photos with your phone).

Not every scan tool uses the terms “current, active, and pending” but they will be similar.

Some scan tools will give you permanent codes. Permanent codes are old and no longer active. You can ignore any code that says permanent. We only care about codes marked current. active, or pending. 

Any code(s) that come back are codes you need to fix before you bring it to us, unless it is an expected code.

Expected code!? WTH is that?

Anything that relates to a modification you made is an expected code. For example, P0011 Intake Camshaft Position Timing – Over-Advanced (Bank 1) might appear if you remove a VVT cam or install a lockout kit in the cam phaser. P0300 Random/Multiple Cylinder Misfire Detected is common on vehicles with a larger than stock camshaft. These are expected codes.

Any codes with the words “high voltage, low voltage, range/performance, circuit, or correlation” in the description are not expected and should be considered as “real codes.” Find and fix the issue before you bring us the vehicle. You probably have a bad sensor, or a wiring issue, maybe both.

If you have questions just email us a complete list of all the codes (that come back after you clear them) and we will help you.

☐ Use the OBD scanner’s live data (sometimes called data stream) feature and check that the following SENSORS are working (oil pressure, coolant temp, O2 sensors, mass airflow, manifold pressure, throttle position).

☐ Oil pressure is not available as live data in the scanner on all LS engines. If it’s available, it should be at least 25 psi or higher when the engine is warmed up (engine coolant greater than 180 F) and at operating temperature. If the pressure is lower than that your engine is probably worn out and needs a rebuild. Your bearings are probably shot, or maybe the o-ring for the pickup tube on your oil pump is bad. At any rate we won’t tune a vehicle with low oil pressure. Too much risk of killing the engine.

☐ Coolant temp should be steady at idle when the engine is warmed up. Anything from 180-225 is okay. If it’s hotter than 225 then find and fix the issue.

☐ O2 sensors for “Bank 1 Sensor 1” and “Bank 2 Sensor 1” need to be frequently switching from about 100 mv (millivolts) to about 900 mv. Here is a link to a YouTube video that shows what working O2 sensors look like (we have no relation to the guy in this video, it just shows what we want you to see). The important thing for you to take away from the video is what the switching of a normal O2 sensor looks like. 

In this video example you need to pay attention to the first and third row on the scanner. Your O2 sensor millivolts (mv) should look like what you see. Notice that BOTH sensors are switching back and forth frequently, this is what we need.

Do your O2 sensors look like the ones in the video? Great, you can quit reading and go to the next check. 

Your O2 sensors don’t look like that? Keep reading for some tips on what might be wrong. 

If one or both sensors read around 450 mv all the time then they are either bad, you have a wiring problem, or maybe both. Find it and fix it. Don’t bring it for a tune until this is resolved. 

If both O2 sensors are stuck at a low value like less than 100 mv or a high value greater than 800 mv then rev the engine up to 1800 RPM and hold it there for 15-20 seconds to see if they “wake up” and start switching. If they do, then you have an intake leak, or an exhaust leak, or maybe both. Find and fix them. Don’t bring it for a tune until this is resolved. 

If one sensor is stuck high or low then you have to find and fix the problem on that “side” of the engine. It could be a bad sensor. If it reads high, you probably have a vacuum leak or exhaust leak on that side of the engine (bank 1 sensor is driver side and bank 2 is passenger side). Other problems that will trigger a high O2 sensor reading are a stuck open or leaking fuel injector, and as a worst case scenario we have seen engines with low compression that have O2 sensor readings that are “stuck” high. Do a compression test or better still, a cylinder leak down test to make sure the engine is mechanically sound. Eric The Car Guy has a great YouTube video where he explains how to perform and analyze the results of a leakdown test. Search and ye shall find.

O2 sensors are the one of the most important sensors for an LS engine to run and drive well, and we need them working to tune the engine. Don’t bring it to us for a tune until both O2 sensors are happily switching like the ones in the video.

☐ The mass airflow sensor needs to read around 6-10 grams per second (g/s) at idle. If it is not reading or reading very high or very low, you have an issue with your MAF (mass airflow) sensor. Clean the MAF and retest. If you still have an issue, find the problem and fix it. Possibly a bad sensor, bad wiring, or both.

☐ The manifold pressure sensor at idle (around 750 RPM) should read between 35-45 kPa for stock cam vehicles and as high as 60 kPa for large cam vehicles. When you rev the motor the MAP sensor should increase and get close to 100 kPa. If you don’t have MAP readings in this range, then find and fix the issue. The next check may be helpful.

☐ Do this next check with the key on and the engine off. Check the MAP sensor reading in live data with the key on but the engine not running. The MAP sensor should be very close to 100 kPa with the key on and engine off. This will change with elevation. If you live in Denver, it might be 90 kPa. Atlanta we tend to see readings around 97-98 kPa. Anything lower than 90 probaly means you either need a new MAP sensor, or we need to adjust the tune calibration. Read below and/or contact us if you run into an issue here.

More about MAP sensors:

☐ Did you add boost to a vehicle that didn’t come that way from the factory? No? Then skip this part. Yes? Keep reading my guy.

You will need to change your manifold pressure sensor so the engine computer can now read boost pressure. We like the old square style MAP sensors for upgrades. You can install them anywhere; you just need to run a vacuum line to them.

The 2 Bar sensors GM Part # 213-1520 / 12569241 / 16009886 / 16040609 / 16254539 / 213-184 / 213-361 are good up to 15 psi of boost.

The 3 Bar sensors GM #12223861 / 16040749 / 12223749 are good up to 30 psi of boost.

Check out this guide on GM MAP sensors for more information.

☐ The throttle position sensor (TPS) should read a steady value when the vehicle is at idle (no foot on the accelerator pedal). Make sure it is a steady value and not jumping around. Check the wiring and replace the TPS if it’s rapidly changing or jumping around by more than a few tenths (0.1-0.3) of a volt or percent.

☐ Did you install a sheet metal style intake manifold or grab a factory upgrade like the TBSS intake? If you have a Gen 3 LS computer and wiring harness (basically anything from 1998-2006) then you will need to buy an LS3 Gen 4 style MAP sensor and a wiring harness adapters to connect it to your wiring harness. Again, check out our guide on GM Map Sensors for details.

☐ Fuel injector stuff. Make sure your injectors are big enough to feed the power you (reasonably) expect to make. Note that GM and Mopar fuel rail pressure is 58 psi (4 bar) and Fords are 42 psi (3 bar). You will need this information for most fuel injector size calculators. We recommend sizing your injectors for 85% or lower injector duty cycle.  

Don’t overthink this. Injectors just need to be the right size. Also know that bigger injectors are expensive and add 0 horsepower so don’t bother to upgrade unless you need to.

Injectors that are too big are as much of a problem as too small. When injectors are too big it’s like you are trying to go 35 MPH but your speedometer has a needle that reads from 0 to 1,000 MPH. You don’t have enough resolution to control things accurately.

Be realistic, your stock head, stock bottom end, used 5.3 NA motor doesn’t make 500 HP no matter how big the cam is. Do some internet research on a setup like yours (cam, heads, longtubes, etc) and size the injectors accordingly.

We recommend taking a picture of the injector part number with your phone (so you don’t have to remove the injector) then look it up online to see what you have. Also search for your specific engine size to get more information about what injector size it has from the factory. The On All Cylinders website from summit racing is a great source of information. For example, search ‘5.3 LS on all cylinders’ or ‘6.0 LS on all cylinders.’

Other useful links:

https://www.maperformance.com/pages/fuel-injector-calculator – good to calculate what size fuel injectors you need for a given HP.

LS_Injector_Guide_2019_Rev_3.webp (2560×1706) (ictbillet.com) – good to determine plug style and physical size of factory GM injectors. Factory injectors are a decent choice for upgrades because they are good quality and reasonably priced. The best price is at the junkyard, but you probably need to run some brake cleaner through them. You can buy various ICT adapters to mix and match factory injectors on different intake setups and fuel rails. ICT is generally very helpful if you call them.

The 25 lb/hr injectors commonly found in 5.3 and 6.0 LS engines are good for builds up to about 400 crank HP. Anything over that power rating will require larger injectors, and it’s not hard to break the 400 HP mark on these engines with a decent cam and long tube headers. You definitely need something larger than 25 lb/hr for a 6.0 with upgrades. L92 injectors are an ok choice (you will need a wiring harness adapter) and LS3 injectors are a great choice (you need wiring adapter and the ICT spacers).

Please don’t buy the set of 8 LS3 injectors on eBay/Amazon for under $100. This is trash. They are made of 100% Chineseium garbage. Look into something decent from FuelInjectorConnection.com or just order them from us. Expect to pay around $450-$500 for a decent set of injectors.  

☐ Fuel pumps and fuel regulators. If you’re using the LS1 style fuel filter and regulator and your fuel pump is rated for more than 190 lph you will have problems. Don’t do it, and don’t bring it to us that way. These stock LS1 filter regulators can’t handle fuel flow over 190 lph. You will have inconsistent fuel pressure, and we can’t tune for that. Just so we are all on the same page, 255 lph is more than 190 lph, and so is 340 lph. If your fuel pump flows more than 190 lph you need an aftermarket fuel pressure regulator.

Any aftermarket fuel pressure regulator should be set to 58 psi. Don’t connect the vacuum port on the fuel pressure regulator unless you’re running boost. The Summit Racing SUM-220066 regulator works well and is about $120. The Radium Engineering RAD-20-1623-00 is a great unit and can usually be found online for about $170. AN fuel hose lines, fittings, and adapters will run you another $100-$150 depending on what you buy.  

☐ Yes we know, that’s a lot. Now do you see why we charge $2250 to do this for you?

☐ Good luck, have fun, you got this, and we will see you on dyno day.