Ping Fix



Yes it pings no mater what TRD says.  

All most all of the people that have installed the TRD supercharger on their 3.4 complains of pinging, some more then others.  I think I have been one of the lucky ones and I never really considered that I had a pinging problem.  It would ping on occasion and I could intentionally induce it, but with my driving style it rarely presented its self.

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 What is ping?

There are two conditions that will cause an audible knock or rattle sound from the engine.  One is detonation and the other is spark knock.

Detonation is a condition that exists in the combustion chamber when the fuel/air charge or mixture is ignited by something other then the spark of the spark plug.  This can be cause by hot spots in the combustion chamber like carbon that is glowing red and igniting the mixture.  It can be caused by excessive compression like in diesel engines that generate so much heat the mixture just lights off.  Forcing lots of air into the engine with a supercharger can also lead to detonation.  I am sure there is dozens of other things that can cause detonation, but the important thing to remember here is that detonation is when the mixture is ignited by something other then the spark of the spark plug.

Spark knock is when the spark of the spark plug ignites the fuel/air charge in the combustion chamber sooner then is should.  If the ignition is to far advanced it can lead to spark knock and you can hear the engine rattling like marbles in a coffee can.  There are things that can contribute to this like a lean mixture, a faulty EGR system and probably a bunch of other things.  Again the important thing to remember here is the mixture is lit by the spark of the spark plug, but just to soon.

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 The Problem

After a few years of tinkering with larger injectors and tons of other things and with the help of my friend Ron, we have determined that the pinging that people complain about with the TRD supercharger is spark knock.  Here is how it presents.  While cruising along at highway speeds you come to a hill and attempt to maintain speed, or try to accelerate a little bit.  It is not enough to unlock the torque converter or cause a downshift and as you apply the throttle and the supercharger starts to make boost and then you start to hear the engine rattling.  This seems to occur more in truck with manual transmissions because they don’t down shift them selves.  This can make tooling along with cruise control very annoying.  This is when you are in 5th gear or overdrive with the converter clutch locked and the engine RPM is around 2000 RPM and you advance the throttle into boost and you get the engine knocking and pinging.  I call this the High Gear/Low RPM Ping or HG/LR Ping for short.

TRD just denied that this problem existed.  Then they came out with an upgrade we called the “ping kit.”  It included rerouted some vacuum lines and removing the Fuel Management Unit (FMU).  It is my opinion that removing the FMU was a real bad thing to do as it compounded the high RPM lean out problem I discuss under another topic.  Some supercharged engines pinged so bad that the owners had the superchargers removed in fear of serious engine damage.  The nice thing is that TRD did cover the cost of removal.

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 The fix that works

There is some hope here.  A company called Split Second was hired by TRD to do some development work on the supercharger kit for the 4.7 Tundra V8.  Apparently it also suffers from the same low RPM high gear spark knock problem.  Split Second developed a device that retards the ignition timing in the narrow part of the RPM band where the spark knock problem occurs.  As of this writing there is no information on whether or not the Split Second device will be included in the Tundra supercharger kit.

The nice thing is that the very same device also works on the supercharged 3.4.  Initially the device was going to be available through TRD for people that wanted to install it on their trucks if they were having the HG/LR Ping problem.  For some reason TRD decided not to market the device under their label.  The lucky thing here is that Split Second has seen a market for their device and decided to market it under their own label.  They are calling it the TMC1.1 for Timing Map Controller version 1.1.  It is a scaled down version of their TMC1.  Many of the features have been eliminated to reduce the cost and simplify installation.

Installation is straightforward and there are four wires that need to be spliced into the ECU wire harness.  A power, ground and then the signal wire from the crankshaft angle sensor is cut and run through the device and then onto the ECU.  The device modifies the signal from the crankshaft angle sensor to trick the ECU into retarding the ignition timing in the narrow range where the spark knock occurs. 

This is a picture of the TMC1.1 with the cover removed.
You can see the adjustment pot in the upper right hand corner.

Because some engines suffer from the spark knock more then others the device has an adjustment that lets you control the amount of ignition retard so you can dial in just what you need to suppress the knock.

The original prototype unit was installed on a supercharged Tacoma with a serious spark knock problem.  That truck needed 9 degrees of retard to suppress the spark knock.  I received the very first production device and it came preset with the 9 degrees of retard that was needed on the test truck.  I found that to be way to much for my truck and that much retard caused the truck to be very sluggish between 1500 and 2800 RPM where the device retards the timing.  Once the RPM when past 2800 I got a big surge in power.  It was clear that I needed to reduce the amount of retard.  After a little test-driving I found that my optimum setting was just a hair up from zero.  Set a zero as if the unit was not there it would ping and with just a hair off of zero it does not.  After consulting with Split Second, that setting should work out to be somewhere between 1 to 1.5 degrees of retard.

There is one thing that I do not like about the TMC1.1.  It retards the ignition all the time and not just under boost where it is needed.  I asked Split Second to include a pressure switch that would be activated by boost pressure like their ESC1, but it is just not going to happen.  I had some concerns about reduction in MPG with the TMC1.1 retarding the timing all the time, but after a test it appears that with the low setting that I am using there is not a reduction in highway MPG.  There does seem to be a very slight reduction in normal driving MPG by about .5 MPG as far as I can tell on my truck.

Now after years of denial that the problem existed, and after a failed “ping kit” with the removal of the needed FMU there is a real and true fix for this problem.  It is sad that is not from TRD.

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 Get yours

If you have a supercharger and are plagued by the high gear/low RPM ping then the Split Second TMC1.1 is the solution to your problem.  It is available at a discount from Underdog Racing Developement for about $180.

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