Tuesday, Feb 15, 2005 at 07:12
Self adjustablity, for the consumer, who has no dyno, and no egt gauge, just what a diesel engine needs, and proves what I mentioned first up.....
Read this, and Im sure the real differences will become apparent.
"What the above product [tunit] has done is to simply mimic the main set screw of a traditional Toyota mechanical injection pump and cause a fixed change in the amount of fuel injected regardless of engine RPM and engine load. "
a diesel tuning
"
With the advent of electronic control of diesel injection systems, a plethora of tuning devices have been released on the market to tempt the Land Cruiser performance enthusiast. With these devices, promises of improved power and torque are often realized so no matter which of the readily available chips or computers is chosen, gains will be felt through the
seat of the pants.
One could easily draw the conclusion that they are all essentially the same. After all, they simply alter the state of tune of the engine in order to improve performance. One may quote a power figure and the other a tad less. And to confuse the issue further, the one quoting less power may, in fact quote more torque than the first, And so it goes, leaving the consumer even more confused and eventually making a choice without being fully informed.
Toyota has made it very easy for anyone with a basic knowledge of electronics to modify the fuel injection characteristics and to create what is essentially an electronic version of the main set screw from a good old mechanical pump. Indeed, most of the chips available are just that - simple devices that alter the amount of fuel injected into the engine. Whilst performance is improved, they are very crude and do little more than "turn up the fuel" as the old timers would say.
At the other end of the range, there are complete computer systems that have independent control of the injection timing, the amount of fuel injected, a variety of compensation strategies for situations such as high heat etc and perform these functions at precisely controlled intervals throughout the engine's operating range and throttle range.
There is little sound technical information on all the devices available to the consumer, yet wrong information is in abundance. More often than not, the truth is in what is not said - yet there is a great deal to be said. Much of the wrong information comes from some of the "chip" industry itself, though unlikely that is is spread for malicious reasons. More likely it is through having little understanding of the important issues in tuning a modern Toyota diesel engine. You see, many of the diesel specialist who market these devices have only a finite understanding of their own products and are more confused regarding the capabilities of competitor products. So, it is unlikely that clear, concise and factual information will be made available to the consumer when the very people who deal with these products are themselves confused.
The above statements should not really be seen in a negative light or as condemnation of the diesel tuning industry. Electronic control of the injection system is relatively new and much of the emphasis on creating tuning chips has evolved from the diesel industry's experience with mechanical pumps where external adjustments are relatively course with bulk changes made to the entire fuel injection volume through the main set screw, the entire injection timing through the base timing position etc. On turbocharged diesel vehicles, adjustment through the boost compensator to meter fuel relative to turbocharger boost pressure. In other words, most diesel performance chips mimic these mechanical adjustments through electronic means.
Conversely, computer chips targeted for EFI petrol engines generally have independent control of fuel, ignition timing, boost pressure via an array of data points that combine engine rpm, throttle position and sometimes turbocharger boost pressure. This allows them to alter the EFI parameters at discrete engine RPM/throttle position combinations rather than a bulk change of, for example, a fixed percentage change to the injection volume regardless of engine RPM or throttle position.
Generally, the diesel computer aftermarket industry has a decade of catching up to do over those who have been developing computers for petrol engine vehicles. That said, there are sophisticated computers for diesel engines that not only employ these advanced features, but also add diesel specific features for advanced engine protection.
There are two equally important issues that one needs to consider. The computer or chip features and the actual numbers or data that is programmed into these chips and computers. No doubt, one can have the most advanced computer hardware, however if the programmed data is incorrect or far from optimum, then performance, durability, fuel economy and throttle response will suffer.
Chips and Computers - how do they go about improving performance?
There is nothing magical about altering the state of tune of a modern Toyota diesel engine. Given the optimum mass of fuel injected into the combustion chamber at the optimum time in the engine's compression cycle and you have the optimum engine power and torque. It really is that simple. The standard ECU has data points stored in its memory that determine the mass of fuel injected and the timing at which that occurs. These data points vary quite markedly depending upon the engine's RPM and throttle position.
At this point in time, all the readily available tuning chips and computers do not alter these stored values but instead take that value and offset it by an amount that is stored in the performance chip or computer. The benefit of this approach is that when the performance device is removed, the engine is returned back to standard control and tuning.
Basic Basic Basic universal fuel increase units....and cheap to manufacture..
The most simple devices attack the fuel side of the injection pump only. Some claim that timing is altered as the fuel volume alters, though this is a tad misleading because the way the pump injects fuel is to hold the injector open for a longer period of time - hence the timing is altered. But this can in no way be called independent timing control.
The most basic of these devices increase the amount of fuel by a fixed percentage across the RPM/throttle range. Some may offer the option of several different percentages via an adjustable potentiometer or jumper switches, but again it's a bulk change across all engine operating conditions. These devices are very cheap to produce and technically
well within the realms of the basic electronics novice. In fact, the ease with which bulk fuel changes can be made has brought out products from people with limited electronics experience who have no diesel expertise or at best, just own a diesel vehicle. At under $1,000, these products may seem attractive in price however when one considers that at most it is $25 of parts from the clearance bin of the local electronics
shop, little or no R&D along with the very poor level of tuning expertise that has gone into the product, it is an item that no Toyota Land Cruiser owner would be associated with.
In addition, due to the increase in combustion particulates through bulk overfueling in either the Prado 1KZ-TE and Land Cruiser 1HD-FTE, engine oil contamination becomes a serious issue and will more often than not require oil and oil filter service interval of 2,500 km instead of the standard 5,000 km interval.
What the above product has done is to simply mimic the main set screw of a traditional Toyota mechanical injection pump and cause a fixed change in the amount of fuel injected regardless of engine RPM and engine load.
"
FollowupID:
356883