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Notes & Comments on Swamp's High-Voltage High-Frequency Injector Driver Modules.

This modification was developed more as a repair technique than as a performance modification, although it has given some very noticeable gains on most trucks. Stock trucks show the most gains, highly modified ones the least.
Any gains are also very dependant on what condition the original IDM is in: If the original IDM is already modified, and the pulse gap is shorter than .36-.38 milliseconds, little to no gains will be seen. If the original IDM is a stock EDU-100A model (used in 1994-1995.5 PSD's), the greatest gains will be seen. (Every EDU-100A I have seen was a weak, sick puppy.) Trucks with higher mileages on their injectors will also see more gains.
The only way to tell whether a truck will benefit from the HV-HF mod is to view the injector voltage waveforms on an oscilloscope. If the pulse gap is longer than .40 ms, if there is a double gap, or a ragged and uneven hold-pulse, then this mod can help.

The HF mod is not nearly as simple as the HV mod; whereas the latter involves replacing a single resistor with another one of a fixed, known value, the HF mod is more of a balancing act akin to changing the rate at which a playground see-saw pivots: the weight of the kids, how far they sit from the center, and how hard they push, all have an effect. The characteristics of the injector waveforms dictate which component(s) need to be changed or replaced, and since no two units respond identically, I often have to solder and desolder components multiple times to get satisfactory results.

It takes a minimum of 1-1/2 hours from the time I crack the IDM case open until I can seal it back on. After opening the case, I hook it up to my test bench / engine simulator which consists of a complete engine wiring harness modified with two PCM connectors (one for 1994-1997 PCM's and the other for 1999-2003 units), an IDM connector, 8 injectors and a cam trigger wheel with a CPS mounted to a variable speed motor which allows testing up to 6000 RPM. A control box allows simulating any sensor input to the PCM--EOT, EBP, IAT, MAT, BARO, MAP, TPS, etc and a custom circuit provides an ICP "feedback" signal to the PCM proportional to the IPR duty cycle. A cutout box allows disabling any injector, and a breakout box allows instant access to any signal into or out of the PCM or IDM, and the wiring harness also has the ODB-II plug for connecting a diagnostic scan tool, so I can monitor the PCM Data Stream, etc, and also run Injector Buzz Tests.
After I get it up and running, I scope the waveforms on all 8 injectors. Then I start making notes on a form: customer data, IDM model & serial number, PCB revision number, and a dozen or so voltage, frequency and duty-cycle readings. The voltage and frequency readings are re-recorded after any change is made. Once I deem the waveforms to be satisfactory, I do what I call a "Heat Stress-Test". A stock IDM draws 10-12 amps at full load, a HV one 12-14 and a HV-HF 18-20 amps, causing a substantial increase in temperature. For this test I put a thermocouple probe into the heat sink for the low-side switching transistors (the hottest components), wrap the IDM in a heavy bath towel, and run it at 2 ms of injector pulse width and 3,000 RPM, recording the temperature at 5 minute intervals while monitoring the injector waveforms. If the unit is still running normally after 25-30 minutes, I call it good.
If it fails, usually evidenced by injectors dropping out and not firing, but sometimes a complete shut-down with it recovering after it cools, or occasionally something something going up in smoke, then I fix the problem and then repeat the test until it passes.
The 2 ms / 3000 RPM is based on an engine running WFO under a sustained, heavy load mile after mile, and the engine will probably melt down before the IDM overheats. However, I currently do not want people who do heavy towing to order the HV-HF IDM's; we still need to do more testing in this area.

All IDM's that we sell will now have both the Hi-Voltage and the Hi-Frequency mods done to them. Price is $275.00 with a $200 core charge if we don't get your old IDM back, and it includes return shipping to send your core back. (We don't want your $$$, we just want our cores back. :) )

Warranty is one year.

If anyone has an extra IDM, we will mod one of them in trade for the other one. If you have non-working IDM's, 2-3 of them will get your good one modded.
 

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are all IDM's vehicle spacific?
 

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Oooo, White Lightning !
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What about PCMs.......I have an 02 manual spare from my auto swap.....Will you take that on a partial trade or something ?
 

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look what i can do
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how much of a difference would there be in ya'lls idm and the everybody else modded idm? would i be able to tell any difference
 

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look what i can do
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how much diff is there in ya'lls and the modded one i have now? i am about 30 minutes from ya'll guys and if there is an increase from what i have now i might take a ride over there and i got an idm i'll trade ya
 

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how much diff is there in ya'lls and the modded one i have now? i am about 30 minutes from ya'll guys and if there is an increase from what i have now i might take a ride over there and i got an idm i'll trade ya
you will deffinately see a difference since you have an obs
 

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do i understand right $75 if i send my idm in to be modded
 

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We do the high voltage & high frequency mods for $250, if we get back a good core. Plus shipping & insurance.

$400 if we get back a bad core. Plus shipping & insurance.

All IDM's will be extensively tested (30 min load test) & verified to be working properly prior to being returned to the customer.

take care~

Dave
 

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Never Fry Bacon NAKED!
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All IDM's that we sell will now have both the Hi-Voltage and the Hi-Frequency mods done to them. Price is $275.00 with a $200 core charge if we don't get your old IDM back, and it includes return shipping to send your core back. (We don't want your $$$, we just want our cores back. :) )
We do the high voltage & high frequency mods for $250, if we get back a good core. Plus shipping & insurance.

$400 if we get back a bad core. Plus shipping & insurance.
For clarification, is it $275 or $250 for a HV/HF modded IDM?

Stewart
 
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