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PCM's: E99 Cali DPC-411/ZDR3 vs 2000 non-Cali DPC-421/DAC3 RESULTS
OK guys. While I was troubleshooting and issue and determining the health of my HPO system, I did some testing with a different PCM. @BWST Encouraged me to do some comparison testing between the two PCM's. Due to my own searching, I know information out there about the differences between early 99 vs later and Cali vs non is sparse and a lot of posts on the subject appear to be speculation. I hope this thread will help others who are searching for the same information I was.
My truck is an early 99 (09/98) and a California model and manual transmission. No engine mods. A while back, I came across a good deal on a DPC-421 DAC3 PCM out of a 2000 F250 and picked it up. I did a bunch of searching and couldn't figure out if it would even plug in to my Cali truck, let alone function properly. There were plenty of people saying that upgrading from an early 99 Federal to later made a big difference in performance and driveability and plenty saying that there would be no benefit. Well, I went ahead and tried it myself and can confirm some things.
* Yes, it is plug and play. The truck started right up after the swap.
* I didn't modify my glow plug wiring and have no codes related to that.
* There is a code for AIH since my early truck doesn't have one.
* No codes other than AIH except P1000 (power interruption) which I cleared and it didn't come back.
* There is a difference in engine operating parameters.
* There is a difference in performance!
I started with the DPC-411 in the truck and made sure it was thoroughly warmed up and drove the 5 miles to my test location. This is a straight, flat stretch of country road. I held 45mph in 4th gear for about 1/4 mile and at a reference point, floored it. I held the throttle down until past 70mph and then backed off and completed my loop back home. I swapped in the DPC-421 and went and performed the same test. There was about 45 minutes between tests. All of this was logged in FORScan. After I got home I put the PID data in the chart spreadsheet and compared the results. I was able to identify the point where I dropped the hammer to the point the truck hit 70mph, within a couple of milliseconds to determine the times. The first pic below is with the DCP-411 and the second is with the DPC-421.
Edit: This is while towing a 6000lb TT.
Edit: I marked up the top pic with 33 PSI of EBP. It should have been 43 PSI.
An important detail I left out is that I was towing my 6000lb TT while performing this test. Those would be some pretty embarrassing numbers otherwise!
Some observations: The early PCM seems to limit ICP to 2500 PSI and generally runs a lower PW in most conditions. The later PCM builds less boost and also (maybe because of) shows a lower MFDES, yet it out-performs the early. There must be significant difference in the timing strategy between the two PCM's.
interesting post. i too have an e99 zf6 that i primarily use to tow a toyhauler camper. a few years ago i was having issues getting decent tunes with a tuner. he suggested swapping to the dcp 421 ecu to get tunes. i did find a used one and it is the dcp 421 with the DAC3 as pictured above. never installed it as i didn't believe that should be necessary ........ now i sort of wonder hmmmm
Update: I towed my boat over the coast a couple of weeks ago and my travel trailer last weekend and there is a noticeable difference in towing performance with the later PCM. Not dramatic and I don't have definitive data points but going up the grades, I can maintain the same speed and now have some throttle in reserve where I didn't before. It's too early to tell for sure but it appears that I'm seeing a 5-10% gain in towing economy. Unloaded fuel economy hasn't changed either way. I still have a box full of Riff Raff parts in the shop to install so these gains are with no other changes from stock.
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