[vortech]

Yesterday I decided to pull out my scanner and check my LT fuel trims with the donaldson. I noticed that they were in the 15-19% with the IAT sensor reading 105 degrees. From what I understand if they go over 25% they will throw a code. The car has had over 1000km to compensate for the extra air but I would still get a code say every 300km. Yesterday I took my stock factory 2002 airbox and cut the top and sides off it( looks like Doug Rippies piece) and installed a fram CA3914 air filter. Drove for about 100km cruising, racing stop and go and checked LT fuel trims again. They were now in 6-7% range and the IAT sensor was reading only 75 degrees. Now I could not feel any seat of the pants difference between the two. Is the donaldson flowing so mauch air that my computer cannot compensate? I will be taking the 2 setups to track this weekend weather permitting to test-I also just got my cold air box for the donaldson to test as well. I don't have any dyno numbers as I feel the track is the best way to see what performs better.

 

[Halltech]

Yesterday I decided to pull out my scanner and check my LT fuel trims with the donaldson. I noticed that they were in the 15-19% with the IAT sensor reading 105 degrees. From what I understand if they go over 25% they will throw a code. The car has had over 1000km to compensate for the extra air but I would still get a code say every 300km. Yesterday I took my stock factory 2002 airbox and cut the top and sides off it( looks like Doug Rippies piece) and installed a fram CA3914 air filter. Drove for about 100km cruising, racing stop and go and checked LT fuel trims again. They were now in 6-7% range and the IAT sensor was reading only 75 degrees. Now I could not feel any seat of the pants difference between the two. Is the donaldson flowing so mauch air that my computer cannot compensate? I will be taking the 2 setups to track this weekend weather permitting to test-I also just got my cold air box for the donaldson to test as well. I don't have any dyno numbers as I feel the track is the best way to see what performs better.

If any LT Trim in any of the Closed Loop Fuel Cells registers over 23% for more than 6 seconds, you will throw a MIL for code for lean Bank 1 or 2 or both.

The reason for the high percentages, is due to turbulence at the MAF sensor and the injector sizing this year. This is why GM has the screen on the MAF in 2001.

In 2002, they discarded the laminar screen, which works fine with the stock box, but presents many more issues for the aftermarket. We have solved all of these issues with our TRIC and T1 intakes.

Halltech has spent the last month with the AutoTap, working around this problem.

First of all, the stock injectors are sized at 255cc/min @ 43 psi, which is the same size as the 2000 LS1. Why? Probably to help with the smog cert, now that the pups are gone.

Once you add a freeflowing aircleaner, the injectors end up in 90% duty cycle or above.

Our 30# injectors brought all of our LT Trims back to 1 to 3% where they belong. The stock injectors should be ok with the Donaldson, but the design of the filter causes turbulence at the mouth of the MAF, requiring the screen.

I will make the AutoTap Log available here from our last test, for comparison. Anyone with the AutoTap software should be able to run this and see our results.

Also, with that much airflow being missed by the MAF, you could be getting severe spark knock retard.

Check the knock retard next time you AutoTap.

Jim Hall

 

[BrianK]

That's good info, Jim.. The 90% duty cycle on the injectors really suggests they need to be replaced if someone expects gains from more major work like exhaust mods, etc.

In another post I've asked about flow numbers for various intakes. And while important, maintaining the accuracy of the MAF is much more important. The Big-3 put a lot of time into MAF calibration with different intakes (and do it at all temps).

How an intake impacts the calibration and drivability is more important (for some) than even the dyno or track numbers.

I've done quite a bit of composite fabrication over the years. Banging out my own intake would not be difficult. And while I would enjoy shaping the buck necessary to do this, I could also just ring a friend at Ford and have him do a quick design in SDRC-Ideas. He'd then send that over to have a cubital or stereo-lith model made. Wrap it in fiberglass & it's done. Even tooling up epoxy molds to do short runswould be fairly easy.

Cost/time effective? Heck no! You do something like this because you want to run *your* intake.

BUT, the development work is the gotcha. Refining the design to work well with the stock MAF and engine calibration is the very tricky part.

Unfortunately, the impact of those efforts on maintaining drivability aren't going to be seen in a dyno test.