Increasing air flow - how far w/ stock PCM?

[sloban]

Forgive the remedial question, but this is the first car I've worked on or modded since a 1974 Pinto about 25 years ago. I don't really understand how modern cars with an ECU/PCM work. My understanding is that it will adjust the fuel-air ratio and ignition to adapt and that increased airflow through the system will provide a minor boost in HP, assuming that the PCM adjusts other settings to compensate.

I've installed a K&N filter and vented my airbox by adding a 1 1/4" hole to the bottom. After resetting the PCM and letting it relearn, it's running smoothly. I did not bother with a dyno before or after and I can't tell any difference in power, but the exhaust note is a little throatier and I like it.

I'm thinking about increasing the airflow more by adding another vent hole to the airbox. My question is, how far can I go with the stock PCM before it can no longer adjust? Is there a limit where if I go past that, I would need to get an XCal and retune?

I've been reluctant to buy an XCal for two reasons: we do not have 93 octane available in San Diego so real performance improvements seem unlikely (the stock tune is for 91 octane) and I'm concerned that flashing the tune will leave a "fingerprint" (like a timestamp or something) that would give service an excuse to void my warranty.

What say you about these things?

 

[Quik LS]

You will not be able to go too far with venting - many of the CAI kits leave the filter hanging out in plain air, look here -> http://www.lincolnvscadillac.com/showpost.php?p=175973&postcount=1 - no airbox at all. I run a hood scoop feeding into a sealed box - no issues with the stock PCM.

retuning with an XCal2 will maximize the hp you can get from that type of mod.

don't worry about the 'fingerprint' - a have flashed mine back to stock right in the dealer's lot. they obviously know my car is modded but they have specifically look at the PCM - and could not find any tampering - they told me they looked. you have to remember to go back to stock.

 

[2001LS8Sport]

You will not be able to go too far with venting - many of the CAI kits leave the filter hanging out in plain air, look here -> http://www.lincolnvscadillac.com/showpost.php?p=175973&postcount=1 - no airbox at all. I run a hood scoop feeding into a sealed box - no issues with the stock PCM.

retuning with an XCal2 will maximize the hp you can get from that type of mod.

don't worry about the 'fingerprint' - a have flashed mine back to stock right in the dealer's lot. they obviously know my car is modded but they have specifically look at the PCM - and could not find any tampering - they told me they looked. you have to remember to go back to stock.

Quik...you need to know that flashing the ECM indeed DOES leave evidence of doing just that. However, it is not readily apparant and most techs do not know where to look. I have even talked to Diablo about this and they admit there is evidence that can be detected. This has become a huge issue on our Cobras since everyone seems to flash or chip them. It has become so prevelant that SVT service reps are now requiring that the ECM's be checked prior to any major engine warranty...and they know how to find it in the ECM. I don't know exactly where they look...or what they see, but there have been SEVERAL Cobra boys have their warranty denied because of this.

Of course, a chip is readily apparent if one has been installed and removed. But I'm not that familiar with this ECM and can't tell you if it has a service port...and if it does, I know of no chip available. But my guess is when they looked at yours, they looked for a chip rather than a flash.

That being said, modding of the Lincoln LS is NOT a major issue. (not too many guys bolt puffers on 'em!! LOL) I can't imagine why any dealer would consider that an issue. Not only that, engine failures due to modding is extremely rare on the LS. As a matter of fact, engine failures are rare for any reason!

But I am here to tell you...flashes CAN indeed be detected. Ask SCT to give you something in writing saying they can't...because I'm betting the farm they won't.

 

[Quik LS]

Quik...you need to know that flashing the ECM indeed DOES leave evidence of doing just that. However, it is not readily apparant and most techs do not know where to look.

you are correct - they have to look for it - problem is - I have done some obivious things like removing the rev limiter in N/P. So right away you can tell....

I'm stuck now away - with the SC on top..... no returning to stock tune for me...

 

[402777LS]

The engineers @ Lincoln have said that the PCM is calibrated to compensate for 10% variations in airflow.