I have a 2004 SCREW 5.4L 2WD and just installed the Diablo performance tune(91 octane). My vehicle mods are airaid cold air intake and Borla rear dual exhaust. With those two mods my truck has been running great. I have ran thru 2 tanks of 91 octane before installing the Diablo. My help question is this. I installed the tune with no problemm and boy did it put life into my truck. It runs with no problems or pinging, but the engine help light is on on the dash. Now I just put the original tune back in the truck and the light went off. Has anybody that has installed the Diablo had this problem and know what is causing the light to come on. Again there is no performance problems that I can feel or hear, just the engine light is on. Thanks in advance for any advice or help.

 

Does your tuner read codes? Pull the code and post it in the Engines section. If it does not read them try a parts store and they can tell you what the code it. Just make sure thay give you the code #. I.e: P0174.

JMC

 

That is in many cases caused by a lean condition in the 2004 3-valve 5.4, but just as JMC said, you need to have those codes read and see just what the PCM is actually reporting. To do that, you'll need to reinstall that tuning and then as soon as the MIL light illuminates on the dash again, read the codes - during that time don't do any towing, for example, just to be cautious.

Just so we're clear - - you *must* have those codes read. There is no such thing as any one cause for all Service Engine Soon lights, so there is no other way - you must have the codes read when that condition is present (SES illuminated) in order to know what the PCM is reporting - and from there diagnose the actual culprit.

Also, remember that anytime you flash the PCM, the PCM is cleared of any codes as part of that process - so you're wiping out the stored codes when you flash the PCM. Now you did the right thing in terms of going back to the stock program if you felt the Diablo tuning is causing that problem (and I wouldn't be surprised), but that also clears the codes, so it may be some time before any such codes are reported again by the PCM.

For example, this might not be the tuning at all, but instead, could easily be a problem with the installation of that Airaid intake kit - it's gasket at the end of the air handling tube where it attaches to the throttle body takes some real time to install correctly on that tube so that it is properly seated and sealed - and then that tube also has to go all the way down to the ledge on the throttle body. Failing to do either of those properly will cause a lean condition in the 3-valve 5.4 F-150. It can take a number of drive cycles for the SES to come on in those cases, so it might not happen right away, but instead, might take a day or two, or even a few weeks. I don't know if you had the Airaid on long enough before the tuning was installed to know for sure that the Airaid's installation wasn't causing a problem, but if they both went on at the same time, it could just as easily be the Airaid's installation. Or, if it's one of the earlier Airaid units for the 2004 3-valve 5.4 F-150 (say, it's more than 5-6 months old), the Airaid unit itself could have a problem - we only use what we refer to internally as the 3rd generation of that kit.

Bottom line - go ahead and scan for codes now just to see if anything is in there. And if no codes are present, then you'll have to reinstall that tuning and wait for the SES light to come back on and *then* scan for codes while the SES is illuminated to see just what the PCM is reporting to determine the real culprit.

Good luck!

 

I just had the same thing happen..Here is the fix go to www.diablosport.com click download go to the ford revision and update the predator using "2004 F150 initial revision" this is located below the revisions that say F150. Read my other post or email me. I fought with this for two days now all is well. Running great. Read my other post and that should help you out.