CAI, tune and engine light AARRGGHH!


New Member
Mar 31, 2005
Hello everyone, I installed the JLT CAI and a custom tune from JLT using the SCT Xcalibrator. The car seems to drive better but I keep getting the engine light coming on. I can reflash the computer and the light will stay off for about 10 miles and then comes back on.
The problem now is that the generic ODBII readers dont seem to be able to read the error code so I can let the guy who did the tune know what the code is.
So now I have to either take it to a shop that specializes in mustangs to have the code read (and more $), or take it to the dealer and who knows what they will say about a CAI and tune?
The Diablo would have been nice because I could have read the codes without taking it in somewhere, but they didn't have the tune on a Diablo when I bought it.

The guys at my local mustang shop suggested that I send the SCT back and have them put a tune on with the Diablo but I know they (JLT) spent a lot of time on the dyno creating this tune so I would like to use it.

Any one else have any problems like this with a CAI? I also disconnected the negative on the battery to see if that would get rid of the light.
Still there :bang: .
Maybe some black tape over the dash would take care of my problems!
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call tucker at JLT and see if he can help you.Im sure he can help work it out. The mass air sensor is very sensitive,check to see if it is installed tightly with no air leaks.

Im waiting for the SCT Xcalibrator 2 to come out before I order my JLT.It will have all the features of the diablosport and will come with the JLT/DTP tune already in it.Any day now is what I hear.
My experience with mass air sensors that have a CAI kit of some kind is ---
There is a very common problem with Oil soaked filters. Some filters can be more saturated than others. Allot of people including myself have installed a CAI kits and had the CEL come on. Oil from the filter can end up on the small wires of the MAF and give erroneous readings causing a CEL.
On my car it happened after I cleaned the filter w/K&N recharge kit for the 2nd time (clean it every 6 months). My CEL came on I pulled the MAF. Cleaned it very carefully with q-tip and alcohol (some people just spray starter fluid or something that will clean oil off and evap fast w/out residue)

Reinstalled and it was fine.

Again this was not on a mustang and I’m not familiar with the MAF on the new Stangs but would like to help out. This problem happened to allot of people on my Ricer Forum with brand new filters.

My advice is try to clean the MAF. Reset ECU. Couldn’t Hurt.
You need to check the screws that hold the MAF in place. Many People have had the CEL problem and it is solved by taking the MAF back off and useing a glue compound to seal the MAF in place. Also hold down with a little pressure as you tighten the screws. Tighten them down evenly, like you would head bolts. the CEL is caused by an air leak at the MAF. Dont overtighten the screws. If you need additional help just call Jay, he is a standup guy and will be more thatn happy to help you with any problems with his product. Good luck.
Thanks guys I will take the MAF and make sure that it is very clean. I did notice that it doesn't look like there is an airtight seal at the MAF.
The MAF not being airtight could definately be what the problem is.
I did make sure I tightned the clamps with a ratchet on the intake hoses because I read in another thread that that was causing this problem.
I also have been working with Jay and he is a good guy, they can't really do anything for me untill I at least get the engine code for them to go by.

On a good note I have had no problems with the car at all (that I didn't create myself) and I love driving it! The 4 months on order and dreaming about it was all worth the wait. :nice:
OK I think we are on the right track with the MAF. During a break at work yesterday I went out and made sure the MAF was clean and tightned the screws down carefully. The light stayed off all the way home and then back into work this morning but it came back on at lunch today. I think I will try something to seal better. I know that Silicone would do the trick but I want to be able to reuse the MAF if I need to put it back to stock. Do you think something like Plummers putty would work? I want to be able to use something that I can reuse the MAF.
Hey Old School 77, what kind of glue compound would you recomment to seal this?
It may be also that the screws are just loosening, I did notice they didn't seem too tight when I checked on it. Loctite should fix that.