C&L causes me to run lean?

Bad92GT

The 5 Minute Plan Man
Jun 10, 2004
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My GT runs slightly on the lean side.. 24# injectors, Kirban FPR and a C&L MAF sensor.. i've heard rumors that they cause you to run lean.. also could the fact im running a filter on the end of it throw the readings off (electric fan)? help please lol
 
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What are your mods - I have heard the same thing about C&L's but I love mine - I noticed a seat of the pants improvement as soon as it was installed - on a normally aspirated ride it will make a bit more power. All I have done is a E303, 1.7's, 70mm t/b, 76mm C&L, 19lbs, AFPR set to 42lbs, 14.5* timing, Edelbrock Performer, CAI inside fender, Crane Fireball, Plasma Booster (multi spark unit), pullies, elec. fan, mild exhaust port work on E7's, MAC equal length shorties, high flow cats, Flowmasters, 2.5 pipes, rebuilt 5spd, 3.73's, etc... I have some 24#'s and 24# tube ready to install and am wondering if it will make any more power or if it will make it run rich - I hear best economy/power balance is at 14.7 A/F ratio that the computer tries to maintain that based on O2 sensors signal and that the computer will cut out pulse width on 24#'s to compensate and that the C&L is allowing more air into the system "fooling" the computer and making it run a bit lean thereby giving more seat of the pants power. I get so confused too - I hope somebody else knows
 
The turbulent air that a CAI can pick up when the air filter is in the engine compartment can cause problems.


Get one of your buddies to ride along with you. Find a level stretch of road where you can do some testing. Don't choose a speed range that will make you shift gears, the shift quality & speed will affect your results. Use 2nd or 3rd gear and do a run from 2000 RPM to 5800 RPM. Call out the RPM as it increases and have you buddy record it and the elapsed time. If you have one of those cheap digital watches like I do, a stop watch is built in. Start the fuel pressure at 36 PSI, vacuum off and make a run. Turn it up to 37 and make another. Be sure to reconnect the vacuum every time you set the pressure. Keep turning up the pressure and making runs until you notice a drop off in time. If your bud was careful to record the results, you'll have a nice chart to use to find the optimum pressure.
 
Bad92GT said:
My GT runs slightly on the lean side.. 24# injectors, Kirban FPR and a C&L MAF sensor.. i've heard rumors that they cause you to run lean.. also could the fact im running a filter on the end of it throw the readings off (electric fan)? help please lol

How do you know you are running lean? WB O2?

The C&L (just like other aftermarket MAFs) send a tweaked signal to the computer to get the desired results without having to change the MAF Transfer (the MAF calibration file in the eec).

Have you verified that you have the correct size sample tube in the C&L? Sometimes the color coding gets wiped away, so check my website for a color/diameter break down.

Are you using the stock 5.0 HO MAS? I am asking only about the black sensor box on top of the MAF tube. The 70mm MAS sensors can cause some problems (possibly).

The fan could be causing some issues. Have you tried running the car (for a short time) with the fan unplugged? This may help determine if the fan is screwing things up or not.

jason
 
back fires through the intake alot.. fan stays off half the time.. i think it might be the tube thats causing me some problems.. the module is straight from my original MAF sensor...
 
Yes, a conical filter attached to the end of the C&L will make it run leaner. The C&L was "calibrated" to work with your stock airbox. Install your stock airbox back on and your car will not run as lean.


Sounds like you might have other issues as well. Check for codes, or borrow a buddy's MAF and try that one.. Also make sure you have the proper sampling tube installed for your injectors.
 
Sampling tube install direction wrong ?

Hey while you guys are on the topic of C&L mass air setups. Is it possible to install the sample tube backwards at all :eek: , the mechanic who did mine said "That he might have put the tube in backwards.:jaw: ", is this possible:shrug: ? I have looked inside and the wedge or sloping shaped part is in front is this correct???:bang:
TIA :D ,
Hink
 
Make sure you use the stock air box! I was using a conical K&N air filter that was receiving air through a Cervini hood with ram air kit. The car did not run well, but it ran awesome as soon as I installed the stock air box.
 
I ran a conical air filter on the same C&L I am using today for several years with no issues.

There have to be other contributing factors, if the lean condition being experienced is going to cause backfires.

jason.
 
Why not just get a Fender mount Cold air system. I would recommend this over reinstalling the stock air box. But ONLY If you your inlet tube is THE SAME SIZE as the mass air meter. MOST CAI are atleast 70-75mm on the inlet side for the Mass Air Meter. But if your just trying to figure out what is causing your problem. The stock air box is a great idea if you still have one? If you car is just now starting to this? I don't know where you live? But it is summer here & the Heat Index is right around 100 degrees. Just imagine how hot it gets under your hood & the filter is only suckin' HOT AIR. Hope this helps. Regards.....Wayne H.:SNSign: