Problems Arise With Cone Intake

[vash169]

I recently got a cone filter for my Alltrac and popped it on, ditching the airbox. Instantly my car had problems; stalls out after a few seconds at idle, struggles to accelerate, jerks when maintaining speed, it was terrible! I switched back to the airbox and the problem disappeared.

After removing the cone entirely and moving the AFM into a few different positions, resulting in the same idle problem, I think I'm running too lean without the cheapo paper filter in the way.

Or maybe I'm way off-base! I inspected the intake hose as closely as I could without removing it, and I tried an AFM from an RX7 to rule that out, and even now I've tried to return to the previous condition and the problem is persisting. Anyone else got any ideas?

[Pineapple]

Try pull the battery to reset ECU. Check for boost leak. Make sure AFM is install correctly and is clean.
Do you have lots of mod and pulling more HP to make the stock filter a bottle neck? If not, your lean problem is caused by something else. How do you know you're lean?

[roushians]

whatcha do with the air temp sensor?

[vash169]

Originally Posted by Pineapple

Try pull the battery to reset ECU. Check for boost leak. Make sure AFM is install correctly and is clean.
Do you have lots of mod and pulling more HP to make the stock filter a bottle neck? If not, your lean problem is caused by something else. How do you know you're lean?

I did the ECU reset and checked for leaks each time. The AFM is in good shape, it behaves just fine with the airbox in place (although I notice the previous owner had it opened and modified to lean it out a bit, I plan to replace it). I don't have a lot of mods, just a 3 inch exhaust from the turbo back with no cats, I've gotten only good results out of it. I'm guessing I'm running lean based on the fact that the AFM was changed to run more lean, and removing the filter entirely without changing anything else yielded the same result. I figure having the cheap paper filter in the clunky airbox is restricting the airflow enough to prevent it from running too lean. Really it's just an educated guess, I'm starting to think the wiring in the plug for the AFM is damaged, I plan to look more closely into that.

It's interesting the air temp sensor was brought up, someone else had the same idea. I installed a cone filter on my GT when I had it and it was the simplest thing I'd ever done, it worked instantly. I'm not sure the colder air charge would cause problems like this, my car was on the road all through the winter (and survived a few snowcross events) and this never happened. I am kind of at wit's end though. How could I change the sensor to compensate for the cone?

[hatchy_gt-s]

ya not having cats could cause a problem seeing as you dont have a downstream o2 causing for a lean condition

[vash169]

So the exhasut velocity is increased to the point where the O2 sensor can't read it properly? That kinda makes sense.

[hatchy_gt-s]

when hydro carbons and NOx(gases formed by combustion) go threw your cat it reduces them as best as possible when you no longer have a cat your downstream O2 (post cat sensor) reads those as excessive emissions telling the computer you have to much fuel (ie not enough air), but the computer reads its getting decent air so it pulls back on the fuel and when you instal the cone it alows less resistance but same amount of air causing for loss of manifold pressure.

[toyomoho]

The engine runs OK with the stock intake system, stock filter on or off?

The cone filter could be causing too much turbulent air for MAF/MAP sensor resulting in signal output errors.

Try running with the cone filter on but unplugging the MAP/MAF sensor. If the problem goes away the issue is with the sensor/filter combination.

[vash169]

Originally Posted by hatchy_gt-s

when hydro carbons and NOx(gases formed by combustion) go threw your cat it reduces them as best as possible when you no longer have a cat your downstream O2 (post cat sensor) reads those as excessive emissions telling the computer you have to much fuel (ie not enough air), but the computer reads its getting decent air so it pulls back on the fuel and when you instal the cone it alows less resistance but same amount of air causing for loss of manifold pressure.

The others I'm not so sure of, but the 4th and 5th gen Celicas only have the single O2 sensor right before the primary cat, there's definitely no additional sensors through the pipe.

[vash169]

Originally Posted by toyomoho

The engine runs OK with the stock intake system, stock filter on or off?

The cone filter could be causing too much turbulent air for MAF/MAP sensor resulting in signal output errors.

Try running with the cone filter on but unplugging the MAP/MAF sensor. If the problem goes away the issue is with the sensor/filter combination.

Yeah I tried firing it up with the MAF unplugged, it cranked but refused to start and gave me the ol' check engine light. I also tried removing the filter entirely and left the meter to suck nothing but fresh air; same result as with the cone.

I may have found the issue within the MAF sensor itself though. You can adjust the clock spring to tell the ECU there's more/less air incoming so it adjusts more/less fuel to create a lean/rich environment. The meter was modified by the previous owner, so I adjusted it back to stock as close as I could. I assumed the system was running too lean with the higher air flow so I adjusted it rich and used the stock airbox. I got the same results that I did when running with the cone filter; clearly with the cone in place I'm running rich. It kind of flies in the face of logic (more air = running too rich?) but I think this is the case.

I adjusted the meter leaner than I had it (which was actually how the previous owner had it set originally) and the problem vanished. It even feels a little bit more peppy now, too! I'm going to try it with the cone and see how it goes, but I believe it'll work now.