Cold Air Intake Adventure

[Wess]

Today I had a local shop bend a 3" stainless steel pipe so that I could get a cone in the fender. I've been collecting the parts for several months, maf adapter, filter, etc. The last thing on my list was a grommet to mount the IAT in the tube, which I planned on getting later.

The fitment went quite well, not perfect, but very snug. We were able to do it without relocating the battery, we just had to adjust the angle of the MAF assy. a little bit. We left the IAT sensor outside the intake assy., as we didn't have what we needed to mount it.

The road test didn't go well.

For one, we didn't disconnect the battery initally, which we thought confused the computer a little bit. When I first started out, it seemed like there was minimal improvement. As the road test went on, the situation got worse. The car couldn't find it's idle and was stalling. Also we noticed a strong odor from the exhaust - she was running rich. When we brought it back to the shop we reset the computer and fired it back up. The idle got better, but it was still running rich. We plugged into the ODB and confirmed this.

Took it back out on the road and still no improvement. When we plugged in to the OBD system this time, we noticed the fuel values were normal at idle, but when the gas was stomped, they went off the charts (rich). It was then I decided to throw the stock airbox back on. We reset the battery, plugged into the OBD, and all was normal at idle, and at high RPMs. My trip home confirmed this, the car ran great!

After putting everything back together, the only conlusion we could draw was that the IAT was sitting in the open air of the engine compartment at 100+ degrees, while the intake air temperatures were in the nieghborhood of 70 or so. The tube itself was cool to the touch (which was encouraging), while the rest of the engine compartment was nice and toasty. This is the only factor (outside of the obvious increase of airflow) that we figured could have changed. I'm thinking we underestimated the role that the IAT sensor plays in the advance of timing on the V8 SHO. I'd appreciate your thoughts on this. Thanks!

 

[SHOerwin]

Sounds logical. Maybe you could install your new pipe to the factory airbox with your cone in the fender. With no panel filter, you may be able to obtain your desired results. Just a thought.

 

[Mr. SHO]

I doubt the IAT sensor had anything to do with it. It's funny you should have these symptoms though... I had almost the exact same thing happen to me a few weeks ago. My CAI setup involved replacing the accordion hose with a Fernco 3" pipe coupler. Well, that worked fine until the 3rd or 4th time I pulled the PCV fresh air hoses out of the coupler... I noticed that the edges of the holes were starting to get crumbly, and I was worried about little bits of rubber being sucked into the engine.

When I replaced the Fernco with the original accordion hose, the car wouldn't hold an idle. I had cleaned up the TB and disconnected/reconnected some of the IAC/IAB, TPS, and MAF sensor connections, so I figured one of them must have been the culprit. After some trial and error with the TPS, MAF and IAC/IAB connections, the problems went away at idle, but the car would occasionally just refuse to accelerate unless I gently coaxed the throttle (which pretty much kept me from accelerating too fast anyway.) After fooling with the connections again and triple checking that every connection was perfect, the car returned to normal behavior.

Sounds to me like one of your connections was fouled, and you happened to fix it when you put the airbox back in. One unorthodox fix for these connections is to use needle-nose pliers to twist the male tabs inside the connector a few degrees, thus increasing the contact force across the electrical connection. Make sure the seals are intact, and use a little dielectric grease to keep moisture/corrosion problems to a minimum.