Induction System Cleanup

2COR517 · September 7, 2009

This is a project I did some time ago. I didn't realize I had not posted it on this forum yet.

I did a little work on my 97 GMC a few weeks ago. With 135,000 miles, I thought I would give it some induction maintenance. I pulled the Mass Airflow Sensor and cleaned it with CRC MAF cleaner. Super easy job. Then I pulled the throttle body and cleaned it, along with the Idle Air Control. TB came off in just a few minutes. Two Torx screws for the IAC, two more for the Throttle Position Sensor. Took the TPS off so I wouldn't have to worry about damaging it with excess TB Cleaner. Sprayed some TB cleaner on the TB and used an old toothbrush and scrubbed it down. Cleaned the bore,throttle plate, and IAC port. Took a couple of passes, but it cleaned up very nicely. Gave the IAC a couple of quick squirts. Put everything back together, truck started right up. I reused the TB to intake gasket. Once she was running and warmed back up, I pulled the brake booster vacuum line. Poured a bottle of Sea Foam in very slowly (use a funnel). Had some pretty nasty crap coming out of the tailpipe. Put another can of Sea Foam in the tank. I have since run that tank down and filled back up.

There have been some very noticeable improvements since I did this. First of all, and immediately, the throttle response is much better. Truck feels much smarter off the line. The idle is smoother, the whole truck feels smoother. I didn't think it made much difference under a light load, but have noticed I have been speeding more often in places I go frequently. And I noticed the truck is holding OD longer before downshifting.

More details on the Seafoam procedure. I actually did it again with much more dramatic results. With a nice hot engine, pull the air supply from the TB. Start the truck. It will not run too well, don't be alarmed. Pour the Seafoam directly in the TB. Getting it in the IAC port on the back of the TB seems to be very effective. There will be quite a sucking noise as it is pulled through the IAC valve. You can also pour it on the throttle butterfly. Either way, it's getting in the engine. Pour it in just slowly enough to not stall the engine. Once it's all in, shut off the engine. Put the air cleaner back together, and pull the ECM fuses under the hood. This will clear the SES light. After an hour or two, start it up and head out on the road. There will be a tremendous black cloud behind you. Really open it up to clear it all out.

So, for an hours time and $25 bucks or so, made a great improvement in the truck.

Here are some before and after pics of the TB. It was pretty nasty