Induction System Cleanup

2COR517 · July 24, 2009

Hey I thought I would share this little project I did recently. I posted here, I'm not allowed to post to the How To forum.

I did a little work on my 97 GMC last weekend. 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 tonight I noticed the truck is holding OD longer before downshifting.

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

After

Little bit of an update about a week later. Put the truck to work hauling my dump trailer today filled with roofing. Truck and trailer combined at least 14K pounds, if not 15K. This thing seriously feels like a brand new truck. The mid range power is amazing. Hauling the trailer, I didn't even feel it on the flats. I was able to accelerate on hills that I could barely maintain speed on before, all in higher gears and lower RPMS. I didn't even have to go wide open on the big hill before my house. That used to be wide open, drop all the way to first, 30 mph. Was doing 45 in second with the TC locked up this time.

Six months ago I thought I would be changing motors. Ripping out the Bosch+4 late last winter and putting in the AC Delco's gapped at .040 made a big difference, the truck was at least driveable. The work last weekend really woke the truck up. Some time spent online really paid off.

Just these weekend I rolled out of the pit over 19K. It was alot needless to say, but the truck did OK for a little ole 350.

alwcurlz · July 25, 2009

Great info on that tuneup and cleanup process! I've been thinking of cleaning up the throttle controls since mine is kinda sluggish off the line.

Spurshot · July 27, 2009

Thanks for the reminder, Palmer.

I've been meaning to do this since my throttle is a bit sticky on my 99 truck. Just been putting it off. Nice "how to" and pics.

Spurshot · July 31, 2009

Replaced the old K&N air filter element I had put in the 99 some 150,000 miles ago. Put in a Fram Tough somethin or another. Pulled the MAF sensor and hosed it with CRC MAF cleaner and then pulled the throttle body like Palmer did above and cleaned it with some CRC throttle body cleaner (actually my brother, who is borrowing this truck for a couple weeks, did it). The TB was terribly dirty with a thick layer of sooty carbon on the butterfly and in the gulp valve. It took some scowering with Scotchbrite to get it all. Seemed to have a better low speed and granny driveability. Sticky throttle is gone. But, my brother took it tonight so I can't say how much it helped. Might need a new EGR valve.

2COR517 · July 31, 2009

Did you pull the IAC? It's almost impossible to completely clean the passage way otherwise.

Don't forget the SeaFoam down the brake booster vacuum line.

Spurshot · July 31, 2009

Palmer,

Yes, we pulled the IAC (called it a "gulp valve" from days of yesteryear). Didn't do the SeaFoam. Seemed to eliminate the sticky throttle at the fully closed position. Also seemed a bit smoother down low. I didn't drive it much since my brother took it right away for a trip to the central Calif Sierra he's leaving on next Monday. It had the "Service Engine Soon" light on for a few days now. He's going to read the code and fix that. I suspect the 02 sensor and actually had one.

97SierraGMC · July 31, 2009

nice, my truck had 135,000 when i did my intake manifold gaskets and i did the same thing i also cleaned the plastic upper intake thing too along with the stuff you did