KC_kid

iTrader: (5)

2001 Silverado ECSB 2wd 5.3L 4L60E, no codes read from Scangauge II.
My pops drove this truck from 1500 thru 90k. His driving was 80% hwy miles, so he was always looking to improve his mpgs. Along the way he bought a K&N FIPK hoping to help out mpg but he noticed a MPG loss on the highway, 2-3 mpg. So he took it off, put back on stock box and away he drove.

So I bought this truck from him for cheap @ 90k. It has always ran very strong, getting 20 mpg on the hwy pretty easy, sometimes 21. At some point I grabbed the FIPK off the shelf and installed it. Throttle response was a little better and the sound was pretty cool, but I too noticed a 2-3 mpg loss.

What gives? Everyone says these gain mpg, hp, throttle response, etc... Intakes on these motors are supposed to be great! I still drive with the FIPK on for right at a year now and still have never gotten above 17.5mpg on the hwy since. In the past 4 months, I have gotten a Nelson mail order 91 octane tune, hoping to regain some MPGs. The truck responded great, so much more power, better shifting, everything is great with this tune, I love it, but still not more than 17.5 MPG on the hwy??

Any ideas guys? Do I need to get a wideband and see if this thing is running rich, eating my gas?

Thanks for any response. I did some Google searching and not many (any) people have this problem with K&N FIPK.

KC_kid

iTrader: (5)

I might try an experiment and put the stock airbox back on, just to see what the hwy mpg are. Could there be any harm in doing that since my Nelson tune was made with the FIPK in mind?

AKlowriderZ71

iTrader: (22)

At that mileage, I'd replace the spark plugs & fuel filter, clean the MAF sensor, and maybe even the front O2's. That should bring back your MPG's.

I doubt that it has anything at all to do with the air cleaner/intake tube. Any slight difference in the airflow would be taken care of with the PCM fuel trims, if the tune up is good.

KC_kid

iTrader: (5)

Thanks for the reply, thats what I thought too. BUT this has happened for 2 different people at two different points in the trucks life, with the same MPG loss, immediately after the K&N. And when my dad switched back to stock airbox, he regained MPG.

I have changed plugs & wires, originals looks great, cleaned the K&N filter and LIGHTLY oiled, cleaned MAF multiple times, cleaned throttle body, checked ERG valve. I have wondered about the O2s but havnt done them, I figured they would throw a code if they were bad. Maybe I should look into the O2s....

Tim94gt

iTrader: (1)

If MPG's are your goal, switch back to the stock airbox.

At 90K, I would replace the o2's anyways. I would also replace the fuel filter and think about seafoaming it. You might get your missing MPG's back.

pasadenaman

iTrader: (3)

That oil for the K&N, if it gets on the maf, your going to have problems. Did you cut the botton plate where teh cone filter sits above?

pasadenaman

iTrader: (3)

x3 on the seafoam

KC_kid

iTrader: (5)

Thanks for the comments. I guess I expected that you can increase performance and still maintain MPGs. I have read were people report a MPG gain from the same K&N, so I don't get it.

I replaced the fuel filter at the same time as the K&N install, then again when the fuel pump crapped out this winter. I also seafoamed it a while back, in gas tank, in oil and intake. I also did the water decarbon trick. I don't think I had much carbon build up, but when I changed the oil after about 100 miles with seafoam in it, it was like chocolate. Worst oil I've ever seen from this truck. It's had Mobil 1 synthetic since 30k.

Maybe the O2s will help out. Would it be worth doing a wideband while I'm doing it?

KC_kid

iTrader: (5)

I did not trim the air box below the K&N cone filter. There is a pretty big hole in it already, I felt. When I cleaned the K&N & reoiled, I let the oil sit overnight to wick. I also oiled as lightly as I possibly could. And I cleaned the MAF, and cleaned again a few weeks after the air filter clean & re-oil. The MAF is not descreened. I have run Lucas injector cleaner through the fuel system also, in addition to Seafoam.

I used to get 14-16 in town, now I'm at 11.5 mpg.

pasadenaman

iTrader: (3)

what do your spark plugs look like?