TOPIC: 2005 chevy suburban 1500 5.3L

Hi, again I'm new here, found this site online, ordered a throttle body for my 2005 chevy suburban.

Ron suggested that i do a few things, gap the plugs which i did, the dealer says they should be gapped at 45 thousandths, the ngk double platinum plugs i bought two months ago came pre gapped at 40 thousandths. I plugged in a spare plug and couldn't see any difference all the way up to 90 thousandths.... seemed outrageous to me, but tried it. Runs totally awesome!

It does accelerate better...... am tracking gas consumption to see where she falls.

Also capped the pcv valve.... Really this all started a few years ago, like with my astro van, trying to improve gas mileage, which has been around 17.7 L per 100 km, (15.96 miles per gallon) it has the on board computer display. So this would be an average of in town & hiway, but it does get a little better on the hiway, but only long trips, which don't happen very often.

Recent work is as follows like my astro: new magnaflow y pipe, tail pipe and muffler, but we found the muffler is too loud for my wifes liking, oxygen sensors, plugs, wires, even cleaned the throttle body with seafoam spray and seafoam tank additive..... plus regular maintenance, none of this improved the mileage here either.....

So I'm hoping the recent changes will make a huge difference, and after the throttle body arrives, I'll consider it for my astro, I'll update this profile once i know numbers!

Thanks!

Steve 

Well, found that my suburban also had a vacuum leak, after gapping plugs and capping the pcv valve, gas consumption went up to mid 19 L per 100 km...

Since I've been experiencing this along with my Astro Van decided to order some parts and do some repairs, so I reconnected the pcv valve till things arrived. Gas consumption dropped to 16.8 L per 100 km.... the only change being plugs gapped to .090.

Yesterday I tore apart the intake manifold to change the gaskets, capped the pcv valve again, did a few other things as well, did the ecu relearn, mostly completed now and driving it.

Will wrap the exhaust and replace the exhaust manifold gaskets when i have more time....

Runs good, no hesitations, lots of power, tracking mileage! Yeah!

Here is another update...T

Today i worked on both my vehicles, probably for five hours... Can't do that very often, ignores my family and frustrates my wife.

Started with our suburban, reattached the pcv hose, then searched for vacuum leaks with a bottle of carb cleaner... Found that I had two. At the back of the throttle body, and the lower valley cover, tightened five bolts, i could no longer stall the engine, nor does it effect the idle.

Drove it into town tonight, the on board display was at 16.9 then 17.....frustrating... i decided to reset the display and let it go through its cycle, thinking maybe it would take too long for the ecu to realize there was a change. After hitting the reset the display went to 99.9 L per 100 km.... wouldn't that be scary? It quickly started dropping...within a block it was at 25.0. By (the time I got to) quadra and the pat bay it was around 13. So i decided to take her on the highway. Used cruise control, by the time i got to Mt Newton where I turned around it was at 11.3 L per 100 km.

It takes a while to settle down once you reset it.... probably a week or so of driving. Every time you hit the gas you can raise the numbers.

By the time I got home it was at 12.5L. Yahoooo! I found the problem!

Gadgetman said i need measurable changes. Well started at 17.7, increasing plug gap dropped it to 16.8, the only other change at the moment is I installed the grooved throttle body.

The pcv is as normal, I'll disconnect that once things settle down. After that I'll wrap the exhaust!

Steve

a fellow Canadian! Hello!
As I also reside in a humid region, I can't say enough about MAF sensor cleaning on a semi-annual basis; spring and autumn. The haze/patina that builds up REALLY makes a difference in terms of the computer crunching the numbers correctly for "14.7:1" fuel delivery.
I wouldn't worry about new o2 sensors (Ron has probably told you the same): increased water vapour in the exhaust from more complete combustion will steam clean the carbon right off as you drive.
Next time you're under the hood, you might want to look at your engine timing now that you've upgapped the plugs (and if there are plug wires involved rather than COP, spring for the Granatellis with your fuel savings for increased dividends: larger sparks are good, but stronger sparks are best); 2005 probably means a MAP sensor rather than twisting a distributor, and if you're going there, you'll also do well to consider modifying what the ECU sees on the exhaust side, because that affects fuel delivery (more oxygen in the exhaust causes the computer to increase injector duration). Another thing you might consider looking at is internal engine surface treatment, if not the entire powertrain.

This is all GREAT information, guys!

Steve, remember one thing. "Make your changes small and incremental." Otherwise, you complicate to the point of impossibility the diagnostic process.

So, it would have been best to FIRST install The Groove, and and the PCV cap. Based on the response to THAT, we would have moved DIRECTLY to checking for vac leaks, as is advised in about every document I put out on installing and diagnostics of The Groove.

Of course, you found some, and the fuel economy jumped!