Yukon/Tahoe Performance

[L31MaxExpress]

Yeah, who would do those expensive mods on a van anyway?

The resources on this site are invaluable and I for one thank you all. The rebuild of my 89 K1500 SLE should go smoothly now.

I did and for a good reason. I tow my travel trailer and an open deck car hauler with it. I don't like being stuck behind big rigs in the climbing lane.

The van is paid for and has been for years.

I guess it would blow someones mind that I have had a TPI Vortec 383 powered G-van, the Express van and now also have a LQ9 6.0L powered 1987 G20 van as well. The LQ9 has a small cam, headers and trailblazer SS intake. I also have a cammed 8.1 powered Tahoe.

 

[df2x4]

I guess it would blow someones mind that I have had a TPI Vortec 383 powered G-van, the Express van and now also have a LQ9 6.0L powered 1987 G20 van as well. The LQ9 has a small cam, headers and trailblazer SS intake. I also have a cammed 8.1 powered Tahoe.

Why do you think anyone here is going to believe a single thing you say after you've been outed for claiming other people's dyno sheets as your own?

 

[Christian Steffen]

found the popcorn imoji.

 

[skylark]

I did and for a good reason. I tow my travel trailer and an open deck car hauler with it. I don't like being stuck behind big rigs in the climbing lane.

The van is paid for and has been for years.

I guess it would blow someones mind that I have had a TPI Vortec 383 powered G-van, the Express van and now also have a LQ9 6.0L powered 1987 G20 van as well. The LQ9 has a small cam, headers and trailblazer SS intake. I also have a cammed 8.1 powered Tahoe.

I can agree with your reasoning 100%. You are the guy who seems to be constantly putting down the LS as well the 6.0 so I have to wonder why you'd have an LS swap.

 

[L31MaxExpress]

I can agree with your reasoning 100%. You are the guy who seems to be constantly putting down the LS as well the 6.0 so I have to wonder why you'd have an LS swap.

Because I happened to have a $400 70K mile LQ9 fall into my hands complete. The Van had an oil leaker of a 305 TBI in it but a solid TH400. I have less in that whole van with the 6.0L swap than most people do in their 6.0L.

I have had a couple $200 or less 5.3s fall in my hands too. I also paid $100 for a 4.8 woth a stuck lifter. I put them in trucks I bought off craigslist and flipped. I have flipped a 1500HD and and 2500HD with 5.3s and a 2500 HD with a 4.8. People I sold them to did not care they no longer had the 6.0L because they were oil field special work trucks.

 

[honkon]

Ironed out another issue with the engine controls on my slow Yukon. Had an intermittent P0327 Knock Sensor Circuit code.
Did some investigation and found that the knock sensor signal wire had continuity to ground, even when unplugged at both ends. Found 5v signal voltage at the pin on the VCM.
The knock sensor signal wire, along with the starter solenoid wire, run together across the back of the engine in a small wiring loom, right above where the block and bell housing come together.
This makes the second time I've pinched the knock sensor wire between the engine and trans while replacing one or the other.
It's fixed, hopefully for the last time. No more P0327, SES is no longer illuminated, Yukon is still slow. Maybe it'll help gas mileage at least.
There are also pending P0157 and P0300 codes. P0157 is nothing new, but the P0300 Random Misfire is. Plugs and wires have under 10k miles on them. I haven't replaced the distributor cap or rotor. The vortec distributor gears are known to wear out, but I'm not inclined to think mine is because I had no trouble setting the timing and it seems to be holding it.
I think it's time for a new cap and rotor. I also would like to check the fuel pressure, just cause. Someday I'll deal with those pesky catalytic converters. The o2 sensors are suspect as well.

 

[honkon]

Did the cap and rotor. Still slow. Idle is a bit smoother but not much. There weren't really any other drivability issues to fix, just kind of did it for the hell of it.
But now it's ******* pinging. Started immediately after the new cap and rotor.

 

[honkon]

Had the cats removed not long after my last post. That was the problem. It had a lot more power and was way more responsive. Timed a few 0-60s and got an average of 9.5. Pretty happy with that performance. I noticed as well that the engine and transmission seemed to work a lot better together with the increase in power. The transmission behavior was designed with 255hp in mind.
Unfortunately the transmission then decided to completely go out a few weeks after the exhaust work. Oh well. It was fun while it lasted. Never figured out the pinging, but it was minor and only happened under pretty specific conditions. Seemed like it was getting better on its own too. Somehow.

 

[honkon]

The Yukon has been sitting since my last post until last weekend when I got a transmission put into it. Now it's driving again and I'm back on these issues.
Sitting for 6 months didn't do any good for it. Engine light is on intermittently with P0157, P0300, and P0301.
Fuel trims for both banks are -10% at idle, 0-5% with some revs in park, and 5-10% while driving. Not really sure what to make of that.
The MAF is over reporting by 2g/s at idle. Just cleaned it the other day.
P0157 is Bank 2 Sensor 2 low voltage, but I'm not concerned about that. What I am concerned about is bank 2 sensor 1 sticking lean. Most of the time it's around 0-50mV, will sometimes lazily switch, highest it went while monitoring was 400mV. I don't know how that isn't throwing a code or affecting fuel trims. It's in closed loop. Bank 1 sensor 1 has a pretty healthy wavelength, yet the fuel trim is the same between the two banks. I want to get to the bottom of that before proceeding with anything else.

 

[RDF1]

Swap front oxygen sensors from driver to passenger side and passenger side to driver side. See if the issue follows the sensor. If so, replace sensor. If not look for wiring issues and such.

Sent from my HiDiNg PlAcE