I'm starting a new thread to better organize the info and make it easier on you guys. The UltraGauge arrived today so I've added that info too.

Symptoms:

• Runs perfect for first 10-15 seconds
• Then lots of white smoke. Dissipates quickly but does NOT smell like coolant to me. Just smells like exhaust/gas, not sweet.
• Smoke disappears after engine warmed up hot, but still idles like crap
• Has two modes of idle, weak and high, which it seems to switch between randomly as I'm driving.
• Weak mode: Idles ok, but not great, in neutral. Struggles or stalls in drive/reverse when stopped.
• High mode: Idles anywhere from 1500 to 2500 rpm. 800-900 in drive when stopped. Only started after I disconnected TPS from the throttle linkage and turned it manually to see what would happen.

Info:

• New rings, honed cylinders, main bearings, turned crank, cam, tappets, pushrods, rockers, rocker shafts, timing set, oil pump
• Heads and block surfaced and flat
• No cracks detected by machinist
• New composite HGs
• ARP head studs carefully torqued to 66 lb-ft
• Idled ok, and smoked less before rebuild, even when it was burning coolant from blown HG.
• New Kingsbourne wires, and NKG plugs gapped to 0.035
• All new vacuum, PCV, coolant, oil, and trans oil lines/tubes
• Cleaned MAF
• Oil levels at full
• Redid valley pan gasket with RTV to ensure good seal
• No bubbles in coolant detected when running.
• Plugs were sooty dry black, but now have all turned silvery grey.
• All cylinders have compression around 150-160 psi except #3 at 140 (was 120 a few days ago)
• Adding cap of oil to #3 boosts compression 10 psi.
• Oil samples do not appear to contain coolant
• Engine is still in break in period.
• Fuel pressure is 35 PSI at idle

Ultra Gauge:

• Codes: P1313, P1314, and now P1316
• Alarm: CAT Bank 1 Sensor 1 F: 8789, max 2011
• Timing at high idle is 42, falls when not idling high
• Throttle position: 11.9 (min), 92 (max)
• Coolant F: 188-192 when warmed up

I'm really most concerned about the amount of smoke and weak idle. Those have been the problem since first starting the rebuilt engine. I'm almost positive I caused the high idle problem by confusing the ECU when I removed the TPS.

Cold start and Ultra Gauge video:
97 Discovery - Weak Idle, Smoke, and Ultra Gauge - YouTube

Short drive with lots of Ultra Gauge data (unfortunately I forgot to add O2 bank 2 sensor 2):
97 Discovery - Test Drive - YouTube
At 11:15 it started losing power. I gave it throttle to go and it would barely accelerate and seemed to be misfiring. This is the first time it wouldn't accelerate like that.

 

I'd not worry about the smoke if it goes away quickly, it's probably just condensation. I would be a little concerned about the misfire codes you are getting.

The idle problems sound very typical of people that have computer issues. Any chance you have looked inside it for corrosion? Could also be a sensor I suppose.

 

Open the ECU up very carefully and examine for things like corroded ground connections, corrosion degrading conductors/components/circuit board traces.

Are there signs of water intrusion present?

Possibly clean with CRC PCB or similar cleaner.

Seal the case or even encapsulate if you dare. Pros and cons do exist on that issue.

I would look into replacing the TPS or at least trying to do resistance readings on it to see what condition it is in.

I had been getting a P1316 a few times lately, but I cleared it a couple of days ago and it is still off right now. I have not pulled the plugs again to see how mine are looking, they were similar to yours black sooty, and I put new ones in.

Mine will idle rough at start up with a little bit of vapor, but runs like a raped ape when you do throttle down on it. Stronger than it's ever been with the new NGK wires, Champion Copper plugs, and the CRC cleaner for the MAF.

But until you get yours figured out, I ain't touching the TPS.

 

It does sound like the plug condition improved on yours!

Maybe it will get better with time.

Watch all the data points you can concieve to see what is out of spec!

 

I thought your sensors should fluctuate esp sensors 1, if they are staying the same then there is an issue

 

Throw a new set of O2 sensors in the fronts. Both sides. Then at least you got a better baseline starting point. Otherwise I think you are chasing your tail. And if it has run rich a long time or excessively rich, you may be looking at new cats as well. I think that is one of my issues as well.

 

But why would it have run well before the rebuild (other than a failed hg) and now run flaky if it were the ECU? I have a spare ecu you can try if you like if you have a local indy shop with a testbook or similar that could reprogram your alarm module to play nice with it. I'm not usually one for throwing parts at a problem but possibly put a set of champion 318's gapped to .032 and see if the clean plugs and closer gap help. 14 bucks on a new set of plugs isnt a lot at this point lmk if you want to give the ECU a shot, when i bought my truck it came with two spares..

 

Updated post with more info and video!

 

break in fluids that burn can coat nice new O2 sensors and cause false readings as they can insulate the zirconia or metal.

 

If I recall, he hardly got to drive it when he bought it.