Rebuilt - Now White Smoke and Weak Idle (w/ pic and videos)


Well-known member
Nov 26, 2011
Darien Gap
  • 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.
  • Just started hesitating and barely accelerating in video below.

  • 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.

Thanks for the consideration
Last edited:


Well-known member
Nov 26, 2011
Darien Gap
Thanks I've been analyzing the video data, looking for clues and here's what stands out to me:

CAT F B1 S1: either ERR or 8711. Anyone know what this is?
Timing seems high
MPH is about 10% slower than analog gauge

Bank 1 O2 1 varies and drops from 1.020 to as low as 0.26, while Bank 2 O2 1 stays at 1.020
At the same time Srt Tr1 (Short term fuel trim bank 1) varies and drops from 24% to roughly between 20 and -20, while Srt Tr2 stays at 24%.


Well-known member
Mar 28, 2011
West Des Moines IA
Also have you checked for spark and fuel? I am thinking something along the lines of bad coil pack based on the tip of that plug. I would check for spark - did all of your plugs look like that?


Well-known member
Nov 26, 2011
Darien Gap
Well I ordered two new O2 sensors, an IACV, and plugs. Hopefully that takes care of it. I'll post an update when I get them installed. Thanks guys.

From RockAuto:
NTK 25044 Oxygen Sensor $53.79 2x $107.58
STANDARD MOTOR PRODUCTS AC151 Idle Air Control (IAC) Valve $43.79 1x $43.79
CHAMPION 318 Spark Plug $1.86 8x $14.88


Well-known member
Nov 26, 2011
Darien Gap
I don't know exactly. I'll have to ask my machinist if he kept a record, as he did that part. I vaguely remember him saying he wanted to put in forged rings, but I may be way off on that.