14CUX Rover V8 - Throttle Position Sensor and CO Trim

[wheelbarrowman]

1. # background

I have a recently converted my 3.5 Rover V8 from Stromberg Carburetors to running open loop (no cats) with the 14CUX hotwire type injection. The engine is installed in an early defender 110.

Whilst doing the above I replaced the camshaft and followers, and shimmed the rocker pedestals as recommended. I also refurbished the ignition system,. including new plugs, leads and ignition amp, vacuum advance unit.

Immediately after getting the engine running i went on a euro road trip, including a significant number of alpine passes. Generally the engine pulls ok, but I'm not convinced it's making as much power as it should be capable of. I made it over the passes, made plenty of glorious V8 noise, but didn't sail over quite as easily as expected. I attempted a vmax run when I was sausage-side, and topped out at 90. My dad had a range rover that would pull to over 110mph with th same setup. I will stress I'm not looking for 100mph+ from the landy, it just seemed a good test of engine output.

One aspect that I need to correct ASAP is the vehicle road speed sensor. I didn't have time to get this hooked up, so have been running with out.

1. #questions

Although the engine generally runs smoothly, it doesn't feel to me like it's making as much power as it should. It has an occasional slight misfire at partial throttle (typically at 30mph ish) cruising round town.

I have been observing the parameters displayed in rover guage.

No report faults excepting one for road speed sensor.
Running fuel map 2 (no cats).

I seem to have the throttle permanently 9-10% open. I have checked that the throttle is closed (throttle cable not mal-adjusted), and still registers 9-10%. What is normal for 14CUX Idle running no cats?
Is the TPS cleanable? Or serviceable?
I have checked that the TPS readout with the throttle being progressively opened, it registers values from 9% to 99% with the pedal to the metal.

The CO trim value reported in rovergauge is 1.9-1.99. I understand this should be set to 1-1.5 for a no cats setup? My airmass meter came from a disco with cats. I assume it is set higher for this reason. Am I likely to see an improvement in power from adjusting this trim pot value?

My feeling is that I'm struggling for fuel hence not making full power. I will look to test fuel rail pressure asap. I understand the regulators can struggle to maintain proper pressure?

[GreenV8S]

What ignition advance settings do you have?

What fuel pressure?

Do you have access to any exhaust gas oxygen sensors, preferably wideband?

[wheelbarrowman]

Timing is set to 8 degrees btdc static, then incremental increases on an uphill road to find best advance.

Fuel pressure is undt investigation.

Nothing terribly easy for exhaust gasses measurement.

[GreenV8S]

wheelbarrowman said:

Timing is set to 8 degrees btdc static, then incremental increases on an uphill road to find best advance.

That's about right static. You should have about 20 degrees mechanical advance and 15 degrees vac advance. If you have a vac delay valve in the line between the throttle body and the dizzy, I suggest you get rid of it. Can you confirm the vacuum tapping point you're using gives you ported vacuum i.e. so the dizzy doesn't see manifold depression when the throttle is closed?

wheelbarrowman said:

Fuel pressure is undt investigation.

For a standard map you would be running at a fixed 2.5 bar above the manifold pressure. There are so called 'rising rate' fuel pressure regulators which make the engine run leaner at low throttle and richer at full throttle - you don't want that sort.

wheelbarrowman said:

Nothing terribly easy for exhaust gasses measurement.

That's unfortunate.