Rover SD1 Forum Snippet #12 - Stop Efi Power Losses in 15 Easy Steps


Use the same 15 Steps as an SD1 Efi Health Check

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1 Clean all ignition components externally and internally, spray with moisture inhibitor such as WD40 and wipe dry. Ensure the distributor vacuum and mechanical advance mechanisms are lightly lubricated, working correctly and the springs/bob weights are free of any corrosion.

2 Check security and eliminate any corrosion on all ignition Low Tension connections right back to the ignition switch, including all local earth connections. Get some ideas here:

3 Clean and re-gap the spark plugs - replace if necessary.

4 Check for damaged or out of specification (measured suppression resistance) High Tension leads, Pay particular attention to the rubber boots. Clean and replace if necessary.

5 Set ignition timing to just eliminate pinking with normally available fuel. See here: for a neat process. (Note: Items 1-5 are to guarantee and maximise the best possible spark at exactly the right time. Check workshop manual for recommended component and timing specifications.)

6 Ensure the plenum idle air gallery is clear and not contaminated with goo.

7 Thoroughly clean the plenum breather gallery, flame trap and LH rocker cover breather filter

8 Ensure the throttle disc(s) is correctly seated at idle (or set to the recommended disc to tunnel gap where specified) to prevent "idle speed hang-up" and that the whole throttle mechanism is free of unwanted friction right through from accelerator pedal to throttle pot. (Note - items 6-8 are best performed by taking the Plenum Chamber to the workbench). Go here: for Plenum Solutions.

9 Set the AFM CO content to the recommended range erring just on the weak side of the mid-point. If a CO meter is not immediately available set the adjuster screw to 2.5 turns out, from fully home. See here: for AFM stuff. Reset idle speed to the recommended level. The settings are interactive so recheck both.

10 Set the Throttle Position Sensor residual voltage to 325mv (some spec's call for 350mv). Ensure the sensor is not electrically noisy, causing random overfuelling. See here: for full detail.

11 Verify the fuel pressure operates in the range 26 to 36 psi. not more, not less. Details here:

12 Test the integrity of the plenum and all its air/vacuum hoses for rogue air-leaks. How To here:

13 Check all Efi loom wiring/connections for faults/corrosion including the Efi engine earth AND the engine earth strap. Unusual Efi Earthing Issues here:

14 Check and replace air and fuel filters if necessary. Ensure fuel tank is not generating crud.

15 Because the Plenum must be removed for proper cleaning and adjustment, lift and service the injectors, replacing filter baskets, pintle caps, fuel pipes and injector to manifold seals. See here:

None of the above can yield anything over and above the system performance that existed when it was new but, be amazed at the horses the above program will release from a tired and maladjusted Rover SD1 Efi V8 system.

And the beauty of it is, apart from time, most of these actions are low cost, or cost free.

To improve performance beyond its original spec there are three relatively simple things to add.

1 Have the ECU re-mapped for one's specific needs, or fit something from the aftermarket.

2 Fit a rising rate fuel pressure regulator designed to generate more "Oomph" under acceleration and high throttle positions. Expect fuel consumption to deteriorate.

3 Fit a sports exhaust system that effectively improves overall breathing and minimises exhaust losses, as opposed to simply adding power which, of course, it can't do. Exhaust Science here:

Note that various links have been included above to the comprehensive archive of Efi Component information - Index here: Trawl through the other technical archives here: for more specific examples of solving particular issues.

And going back to the basic 15 suggestions that form the core of this article, If, dear reader, you decide to hit just a few of them, think about the young bull who remarked to an older bull, "Look! There are some moos down there in the meadow! Let's run down and sort a couple of them out" to which the older bull replied "Nah! Let's walk down and do the lot! Otherwise, you'll never know how much fun you coulda had!"

The SD1 Efi Diagnostic Challenge Continues

Please contact me regarding Errors and Omissions.

For more Rover SD1 Snippets, click here:

Rover SD1 Tech'l Articles:.......................................................................................................Site Contents:

Even the best Twin Plenum has to be Correctly Set Uo!

Frequently, we hear a plea for help to increase the power output of a Rover SD1 Efi engine because an owner craves improvement and is convinced spending hard earned cash on innovations to the basic system is the route to success. Typically:

Question: "I want to tune my Rover SD1 Efi looking for power! What is the maximum improvement I can get and what sort of money would I end up paying?"

My vaguely simplistic response is: "Loads!", and "Lots!", followed by: "How big is your Wallet?" and "How much power are you already losing?" It is the Efi Power Losses that I choose to address here:

Before dipping too far into the cash tin and because the Rover SD1 Efi V8 is capable of producing some pretty impressive 200 horses, the first task is to ensure minimum power is lost. Getting the best out of our engine cannot be achieved in one lump, but bit-by-bit, until there are no unavoidable losses.

Assuming the engine is in good mechanical condition with correct cam and lifter performance and timing, good compression within acceptable limits on all eight cylinders, good exhaust system with no leaks and fresh lubrication plus clean filters, then there are 15 easy steps to attend to with the Rover SD1 Efi V8 system to improve performance from its current condition.

Stop Press

A Major Review of Rover SD1 V8 Electronic Ignition System

Description & Analysis Here:

Components & Testing Here

Ramon Alban


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