back firing and rough idol

[jcmandia]

On my 94 LWB I am getting a rough idol and backfire. Once up to speed no issue but sluggish to get there. When I disconnect the MAF it runs fine. I have cleaned the MAF and still happens. Also have replaced the alternator, ignition module and installed new plugs and wires. I am thinking it is something electrical because the battery light now comes on when headlights are on and I step on brake. Any thoughts on this would be great. Thanks.

[rangerover]

Every time my RRC has a rough idle the first thing I check is the idle-air bypass valve off the plenum chamber. It unscrews and then I wipe it down with a towel soaked in brakes part cleaner. Just be sure that you do not extend the valve when cleaning it.

As for the back fire, that can be caused for a number of different reasons such as bad gas, bad wires, or a timing issue. You said you have replaced the wires, so the next step I would do is check the distributor. Look for a lot of corrosion on the cap or rotor. Both are cheap and easy to replace.

The battery light indicates that either the wires on the back of your alternator have not been tightened properly, or that the alternator is not putting out enough juice. The wires are simple to check first and tighten if need be. If the alternator is actually bad, then you need to be very careful when driving it. If the battery dies the truck will literally shut off where ever you are and leave you stranded. If you have a shop that can run an alternator test nearby (ie. advance auto) then charge your battery overnight, then during day-light hours limp down with all electronics (headlights, radio, etc) off, and run the test.

Hope this gives you at least a starting point to continue your troubleshooting!

[mearstrae]

It's possible you have two separate issues. The MAF may be the first, your troubleshooting seems to point that out. And you may have a bad battery, as the alternator was changed and won't keep the battery topped up to 14.2volts. And as always on a Land Rover clean all the grounds and check the other wiring connections. Also check all the rubber lines on the intake for splitting or looseness.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 2500S

[o2batsea]

Another thing that can cause the rough running is a vacuum leak. Check the rubber hose connectors especially the one for the charcoal canister and the idle air bypass hose on the back of the plenum. They get old harden and crack, leading to excess air in the chamber.