We've just had a similar problem voiced on the RRR forum.
Seems the problem was caused by moving the seats back and forth.
A wire from the ECU had been cut by the runner.
It's worth a look.

 

I am thniking it was the washing of the engine compartment. Leave the hood up and let it dry. I have had this happen on more than one occassion. It may take a little time to dry.

Parker

 

HT leads is always a good start. Worth changing anyway if they are over 2 years old.

 

OK getting a little odder. The check engine light came on and it started running fine, just a sight rough idle like it has had. I stopped for lunch and shut it off. When I started it back up the light was still on but it returned to the real rough idle and missing. So this problem is a little random. I checked under the drivers seat to just check, but the ECU is on the right side and our drivers side is the left.

HT Leads? Please feel me in?

Thanks alot for the help guys.

 

I just talked to a Rover tech and he said the speed sensor could be the problem. Any ideas?

 

I think the speed sensor would cause the stall if it failed as the gearbox may be getting confused with the speed of the vehicle.

I think it could possibly be a HT lead. If the lead isn't fully working, the temperature changes can cause a random misfire. :think:

 

The 45 code is showing so its the right oxygen sensor. I cleared the code and went for a drive, it fired the 45 code again. Has anyone cleaned a o2 sensor before? I was thinking clean it with maf cleaner and clean the conector to try and get by this weekend. British Atlantic cant deliver til mid next week.

The guy we bought it from said that you could use a nissan? O2 sensor? Anybody heard of that?

 

How thoroughly have you checked for water in the electrics? If it started after you washed the engine it's almost certainly related.

You need to take the dist cap off and check inside there, have a good look at it and the rotor button while your at it (of you don't know what to look for just ask). Then remove each HT lead (the ignition leads that go from the dist cap to the spark plugs) in turn and again check for water ingress, even better, put a new set on as advised.

You also need to remove and check each connector related to the EFi/ignition system, which is pretty much every one under the bonnet and with a can of compressed air/air compressor gently blow out each one, be careful not to blow away any rubber seals in them.

Don't get too wrapped around the axles about the o2 sensor, it's normally the first thing that buys it when you have a misfire or engine problem as it's right in the firing line and doesn't like being hit with the wrong mixture. Although you will obviously have to replace it eventually. It failing more likely to be a symptom of another problem rather than the cause of the problem itself.

 

Mine is currently running rough, as I had a slight coolant leak from the heater valve, water was leaking from the drivers side down onto the HT leads and into the middle of the engine... :think:

Came back home tightened all the hoses up and sprayed WD40 on all the components there, seems to be running smoother again.

When I think of it though, from the time I effectively stopped the water getting into the engine bay, the engine ran smoother :think: there was a leak that went into the 'V', wonder how that would effect the idle and general running though :think:

 

also for some of the 3.9s with the ignition module still stuck on the distributor this may cause some trouble.

 

Hello

I've got a very similar problem on my 93 4.2. Until the engine has warmed up completely, the engine's revs drop and sometimes stalls when I pull up to a stop. If I take the car out of Drive or just pepper the accelerator it sometimes recovers to about 600rpm, but not always

As I've still got the problem I don't have a solution and I'm afraid there are lots of items that could cause it: MAF, stepper motor, base idle, o2 sensors, potential meter, wiring being dislodged or just old, ecu, timing, amplifier on side of distributor, plugs and cables, fuel filter and fuel injectors.

If it all worked fine before the wash I would suspect wiring. The problem is all the items metioned have cables running from them. If the idle is bad all the time, I would make a list of all the components and then work your way round them wiggling the wires and see if anything changes.

If you could hook up to a diagnostic tool that might help see what the ecu thinks is going on.

Good luck
NKG

 

simple atart with the basics cap leads rotor arm and plugs use gen items only,clean out the steppermotor housing and the throttle pot start engine allow to run up to temp ensure you have no air leaks then connect a seperate tacho and use a brake pipe clamp to clamp the air hose from the plenum to the stepper motor housing at the rear of the plenum the revs should drop (ensure you have no electrical load on and the air con is off) the base idle should be 520rpm +/- 20rpm if not then remove the bung in the top of the plenum and adjust the air flow untill it idles correctly then slowly release the clamp and road test if you are still having a fault of heistation suspect afm at fault

 

bringing back an old thread to see if there was ever a solution to this? My 93 has been having some idle issues, giving me the stepper motor code. I had replaced it with the ac delco part (about 6 months, 4k miles ago), which initially helped, but i was still getting check engine lights with the stepper motor code and occasional bad idle. I finally bit the bullet and ordered a genuine LR stepper motor, which is in route. Past few days now i'm getting the rough idle, misfire and the 45 code for right O2 sensor. Wondering if i really need the O2 sensor of if it's related to my possibly bad stepper motor. All the wear items are up to date, plugs, cap and rotor, air gap, base idle, vacuum hoses etc. Today, i actually had a check engine light with no fault codes on the diagnostic display. Eventually the 45 code came up for the o2 sensor. The rough idle is actually worse today, and i have a slight hesitation just off idle when driving.


Any thoughts or follow up to the original post?
Mike

 

also dirty or clogged pcv hoses can cause this . disconnect o2 sensors see if it runs any different .