D2 v8 rough running

[Haddles]

I have one of those terrible intermittent problems. A rough running engine that seems to run fine just as you are nearing a mechanic.
The problem mainly occurs when the torque converter locks up and the engine is under load. I.e under 1500 rpm up a gradient in top gear. It seems to stutter along. Under light load and in lower gears it seems fine although idle can sometimes be rough.
I run it on 95 or 98 octane and tried cutting e95 out of its diet to see if that was the issue but a few tanks later it is still doing it.
I was wondering if it was vacuum related due to the load factor bringing it on as I have eliminated poor fuel. I can't see any obvious leaks.
As these cars seem to have common faults I was wondering if there was a regular offender with regards to this problem.
The car has 140k on it, it is a 2000 model and got a new engine under warranty at 40k (as you do).

[justinc]

When did it get spark plugs and leads last?

JC

[NPEP]

justinc, I had a similar problem with my D2 V8 and it was the Mass Air Flow Sensor (MAF) but you will only be guessing unless you get the codes read.

Cheers NPEP

[NPEP]

Sorry justinc meant the reply for Haddles

[justinc]

Yes a faulty MAF will cause poor running, usually symptoms are worse when engine is cold.

JC

[Haddles]

Not sure when it got plugs and leads. Not on my watch anyway. I held the leads while it was running and never got a belt from them. Plugs look ok but I am no expert. Funny thing is I have a pajero that has done 100k and is still on the original plugs and leads and runs perfectly. I did tighten up an air lead into the inlet manifold and it started to run ok but is back to running rough and the air hose is still tight. It annoys me that it does it on and off. A mate just bought a code reader so I might plug it in and see what gives.

[bee utey]

I drove someone's Volvo today that had a similar problem. The plugs were new but the mechanic had disturbed the leads and they weren't plugged back onto their connectors properly. So I suggest:

1. Remove the plugs, check them for gap and cleanliness.

2. Run the engine at night, have someone operate the throttle while in gear with the handbrake on, look for little sparkles from a damaged lead.

3. Get a new set of leads fitted if you are still running the originals, they are around 9-12 years old?

[Freddofrog42]

Mines done 166K. I've owned it since new so know the complete history. Mine had a new short engine at just 4K - porous block, which is quite common. Fine since.

First the MAF failed at about 150k. It didn't thrown any codes via Scanguage but did result in jerky and/or delayed gear changes, general hesitation and so on. I managed to get just the sensor part from a UK supplier - i.e. used my original housing. Cost was about $120 from memory and the sensor itself is common to quite a few vehicles e.g. VW and BMW. 2 mins to change just the sensor, 10 mins the complete MAF

Later 2 of the plug leeds started to fail - of course it had to be 2 just to make things harder to trace. No obvious outward signs, just a misfire under load.

From your symtoms I would suspect the leads first. They're cheap but a pig to replace. You need small hands and lots of patience but it can be done, just..

Both these problems are common on the V8..

Oh, and while your at it tighten any water hoses you can see - the OEM clips worked loose on the thermostat on mine and one of the hoses came off a couple of years ago. Fortunately I noticed straight away and it never got too hot. If it had though I'd have been up for all kinds of pain.

FF

[lewy]

I managed to get just the sensor part from a UK supplier
sorry to change the subject but any numbers and were did you get just the internals.

[Haddles]

From the Service history I think mine did a rod. It was towed in to the dealer not running and with an oil leak. Got a whole new block, crank, rods and pistons, cam and even sump so it must have gone bang. Hopefully the replacement block was a non porous, well sleeved one. Got a new computer as well.
That can't have been a cheap warranty repair.
Anyway I have inherited its second phase of problems albeit hopefully less dramatic.

[camel_landy]

The Rover V8 is VERY fussy about the HT leads.

Change the leads & make sure they're good quality.

M

[Freddofrog42]

I got an original Bosch part as follows from www.worldcarparts.co.uk (http://www.worldcarparts.co.uk) although I had a quick look and they no longer seem to list them. It's the same part as fitted to an BMW M5 and several VW/Audis from what I can see. Took quite a while to find the right part number as that's critical as it's the Bosch number rather than a BMW/LR number and just refers to the sensor itself rather than the complete housing.

Might be worth giving them a call as they do continue to list several others in the BMW section for example so might still be able to order them in.

**********
Order Date: 10/12/2010 09:54
Order Contents
1 x Original BOSCH Air Flow Meter ( Sensor) F00C2G2029 @ £68.00
Sub-Total: £68.00
Shipping & Handling: £9.95
Total: £77.95

[Haddles]

I might shout it some new leads. They seems to ba reasonably priced on eBay for genuine ones. I am not yet convinced it isn't vacuum related. I might spray some start ya bastard at the hoses and connectors while it is running and see if I can detect a rise in revs. The hose on the front left of the manifold (when looking at the motor) was loose where it bolts in to the manifold so I might go over the engine, do the plugs and leads and cross my fingers.
The rough idle was present prior to this missing under load started happening so I am not sure they are related. The rough idle is worse when the engine is warm.

[diesel]

If you suspect MAF you can disconnect it. The ECU will run a default program & if the MAF is faulty the engine will run fine.
After cross referencing I bought a MAF for a Mercedes, saved around 30% in cost & just swapped the MAF between the plastic casing.

M