volvo 760 2.8 gle engine problems

[Laird Scooby]

Originally Posted by gordyctill

I have changed the spark plugs the the maf is a lucas make I have look at bosch but dam expensive

What plugs, what gap and when?

[gordyctill]

hi have got a second hand maf but my original problem is still there and the problem is when it is idling it sounds like it is dropping some cylinders and so the revs go up and down. can you help thanks

[Laird Scooby]

Originally Posted by gordyctill

hi have got a second hand maf but my original problem is still there and the problem is when it is idling it sounds like it is dropping some cylinders and so the revs go up and down. can you help thanks

Originally Posted by Laird Scooby

What plugs, what gap and when?

As above - what plugs are in it, when were they last renewed/checked and what gap did you set them to?

There is a process to finding the problem, it starts with a single step, in this case the plugs.

Did you pull fuse #22 to erase the fuel trims after fitting the secondhand MAF?

[gordyctill]

I got new old stock volvo plugs but not sure what to set the gap on them as for the fuse I had the battery disconnected before I fitted the maf this has been an ongoing issue starting from cold its fine as it slowly worms up then it starts dropping a cylinder and then revs go up and down sorry I keep on but I would like to get to the bottom of this thanks

[Laird Scooby]

The gap should be 0.7mm or 0.028".

However, it sounds again as if the problem is an air leak somewhere between the MAF and throttle body which would include the hose that goes to the AICV and also the breather hose that goes to the flame trap.

What fuel are you running it on? Also does the misfire happen more when you have had to sit in traffic and when you've just started the engine and clear as you use it only to return when you come to a stop again?

[gordyctill]

I will check the pipe work again but I think it's fine and it's tesco finest petrol don't know about sitting in traffic I havent been that far yet.

[Laird Scooby]

Originally Posted by gordyctill

I will check the pipe work again but I think it's fine and it's tesco finest petrol don't know about sitting in traffic I havent been that far yet.

Has the car been sat for a long period of time?

[Martin Cox]

About 25 years ago I had a 1987 760 GLE estate with the B280E engine. I still miss it sometimes but not its thirst! I vaguely recall it doing something similar. My daughter who was about 12 at the time said it felt like the car was shivering. A very apt description. A new distributor cap and rotor arm effected a cure.

Might be worth a look at these if you haven't already checked them.

Martin

[Laird Scooby]

Originally Posted by Martin Cox

About 25 years ago I had a 1987 760 GLE estate with the B280E engine. I still miss it sometimes but not its thirst! I vaguely recall it doing something similar. My daughter who was about 12 at the time said it felt like the car was shivering. A very apt description. A new distributor cap and rotor arm effected a cure.

Might be worth a look at these if you haven't already checked them.

Martin

They can be thirsty animals! Generally i get 21-26mpg on my usual running about but on a run i have seen 38mpg so they're not all bad in that department.

There are many things that can cause the misfires the OP has, fuel filter, plugs, leads, timing sensor not on the correct plug lead, dirty injectors, bad fuel, leaks between MAF and throttle body, incorrect adjustment of the throttle butterfly and/or the TPS to name just a few. Could also be someone has changed the HT leads and swapped two of them over which will also do it.

[gordyctill]

yeah I know its a nice car I have had it about 10 years now I would like to keep it I have got a new set of spark plugs to try I would like to change the ht leads but dam expensive I will keep you posted