P38 is really stressing me out

[grafter]

Hi all I have 2000plate 4.6 v8 petrol / LPG omvl multipoint 147000miles
I’ve had an on going problem for a long while my problem is the p38 is trying to stall when approaching traffic lights and holding back on dual carriageway journeys
This year I’ve replaced
Maf sensor with Bosch
Iacv
Had adaptive values reset
Replaced lpg injectors
Replaced all gaskets and rubbers in lpg condenser/vapouriser
Changed gearbox oil and filter
She was running brilliant for a few months and after lpg over haul she ran perfect so much power and better fuel consumption but then started to nearly stall and hold back after a few weeks so new maf and had adaptive values reset and run lovely again for about a week now running worse than ever
It’s not bringing up no codes either
Last year I changed exhaust gaskets
Inlet manifold gasket
Spark plugs
Water pump
Radiator
Thermostat
Crank position sensor
Throttle position sensor
Can anyone help and advise what to do next or know what’s wrong with it
Any help much appreciated

 

[wammers]

Fit diesel engine.

 

[Saint.V8]

Coked up O2 sensors?

Worn mechanical components? I.e Camshaft or followers?

 

[Grrrrrr]

Coked up O2 sensors?

Worn mechanical components? I.e Camshaft or followers?

Why does it get better each time he changes the MAF? Might be worth cleaning the MAF and see if it improves?

 

[Saint.V8]

Why does it get better each time he changes the MAF? Might be worth cleaning the MAF and see if it improves?

I suggested O2 sensors, as they work in conjunction with the MAF.....he has changed everything else!!!

If it was an aftermarket MAF then I would say try an OEM one and see if that helps - AM MAFs have been known to fall over after 6 months or less!

 

[Datatek]

Fit diesel engine.

+1

 

[Grrrrrr]

I suggested O2 sensors, as they work in conjunction with the MAF.....he has changed everything else!!!

If it was an aftermarket MAF then I would say try an OEM one and see if that helps - AM MAFs have been known to fall over after 6 months or less!

Says Bosch for the first one so presumably the replacement too. O2 sensors makes sense.

 

[grafter]

Thanks for the reply’s I cleaned both oxygen sensors and she ran perfect again I’ll just see how long it lasts this time or should I just renew both sensors

 

[ukadamwest]

how long have the cats been on ? if they are old and breaking up / clogged that would cause the symptoms. get a rubber hammer or the side of your fist on your back and tap or thump the cats.. do they rattle at all ?

 

[tomcat59alan]

how long have the cats been on ? if they are old and breaking up / clogged that would cause the symptoms. get a rubber hammer or the side of your fist on your back and tap or thump the cats.. do they rattle at all ?

They will after a good thumping.​

 

[Grrrrrr]

how long have the cats been on ? if they are old and breaking up / clogged that would cause the symptoms. get a rubber hammer or the side of your fist on your back and tap or thump the cats.. do they rattle at all ?

That's the question: why does stuff keep clogging up?!

 

[ukadamwest]

That's the question: why does stuff keep clogging up?!

you asking about your exhaust or the P38?

 

[Rick-the-Pick]

Heres a long shot. On the front of the engine, you have two throttle cables with a thumb wheel. These can be knocked & this can cause high or low revs. A slight adjustment may be all that's needed. A garage changed an alternator on a V8 & this same problem had occurred since. Umpteen visits back to the garage couldn't find the problem. We noticed the bolts were loose & this effected the tickover.
Just a thought.