Backfire damage

HI THERE
had my 4.0 se p38 for aprox 10 months , sorted all the usual faults and has been gong great until 2 days ago when it backfired twice and stalled.
had blown a hole in the intake hose,duct taped it up started no probs and drove home at low revs.rplced hose and car start fist time only if i rev it beyond 2000 rpm it goes haywire revving up and down coughing and spluttring until i unplug the maf then settles but still goes haywire when i try to rev it hot or cold, changed plugs and leads cant see any arcing in the dark,cant see anything leaking coud it have damaged the plenum or inlet manifold or something else,i noticed an earlier post with exact same symtoms although
does not mention the final cure.. any help appreciated.. cheers

is it lpg or normal??

Hi on both , but been using petrol for ages.tried it on gas yesterday and just behaves the same...cheers

BACKFIRING is an expression used to describe a big bang in the EXHAUST.


In a petrol or gas engine, SPIT-BACK into the inlet side is almost always caused by a LEAN MIXTURE.

Occasionally a burned inlet valve can cause the same symptoms, that is, you can rev the engine up a bit if you do it gently, but if you try to give it some throttle, it SPITS BACK into the inlet manifold where the mixture there explodes, and can do some damage.

If it's a fuel injection engine look for low fuel pressure, or a duff fuel injector making one cylinder run lean.

In a carburettor engine, blocked jets or a poor fuel supply can cause it.

If LPG is backfiring, it will be caused by the ignition system. It could be either plugs/leads worn - you do need LPG compatible plugs/leads as they are under more strain (burns much hotter)

Other common problem is the Lambda sensor. These take a battering due to the hotter running, and don't tend to last that long. This knocks out the fuel delivery and causes the back fire. Easy to fix.

Backfiring will cause another few problems. Firstly, it will blow the wire in the maf sensor. Take the pipe off and make sure it is still intact. Secondly, the excess petrol/gas in the exhaust can 'cook' your Cat - the inside effectively melts. You will find this come next MOT if it is a problem. You may notice a smell from the cat (eggy smell) on tickover, or after a very short run which would show it is getting hot (blocked)

LPG vehicles do need to be inpeccably serviced in order to run correctly - LPG is very fussy!

auto said:

LPG vehicles do need to be inpeccably serviced in order to run correctly - LPG is very fussy!

Click to expand...

Is LPG worth the trouble expense and grief?

What's wrong with a diesel?

CharlesY

CharlesY said:

Is LPG worth the trouble expense and grief?

What's wrong with a diesel?

CharlesY

Click to expand...

You only have to service it regularly - then enjoy driving a 4x4 with better fuel returns than a 1.4 eurobox!

If you keep it serviced, you won't have the associated problems above. Most of those problems are only a result of poor servicing/ or ignition problem. In these cases, people don't understand and drive until they stop - you just need to switch back to petrol until you fix it.

Usually just a plug or ht lead.

CHEERS GUYS.
had it down at barttec in airdrie , ignition , pressure test ect all ok . one l.s showing - reading other showing + high reading . bassically one of the cats has melted and is choking one downpipe causing products of combustion back up the inlet valves then it gets drawn in instesd of air and causing poor ignition .can the lambda sensors be easily checked as only fitted the downpipes in october ,so going to try and cut out the cats ,as my last downpipes had been cut and welded,can i disintegrate the converter chemically without poisining my myself.or knock it out...initial fault was caused by a split in the air intake hose causing it to run lean maybe causing the backfire , anybody know where i can get a new hose from and thanks again , appreciated..
will let you know how i get on...................................rab.

i've found a leaking exhaust causes a backfire

HI THERE ,turns out exhaust is fine , main problem was the crank positioning sensor was breaking down when hot , bloody computer diagnostics showed it as ok , persavere and you will succeed . i right. going to do the head gaskets next before i need to , any advice please.....

CharlesY said:

BACKFIRING is an expression used to describe a big bang in the EXHAUST.


In a petrol or gas engine, SPIT-BACK into the inlet side is almost always caused by a LEAN MIXTURE.

Occasionally a burned inlet valve can cause the same symptoms, that is, you can rev the engine up a bit if you do it gently, but if you try to give it some throttle, it SPITS BACK into the inlet manifold where the mixture there explodes, and can do some damage.

If it's a fuel injection engine look for low fuel pressure, or a duff fuel injector making one cylinder run lean.

In a carburettor engine, blocked jets or a poor fuel supply can cause it.

Click to expand...

Get back to yer email !! I suppose you'll be in here looking for jokes ?