Engine cutting out and backfiring

BX Tech talk
TimG
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Joined: Thu Jul 09, 2015 12:29 pm

Engine cutting out and backfiring

Post by TimG » Sun Sep 11, 2016 12:06 pm

Hi All. I have a recurrent problem with my GTI 8v - when it's been left for a couple of weeks, it starts first time and then is a bit juddery when it drives, particularly in second gear. Eventually, it cuts out at the traffic lights and backfires when I try to restart it causing pedestrians to run for their lives! If I then leave it for a few hours, it will be OK until the next time...........
The local garage have had it in and cleaned the throttle and played around with the fuel injection system but I don't think they really know what they are doing. Any ideas? Also, does anyone know of any mechanics in London who know their way around a BX? It's my pride and joy, everything else works perfectly so would be reluctant to get rid of it. Any help very gratefully received.

Adrian E
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Location: Surrey, UK

Re: Engine cutting out and backfiring

Post by Adrian E » Sun Sep 11, 2016 12:30 pm

There's only limited things it could be - could be a service item (plugs, leads, dizzy cap/rotor) or the ignition amplifier, or something else like the wiring plugs to the injectors. If it's OK in regular usage it suggests not one of the service items, unless the time left standing becomes a factor (damp in the cap etc)

My old one used to throw a similar wobbly (16V) and what eventually cured it was replacing all the 2 pin plugs on the injector loom - I only discovered when I was replacing the starter motor that somebody had managed to break EVERY plug in some way on removing them in the past so they weren't getting a terribly positive connection.

Kitch is down on the South coast and would be able to help. I used to use a company in Merstham called Witmun Engineering, but the owner died and would need to check if anyone there is BX knowledgeable now.
1988 Citroen BX GTI 16V p1
2002 Audi S8 4.2
2011 Audi S5 Sportback

TimG
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Joined: Thu Jul 09, 2015 12:29 pm

Re: Engine cutting out and backfiring

Post by TimG » Sun Sep 11, 2016 12:57 pm

Many thanks Adrian, very helpful

rutter123
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Re: Engine cutting out and backfiring

Post by rutter123 » Sun Sep 11, 2016 5:19 pm

There are a few things that can cause this, bx's with fuel injection hate any type of air leaks pre throttle body even the tiniest leak will cause starting/running issues, i would check all your rubber pipes for splits and the like, backfiring is normally a timing issue which could be caused by the distributor or the ignition module.
I had an 8v gti myself which would run lumpy all the time after replacing just about everything electrical under the bonnet i eventually found 2 breaks in the engine wiring loom, it may be worth spending some time stripping out the whole engine loom and thoroughly checking it for dry joints and breaks especially on the injector part of the loom as these are soldered at the factory, also the relays that supply the fuel pump and injectors. I would start with replacing the leads, dizzy cap and rotor arm and plugs and check that the fuel pump is running at the correct pressure of 2.5 bar.
Which ignition set up do you have Motronic or Jetronic?
Its going to be a process of elimination but most likely an electrical issue if your symptoms are backfiring.
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