I recently had my van serviced. Prior to service it did a nice little goodbye backfire when I switched the engine off. Post service I heard it back firing lots whilst slowing down at roundabouts etc. The garage had said bring it back if you’re not happy with how it’s been set up as it’s been put back to factory settings. I took it back but it’s still backfiring/popping when I’m in traffic. It’s ok on a fast run but not slow. The garage man said I have a bit of a blow on the exhaust but the popping was defo not there before. I don’t like it as I want folk to think, what a fab van that is, when sitting in traffic, not, what a noisy old nail that is! The van ran quite quick on idle (pre service) with no popping. Will it do it greater harm continuing with stupid popping noise, or having it reset to idle faster? It’s a 2 litre twin carb. Thanks
Always thought,backfire was due to unburnt fuel in exhaust system because of timing issues but the bottom line is that there's too much unburnt fuel so either timing or mixture. If it's timing, it's not great for engine...if your exhaust is on its last legs, the backfire could finnish it off. Out of curiosity, who is the garage you speak of ?
Garage said there is an exhaust leak, that may be the cause. I would go back to your garage with the van and ask them to show the exhaust blow.
Popping and banging on the overrun is usually an exhaust leak somewhere, which ties in with what the garage say. If it was idling high before, that was probably masking it. Fix the exhaust leak, and the backfire should magically disappear.
Autohaus Dolby in Sheffield. I’ve used them a few times before and they have s a good reputation. I had a new back box a couple of years ago but he said the leak was further back and told me about a good exhaust person down near my dads.
Same as I use....was looking for a back up garage...can't quite get the measure of Matt.....and £ 54 an hour hurts....it's nearly what a plumber, sorry heating engineer, charges!
I also use just the local garage but thought I’d go to autohaus had a decent fixed price for the service. Problem is it’s the other side of Sheffield to me so a bit awkward to get to so a pain to get and the local garage is easier (and cheaper)
When mine had a backfire, it was the advance weight in the dizzy that wasn't moving....refurbished dizzy sorted it ( Matt initially missed it .) I have a slight popping on tickover but I'm advised that is a slight leak in the exhaust system.
I may get the old chap at the farm to reset it. He did last time and I’ve been driving it for a couple of years. I didn’t have the popping before I went in tho so that’s why I wondered about the set up as I don’t think the exhaust condition had changed overnight
I had backfiring which was due to overfueling, I had to fit a fuel regulator now the backfire is no more, what carbs do you have Alex?
The problem with the Sheffield ring road .. is all the dippy students constantly pressing the pedestrian crossing buttons and halting the traffic.. They need under passes...
Alex with the handle of a screw driver tap the body of the float chambers if the back fire disappears then you probably have warn needle valves, if your carbs are Weber 34 icts they need a very low fuel supply of no more than 2psi, most low pressure fuel pumps supply fuel at 3.5 psi which is too high and will eventually wear the needle valves, my money is on the above especially if the backfiring has only recently started
Dirty , inside that is or cracked dizzy cap too. Exhaust system leak is a common cause, port gaskets the whole lot.
When your engine is idling properly, it's not pulling air through the idle jet, just the idle mixture screw. If your engine is idling high, it draws air / fuel through the idle jet, which changes the mixture. Backfiring is essentially just unburnt fuel igniting in the exhaust, which is made worse by an air leak in the exhaust system. Generally speaking, the worse the problem, the nearer to the heads the leak is. Usual suspects are where the heat exchangers bolt up to the head, and exchanger to silencer joints. Check for tell tale signs of soot, or poke your ears at the joints with the engine running