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Novice Mechanic needs advice

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My car pops under engine braking. Didn't used to do it.

I've cleaned the plugs, rotor arm and distributor but this doesn't seem to have helped. The plugs were a little sooty so and I haven't cleaned the air filter yet. Could ths be causing the popping or is it something else.

Ta

Mark


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I had this problem develop on my '87 HC Esprit and it turned out to be down on compression with due to burnt out exhaust valves. The comment back was "I am surprised it runs this well, in fact I am surprised it runs at all".

Get a compression test or check for other leaks in the exhaust system close to the head.

Good luck.

cheers

-Chris

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hello Mark i have recentley had this on my s4, i seem to get it when the fuel gets very low so maybe some dirt in the tank or something, or possibly poor petrol, i use the filling station just up from you as im sure that the one near me is shorting. mind you my wife has put in ron 95 as i put in 97 or 99 (from tesco) it could be also be down to mixing

all the best


It's Oogies turn to boogie

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Popping is often down to unburnt fuel igniting in the hot exhaust. Mine does it all the time but I know she runs rich as that's the only way she'll run well. I recently rebuilt the carbs and that hasn't helped. I quite like the popping.

Pete


Pete '79 S2

LEW Miss September 2009

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I had this myself when the vacuum take off for the brakes developed a leak. Other symptoms were loss of power assistance to the brakes and a pulsing sucking noise from the engine bay.


Regards

Mat

post-1-0302470001278592957.jpg

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Aerobats S4 pops and shoots fire... it's loud enough to hurt your ears.. but that's because he doesn't have a cat and he's running a Larini exhaust.... I personally love it!


Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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Check to see if you have any small leaks in the exhaust system. Flanges, slip joints, etc. If air is drawn in it will help ignite any unburned fuel.

Jeff


www.espritturbo.com

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OK so I ran the car today and all I'd one was clean the air filter. It ran fine no popping!

What the car was popping it was hot, so hot the fan came on driving at 40 mph, could this just be how it is, or is it something I can sort?


Look what Q's brought us. Isn't it nice!

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Aerobats S4 pops and shoots fire... it's loud enough to hurt your ears.. but that's because he doesn't have a cat and he's running a Larini exhaust.... I personally love it!

My TE is effectively an S4 (or S4S- can't remeber which code it's running at the moment), and pops, bangs and shoots flames.

Proved popular sound at the charity day, if you blip the throttle slightly, thenblip it big itme, it gives a tripple crack on the 2nd engine run-down, sounds a bit like a machine cun rather than a single cannon.

Andy

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I think the key here is, if it is popping now and it never used to and you haven't modified anything then you almost certainly have an air leak somewhere in the system. Cary out the basic checks on the pipework and compression as a good place to start.

cheers

-Chris

Edited by cweeden

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Andy I did see people ducking and running for cover when you started your engine...or maybe that was the rain?


 

"Belief is the enemy of knowing" - Crrow777

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My 86 HCI will do this if the throttle position sensor is not setup correctly. I believe it controls the overly rich mixture that occurrs just as you brake and deccelerate.

Sorry, I dont know the carb models, in fact I am still trying to get mine working corectly. Just a suggestion-sounds overly rich, and then when the mixture hits the hot exhaust........BANG.

A couple of low rumbles and pops should be okay. They sound cool!

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Hi. This is my first attempt at replying to a chat room item so lets hope it makes sense. We'll add the fancy bits another time. To add my experience with my 1982 S3 N/A after a lot of work as a result of a throttle spring bracket jamming, giving full throttle and over reving, bent valves etc. :wub: , I would check the exhaust system for any slight leaks or blows. I have a SJ stainless system that is a bit fiddly to fit. Mine was leaking slightly from one of the head to manifold type joints. I had trouble freeing the 4-1 joint so tried easing the pipe away from the head and getting some exhaust assembly paste in. Marvelous. The popping disappeared and the idle performane improved. Finally it is finished enough and I can drive it again (6 years later !). Only problem now is the 4-1 joint is leaking where I disturbed it. But it was a good 26 mile drive :baby: ! Think I will have to bite the bullet and dissassemble it completely and refit it all very carefully (new gaskets etc) with plenty of assembly paste in the 4-1 as it is not the easist of designs to work with. That said it is much better than the original cast item with all its cracking. Oh and whatever you do make sure you have a rev limiter fitted. The

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I FEEL A FLAME OFF COMING ON! to be fair i haven't seen bibs' flames but mine are quite spectacular by all accounts (never having seen them myself!) but i get quite a bang in the cockpit - it almost shakes the car! Anyway bibs has a fuel injected car and so is never going to get flames like a carburetted car unless he has cheated by putting a specialised coil on which is cheating if you ask me! or he is putting meths in the fuel tank!!


REHABS FOR QUITTERS!!

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Simon, the back of my car makes this look like a cheap lighter...

WNUS_16-50_mk7_Iowa_pic.jpg


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

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Warwich and Jeff are on the money with an air leak around the exhaust system. Those pesky manifold nuts are always working loose, or in my case, the triple clamp flange was sucking in air and causing a backfire.

The 'experts' have a leak tester, with a copper(?) based gas that burns green. They apply this around the joints and watch for green flames. cool.

Iain

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Hi Iain long time no speak.To stop your nuts coming loose use stainless studs a spring washer and brass nuts.mine always stay tight and they never siese up .happy nut tightning ;)

anyway it could be a crack in the manifold.I have a very small hairline crack and it makes it pop on the over run.

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Hi Mark,

You are correct with the washers. When I recently replaced the head, I checked on the installed washers that I had on the exhaust manifold and found out I was supposed to have spring washers. I just goes to show that you always need to check the original fit - not what is installed. No cracks for me in the manifold - that would be a bad day (touch wood).

Iain

Edited by iainskea

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Well my backfiring ended up being caused by a faulty radiator fan! The fan was coming in too late so the engine was getting too hot (usually in traffic) this must have been causing the fuel to vaporise meaning the car was running on the wrong air fuel mix, therefore backfires! I noticed it only backfired when hot and also all my manifold nuts were OK.


Look what Q's brought us. Isn't it nice!

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Nice to see that your nuts are OK. :lol

I would never have guessed that the fan was the culprit but I can believe it. Glad it's sorted.


S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

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