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Showing results for tags 'misfire'.
Found 5 results
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My car has been fitted with an accuspark electronic ignition. It's been running really lumpy, as if some cylinders weren't firing. Poor and juddery acceleration, masses of popping and banging at the exhaust end. Not too bad when at speed, but something didn't quite feel right. Not as smooth as the engine should be. One cylinder at least wasn't firing properly. I did a bit of googling and was starting to worry it was going to be a long, drawn out and expensive business replacing bits one by one untill the problem was eliminated. Anyway I took the car to go food shopping this morning and it was really bad. When I got home I removed the plugs one by one. All were as they should be. I considered the HT leads, but dismissed that idea as all the spark plugs looked identical. I popped off the distributor cap and discovered that the black wire was rubbing on the rotor arm and the copper was exposed. I wrapped some amalgamating tape around it, moved it away from the the rotor, replaced the distributor cap. I took the car for a spin. WOWWWWW!!!!!!!!!!! So a very simple fix. Hope this helps someone.
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Hi all first time posting here. I have a Vitesse 6 that runs fine at low RPMs (up to 3.5K) or when cold. Once the car warms up or the revs exceed 3.5k or so the car develops an aggressive misfire/ splutteing and refuses to rev any higher. The misfiring continues to get worse as the car warms up to operating temperature, eventually causing it to stall even under no load at idel. To try and diagnose this issue: I have set the timing at idle with a timing lamp to 10° BTDC. Both the mechanical and vacuum advance work. I’ve also checked the mixture on the carbs (Stromberg 150CD without emission control); with the lifting pin, the revs increase briefly and then go below idle speed, but the misfire still persists. To see if the misfiring was caused by a lean mixture; whilst the car was misfiring I pulled out the choke, but this only made it splutter harder. Checking if the misfiring was caused by a rich mixture I made the mixture intentionally lean but this had no impact on resolving the misfire. I then moved onto the plugs, I found that they were sooty so I cleaned the soot off but the problem still persisted so I retried making the mixture richer or leaner, but had similar results. Thinking the problem was fuel related I took apart the fuel pump to see if the diaphragm or valves were clearly damaged, they weren’t. I have also checked the operation of the fuel pump when hot by lifting the priming lever, but fuel still came out of the pump. I then checked if fuel was getting into the bowls, expecting it to be a vapour lock issue on the carbs I removed the brass mixture adjuster on the bottom, there was plenty of fuel in the bowls, which were also cold. I then wondered if the misfire was caused by some kind of blockage between the fuel tank and pump so I ran the car off a fuel cell that used the cars mechanical fuel pump but the problem still persist. I then wondered if the problem was caused by a head gasket failure (at this point I’m clutching at straws) but there wasn’t any oil in the radiator or water in the oil. At this point I am stumped so would appreciate any help from anyone.
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Hi everyone, I've got a really confusing idling issue that I just cannot find the solution to. It's on a Mk3 Spitfire (FD engine) 1300. The engine seems to have developed an irregular misfire and/or very rough idle (please see the two videos below, as they show it better than I can explain!) which I cannot seem to remedy, no matter what I do. The revs can vary wildly (sometimes as much as between 1500-3000rpm) running fast or nearly stalling, with no apparent pattern as to when it will/won't misfire. I have swapped in and out various components (list below) and re-set and adjusted the timing, mixture, and idle speed screw settings every which way I think I can with no results. There is good supply of fuel to the carbs, and the car has run well on this same tank of fuel before (so I don't think it's contaminated) and a good spark from each plug. If I had to describe it (and I am clutching at straws at this point), I would say it seems like the timing is maybe 'wandering', with the time of spark meaning the odd late/early/missed detonation. It's an AC Delco distributor. I don't have much knowledge about distributors, but could the centrifugal weights sticking cause this sort of issue? I haven't had chance to get my timing light out yet to see if there is anything noticeable there. Video 1 (Revs) Video 2 (Engine bay) I have swapped around and used various different combinations of the following components: - HT Leads (old set & new club supplied set) - Plugs (original Champion N9YCC & new Bosch WR7DC+) - Condenser (original & two new ones) - Points (original & club supplied set) - Distributor cap (original & club supplied) - Rotor arm (original & club supplied) - Coil (original & new Bosch) I have recently replaced the following: - Float chamber needle valves and floats. Also cleaned thoroughly, breather hole clear, valves moving freely, appears to be good fuel flow. - Air filters. I have reverted back to standard from the K&Ns I had fitted before, until I can get things running right. I have been running without air filters while trying to get the idle to settle. - Cable from coil to points (had no effect) - Cable from distributor base plate to outer casing (replacing the cloth covered original, had no effect) I have also done the following engine jobs, but before this problem arose (so hopefully won't be a part of it): - Replace manifold gasket and seal with blue Hylomar - Replace and seal around carb/manifold gaskets with Loctite 574 - Thoroughly clean and check carbs, needles, jets, etc. - Fuel pump - All fuel lines, mostly rigid copper line with Codan R9 flexible hoses in the necessary places. - In-line fuel filters (glass), one after tank, one after pump. Both appear full with good fuel flow. Any thoughts greatly appreciated... Matt
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Hi all, trying to sort a misfire out on my Gt6 mk1. Initially I thought it was the coil, had a good read of the posts on here, and thought I’d covered everything. So open to suggestions really. it happens when hot, on a day like today, car starts to lose power, eventually coughing, spluttering and finally backfiring when under load. Let it cool down all fine again for a bit. I’ve looked at the ballast situation, looked at my wiring and no obvious signs of ballast resistor or wire, straight forward white/red from starter to fuse board, white to coil from ignoition. No pink flecks or white and yellow wires so have assumed not ballast. Changed to a good quality coil of 4.5ohm, same imp as rubbish inter motor one that was on there ( on local tuners advice, it’s the only one he had! ) changed back to points and condenser, to check the module, still got the problem? I’ve assumed it’s not fuel as I’ve had this problem before and you don’t get all the backfiring ‘popping’ stuff with the power drop. The engine has only covered a few thousand miles since rebuild, but the only thing I didn’t touch was the distributor. It does appear to have a slightly wobbly base plate, I was considering replacing with an complete electronic unit from the club shop if the module was found faulty, but I don’t think that’s the problem as the points proved. Was planning to take it to SEM next weekend, but not looking to hopeful at the moment. ☹️ As always any help appreciated. Thanks hag
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Can anyone help with regard to a problem I cannot resolve. I have a 1972 GT6. Apart from sports exhaust and K&N filters the engine is pretty much standard. The engine has developed a problem when it gets to full operating temperature. Starting up and running while warming up it is fine. After about 10 to 15 milles and under load the engine looses power and runs very roughly. I have to ease of the throttle and allow the car to accelerate very slowly and even then it is constantly missing. If I stop and allow it to cool a bit it runs smoothly again until it heats up. The carbs were replaced about two years ago and colourtune shows them to be set correctly. The timing is correct. I have fitted new HT leads, coil, distributor cap and rotor arm. All made no difference. The car has electronic ignition. I have just set all the valve clearances and although the car then started running better the old problem came back after 30 or 40 miles. I am running out of ideas and getting fed up of buying new parts that make no difference. Anyone got any ideas where I should look next? Thanks.
