jimmct Posted June 24, 2015 Share Posted June 24, 2015 Car has all of a sudden started to sound rough at lower revs and popping and banging thoughout the range. 1600gt cross flow running 40DCOEs. So far I've tried:-checked for leaks around manifolds and exhaust - nonechanged the coil - no differencechanged rotor, dist cap, leads - no differencechanged sparkplugs - nopeChecked carb balance and floats -nopeChecked the O-rings on the inlet manifold and they all looked okplenty of fuel getting to carbsi'm at a loss .........any ideas?James Link to comment Share on other sites More sharing options...
DJ. Posted June 24, 2015 Share Posted June 24, 2015 How about bad fuel? Link to comment Share on other sites More sharing options...
OliverSedlacek Posted June 24, 2015 Share Posted June 24, 2015 The symptoms sound more like a carb issue than sparks, but have you tried a timing strobe just to be sure? I'd also try looking at the plugs, particularly just when it's running rough. In the past I've had trouble with the cold start circuits, so make sure they are fully shut. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 25, 2015 Member Share Posted June 25, 2015 Were you using it frequently before this happened? Any changes made that might have affected anything?Jonathan Link to comment Share on other sites More sharing options...
jimmct Posted June 25, 2015 Author Share Posted June 25, 2015 Don't think its fuel as I've been filling up often due to putting in the miles and there is about 1/5th left in the tank from the last fill. Problem has only just now started - no issues over the last month / 500 miles.Seems to run smoother at higher revs (with the odd pop). Link to comment Share on other sites More sharing options...
Caterham Super Sprint Posted June 25, 2015 Share Posted June 25, 2015 Popping where it shouldn't sounds like timing issue. You're getting ignition during the exhaust cycle. Cross firing can also cause this (rotor arm arcing across to next terminal). Link to comment Share on other sites More sharing options...
SM25T Posted June 25, 2015 Share Posted June 25, 2015 Is there a condenser in the distributor .... try that. Link to comment Share on other sites More sharing options...
F355GTS Posted June 25, 2015 Share Posted June 25, 2015 Check voltage to ensure alternator/ dynamo is outpullting and electrics are getitng good power Link to comment Share on other sites More sharing options...
Caterham Super Sprint Posted June 25, 2015 Share Posted June 25, 2015 I had a similar issue when I fitted the Emerald M3D Ignition ECU. This retaines the distributor for switching using the lumention optical eye and spark distribution. However, the bobweights are secured shut as the ECU will take care of advance.The mistake I made was having the bob weights welded partially open, so the optical eye was itself partially advanced with respect to the rotor arm and cap position.Timing was set absolutely correct and everything worked as it should. After a while the engine faultered, popped where it shouldn't and failed to run smoothly. The 7 was flat bedded to Dave Walker at the old Emerald Cams site in SE London (back in the day, now moved).He found the rotor arm was firing at the correct cylinder but due to the advanced base plate was also partially cross firing to the next cylinder at the same time. This cross firing partially ignites a charge in the exhaust cycle causing the missfire situation.Dave filed a new slot in the distributor shaft to flip the rotor arm to a better position and moved the cap to suit (something like 180 degrees but i would need to look again). All has worked perfectly since. He called this cross firing.I only offer the story in case you have done something with your distributor sensor and this gives a clue. This will not show as an error in ignition timing value. King Willy Link to comment Share on other sites More sharing options...
SM25T Posted June 25, 2015 Share Posted June 25, 2015 Friends had something similar .... despite the fact they had recently replaced the distributor cap and rotor arm .... it was found the sprung carbon pin in the middle of the cap had worn away to nothing. Amazed it ran at all. Link to comment Share on other sites More sharing options...
jimmct Posted June 25, 2015 Author Share Posted June 25, 2015 I'll check the timing and the voltage in the morning. No condensor. Spoke with Northampton Motorsport and they reckon it may be a valve issue since the car (1997) still has the 4 star head running on unleaded with leaded additive which they didn't rate - any idea on the cost of a conversion if they're right? Link to comment Share on other sites More sharing options...
jimmct Posted June 26, 2015 Author Share Posted June 26, 2015 Success..........small blockage in the idle jet.Many thanks for your advice.James Link to comment Share on other sites More sharing options...
john g Posted June 26, 2015 Share Posted June 26, 2015 I like these 'quick fix' solutions. The penultimate post costing £100's to the last post costing £0. Relief hey James! Link to comment Share on other sites More sharing options...
DJ. Posted June 26, 2015 Share Posted June 26, 2015 Glad it's sorted Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now