What would cause a miss under load? 98 LS1 TA
08-26-2011, 10:57 PM
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What would cause a miss under load? 98 LS1 TA Just picked up a 98 TA m6. 146k. Stock with SLP lid and intake manifold and a muffler. Has a miss under load. I'm thinking fuel delivery problem like the injectors or possibly fuel pump (origional). Does it at all RPM's and sometimes worse then other times. Seems not as bad on hwy, any thoughts?
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08-27-2011, 04:59 PM
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No light , dirty injectors or fuel filter or weak fuel pump , are You sure knock sensors are online ? Could be exhaust a little clogged . Just drive it until it stores a code and go from there .
08-27-2011, 05:03 PM
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Ignition component breakdown is where you will almost always find the cause of a misfire under load.
Like posted, check plugs and wires. Check spark strength at each coil as well, a weak coil will do that too.
Changing the fuel filter and cleaning the MAF are good ideas but they are not going to fix the misfire.
Injectors are pretty consistent, they generally work or they don't.
So again, check ignition components. Most likely it is a plug. LS1 coils and wires are very durable.
Like posted, check plugs and wires. Check spark strength at each coil as well, a weak coil will do that too.
Changing the fuel filter and cleaning the MAF are good ideas but they are not going to fix the misfire.
Injectors are pretty consistent, they generally work or they don't.
So again, check ignition components. Most likely it is a plug. LS1 coils and wires are very durable.
08-27-2011, 10:47 PM
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OK guys did a fuel pressure check tonight, 58-60 psi any throttle. That eliminates the pump. I picked up some new delco platinum plugs and a fuel filter and will go to town on her as soon as I find somewhere that has some good wires in stock. Only thing they had was durlalast wires at the local autozone and im not running that junk on this car. Anyone have a brand they have had luck with? I was thinking MSD. Also is there any way to easily test each coil to see if ones weak?
08-27-2011, 10:51 PM
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Also I did get into it a little tonight to try and get it to throw a light with no success, I didnt wanna push it too hard acting like that, but I did notice sometimes its worse the other times. I dont think that helps narrow it down at all though does it?
08-28-2011, 06:55 AM
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There are two schools of thought on choosing spark plugs. Many of the folks that post in this forum prefer to run less expensive non-precious metal plugs (usually copper) and change them frequently. Others prefer to run the more expensive precious metal plugs (copper-based with a platinum, double platinum, gold-palladium, or iridium coating) and change them less frequently. For your purposes of eliminating a misfire either choice will work - take your pick.
With regard to spark plug wires, the OEM sets are hard to beat in terms of cost/performance. Granatelli wires offer the lowest resistance (measured in ohms) but are expensive. I also like Firecore 50s. My tuner forbids me from running MSD wires (which are popular) because of their failure rate.
With regard to spark plug wires, the OEM sets are hard to beat in terms of cost/performance. Granatelli wires offer the lowest resistance (measured in ohms) but are expensive. I also like Firecore 50s. My tuner forbids me from running MSD wires (which are popular) because of their failure rate.
08-28-2011, 11:43 AM
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There are two schools of thought on choosing spark plugs. Many of the folks that post in this forum prefer to run less expensive non-precious metal plugs (usually copper) and change them frequently. Others prefer to run the more expensive precious metal plugs (copper-based with a platinum, double platinum, gold-palladium, or iridium coating) and change them less frequently. For your purposes of eliminating a misfire either choice will work - take your pick.
With regard to spark plug wires, the OEM sets are hard to beat in terms of cost/performance. Granatelli wires offer the lowest resistance (measured in ohms) but are expensive. I also like Firecore 50s. My tuner forbids me from running MSD wires (which are popular) because of their failure rate.
With regard to spark plug wires, the OEM sets are hard to beat in terms of cost/performance. Granatelli wires offer the lowest resistance (measured in ohms) but are expensive. I also like Firecore 50s. My tuner forbids me from running MSD wires (which are popular) because of their failure rate.
08-28-2011, 11:01 PM
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only had time to pull 2 plugs tonight, both are destroyed, white and the electrode is gone...some sort of bosch platinum plug (too hot or improper gap???). Other thing I'm wondering about is this, I picked up some NGK platinum plugs and they gave me part #3186 which is "5" heat range plugs. I always thought TR55 was the stock heat range on LS1's as far as the copper anyways? Also as far as I know stock gap is .060 and according to the person at the parts store NGK calls for a .040 gap. I dont see why it would be that different so the 2 I put in already I gapped at .050, anyone else experienced this?
08-28-2011, 11:50 PM
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I did in my 2000 M6 TA. When cruising in any given gear, at a low rpm under any considerable kind of load, you could tell there was a miss. 60mph, 6th gear, WOT, it was bad. Only had it happen twice that day, got so violent, I was up until 2am doing a plug/wire change. Got 7 of them done, and it dissapeared. That's all I can give ya, as far as a similar first hand experience