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Sputtering problem..

3K views 39 replies 5 participants last post by  96lt12011 
#1 ·
I recently replace plugs and wires on my stock lt1, i switched to the MSD 8.5mm super conductor wires. Now my problem is that it starts up fine and runs fine in park and nuetral, but when put in any gear it sputters. Could this be a swithced wire on the optispark? No CES codes either
 
#2 · (Edited by Moderator)
Try running the engine again. Make sure (....gas tank is over 10% full and .. oops probably not pertinent to a 95 or 96) that you keep the throttle steady for a few seconds at least. That way any misfire codes that might be pending will get set. It takes at least two ignition cycles to set the MIL for misfire codes.
 
#6 ·
Those readers are great... but somewhat limited. Consider two other possible ways to go:
1. If you use a smart phone, get a $20 Bluetooth OBD2 adapter (http://www.amazon.com/Elandpower-Bluetooth-Scanner-OBDII-Diagnostic/dp/B004B7YXOM/ref=pd_sim_auto_2) and download the Torque app ($5), or
2, If you have a laptop PC, get a $15 USB adapter (http://www.amazon.com/HDE-ELM-327-Diagnostics-Cable/dp/B004B7PSA0/ref=pd_sim_auto_5) and use a "free" app like OBDWiz or mine (GDScan) and do the same on a much larger screen.
Either way will give you way more information than a simple code reader. For example, you will get misfire counts by cylinder# even when there are not enough to light the MIL. Also graphs, virtual gauges (not on mine), and data logging.
 
#11 ·
"Multiple misfires" doesn't help much. Can you access the misfire count by individual cylinder? That's where you find out if it's truly random, or related to one or more cylinders - e.g. cross-firing plug wires.
 
#24 · (Edited by Moderator)
Were you asking how I routed my MSD 8.5mm wires? It won't help you, because I run 8 LS1-style coils, hanging behind the lower radiator support:





If you have the 8.5's wedged through the power steering pump bracket, make sure the serpentine belt has not rubbed a hole in one of the wires.
 
#13 ·
My guess is that one or more wires are DOA, or that one or more terminals aren't pushed in/on all the way. BTW, when I was testing my OBD scanner software, I unplugged one wire to force the cylinder#1 misfire code and the engine idled pretty much normally also.
 
#14 ·
Checked all the wires on both sides, and all of them were connected properly. It ran fine, but as the more i drove it the worse the sputtering came back. Next thing i know the CEL light was flashing then stayed on. Could it be the gap on the plugs that can cause the P0300 "multiple misfire" code? What is the correct gap to be set at .50?
 
#18 ·
Not sure if it applies on the older cars like ours but its worth a shot, disconnect the battery and while the battery is disconnected clean the throttle body and blade then reconnect the battery and let it idle with the a/c off for a few minutes. A lot of newer vehicles require this as part of the spark plug replacement.
 
#20 ·
When I changed the plugs and wires on mine I spun the wire the wrong way and burned it on the header and had a p300 code for the #4 and #8, changed those wires and all fine. But the saving grace was the misfire count feature. On a older bird I had the MSD 8.5mm wires and they worked pretty bad, ran a 8mm set from Autozone and it ran perfect. The other thing to check is if the coil wire is all the way on and if the coil is working properly. I just had to change mine last week for the same issue you are having. $60.00 at Bennett for the AC Delco unit with a 1 year warranty.
 
#22 ·
Very smart, I do the same thing, mabe have a
, that helps too, lol
 
#27 · (Edited by Moderator)
A buddy of mine tried the Bosch multi-electrode plugs in his LT1 and hated them. Best way he could describe them is "funky". Replaced them with conventional plugs and it ran great. The E3 plugs are "gimmick" plugs, just like the Nology "silver" core plugs.... a huge waste of money, with no measureable performance gains. And as you can see, may even involve a degradation of performance. They don't offer anywhere near enough variations in plug heat range, dimensions, etc. to correctly match the plugs specified for every possible engine, so they offer a few choices, and use them in way too many variations of engines, some of which they are simply not correct for.
 
#28 ·
That's what im starting to wonder. But they wouldn't throw that P0300 code, but then again everything was kosher before i put those plugs in. It almost sounds like the car has a small mild cam when running. Which are best bang for your buck plugs? Not trying to spend another 5.99 per plug
 
#29 ·
Just get the correct NGK Iridium plugs.... TR55-IX I believe. They may cost more, but the last wayyyyyy longer, holding the recommended 0.050" gap. That's why the factory installed platinum plugs - so they could provide a 100,000 mile emissions guaranty with no parts replacement. Iridium is a step up from platinum. Yes, a $2 conventional, non-precious metal plug will be cheaper, but it may only last 15-20K miles, the gap will open up, and then you'll be back under the hood scraping your knuckles.

I run conventional plugs, but only because nitrous does not play well with the platinum plugs, and I have to pull them regularly to check for signs of detonation, so it's no big deal to put a new set in every once in a while.
 
#31 ·
Yes.

It's also possible that one is loose, or that you cracked a porcelain insulator while installing them.
 
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