Backfires and Loses Boost-Ignition Related?

DaveyX87

Member
Joined
Oct 22, 2012
I have been trying to figure out why I can't build more than about 10 lbs. of boost before it backfires/sputters through the intake and looses pressure. It doesn't throw any codes either–all parameters look good. When I did the E85 conversion and turned up the boost, the car ran great the first handful of times I put my foot into it. Now it falls on its face when I get on it. It has a relatively new coil pack, wires, and ignition module. The plugs are new as well; I took a couple off to inspect and they look normal. Eventually I want to switch to the TR6 set up but I don't want to keep throwing money at the problem. Perhaps I need hotter plugs for E85? I've heard these cars eat up coil packs and ignition modules. Any help would be greatly appreciated.
 
Typically, an intake backfire points to a lean condition not an ignition issue.

While there are always exceptions and folklore, these cars do not eat coil packs and modules if it's OEM stock replacement and everything is working correctly.

Do you know the FP and AFR right before the sputter?
 
I had a bit of a similar issue when I tried to gap my spark plugs higher than .035?( new un-adjusted). Run them closer to .028 now and haven't had the issue.
 
it's ignition related, check your grounds. I once had the same issue with the TR6 eating up LS coil packs so I gapped the plug at .020 and the problem went away. I switched over to traditional coil pack and module BWD brand and havent looked back. As mentioned gap your plug tighter and see if the problem goes away, if it does the coil is having issues jumping the gap and needs replaced.
 
I had a similar issue and my muffler was so old it was causing crazy back pressure I couldn't build more then 9lbs without the cutout open
 
I'll try new plugs with less gap first. It could be the stock restrictive muffler as well. It seems more ignition related though. It's much harder to start in the morning than it ever was.
 
I'll try new plugs with less gap first. It could be the stock restrictive muffler as well. It seems more ignition related though. It's much harder to start in the morning than it ever was.
Also double check for hairline crack in the porcelain part of spark plug and get a quality set of plug wires.
 
So I finally fixed the problem after several unsuccessful attempts. I started with the plugs and various gaps. I tried wires and different coil packs. I ended up installing the TR6 and problem solved. The car has never ran better. Thanks to all of you for all the helpful information.
 
Glad its fixed. Thanks for letting us know. Do you know what brand ignition module you had? I've only had good luck with ac delco. I was reading my notes on my car recently and when I had this problem it was due to a clogged fuel filter.
 
Rick, I had the original ignition module. I tried a friends Delco as well. Perhaps they were both bad. The car would run and idle fine but the problem always occurred under boost.
 
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