Backfiring through intake after opti install
Thread Starter
Teching In
Joined: Aug 2016
Posts: 15
Likes: 0
Backfiring through intake after opti install Finally got a new (parts store) opti in my car, started and ran like crap, so I made sure all the wires were on correct best I could, I had #7 & #1 mixed up at first, fixed that and it ran only marginally better. Pulled the opti back off this morning and reinstalled making sure everything was right, found one wire a pulley cut into and another it grazed a little bit, put some electrical tape over the small damaged part on one of them (lol I'm really sick of going to the store just a bandaid momentarily), tried to start it and it back fired through the intake a couple times and I stopped, I don't think that the damaged wire would be causing that, it ran fine but shut itself down when it actually started prior to this with the old opti.
I'm sure it could be the parts store opti.
I'm sure it could be the parts store opti.
Thread Starter
Teching In
Joined: Aug 2016
Posts: 15
Likes: 0
Thread Starter
Teching In
Joined: Aug 2016
Posts: 15
Likes: 0
That would be the reason I'm lost. I'm not saying it isn't the timing I'm wondering what has caused it to be off. I'm going to recheck plugs again when I have a chance but I am fairly positive they are correct.
Last edited by Thirdgens88; Aug 26, 2016 at 01:04 PM.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
OP
Three things could cause your issue after a Opti swap
1. Cam dowel pin is not in correct slot on opti
2. plug wires are on wrong
3. your "new" opti is bad (Way more likely if it is not a AC Delco or Delphi)
the Opti should sit dead nuts flush against timing cover , which it will installed correctly, and should NOT be pulled in tight to timing cover with the hold down bolts
whatever Opti you get, remove rotor and use loc-tite on rotor screws
Three things could cause your issue after a Opti swap
1. Cam dowel pin is not in correct slot on opti
2. plug wires are on wrong
3. your "new" opti is bad (Way more likely if it is not a AC Delco or Delphi)
the Opti should sit dead nuts flush against timing cover , which it will installed correctly, and should NOT be pulled in tight to timing cover with the hold down bolts
whatever Opti you get, remove rotor and use loc-tite on rotor screws
Trending Topics
10 Second Club
Joined: Oct 2007
Posts: 2,630
Likes: 28
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo Thread Starter
Teching In
Joined: Aug 2016
Posts: 15
Likes: 0
Took the pos "new" opti out and cleaned and reinstalled the old one because I didn't want to drive to get a replacement today and wanted to make sure I hadn't installed something wrong , the new junk opti dimensions must have been off because every way I tried it it sat off the cover a couple mm while the OEM one sits flush like i assumed the new one should. With the old opti in it fired right up but still shuts off randomly soon after starting,(my problem to begin with), the problem was definitely the new opti.
If it's ignition then that could be a coil issue. If not then your fuel pump may be on its way out. Get a fuel pressure gauge and test fuel pressure first. With the vacuum line off the fuel pressure regulator it should be between 43 and 45psi with 43.5 being optimal.
Thread Starter
Teching In
Joined: Aug 2016
Posts: 15
Likes: 0
Looked at alot of stuff it could be,ICM,coil & 42~ fuel pressure constant, was having no spark and no injector pulse when it didn't run with the old opti. Runs off and on like an ICM issue sometimes for extended periods sometimes won't start at all. It gets a SES light before it shuts down if it runs for more than a minute. With new opti in it started and ran every try as long as I had my foot on the gas to hold the rpms up which is why I pulled it back out and reinstalled. I bought it with a "bad fuel pump". It very well could be something else other than the opti but from where I am I think the optical sensor is the issue but I could be wrong.
Thread Starter
Teching In
Joined: Aug 2016
Posts: 15
Likes: 0
Switched optical sensors from new opti into old and it runs. Probably going to order a GM opti in a couple days now that i know thats my issue. Sprayed the opti down pretty good because I didn't have a good clamp on the hose that is right over the optical sensor. It misses and backfires through intake when you give it too much gas at once now, going to do plug wires since I ruined some of mine with a pulley and let the opti dry out and see what happens from there.