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HellTeeOne's 97 Z28 made some pulls this morning for a tune after the AI 200 H/C/I install. It misfired at 3700 and broke up at 4000. Dyno shop says opti, but it was good before the recent work. Wanted to see y'all's thoughts before pointing at the opti.
We are planning to ohm out all the plug wires and check the plugs to rule that out. Any other thoughts???
http://youtu.be/3RoNLZQqu2I
Attachment 21792
This was the first and only baseline pull btw. Thanks for any input
Are they tuning...or just making pulls?
Co-Owner/Admin @ LTXtech.com
What kind of plugs and gap are you running?
They are tuning it. He's running ngk TR55's gapped at .045
One thing I learned...if the timer does not have INTIMATE knowledge of the LT1 platform and tuning...no matter how much thry try to.convince u that "tunimg is tuning..."
its not...and the first thing those tuners will blame is...the opti.
Ask me how i know...how many optis I swapped listening.... And how many dollars and tuners I ent thru ...till my car landed on the roller of a tuner that know lt1s.
Co-Owner/Admin @ LTXtech.com
The shop that is tuning the car mainly does LSx stuff these days (doesn't everybody?); but the tuner knows LT1s well enough. I've known the guy for the better part of a decade and he's owned 2 LTx cars, one of which ran in the 10s. I know what you're talking about though Larry, people almost always automatically blame the opti and many people have bought optis that they likley in the end didn't need. It's an expensive part to buy for it to end up not being the culprit.
This time was no exception. My tuner said he'd be willing to bet a large sum of money that the opti was the culprit. This indeed may be highly likely given the way the car is behaving, but two factors give me pause on that in this particular case. One, the opti was working perfectly before the car was torn down and the top end job was done and two, the car was almost completely apart and there's a fair chance we overlooked some minor detail while getting everything zip-tied and buttoned up prior to start-up. The only thing done to the opti before re-installing it was me spraying the outside down with brake cleaner to remove accumulated filth. Diagnostic session tonight at still2slow's LT1 surgery facility.
Things I'm looking to check/test tonight:
-coil
-coil wire
-all plug wires (brand new Taylor 8mms, btw)
-all grounds and connections
-plugs (to make sure none are cracked/chipped)
-fuel pressure
Anything else we should look at before we condemn the opti?
I'd definitely check the fuel pressure first.
Posted from my Rooted and ICS'd Rezound
Checked some stuff yesterday.
It's definitely got spark issues. Lots of them. Stumbling and breaking up everywhere.
The plugs and wires checked out fine, no problems there. Pulled an ICM off another LT1 and slapped it on there, didn't seem to make any difference at all, so that's not it either. Coil and coil wire seem fine. Grounds and connections all checked out fine as well.
Are there any more tests I can/should do in order to confirm it's the opti before I place an order for one?
Also, it's seemingly running out of fuel. Under heavy acceleration, the fuel pressure will initially be ok, then drop to 25-30. I'm guessing I need a pump. The Walbro is plug and play it seems, but is the Hotwire kit a requirement as well?
Fp is very bad.... the hot wire kit helps keep contsant and max power happening...but not a necessity.
Co-Owner/Admin @ LTXtech.com
Replace the fuel pump first. That could clear up all the issues. You may be showing good pressure initially, but if it's dropping and you've obviously got a bad pump, replace that before throwing other parts at it.
Thanks for the replies guys. He's ordering a pump, hopefully that will clear it up. Update after part is in. Fingers crossed
Goodluck!!!Quote:
Originally Posted by Still2slow
Co-Owner/Admin @ LTXtech.com
That doesn't look like opti breakup to me, judging by the graph. When mine was doing it, it was very obviously an ignition issue. I was going to say a possible fuel issue before I read the fuel pressure problem. I would definitely get that pump replaced before screwing with the opti.
Probably fuel. But its worth checking out everything. Nothing wrong with double checking everyting.