L98 misfiring
Thread Starter
3rd Gear
Joined: Aug 2001
Posts: 3
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L98 misfiring
I have a '90 L98 with 150,000 miles. I've changed almost everything including plugs, wires, cap, rotor, etc. over the last year or so. I also have converted my HEI over to MSD 6A with Blaster coil, have most of the bolt on mods including a chip, air foil, fuel pressure reg, etc. I have recently developed a misfire at RPM's above 3,000 along with what seems to be a loss of several cylinders for brief moments. I've never changed the injectors, but did replace the ECM with a rebuilt about 75,000 ago. I'm suspecting that to be the problem, but don't want to start changing parts without some of your great insights into what else it might be. Any thoughts would be appreciated. Thanks, Jon.
P.S. The cat is new also....I'm not getting any codes either.
P.S. The cat is new also....I'm not getting any codes either.
Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: L98 misfiring (J. Fenska)
Replace your fuel filter if you haven't already. Check the fuel pressure under load. Put it on a scanner and check the sensor values. This might be an intermittent failure of electrical connection. Could be MAP or TPS too.
Thread Starter
3rd Gear
Joined: Aug 2001
Posts: 3
Likes: 0
Re: L98 misfiring (AquaMetallic94LT1)
Thanks Aqua, I have a new filter, fuel pressure is 45 at idle, but haven't tried driving it yet with the gauge taped to my windshield, but have thought about it. Haven't tried scanning the sensors yet, either. But, your post got me to thinking about all the whinning noise my fuel pump makes when I get even a little low on gas. Maybe my pump's bad and that would show up on fuel pressure under load test you're suggesting. Thanks!
