93 Possible Optispark failure
Thread Starter
7th Gear
Joined: Nov 2025
Posts: 7
Likes: 0
From: Tulsa, OK
93 Possible Optispark failure
Hello, I am having issues with my car bogging like crazy at low RPMs. It all started a few weeks ago with a slight misfire. Then its getting worse and worse and worse. I changed the waterpump last winter, had no problems since until now.
I changed all my plugs and checked wires. Seemed fine.
I am going to change my fuel filter and check the pressure. I haven’t done any tests yet but I am going to before I rule out it’s the optispark. Alright, here's what I know so far. It's hard on startup, it sounds sluggish as hell, and when you barely accelerate, you can definitely hear that it's not normal, like it's sputtering, it's stuttering, and it's just, you know, like very, very hard to drive right now. And when it's low on gas, it does not run very well. I just put eight gallons in it, so that's, more than a half a tank, and it still sounds terrible, and it sounds like it's about to stall, and it sounds fine when it's cold-started, but when you start driving it, like on the highway, it sounds terrible, and it misfires like crazy, and it shakes like it's like not going, if you know what I mean.
EDITS:
I checked for coded, it gave me a H51 & H74 which are not related to my problem.
I changed all my plugs and checked wires. Seemed fine.
I am going to change my fuel filter and check the pressure. I haven’t done any tests yet but I am going to before I rule out it’s the optispark. Alright, here's what I know so far. It's hard on startup, it sounds sluggish as hell, and when you barely accelerate, you can definitely hear that it's not normal, like it's sputtering, it's stuttering, and it's just, you know, like very, very hard to drive right now. And when it's low on gas, it does not run very well. I just put eight gallons in it, so that's, more than a half a tank, and it still sounds terrible, and it sounds like it's about to stall, and it sounds fine when it's cold-started, but when you start driving it, like on the highway, it sounds terrible, and it misfires like crazy, and it shakes like it's like not going, if you know what I mean.
EDITS:
I checked for coded, it gave me a H51 & H74 which are not related to my problem.
Last edited by wnicely03; Nov 2, 2025 at 01:52 PM. Reason: Checked Codes
Safety Car
Joined: Mar 2017
Posts: 4,202
Likes: 1,323
From: LeClaire Iowa
I sure agree with the fuel filter change. The pressure test will tell you something I predict. Your car should not run different based on the amount of gas in the tank UNLESS MAYBE the sock on the pump is clogged up. Dan
Thread Starter
7th Gear
Joined: Nov 2025
Posts: 7
Likes: 0
From: Tulsa, OK
Yes, I changed it. Let it pressure back up, the old filter was surely dirty spitting out black residue however still runs terrible after running for a bit. Even moving it I heard my first loud backfire.
Safety Car
Joined: Mar 2017
Posts: 4,202
Likes: 1,323
From: LeClaire Iowa
If the filter was that dirty some dirt might have gotten passed it. Filters are designed to flow through not to try to hold back 40 psi with dirt. It could have clogged your injectors. Is the gas fresh and has the car been sitting? The sock on the pump could also be dirty and clogged. Report the pressure test and how long it holds pressure after turning off. Dan
