I have an 89 Oldsmobile 98 regency, I have been reading through forums and online info for about 2 weeks trying to diagnose before replacing parts. The car has low miles because it was barely used, lived in a garage and basically sat for the last 18 months (it had belonged to a family member). Now that we are trying to use it I’m trying to work out old age kinks.

The car is hard to start in the morning, only in the morning, and even worse when it gets below a half tank. The fuel sending unit isn’t working, but I’m not sure that has anything to do with the current issue. I have run a couple tanks of gas through and changed the fuel filter, fuel economy is up quite a bit. But I’m also have a random “hiccup” while driving, where it feels almost like a misfire, then the engine light comes on and it runs rough. It goes away and returns to normal if the car is turned off and then back on.

I get a code 42, but everything I am reading about that code says that the car will die all together, or that it is only really an issue on startup.

Im sure there is a bit of experience with this so I’m hoping that you all can give me a place to start

Code 42 electronic spark issue- electronic control module..?
A good place to start would be in replacing the spark plugs and wires as well.
Old gasoline at tank bottom can cause issues and adding a good ethanol stabilizer like Star Brite- Star Tron could really help.
Use a high octane initially.

Here is the criteria that sets the code:

The EST signal did not change when the ECM applied bypass voltage to the ignition module.

At engine speeds below 400rpm, timing is controlled by the ICM, and as the engine speed exceeds 400rpm, the ECM applies voltage on a specific line, which bypasses the timing control of the ecm.

I have had this code pop up, and it was usually a symptom of the stalling, and not the cause. I suspect if the engine tries to stall but doesn't, but drops below the 400rpm threshold in the process, stuff tends to freak out.

I would bet something else is causing the stall. Track it down, and I bet code 42 never comes back.

Correction, ECM bypasses the initial ignition timing of the ICM.

Letters are hard

Check the ECT KOEO after sitting overnight. The reading should very close to ambient temperature.

Thanks everyone I’ll keep tracking it down, new plugs and wires have been installed. I’m going to put new battery cables on also, just as an inexpensive maintenance type fix. Keep working through it.

Look at the ECT in the morning.

Check fuel pressure as well. Bad gas does bad things to all fuel system parts, especially the pump. It could be marginal, and therefore not quite enough pressure during a cold start when extra fuel needs to be delivered, and marginal while driving hence the hiccups.

I found one bad vacuum line that connects into the throttle body. I also tested the fuel pressure, at idle is is at about 34 and drops extremely fast once key is turned off. The pressure regulator looks to be in good condition, any tips to test it? I’m guessing the pump is the issue.

If the pressure is OK the regulator is OK.