A little background.

My car has in the past two year has occasionally refused to start on very humid and damp mornings. The starter cranks and the car sounds like it is going to start but nothing. However later that same day when it had dried up the car starts fine.

Now, in the last month on the way to work I began experiencing power loss while driving. The cars RPS suddenly drop and the gas pedal does not increase or decrease acceleration. The RPS gauge might bounce around a bit and momentarily power might return before the engine eventually stalls. When I stop and go to restart it fires up fine before it begins to lose power and stall again wile driving. I know it is not electrical, as lights and gauges are unaffected by this. In all these cases the car behaved like this in the morning but later in the day ran fine.

I assumed it was an issue with the ignition system, so I replaced the spark plugs, distributor cap, and wires. I was due for it anyway so figured it was a good place to start. It seemed to work and the car ran fine until this morning when it again gave me the issue of losing power and stalling on the road. I did notice however that this time the power drop was more "stable" I guess would be the word. RPMs and power dropped and then stalled without becoming erratic and jumping around like it had before.

I am thinking the issue could perhaps be a bad ignition coil that before was compounded by the older and worn plugs, cap and wires? But the ignition coil is probably the next logical step in troubleshooting this right?

PS: No codes.

 

There are a ton of things that can cause misfires. What you're describing, could be a problem with secondary ignition, (plugs, wires, cap, rotor, and ignition coil). Usually, but not always, secondary ignition problems will set misfire DTC's in memory. Another likely cause is low fuel pressure and or volume, which are not directly monitored by the PCM, so they can't set DTC's.

To accurately diagnose these engines, the "basics" must be correct. (< that's a period ) AC Delco 41-993 plugs, D328A cap, and D465 rotor. They all need to be AC Delco, and yes, it DOES make a difference. The wires need to be a good quality brand, NOT a store brand. Aftermarket stuff might make it 6 months, if you're lucky. Look through the forum, you'll find Duralast caps are the biggest offender. The distributor drive gear and shaft bushings like to wear, both can cause misfires. Camshaft retard needs to be within spec. If not, there will be crossfire inside the cap, guaranteed, and no DTC's to let you know it's out of spec, unless it's more than ~27 degrees out. Fuel pressure and leakdown must be within specs. Follow the steps in this link, and post all 4 readings: https://blazerforum.com/forum/2nd-ge...eakdown-88305/

 

Thanks for the advice. I tested my fuel pressure and it came up a bit light and won't hold pressure as well as it should for 10 minutes. I'll try to drive with the gauge on so if it acts up again I can see if it is a problem with fuel pressure and fuel getting to the engine, and also test at the filter next chance I get.

The thing that is confusing me the most is that it only happens in the mornings. It did it again this morning but I just drove it and it worked fine for an even longer trip. I think that it could have to do with temperature.

 

When you shut the engine off, after it has reached operating temperature, humidity/condensation will accumulate on the under side of the distributor cap. When you start the cold engine, the moisture causes crossfire inside the cap. Once the engine warms up, the moisture evaporates.


State of charge of the battery is at its lowest after sitting overnight, and the starter requires more amperage to crank a cold engine. Combined, these will decrease the amperage available at the fuel pump, which can cause fuel pressure to be low. If the pump is already weak, it can cause long cranking times, and or a no start condition. What were the readings at the service port? Keep in mind, without the readings at the fuel filter outlet, the service port readings are almost worthless.

 

Okay, so I hooked a fuel pressure gauge to it again and really tightened it down and the pressure was all good. It is about 60 when running and when I shut the car off it hold pressure with no drop/1lb drop over ten minutes and beyond. The first time it must have been poorly connected. I have been driving around with the gauge on to see if it loses fuel pressure when it stalls.

Welp, the other day it finally stalled and I did not see any loss of fuel pressure. However it would not restart.

I tried starter fluid and it still did not go, so I think fuel supply issues can be ruled out at this point. I would have tried to test for spark but was not with anybody to turn the key while I watched. Coil finally just died maybe?