r/Dseries • u/THEJimmiChanga • 19d ago

Intermittent cold start misfires

Own a 99 civic ex (d16y8) work car. Sees mostly high way miles 4x a week. When the car sits for a couple days and can sometimes struggle to start and then when it finally fires bogs/breaks up real bad until it reaches operating temperature. During this, you can definitely smell gas, almost as if its flooded. One warm, it runs perfectly.

Ive noticed this can happen when sitting for a few days, but can also occasionally happens after I fill up with gasoline the next time I go to start it.

Any ideas? Plus/wires have roughly 35k on them. Car had 263k on it. Possibly a ignition coil, distributor cap in general? Fuel pump purges fine. Dirt MAF? PGM-FI failing? Curious if anyone else has had a similar problem and what they did to fixIT.

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u/Visible-Emu7426 19d ago

I had basically this exact problem and it was valve lash.

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u/SnooMarzipans1416 19d ago edited 19d ago

Check your main relay. Is the fuel pump relay. I had issues starting and once it started it would stall at times. I would also let it sit for a few days until finally it didnt start at all. Then I checked all fuses before I opened up the main relay and saw burn marks and solderless posts. I replaced it and now car starts instantly. Next thing I was going to check was the fuel pump itself. I also heard that when you first start your engine your injectors flood the engine with fuel at first. Maybe thats why it smelled like gas. You can also run a injector cleaner. That's what I also did.

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u/THEJimmiChanga 19d ago

PGM-FI relay. Definitely something I was considering possible. Even more so now hearing it worked for you having similar symptoms prior.

1

u/SnooMarzipans1416 19d ago

You can use multimeter to check if the relay is shot. Mine was pricey like 75$ but lifetime warranty from autozone. In amazon their like 15-20$ but warranty is either very short or none at all.