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Maybe low compression?

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Old Jan 2, 2024 | 12:47 PM
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ZeroTwo's Avatar
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From: Constanţa
Maybe low compression?

I've seen my car start really slowly when its cold. It takes a solid 8 - 12 seconds of cranking before the engine starts, and I'm trying to figure out what could be the causes. The first thing that popped up was low compression. My FD Idles good, starts up good after being warmed up, and has plenty of power. The engine has been rebuilt 5000 miles ago and I really don't want to believe the apex seals have gone bad already.
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Old Jan 2, 2024 | 01:00 PM
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Originally Posted by ZeroTwo
I've seen my car start really slowly when its cold. It takes a solid 8 - 12 seconds of cranking before the engine starts, and I'm trying to figure out what could be the causes. The first thing that popped up was low compression. My FD Idles good, starts up good after being warmed up, and has plenty of power. The engine has been rebuilt 5000 miles ago and I really don't want to believe the apex seals have gone bad already.
Usually, IIRC, low compression will make hot starts more difficult. Slow cold starts (slow cranking) are usually due to weak battery , starter solenoid, starter, thick oil, etc.
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Old Jan 2, 2024 | 01:06 PM
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From: Constanţa
It makes sense that hot starts would be difficult, but, fortunately, it is not the case. It may as well be to due a weak starter or battery. The thing that I noticed is when the hazards are on, and the I open the door / I turn on the light above the head, every time the hazards blink there is a small dip in power and you can see it as the lights go dimmer for a split second
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Old Jan 2, 2024 | 02:10 PM
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sounds like you may just need a battery. Does the engine actually crank slower (RPM wise) than when it is hot?
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Old Jan 2, 2024 | 02:52 PM
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Hard HOT starting is suggestive of low compression.
Hard cold starts could simply be a battery going south. Most chain part stores will test you battery and charging system for free in hopes of selling you a battery. And most are pretty honest in my experience. To help cold starts you could consider a fresh set of plugs. NGKs in stock ranges unless your modified. Maybe a couple tanks of gas with some quality fuel system cleaner or injector cleaner from that same parts store. I like the BG44 stuff or Chevron Techron.
If the engine isn’t running, lights dimming when other lights turn on is normal. Depending on load, maybe even with the engine idling.
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Old Jan 2, 2024 | 05:05 PM
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From: Bath, OH
Originally Posted by Sgtblue
...To help cold starts you could consider a fresh set of plugs...
Based on his own experience, so not just a theory.
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Old Jan 2, 2024 | 05:14 PM
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From: Constanţa
It usually cranks the same speed, but to be fair, I haven't given it much attention in order to listen for the RPM when starting hot.
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Old Jan 4, 2024 | 04:27 PM
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Check your battery voltage with key on (not running) and while at idle and report back-- Power FC Commander makes it easy, or use a multimeter.
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Old Jan 12, 2024 | 06:52 AM
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Thanks for the info, I will keep it in my mind.
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Old Jan 12, 2024 | 08:09 AM
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From: Constanţa
Do you think it could also be the tune?
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Old Jan 12, 2024 | 08:12 AM
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What ECU do you have?
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