Hot Start issue, low compression is doubtful
 

Hey guys,

Today I drove to the bank, and turned the car off for 5 minutes tops, and then came back and turned it back on but it was struggling. About a year ago I had a compression test done and all numbers were between 7.6-8.2 on both rotors @ 250rpm. I just recently got new plugs/coils/wires in as well. If I had lost compression I am sure I would have noticed worsened cold starts and power loss too(According to dealership people). I feel as if these hard starts only occur if I immediately turn the car off and then back on shortly when hot.

I plan on getting another compression test done soon, but is there anything else that could lead to possible hard starts? Clogged cat perhaps? I was looking into getting the N3Z1 start as well from mazmart.

Thanks guys!

Compression is the easiest thing to rule out....get the test done and then you have someplace to start

There are a lot of possibilities.....when you get the compression test squared away come back and we can help you figure it out

I had the same problem a few weeks ago. After reading that the battery could be a cause, I got mine checked at autozone and oreillys. They both said the battery was bad. After replacing it, the problem went away :)

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Like RotaryManiax said, a low battery will cause a hard start.

Battery, battery connectors, starter. If it cranks SLOW when hot it's one of those three. If it cranks FAST when hot then it's compression. If you listen the whir of the starter sound much different.

Compression test it with a rotary tester hot. What happens is these cars can test fine cool, but when they heat up the seal springs droop and compression drops. Hot start issues are almost always compression related.

I disagree, although that is the the most common assumption. More common than not it is a bad starter/bad battery/failing ignition components and sometimes fuel pump issues. I can't tell you how many people have sold their 8's after being told the same by mechanics.

My buddy buys RX-8's with blown engines, rebuilds them, and resells them. Just the last two he bought (an 08' 6 port auto with 70k on it that was still at a shop when picked up and a 06' six speed Shinka with a reman and 126,000 on the chassis) were both from people who were told by shops that they needed new engines due to low compression. The 08' (still under the factory engine warranty BTW) just needed a reflash (weird auto thing) and it runs like a champ. The 06' Shinka was just flooded and runs like a champ with new coils, wires, and plugs.

One of the mechanics at the shop is the husband of an employee of mine, and he turned me on to the 08' and I told my buddy so he could jump on it. When I told him it later on that it was just an ECU issue and the car was still under warranty for the engine he was blown away because they spent days trying to get it to start and replaced all the ignition, etc. This is an ASE certified mechanic at a rather large shop that has a pretty good rep. They had even quoted the guy like $5000.00 to install a Mazda reman but didn't know about the 8 year/100k engine warranty. The poor seller still had to pay them for the work done and my buddy got the car for nothing because the owner just wanted it gone. Mazda didn't even charge my buddy for the diagnostic fee or the re flash since it was part of a campaign.

Oh and loose or corroded battery terminals and wires can cause issues as well but generally that will affect things hot or cold.

I've seen a loose battery connector cause trouble hot starting. It got so bad that one day I went to hot start the car and the lights went out for a moment, and that's when I tracked down the problem. Maybe it was thermal expansion of the connectors? :dunno: But the problem was only noticeable when the engine was hot, and it would crank SLOW.

Either way I tightened it up and all the problems went away. Oh and I coat my battery terminals with Vaseline now. (or dielectric grease) It prevents corrosion and it's an easy fix.