Hi all

I know the “hot issues” topic has probably been beaten to death and trust me, I’ve been through most of them!

But my issue didn’t specifically come up hence me asking you guys.

My RX8 kuro 53k miles
Bought in may of last year.
Last year August, compression test results were front rotor was in the 600’s and the back was in the 400’s
which I know is really low.

The think is, I’ve never had hot start issues before. It was always cold start issues, Even when I found out on Wednesday I’ve been running on 2 functioning coils.

So I did another compression test 3 days ago, results this time came back with front 700’s and the back 500’s - improvement!! (Mechanic)

I also sea foamed a few weeks back. (Myself)

I ordered brand new D585 Coils and leads, installed them. Now, i have no start up issues but will not start after a drive ( hot start) 30-45 wait to start up again. (Myself)

I can only assume Low compression but find it odd I never has that issue with my old 2 functioning coils.

any help is appreciated

Kieran

 

Hot starts are generally low compression symptoms. Also your numbers are very low to begin with it’s not surprising. Is your starter cranking up good? It should crank the engine at 200+ RPM to get a good start. If that’s not it then don’t know what else to tell you. Might have to face facts soon and look into replacing your engine.

 

Yeah starter cranking up fine *sigh*
its just because on Wednesday just gone, starts up fine hot, I change the coils and doesn’t start at all. Baffling to me.
Thanks for the reply

 

Your coils leads are installed in the right order? That can cause issues. Also, should try another compression test. You sure he didn’t test the engine cold which is why your numbers went up so drastically?

 

What is he measuring compression with? I wouldn't trust those results, they make no sense and don't come with an rpm number. 400 is off the chart failing.

The symptoms match failing compression though. I *could* also be your fuel pump as well, but that will typically get better with a full tank of gas and worse near empty.

What were your cold start issues?

 

I labelled up the old leads and measured the new leads to the old and installed accordingly. Unless I’m missing something?

 

Both compression tests were done by the same guy/
company in Essex uk, Essex Rotary. The website says they have their on Rotary compression tester.

I thought Fuel Pump too, but again, wouldn’t make sense why it didn’t have an issue before the ignition upgrade.

the issue with the cold start was that it took 6 seconds including a few revs, to actually start.
This was diagnosed to be 2 failing coils on Wednesday just gone.

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More info on the compression test would be nice to get too. As Loki said, be nice to know what tool was being used and what RPM you got your numbers at and if the engine was hot or cold while the test was performed.

Here's a diagram of how the spark plug and coil wires should be set up.

Edit: did you also change out your spark plugs?

 

Both compression tests were done by the same guy/
company in Essex uk, Essex Rotary. The website says they have their on Rotary compression tester.

I thought Fuel Pump too, but again, wouldn’t make sense why it didn’t have an issue before the ignition upgrade.

the issue with the cold start was that it took 6 seconds including a few revs, to actually start.
This was diagnosed to be 2 failing coils on Wednesday just gone.
​​​​​​​

 

Perfect, I’ll go have a look now and confirm thanks.

Also, the compression test was done whilst hot, if that helps at all.

 

Basically just removed and reinstalled all leads etc set it up exactly as shown took for a 10 min drive to warm up and same issue

 

spark test showed plugs were in ok condition. But an upgrade would be due soon. Might be worth looking into new ones but still doesnt explain why hot start issues arrived after an ignition upgrade.

 

Sometimes the D585 coils result in lower spark output than expected at idle because of the amount of dwell the stock ECU uses.
Tweaking the dwell tables would help... but if the motor is weak that really isn't the issue long term.

 

Well look at it this way; you were going to need new coils for a rebuilt engine any way.

 

If the ignition system is good then it looks like you'll be needing a new engine I'm afraid... definitely low compression causing your issues, it wont live for much longer. Could just be a coincidence these issues are starting as you changed your coils out.