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-   -   Causes of low compression (https://www.rx8club.com/new-member-forum-197/causes-low-compression-266053/)

YukiNoKo_BB 08-12-2017 02:35 AM

Causes of low compression
 
I need a straight foward answer. I've been rebuilding my engine for a while now and i finally had it in my car for the 4th time. My engine wouldn't turn and i had no clue what was wrong. Called over a specialist and he told me the car had really low compression so he advised me to take it apart again. I see no possible issues other than my side seals were stuck. Do you guys believe that is my only problem and that it should work now? I have the engine fully assembled and i just wanna know the community's opinion because i would hate to put my engine in and back out for the 6th time
Any ideas or opinions will help.

dannobre 08-12-2017 12:42 PM

Wouldn't turn...as in seized? Or wouldn't start?

YukiNoKo_BB 08-12-2017 01:17 PM

Wouldn't start. Sorry

dannobre 08-12-2017 06:22 PM

Often when you go to start a rebuild the plugs get fouled with the assembly lube (often Vaseline)
If you flooded it it can be difficult to start. Before the seals are bedded in a bit the compression is often not great

If you are sure you put it together properly...and it should be good to start...often a quick pull start will get it going

There are so many assembly/install problems that could cause this as well....so you need to start with the basics...fuel, spark and making sure the wiring is hooked up properly

Good luck

YukiNoKo_BB 08-18-2017 09:46 PM

I currently have the engine in and as before it's not starting its trying to though. Any thoughts? Im totaly lost here. Mechanic is out of the question not enough funds for that

gwilliams6 08-18-2017 10:21 PM

https://www.rx8club.com/series-i-tro...t-here-222584/


Starting the Engine
• Starter
• Battery
• Engine Compression
• Grounding Wires
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Fuel Pump
• Fuel Injectors

YukiNoKo_BB 08-18-2017 10:26 PM

Starter,battery,ignition coils,spark plugs,and spark plug wires are new. Engine compression im not sure i don't have a tester. I previously had one done and i had really low compression and fixed the only problem i saw and well almost the same thing. Fuel pump and injectors should be good their condition is ok im pretty sure i grounded everything correctly.

YukiNoKo_BB 08-18-2017 10:27 PM

My engine cranks pretty slow smells like gas after a while and makes like a gulping sound if that makes sense

gwilliams6 08-19-2017 07:45 AM

read through the starting issues thread and see if anything applies to you. There may still be a compression problem.

YukiNoKo_BB 08-19-2017 08:09 AM

Would it help more if i said my car sounds exactly like those flooded ones on youtube. Not sure if its that but it sounds pretty darn close

gwilliams6 08-19-2017 12:06 PM

did you read the whole starting issues thread ? Please do and then diagnose your issues. maybe a fuel pump or injector issue, especially if the pump and injectors are original, worn out and/or clogged.

If all main things you need for combustion, fuel, air, spark are properly working, then it may still be a compression issue with the car. It can also be a front O2 sensor,Maf sensor or ssv problem .

dannobre 08-19-2017 03:33 PM

If you are sure you have everything back in correctly...I would assume it is flooded.

Pull the plugs...are they wet with Gas? If they are it is likely flooded.

If it is a MT I personally would tow it and try and start it that way. It sounds like you have a crappy starter and the pull starting will allow the motor to turn over faster and negate the slow starter. If it is flooded it should start with a huge smokeshow...if it is something else it won't start.

If it is an AT car..the whole deflooding thing is a lot harder to deal with.

BigCajun 08-19-2017 04:08 PM


Originally Posted by YukiNoKo_BB (Post 4832401)
Would it help more if i said my car sounds exactly like those flooded ones on youtube. Not sure if its that but it sounds pretty darn close

Did you try pulling the engine fuse?
I've flooded 3 times, ( I can tell when it's flooded and have never checked my plugs first) and this method always worked for me;

Be sure battery is fully charged, battery terminals are clean and tight ON THE POSTS.
The bolts can bottom out and it seems tight, but they will stretch over time.
I've used post caps or shims instead of replacing the cable clamps.
If you don't have a charger, first be sure your battery is good, (if you're not sure, have it tested) then hook the charger or another battery as a jumper, in or out of another car.
BE SURE YOU DON'T SWAP POS. & NEG!

Pull your small fuel pump fuse in the box under the hood.
Crank your engine for 10-15 seconds, then wait a few minutes as to not burn up your starter.
Do this several times then replace the fuse and attempt to start normally.
If it doesn't start right away but sounds like it might start, it could flood again, and start over, maybe trying a few extra turns.
If it still just spins without any signs of starting, then you'll have to do a proper troubleshooting method.

BigCajun 08-19-2017 04:12 PM


Originally Posted by BigCajun (Post 4832434)
Did you try pulling the engine fuse?
I've flooded 3 times, ( I can tell when it's flooded and have never checked my plugs first) and this method always worked for me;

Be sure battery is fully charged, battery terminals are clean and tight ON THE POSTS.
The bolts can bottom out and it seems tight, but they will stretch over time.
I've used post caps or shims instead of replacing the cable clamps.
If you don't have a charger, first be sure your battery is good, (if you're not sure, have it tested) then hook the charger or another battery as a jumper, in or out of another car.
BE SURE YOU DON'T SWAP POS. & NEG!

Pull your small fuel pump fuse in the box under the hood.
Crank your engine for 10-15 seconds, then wait a few minutes as to not burn up your starter.
Do this several times then replace the fuse and attempt to start normally.
If it doesn't start right away but sounds like it might start, it could flood again, and start over, maybe trying a few extra turns.
If it still just spins without any signs of starting, then you'll have to do a proper troubleshooting method.

https://www.rx8club.com/series-i-do-...lumber-182410/

gwilliams6 08-20-2017 01:36 PM

yes sometimes serious seeming issues have just been flooding. Try the deflooding first.

Though if your engine is right and all parts of the ignition system are in top condition, you should never flood, even if you turn off engine before fully warmed. .

I have never flooded, not even once, in nine years of driving my 2008 RX8.


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