Hey everyone, I spent today searching the forums about a hard start I have been experiences, took some ideas from all that reading and ran some tests today and wanted to post the results to see what everyone thinks. I have about 8,000 miles left and if I need a new motor I want to figure it out now....if possible....

I have an 2004 RX-8, 92,000 miles
OEM
-coils (original)
-starter
-engine

Changes
Plug wires changed within 6 months
Spark Plugs changed 1000 miles ago
changed the O2 sensor about 60K miles back
oil changed religiously every 3000 miles

Coils
First thing I checked was the coils

Manual Specifications
A-B- infinity or 0 ohm is abnormal
C-B- infinity or 0 ohm is abnormal
C-A- 0 to several kiloohm is abnormal

Coil 1
A-B-1.81 kilo ohm
C-B- greater than 1 kilo ohm (limitation of my multimeter)
C-A- greater than 1 kilo ohm (limitation of my multimeter)

Coil 2
A-B- 1.64 kil ohm
C-B- greater than 1 kilo ohm (limitation of my multimeter)
C-A- greater than 1 kilo ohm (limitation of my multimeter)

Coil 3
A-B- 1.72 kilo ohm
C-B- greater than 1 kilo ohm (limitation of my multimeter)
C-A- greater than 1 kilo ohm (limitation of my multimeter)

Coil 4
A-B- 1.72 kilo ohm
C-B- greater than 1 kilo ohm (limitation of my multimeter)
C-A- greater than 1 kilo ohm (limitation of my multimeter)

RESULTS: to me this looks like the coils are within specs

Compression
Now compression checks (I know this is not the Mazda official test, but just a test)
-Recharged the battery to 100% before every test for consistancy
-Measured both the trailing plugs
-Front Plug measures a little less than 80 psi
-Each faces is about ~59 psi from each of the pulses
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-Rear plug measures ~80 psi
-Each Face is about 59 psi from the pulses
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Anyone in the Space Coast of Florida that has a rotary compression guage for a more accurate readings? Otherwise I'll bring it into the dealer.

My next step was to hit the starter. I was going to remove and and run some diagnostics on that.
Any thoughts would be awesome!

Thanks everyone!

 

Wait a second................your C-B readings are infinte, that makes them out of spec.
You sure you measured them right?
You never mention how old the coils are.........typically 35k is too much.

Anyway.........after all that, I think you know this, but you could have the older weak starter.
If you have an OBD scanner............You would like to see 300 RPM or higher. The original starter was rated at 250, but often produced only 175 RPM.

Is your battery voltage okay? I'm assuming if you checked the coils then you have a meter, so what's the battery read with car off and what does it read with it running?

Don't have a compression gauge, but need to know what rpm you did it at(should be 250). Take a look at this thread, it may be of real use to you! Sounds low though.

https://www.rx8club.com/series-i-do-yourself-forum-73/diy-renesis-compression-adjustment-rating-excel-application-180043/

 

Hey sorry about the measurements, I realized they were reading 1, which is the highest my multimeter will go, I updated it above. Infinite would read 0. Coils are original, never saw a reason to change them since they are within spec.

Oh yeah, I mean to say I put a charger on the battery and made sure it was 100% at the beginning of every test.

I'll borrow an OBD scanner tomorrow and check RPM of the starter, that might be easier than removing it.
Thanks, let me know about your friend in Melbourne. I'll pay for his time or use of the tool.

 

What do you think about the overall/average compression of 80 psi.....seems low doesn't it?

 

Go re-read my post above, I edited it.
I will contact the guy over in Melbourne and see if he has one.

You have 92k on the original coils? You are one lucky bastard!
It probably doesn't have anything to do with warm starts, but I'd change them really quick!
There are some decent prices through vendors on this site..........don't go to the dealer for these!

Hopefully it's not the CAT(and not likely it is) as you're out of that warranty by 12k miles.

 

Hey Mazurfer, thanks for the link, I read that earlier, but I really need to rotatory compression gauge to get some good results.

Why replace coils when they are within spec? or more importantly I don;t want to replace them if my engine is bad.

 

True, warm start issues is usually a sign of low compression(as you know). But................since you have an 04, it could be the starter.

 

It depends on the RPM of the test....

At 250 RPM, the standard is 120 PSI with a minimum of 98.6 PSI, a chamber difference of 21.8 PSI and a rotor difference of 14.5 PSI.

 

^............yep.................gotta know the rpm's to make sense out of it.

 

sounds good, if the Melbourne connection doesn't work out I'll head to the Orlando dealer and ask for a compression check this weekend.

I hate to spend 400 on a starter if they replace the engine, but I am afraid that is what they might make me do before they consider replacing the engine.

Thanks again everyone.

 

Curious..................don't like Boniface down here in Melbourne? The few times I've been there they have been good. They do have the #1 Mazda Tech in the world. https://www.rx8club.com/lounge-4/can-mark-wilhelm-really-1-mazda-tech-world-155639/ Even though PBlue had an issue with them........Mark ain't gonna be doing oil changes!!!!

 

Oh, Orlando is just closer to me than Melbourne....Maybe Melbourne might be the better move, if I get Mark.

 

So here is my plan:
1. check the battery tonight, I'm sure it is fine since it was just replaced with a DieHard maybe 6 months ago
2. Replace the starter, since 2004 RX-8s are know to have slow starters I'll drop $100 (at autozone) and replace it and see if it starts up any quicker.
3. recheck the compression numbers against mine, just for comparison

good start?

 

Does your guy in Melbourne have one?

 

heads up..

hard starts can be had by dirty injectors...

but my compression tester is in melborne.. go figure.. bastage has it..

get to him..

beers

 

Oh............thanks Scott.

If the OP still needs the tester, you mind if I get it from Gleyner for a few days?

I need to give him a call, we were supposed to get together a couple of weeks ago and I need an update on how his motor install went or has been going....along with the SC??? I'm so outta touch! I wasn't even aware of what happened until about a month or so ago
when I last talked with him and think at that point it was all installed and just in the break-in period. I told him he should've called me and I would've helped out! I don't even go into the Pettit thread any longer as it's too long and doesn't work well on my computer for some reason.

Which tester is it.............Is it the TR-01 from Twisted Rotors? I've been wanting to get a look at that!

 

starter sound hella weak, check this out http://www.vimeo.com/3653485

 

I replaced the starter today with a Duralast RM one from autozone. My compression is up, 89 for the rear and 107 for the front.

Starts up much better, but would still like to test the compression. Hopefully borrowing the tester sometime this week.

 

If you have 92k miles on your ignition coils, replace them now. Even if they test with in spec they could be failing. Mazda even stats they should be replaced every 30k miles.

 

Where does Mazda state that? Not in the owners manual......

 

Sorry had them mixed up with the spark plugs. But still 92k on your coils is almost unheard of. Trust me replace your coils and it will feel like a band new car agian.

 

Got the compression check done today

Front Rotor
http://www.youtube.com/watch?v=q6XFHmNAyuo


Final Front Rotor Readings were
102 psi (7.17 kgf/cm2)
100 psi (7.03 kgf/cm2)
100 psi (7.03 kgf/cm2)
288 RPM

Rear Rotor

http://www.youtube.com/watch?v=OeZtSkSC5XQ


Final Rear Rotor Readings
100 psi (7.03 kgf/cm2)
97 psi (6.82 kgf/cm2)
99 psi (6.96 kgf/cm2)
288 RPM

From the mac program


So is my engine good or "no good"?

 

Okay so I scaled the numbers down to an 250 RPM and get
Front:6.19, 6.07, 6.07
Rear:6.07, 5.89, 6.01

Based on the mazda spec, the minimum should be 6.9

Any help is appreciated.

 

Hey man, it was good meeting you yesterday.

It looks low for that RPM. I did PBlue's car on Tuesday and he was getting all low 100's at ~238 RPMS.

Definitely take it to the dealer.

 

Compression at 250 RPM=(Test Compression*98.0665/1000+(-0.514*LN(Test RPM)+2.8283))*1000/98.0665

Corrected to 250 RPM equates to below spec of 6.9. Looks like worn apex seals.

Front 6.3/6.2/6.2
Rear 6.2/6.0/6.1