AMCheff

Just purchased a 04 Mazda rx8 and everything seemed fine until a month or so ago. I started to experience problems starting the vehicle it would just turn over and just keep cranking until it started to turn over faster then it would start, but the real problem is getting it to stay on without stalling. Every stop a light and things drop lol the rpms drop to about 800 and it's hit or miss if it recovers or just stalls. So far I have had the intake manifold taken apart and cleaned out the intake valve, had a compression test with a result of 70 50 I don't know if that could be and underlining issue and what should be done to fix it, I'm not exactly a mechanic. The spark plugs and wires where changed as well as the ignition coils so if you narrow it down, I'm really not to sure what is causing it to still take so long to start and keep it from stalling at lights. Any help at all would be greatly appreciated. Thank you....

AMCheff

Any help???

TheClemsonFan

I would start by getting a rotary specific compression test. I am not sure what 70 50 is, but is not the results of a proper compression test.

You should have gotten numbers in a format something like this:
Rotor 1: 7.5, 7.6, 7.5
Rotor 2: 7.2, 7.3, 7.3
250 RPM

AMCheff

It could of been 7.0 and 5.0. I'm not too sure. Is there anyway to go about fixing the compression numbers dropping so low before it's unrepairable or is that still a safe number.

AMCheff

I believe that that compression test was measured in psi

sonicsdaman

iTrader: (3)

OP have you read through the new owner thread ->https://www.rx8club.com/new-member-f...t-here-202454/
check the battery terminals

regardless of rpms 7's are borderline falling comp


Edit: more info will help us interwebz diagnose

AMCheff

50 psi is not even on the chart...could it possibly be an apex seal that needs replacing?

TheClemsonFan

It could possibly be any number of things. But if you have low compression you will need an engine rebuild.

AMCheff

I'm gonna have another compression test and get back to ya

nvsrx8

Hey, guys I just found this Conversation, mine is doing the same thing. What ended up happing with your car? Did you need an engine rebuild? I have already had one engine rebuild. I am not keen for another.

TheClemsonFan

I would read the following links, and then start a new thread detailing your specific issues.

https://www.rx8club.com/new-member-f...t-here-202454/

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

Loki

iTrader: (1)

You guys need to get some actual data. It could be any number of things from a vacuum leak to a worn out engine. Get hold of a Bluetooth OBD adapter that lets you read the engine data on your smartphone. Look at engine codes if any, fuel trims and air flow reading at idle. And a compression test. Report back with numbers

lOOkatme

I have the same issue and I am at high altitude. my car was not doing it at lower altitudes when I drove it up here.


My compression was measured in PSI and one rotor was at 105PSI and one at 85PSI all faces the same. we used my buddies rotary compression tester.


I did a water treatment and I am trying to get the compression of the first rotor higher. it seems to be working with time and slowly as the idle is getting better over time and the car seems to feel like it has more power, we'll see when the temps get hotter here. still doing more testing. My idle has a little over 5 G/S from the mass air flow sensor and I don't think its a vacuum leak.


at lower altitude the compression is 106PSI and 131PSI.


I have replaced a lot of things already as the car was throwing cods every where. so new spark plugs, new coils, new and flow tested fuel injectors (only 3 are new, 3 could be reused), new SSV solenoid, new MAF sensor, etc.




I watch my AFR's at idle and they are going to 17AFR when the car is hot. mine only has issues when the entire engine is heat soaked. It does not do it till 30 minutes warmed up and if the engine bay is hot. If I keep the engine below 82C or so the engine seems to idle fine, when the engine gets above 95C and with the fan off (the inside cabin fan, not the radiator fan) the engine idle fluctuates sometimes and sometimes mine dies. If I get the engine and bay super hot the engine wants to shut off every time. super hot being over 100C temps. I recently ducted my radiator and its keeping temps a lot lower. I also had my fan on inside and the idle AFR was 14.7AFR and the car was idling much stronger and fine. really weird.


I also notice the voltage fluctuates before it dies (when fan is off). It seems like something is drawing power and messing up the engine or shutting it off. It fluctuates down to 12.5V (I think the voltage is causing the shut off, not the voltage fluctuating because of the shut off, but its tough to tell). so I am going to dielectric grease and make some good grounds to ensure this is covered. I do think the rotor compression difference might be a contributor so I am driving the **** out of the engine and trying to get the compression back up in rotor 1. I will probably do a couple more water treatments to the engine as well over time to loosen up any carbon inside the engine if that is the root cause of the lower compression.




Thoughts: Could the difference in rotor compression cause an issue? Is the issue that one rotor is spinning at a faster rate so to speak than the other which then throws off the timing for one of the rotors? Could this be a fuel pump going out? or is the resistor at idle going bad to the fuel pump causing low fuel pump pressure and voltage fluctuations?

lOOkatme

Problem: Car runs great when cold, when car is driven for20-30 minutes continuously the car will sometimes die at idle. I canimmediately turn the car back on with no issues and the car may or may not haveidle issues. Idle fluctuates beforedying most of the time. Typically the car will die after being driven andcoming to a stop, it will slowly bring the idle down and either die orfluctuate for a while then die. Only happens when the car is heat soaked hot,won’t if the car is warmed up but not heat soaked. Car is new to me andpurchased dirt cheap, 130K miles on it. Keep in mind that I don’t have abaseline for some of the cars capabilities and I am unsure if the car isrunning at 100% at WOT. I am also 6,300FT above sea level car was purchased atsea level. Seems like car developed this issue at altitude. The car had badspark plugs and ignition coils before I got it. It also had a failed SSVsolenoid, bad MAF sensor and dirty fuel injectors. These are all fixed. I havethrown codes at one point in time for P2096, P0171, P300, P301, P302, P661,P101,

• No check engine lights.
  
  
  Parts replaced and or cleaned due to othercheck engine lights.
• New MAF sensor (lifetime warranty).
• New O2 front sensor (Denso).
• New spark plugs (NGK Ir). 9’s and 7’s
• New ignition coils (stock oem, made in poland).
• Re-used Magnacore wires (20-30K on them fromwhat I understand)
• Added grounding kit, re-used speaker wire fromthe person before me 8 GA thickness.
• Flow tested fuel injectors, Had to buy 3 newones, re-used the 3 old ones that passed after cleaning and flow testing.
• Replaced a few plastic elbows on intake when Ibroke them.
• Added sohn adapter, lines look to be filled with2 cycle oil and consumption is normal (issue existed before the install ofthis)
• Added catch can, but catches nothing.
• Knocked out cat convertor, although it didn’tlook horrible.
• New battery, Duralast Platinum AGM
• New 2KW starter
• Cleaned ESS sensor
• Cleaned TB
• New Purge Solenoid

Troubleshooting

• Checked all solenoids cold, all held vacuum whenoff, no leaks. Didn’t test hot, and I didn’t test the function of them but theyseem to function well when driven.
• All vacuum lines inspected and look to be ingood condition including the OMP vacuum lines.
• Inspected UIM and doesn’t seem to have anyvacuum leaks or holes/cracks in it. That includes everything on the assembly.
• Looked at the hose from the intake to fuel rail,didn’t look like it had any issues with it, this would be the fuel atomizationline correct?
• Used brake cleaner and shot around the throttlebody, intake elbows, UIM joints, etc. no leaks in these areas. I am unsure howto check the fuel injectors since they could have leaks although I did acareful job with reinstalling them.
• SSV and the other one function correctly with amityvac, they move freely open and close.
• With engine running cold the vacuum of the carpulls a steady 12.5 IN-HG.
• When hot, difficult to tell but the engine pullsaround 10-12.5 in-hg but keep in mind that the engine idle sometimes fluctuatessome. If the engine is steady (hard to look at the gauge outside the car andsee rpms at the same time) it would be a slow lazy move between 10-12.5 in-hg.Points to a vacuum leak I think????
• Vacuum at 2500 rpms held for 15 seconds heldvacuum great, no muffler restriction I can tell of.
• Vacuum rises when throttle closes after 2500rpm release, showing it is drawingmore vacuum, spike is in the 18-20 in-hg range.
• Added a little bit of 2 cycle oil directly intothe rotors through service ports via vacuum, engine vacuum remained the same,no increase or decrease in vacuum.
• Engine runs well through the entire rev range,remember that I have not owned this car for very long.
• Idle moves around when electrical loads areplaced on the car. Idle tends to dip when fans kick on or lights turn on(headlights). The car does have aftermarket fans on the oil coolers from theprevious owner.
• Checked Alternator at Autozone, checked out goodwhen cold.
• Disconnected A/C and idler pulley belt, nochange to idle.
• Checked function of TB and the TB opens andcloses, We noticed that the throttle body would open at like 50% throttle. Notsure if this is normal with the car off and just checking function, but itopens all the way and moves slowly back to position if you slowly let off thegas. Function of TB when car is on is smooth, no hesitation is observed.
• Car sounds normal when running, an occasionalsmall backfire rich AFR sometimes if you blip throttle off idle.
• Rear O2 sensor has a wire going to itexternally, looks like previous owner wired something to it? Perhaps to preventthe check engine light to come on?
• Air filter is clean, K&N, cleaned it andsprayed minimal oil onto filter.
• Lights sometimes dim when idle dips, not sure ifthat is just a function of the alternator slowing down or what, but it’s notanything major. Lights are steady when the car is moving. Sometimes when thecar is about to die the red battery signal illuminates but goes back off, itflickers for less than a second, and not all the time.
• No intake leaks that I can see on the tube.
• Intake filter is installed properly.
• Purge valve seems to work when car is on, canhear it pumping the entire time, at least when cold.
• Car does this idle thing either in neutral orwith the clutch pushed in.
• Plugged brake booster inlet to UIM, no change inidle.
• Pumping the brake does make the idle go crazy,seems like hills also makes the idle move around.
• Installed new alternator and the voltage issteady now and removed some aftermarket fans that caused huge dips in voltage.
• Pulled all spark plugs and they all are tan incolor. All looked very good.

Loki

iTrader: (1)

Jeez, your forum name is spot on. Start your own thread please, troubleshootinf 3 different cars in 1 thread is not going to be effective.

lOOkatme

I was hoping that my problem and the thread starters are the same.

AMCheff

just a little encouragement while we are all trying to sort out our problems lol

AMCheff

I guess that wasn't the finest of j0kes

stucky22

iTrader: (1)

Did you find what's at fault?

TerryG

I have a 2005 RX 8 that had a first engine replaced at only 20K back in 07, then 2nd engine replaced in 2013 due to storm water taken into engine on a flooded road. All has been great for the last 4 years except the car just out of nowhere decided to crank fine but runs rough idle for about 20 to 30 seconds, then calms and runs fine but after a few minutes will drop below 1000 rpms and shuts off. Always cranks back up easy and smooth after first time. Runs great on road but once at red light is starts dropping below 1000rpms and does same thing. Had taken to Mazda Dealer and after cleaning and replace Maf sensor and 3 days or returning with same problem they changes spark plugs and wires. $1100 later it's still doing the same thing. Any help here what to try next? They are saying could be engine needs replaces AGAIN! Why would it run so great otherwise with no sputtering at all?

Loki

iTrader: (1)

Are you getting your $1100 back? I mean they're just throwing parts at the problem, seemingly without proper diagnostics. The Mazda shop manual is very specific on troubleshooting and diagnostic steps for these types of problems. Replacing the MAF is not a diagnostic step unless it's proven to be broken. They can confirm if it needs a new engine by performing a compression test. A Mazda dealer should know this.

Is the check engine light on? Are there any codes? Have the ignition coils been tested/changed? That's a VERY common failure point, which again a Mazda dealer should be familiar with.

Is there any smoke or smell from the exhaust? Are you losing oil or coolant?

Can you start your own thread in the New Member section, rather than bombing someone else's?

TerryG

I know was a waste but I don't trust them now. Went to autozone to try computer reading..no lights, no codes. Sorry first time on here wasn't sure how to post. No engine lights,...they say it might need engine but it runs so good otherwise and cranks up everytime. This only has 50k at the most on a new engine. No leaks or oil loss to my knowledge. Only has smells when idle is going crazy but smooths out quickly after cold start. Then cranks up fine once warm. 2nd mechanic says might be engine starting to fail but when I replace the other engine it never did this. Just never stayed cranked and was shaking like crazy. Totally different feel than then. They didn't replace coils but at this point do not want to put more money into...just want to sell and buy another larger vehicle anyway at this time. Had Autozone put on computer again just for another option and there was no codes coming up.

Loki

iTrader: (1)

Ok well if the coils are older than 35k, you're risking the engine by not changing them. This will be an important point for whomever you sell it to, or they'll be on here the day after purchasing asking why the need a new engine. This should have been the first thing the dealer called out and tested. Seriously, I would go back to them to get money back. $1100 for a MAF, 4 spark plugs and 4 wires is INSANE.

You can get new coils at Autozone for about $200 and if you're at all handy, you can replace them yourself, it's easy.

AMCheff

well, as of right now im kinda in standby mode, driving my Buick, i haven't really figured out what the underlining problem is officially. im still assuming that its the apex seal. according to the guy at advanced auto, they start to go at around 90000 miles and im just over that. i noticed the other day that it was running a little rich and exhaust fumes where poring out of the back. im starting to wonder if it could be a starter or something more than just a apex seal. the vehicle is still taking 3 to 4 cranks to start then stalling at red lights so im not to sure. its off to the dealer within the month, so ill keep you posted.

Z3R0

SO I recently started having this problem on my 2004 RX8 6 speed. I've had my car for a little over a year now and it was running fine with no issues. Almost a week ago, on my way back from the store, my car died on me at a stop light. There was no sputtering, or jerking just a smooth drop in RPM until it stalled. I was able to get it home by keeping the RPMs at 1k. My car has 133960 miles on it. The car would only stall after it was warm but when I first started it, I had no issues until it reached normal operating temperature. I was able to fix my issue today. I changed my coils, plugs, wires and air filter. I also cleaned my throttle body and mass air flow sensor. After I did all of this, not only did it stop stalling but I had much better throttle response and it felt like it was running much smoother in the higher RPMs.