harithac

Hi My 04 RX8 acts strange with AC on , it just dies when slowing down or stopping the car sometime.

Took it to the local rotary garage. And they say its my AC Compressor.
Because I don't have a good history with my cars AC as I used it for a year with a refrigerant leak . What I did was I always topped up r134 whenever it got empty . And it got worse so I replaced the condenser and the evoparter but the leak was yet there so we narrowed it down to a AC hose which was the culprit to cause the leak and got it fixed .
This stalling issue started like 2 or 3 months before even with the time I used it while topping up r134.

So as they say could it be my Compressor which cause me all this trouble.

Addition to this . My friend told me this could be happen if I have a vaccume leak so .. with regard to that once my brake paddle got so stiff and brakes didn't work at a moment and it went away as I put my gear to park and rpm raised automatically and it never happened again. Oho also I heard a whistling noise similar to a pressure cooker . But if its a vaccume leak can it only stall with AC on . as my theory is if its a vaccume leak it should stall even without AC

So what would you guys think .

harithac

Bump

9krpmrx8

iTrader: (46)

Engine ----> Symptom Troubleshooting.

M A Z D A

also check out rx8help.com

harithac

I checked today for a vacuum leak and I couldn't fine any ..

Latest update is that now the car just dies whenever I switch on the AC when coming to a low RPM

Loki

iTrader: (1)

It's not your compressor. AC puts extra load on the engine, a load it's not able to sustain. There are a few possible reasons from vacuum leak to failing ignition coils to low compression.

What's the history of the car? Were ignition coils and spark plugs replaced recently?

RX8Soldier

iTrader: (24)

Herithac, this is why you shouldn't start new threads on already existing issues. You have info in your other thread that members who are trying to help you out are missing right now.

I suggest you pm a moderator and see if they can merge the 2 threads.

It sounds like you have vacuum or compression issues.

harithac

Yes they were replaced on 14,000 KM"S before. (Pugs , coils and wires)

And I did notice a strange thing which is when I rev the car I doesn't rev as it
Used to .. its different now like when ever I pump the gas to rev , it just takes a time to rev like it pauses it self and then rev

harithac

Hi ... was so desperate to Sort out this matter. Yes I will pm a moderator to see if they can do so.

Now Sir this is the issue I need to exact troubleshoot this issue and fix this as I don't want to spend money on stuff which is not broken.

So far narrowed it down to 3 possible reasons
1.) AC Compressor
2.)Vaccume leak
3.) Bad coils plugs and wires

What delar suspects is the AC Compressor might be bad . Because all symptoms leads to that.
According to delar why he suggest AC compressor need to be changed is


# AC is not cold on idle only works perfect when driving the car continues.

# Car idles fine , run smoothly without AC

# using the car for a year only by topping up AC refrigent and not fixing the leak might have weak the compressor and to seez it.

**3 months earlier they inspected coils and plugs when I did a tune up and they said they were pretty good .
So they said it cant be the issue ..
Because car wont show any symptoms of a car that haves bad coils and plugs ...

But yet I need your precious opinion because you guys have helped out me to exactly pin down some issues I had and it saved some lot of cash ..

04Green

iTrader: (1)

Welcome.

It is best to do the easy stuff when troubleshooting a problem. Make sure as much of the car is running right as possible. I suggest you start with the Congrats thread, stickied above, and do any of the steps that include the word clean. I would look hard at the grounding kit, but just the star washer version, not buying a kit just yet. That may help. If not, and you do not know how old the coils are, search for a thread on how to test coils. There are a few. The tool is cheap, and will help sort that one.

I am curious as to what the tune up did if all they did was inspect the coils and wires. To me, a tuneup is clean things, replace coils - plugs - wires.

Let me know how it goes.

harithac

Mary Christmas 04green

as you have suggested I did clean all the ground wires and the maf .. and yes there is a significant improvement n the idle and the vibration . But yet when in Drive with AC on it vibrates and feels like about to stall but not like it used to be . early it was a mess ..but yes now it has been improved much more. But is still stalls down.

and sir there is this slight delay when I rev the car freely . When I put my foot in the gas padle it goes a little bit down and then only it comes up ..

Yes as in the tune up they only visually inspected coils and plugs and told me they were good ..

But yet they have cleaned all the other necessary parts that need to be cleaned like the injectors.

Loki

iTrader: (1)

This all sounds like a vacuum leak, including the delay in throttle response.

Visual examination of coils doesn't really mean anything. There is a procedure in the Mazda shop manual for this car on how to correctly diagnose coils. However, you say they were change 14k km ago, so while not impossible, it's less likely that they have failed. A proper test would confirm this.

Do you have access to a OBDII monitoring tool, be it a professional one or one that works with your smartphone? It would be great to get STFT and LTFT data to help diagnosis. Perhaps your mechanic can help you get this and bring the data back to us? You want a set of readings at idle and if you can manage it, when you press the gas and observe the delay you describe.

Some other simple things that may or may not help: with the ignition on but engine not running, press the brake pedal 20 times in quick succession. This procedure clears some of the computer's memory so it can relearn some sensor inputs.

Is your mechanic familiar with RX8s in general? It's best to work with a specialist as some general mechanics don't understand the rotary and end up wasting your time and money.

harithac

Hi Loki Mary Christmas.
I did the clear the NVRAM that 20 brake padle procedure. When I do it and drive, it holds the idle for couple hours without stalling the car probably a day with AC on .. but yet again the car stall when ac is switched on when coming to low RPM. . After that time period .Then I cleared it agin yesterday but now no luck at all .

As you told I did note down the STFT & LTFT readings

As I started the car
GEAR IN PARK
STFT - 0.0% and -1.6% ( it fluctuate within these two digits)

LTFT - -3.9% and -7.0% did fluctuate within these two digits .

GEAR IN DRIVE

STFT 0.0
LTFT -1.6%
=============================
After a while letting it idle

GEAR IN PARK

STFT -2.3% TO -4.7% Did fluctuate within these digits

LTFT -1.6 STABLE

GEAR IN DRIVE

STFT 0.8 % TO 2.3%

LTFT -1.6 TO -4.7% BUT MOSTLY WAS N -1.6
===========================
and when raving when that delay happens .. when rpm goes down LTFT ALWAYS COME TO 0.0 % AND THE GET +

harithac

Hi

Today also I did bit of look out at STFT & LTFT

After one and half drive I checked the numbers and in IDLE

LTFT WAS settled down in -5 5%

STFT was 1.8% to -3.6% fluctuating within ..

AND ALL THE REDINGS ARE WITHOUT A/C ON...

harithac

Hi guys...

Monday I gave my car to the dealer to properly diagnose this problem .

And yesterday they came up with a possible cause for all of this ..

What they say is they have diagnosed my rx8 and when the AC is only my engine load is two times the normal rate and AC pressure is also really high than normal rate . So that could be the reason my car stalls down when AC is on.
and they say this problem can be resolved by replacing the expansion
Valve and flushing the AC system ...

so guys what would you"ll think.

04Green

iTrader: (1)

How much did they want for all of this?

If the load is too high, it could be part of the problem. The fuel trims above do not indicate a vacuum leak. You would have high positive numbers at idle if you had a vacuum leak.

An interim fix would be to pull some of the freon out to get the pressures in line with what they should be, and see if the idle improves. If the pressures are right, and the AC works, you are good to go. If the pressures are right, and the AC does not work, looks like expansion valve. I need to do one on my sons car for this very reason. Do you know if any AC work has been done to the car?

harithac

Happy new year 04green...
they have still not given me a price. I will be getting the car on next Wednesday.
They said the total cost for all this will be around 200-300$

that's a relief when you said it can be a part of the problem.. as to know that they are in the right track.

yes they have reduced the feron and tried but there were no luck .

So far they have removed the dashboard to remove the expansion valve .. and they said I will be needing a new Condenser filter after the flush.

04Green

iTrader: (1)

If they can do this for that price, and they said that is what is wrong, likely not too bad.

If it runs fine, except when the AC is on, that is the first place to look. After that, motor may have an issue. AC is cheaper than motor...

Good luck! Happy New Year!

harithac

Hi . Finally I got the car back
And everything is fine now , problem have been as 04 green confirmed is a blocked expansion valve , blocked AC condenser,

Replaced the valve along with compressor and car is fine ...
Thank you everyone for the kind help..