Red-Devil

I had to take my RX8 in for some tests due to poor performance above 6000 RPM. After changing oil and sparkplugs there was no change.

The compression test revealed:

Rotor 1: 670, 628, 701 kPa or 97, 91, 101.6 psi
Rotor 2 : 699, 730, 676 kPa or 101.4, 105.9, 98 psi

It also has the G vesion of PCM firmware. Note this is not a USA spec car, so I don't think the M-flash is applicable here in South Africa. However, the compressions should be standard and these look way low.

There is a small chance that the throttle position sensor is faulty too....

Please comment.

Red-Devil

That is what I read in one of the other threads, but I would like confirmation and an interpretation of what the implication is. The car only has ~600 miles on it.

Red-Devil

My 8 now has 950km (<600Mi) and has the following compression values:

Rotor 1: 670, 628, 701 kPa or 97, 91, 101.6 psi
Rotor 2 : 699, 730, 676 kPa or 101.4, 105.9, 98 psi

This is much lower than what I read it should be in another thread. i.e. 123psi and the variation is as much as 10% What does this mean. Should I ask for a new car? I'm not prepared for Mazda to swop engines or open up this one.

Does anybody have the official specs and tollerances?

Thanks in advance....

Red Devil

Huh, I saw the thread with "Red-Devil" at the beginning and missed the hyphen at first. What are the odds someone else has such a similar moniker on the site?

Mine came from back in High School after my red FC Turbo beat another guy in school that had a V8 Mustang. All the rednecks nicknamed the car "Red Devil" after that because they couldn't believe such a small engine could do so much.

ezrider55

From Service Manual
Standard 120 psi
Minimum 98.6 psi
Looks like you have a compression problem.

zoom44

red-devil i merged your 2 threads. it will be simpler for others to keep up with just one thread.

Red-Devil

Ok, So I raise this concern with Mazda and they tell me not to be too concerned. They say the mileage is still very low and as the seals are very hard they take long to break-in and form a good seal, hence the required compression values.

Can I buy this explanation?

wakeech

heh heh, ask them to give it to you in writing

Mr M

The G flash is the same level as the M. Different markets have different names for the flash.

Your compression is out of specification, and it is not likely to come back into specification as the mileage increases. Make sure the dealer had the throttle open and the engine was warm when they did the check. This is the correct procedure. Maybe you can politely ask the dealer to consult with Japan about this?

Good luck

Red-Devil

The plot thickens:

I have now put serious pressure on Mazda. They need to prove to me that the compression is within an acceptable spec for the mileage. They will also have to give me guarantees that the compression will be within spec within a certain maialeage.

It turns out though, that the throttle position sensor was faulty and hence the power loss etc. It may also explain the low compression values, if the throttle was not opening fully or properly.

Does this ring true to anybody?

Mazmart

iTrader: (12)

That makes sense. One other point that nobody has mentioned here is cranking RPM. Very important in relation to compression. Your car should be perfectly fine.

Red-Devil

I took on "Red-Devil" because, by some stroke of good/bad fortune, I got a registration number with "666" in the number. My 8 is red, plus I am going through "hell" at the moment. The car is one "hell" of a ride and makes me do all sorts of "bad" things :D The list could go on... :D

mlx8

Red-Devil
Where are you in South Africa? I believe your compression readings will vary with altitude. If the static 123psi number you quote is a figure given for sea level readings, and you're in Johanesburg at ??? meters, the numbers are going to be significantly lower than in, say Durban.

Perhaps of more concern would be looking for some kind of factory standard for maximum allowable varriation between cylinders/rotor readings. Looks like you have a "low" of 91psi vs. a high of 106.

HTH

mlx8

Oh, and for some "old school" advice try taking a look in
http://www.scuderiaciriani.com/rx7/c...sion_test.html

Red-Devil

Thanks mlx8

I am in Cape Town, which is at see level, so I should not have to make any corrections to the stated values. Mazda is busy with this problem. They have to prove that the compressions are within spec for the mileage by means of proper factory test specs.. Surely these cars are tested in the factory as part of the quailty control system. Compression testing is a good test and I would expect it to be part of the programme. There should be a spec for it at least. The other thing that my local dealer will be doing is to test 3 other cars: a 9000 km one, a 5000km one and a brand new one.

I must say the response from Mazda (Ford in this country) and my local dealer has been very good and they are doing all possible to resolve the issue. However, if I do not get satifactory proof, they will have to give me a new car that meets the specs, or my money back, period.