DISI Compression Results

[shpankey]

I think my low compression is coming from the timing slipping a tooth. Isn't there a known issue about the tensioner on our cars and it being loose? If so can someone link me to that thread. My compression tests perfectly 130 across the board but I don't think it's worn rings.

When I go WOT and do a hard pull, I can feel tiny "surges" (for lack of a better word) where my car pulls real hard like it used to, then goes back to meh, then hard then meh. Sometimes this come in terms of reciprocal surges, sometimes the whole pull is meh and on very very VERY rare occassion it pulls hard all the way.

This is not to say that the car runs like garbage. It is still a fast car, as evidence of dusting a 2000 Mustang GT in a most embarrassing way. Though I was fortunate that was one of the times the car decided to pull hard, lol. It just doesn't run or pull like it's supposed to most of the time. You can decidedly feel it when doing a pull with these surges.

I'm convinced my timing is somehow slipped a bit. I have new plugs (NGK Stock Iridium, pregapped) and just recently cleaned out the EGR and pipe. But yet I still experience an odd idle most of the time. I still plan on stocking out oneday soon when I get some time, and take it to the dealer. I only have a few bolt ons. I'm just really busy and when it comes to downgrading the car, somehow lazy. lol

[darth vader]

Dude, if your engine timing had "slipped a tooth" you'd be picking up pieces of your engine not dusting off Mustangs. The valvetrain is chain drive not belt so, it's pretty unlikely that the cause of the low comp is a mis-timed engine.

Do a leakdown test to determine cause of low comp. Air out the crankcase oil fill is rings, air out the exhaust or intake is valves on that side of the cylinder.

[8.5MS3]

did mine yesterday

2008.5 MS3 16k on the ODO

Drivers side
185
185
183
185
Passengers side

[gsrtype1]

Did mine this morning, I'm almost at 73k. I don't know if this was normal with the gauge when I would crank it would go to target but then lose pressure quick. Like cylinder 1 would to 180 but it would drop so fast by the time I get out of the car to look its at 150 psi. Is that normal for the gauge to drop so fast?

From passenger side.

1. 180
2. 175
3. 160
4. 170

I think pretty decent for my mileage, driving habits and mods. Isn't there a roomer that cylinder 3 gets low because of the balance shaft? If thats tru then next mod.

[2007speed3]

Originally Posted by gsrtype1 Did mine this morning, I'm almost at 73k. I don't know if this was normal with the gauge when I would crank it would go to target but then lose pressure quick. Like cylinder 1 would to 180 but it would drop so fast by the time I get out of the car to look its at 150 psi. Is that normal for the gauge to drop so fast? From passenger side. 1. 180 2. 175 3. 160 4. 170 I think pretty decent for my mileage, driving habits and mods. Isn't there a roomer that cylinder 3 gets low because of the balance shaft? If thats tru then next mod.

The gauge that i use stays at the highest pressure recorded until you relieve the pressure then it goes back to zero. Maybe yours was broken..

[gsrtype1]

Originally Posted by 2007speed3 The gauge that i use stays at the highest pressure recorded until you relieve the pressure then it goes back to zero. Maybe yours was broken..

Yeah I think it was cause it would drop real quick and looking at vids of other people doing test. I couldn't even get out of the car to check and it would already lose 30-40 psi. Maybe that mads it read lower than actually was cause it had a pressure leak..

[FreeFlyFreak]

Originally Posted by gsrtype1 Isn't there a roomer that cylinder 3 gets low because of the balance shaft? If thats tru then next mod.

Originally Posted by gsrtype1 Maybe that mads it read lower than actually was cause it had a pressure leak..

Normally I dont point out the spelling mistakes..... but I LOLOLOLOLOL'd

[rigor]

the little button you push, is a tire stem take it out and clean it or replace it, then it should hold your reading

[gsrtype1]

Originally Posted by rigor the little button you push, is a tire stem take it out and clean it or replace it, then it should hold your reading

Well I rented it from autozone and already returned it. Im gonna try another autzone gauge and try to get a vid this time. if it was leaking that bad im thinking that may have given a lower reading.

On the next one I rent I will try what you said if it has the same problem, thanks!

[djuosnteisn]

Hopefully it's just the gauge Joe.

[gsrtype1]

Originally Posted by djuosnteisn Hopefully it's just the gauge Joe.

Yeah you think thats bad otherwise? 160 in cylnder3 and 170-180 in the others how bad can that be for 70k fully bolted hard miles? Weren't your results in the 160's?

[djuosnteisn]

Yeah mine were, but that's cause i'm at 5500ft. 2.5psi less up here, and with 9.5:1 compression it's like high 180's or so. Regardless of teh specific numbers, usually you look for differences between cylinders.

Your engine was warmed up, right?

[gsrtype1]

Originally Posted by djuosnteisn Yeah mine were, but that's cause i'm at 5500ft. 2.5psi less up here, and with 9.5:1 compression it's like high 180's or so. Regardless of teh specific numbers, usually you look for differences between cylinders. Your engine was warmed up, right?

2.5 psi ? that doesnt seem like alot does it? I let the coolant temp get to 190 idling then did the test.

[cpolly69]

Joe
You are still within factory tolerances if those are true numbers. And honestly 70k fully bolted running the higher boost like you do, I would say that is to be expected. I wouldn't get worried unless it starts to dramatically fall off over the next few months. Like mine did. I went from stock, to 155, to 145 from 35k to 45k. I didn't have that many parts, so that's the point at which I started the big battle with the dealer for a new motor.

[gsrtype1]

Originally Posted by cpolly69 Joe You are still within factory tolerances if those are true numbers. And honestly 70k fully bolted running the higher boost like you do, I would say that is to be expected. I wouldn't get worried unless it starts to dramatically fall off over the next few months. Like mine did. I went from stock, to 155, to 145 from 35k to 45k. I didn't have that many parts, so that's the point at which I started the big battle with the dealer for a new motor.

Yeah thats what I was thinking especially with a faulty gauge.... hope you got your stuff worked out bro!

[djuosnteisn]

Originally Posted by gsrtype1 2.5 psi ? that doesnt seem like alot does it? I let the coolant temp get to 190 idling then did the test.

2.5psi in a 9.5:1 compression motor is close to 25psi difference. (2.5 X 9.5).


Next time you do it, drive around for a while. You want the oil to be up to temp, not just the coolant. Give it a 5 - 10 minute drive and i bet your numbers improve.


And i also agree with cpolly, not really worth worrying about, but maybe check em every oil change or so and look for trends.

[gsrtype1]

Originally Posted by djuosnteisn 2.5psi in a 9.5:1 compression motor is close to 25psi difference. (2.5 X 9.5). Next time you do it, drive around for a while. You want the oil to be up to temp, not just the coolant. Give it a 5 - 10 minute drive and i bet your numbers improve. And i also agree with cpolly, not really worth worrying about, but maybe check em every oil change or so and look for trends.

Ahh cool I didnt know 2.5psi is close to 25 cause of atmosphere. im gonna do another check next weekend with a different autozone gauge and get it on vid.

[cpolly69]

Originally Posted by gsrtype1 Yeah thats what I was thinking especially with a faulty gauge.... hope you got your stuff worked out bro!

Yeah after 2 months and a massive battle I got a new engine. All thanks to Mazda Corp and no thinks to my dealer...

[gsrtype1]

Originally Posted by cpolly69 Yeah after 2 months and a massive battle I got a new engine. All thanks to Mazda Corp and no thinks to my dealer...

Sweet!!! Its cool that Mazda helped you out! Hey do you or does anyone know if the max variance "28.5psi" applies to all cylinders in general or referring to side by side cylinders. Like with my numbers is my variance 15 or 20?

[cpolly69]

Joe
My understanding is that it doesn't make any difference if you were talking about cylinders side by side or cylinders at opposite ends of the block. If there is a difference beyond that variance from any cylinder to another, it's worth being concerned.


Sent from my iPhone using Tapatalk

[gsrtype1]

Originally Posted by cpolly69 Joe My understanding is that it doesn't make any difference if you were talking about cylinders side by side or cylinders at opposite ends of the block. If there is a difference beyond that variance from any cylinder to another, it's worth being concerned. Sent from my iPhone using Tapatalk

Thanks yeah just called the dealer and thats what they said too. They said my numbers are well within spec and are good. I'm still gonna get another gauge and try again this weekend.

[Cataphract_40]

Just did this, my local AutoZone had one of these in the store:

Amazon.com: Actron CP7828 Professional Compression Tester with Storage Pouch: Automotive

Amazon.com: Actron CP7828 Professional Compression Tester with Storage Pouch: Automotive
Amazon.com: Actron CP7828 Professional Compression Tester with Storage Pouch: Automotive

[gsrtype1]

Originally Posted by Cataphract_40 Just did this, my local AutoZone had one of these in the store: Amazon.com: Actron CP7828 Professional Compression Tester with Storage Pouch: Automotive so I bought it and did the test. I got: Passenger side 188 190 190 195 Driver's side 26k miles, entirely stock block

Dang impressive man! I will say though I have heard that gauges read different and why u and some others read higher than 185 seems wierd....

[KayWhy]

185, 180, 180, 185 good?

[gsrtype1]

Originally Posted by KayWhy 185, 180, 180, 185 good?

Peach 185 is new...

[Lex]

Nice numbers we're seeing on some of the lower mileage speeds. KayWhy, how many miles on the car?

[shpankey]

Originally Posted by cpolly69 Yeah after 2 months and a massive battle I got a new engine. All thanks to Mazda Corp and no thinks to my dealer...

I'm about to begin this battle myself (130 on all cylinders for mine). Any advice? Note I'm not throwing a CEL or anything and the car runs fine, other than the quite dramatic loss of power. I refuse to race anyone anymore, just don't want them thinking they waxed a real Speed 3 when I'm driving around a limped one.

[cpolly69]

Originally Posted by shpankey I'm about to begin this battle myself (130 on all cylinders for mine). Any advice? Note I'm not throwing a CEL or anything and the car runs fine, other than the quite dramatic loss of power. I refuse to race anyone anymore, just don't want them thinking they waxed a real Speed 3 when I'm driving around a limped one.

Don't show up with any mods on the car and if your ecu has been flashed in any way, don't bother showing up at all.
Bring your complete oil change records. Write down a list of symptoms - make sure to include loss of power, smoke out the exhaust, and sputtering.
Tell them you did a compression test, it tested low, and you want them to do a leak down test - under warranty. If you don't get the answers you want to hear in a reasonable time frame - couple weeks - call Mazda Corp and explain.

[shpankey]

Cool, will do. Thanks man. I have never flashed my ECU or ran an AP or anything like that. Just basic mods so I think I'm good. I'm an oil fiend and have a huge stash of oil. I buy it all the time on sale, so I have enough oil change receipts for 5 cars. lol

[Realgib3]

Just did mine today for the hell of it...

from pass side

190
190
193
193

25K on the odo, 12,500 on the motor... VERY happy with the results!

[Cataphract_40]

Originally Posted by Realgib3 Just did mine today for the hell of it... from pass side 190 190 193 193 25K on the odo, 12,500 on the motor... VERY happy with the results!

very happy to see those numbers, too. I was starting to wonder if mine were off... I mean, I'm pretty sure I did the test right...pulled the plugs, pinned the throttle, turned the engine over for about 6-8 seconds until the needle on the gauge stopped going up...

[Realgib3]

i'm starting to wonder if the break in of these motors is affecting this. I know i beat this new motor up from day one and am seeing some of the best readings i've seen anywhere... what do u guys think? not askin whether or not to romp on your new motor from day one, but could this actually be havin some lasting effect?

[FreeFlyFreak]

Originally Posted by Realgib3 i'm starting to wonder if the break in of these motors is affecting this. I know i beat this new motor up from day one and am seeing some of the best readings i've seen anywhere... what do u guys think? not askin whether or not to romp on your new motor from day one, but could this actually be havin some lasting effect?

I know I romped on mine from day 1....
Guess I should do a compression test, test ur theory.

[djuosnteisn]

This is a huge controversy from what i've read. Not sure how much merit it has, but who know's i'm noob as shit still.

[shpankey]

Originally Posted by Realgib3 i'm starting to wonder if the break in of these motors is affecting this. I know i beat this new motor up from day one and am seeing some of the best readings i've seen anywhere... what do u guys think? not askin whether or not to romp on your new motor from day one, but could this actually be havin some lasting effect?

I did the same thing. I drove it incredibly hard right off the bat. Heck, even the test drive when it had 6 miles on it. My compression is completely shot now.

[cpolly69]

Originally Posted by shpankey I did the same thing. I drove it incredibly hard right off the bat. Heck, even the test drive when it had 6 miles on it. My compression is completely shot now.

+1
I drove the shit out of my car since the day I got it and my compression started dropping at around 30k and my first motor was done at 45k.
I'm going to stick with what I've always said.
Some of these motors are shit and some are great.

[shpankey]

I took my car in. My shifter broke so it made me go ahead and get down to business. They replaced the shifter but told me my car was fine. They said: there is no CEL so the car is perfectly fine. I explained to them that I've lost power dramatically and that I had two independent Compression tests done. Both came back at 130psi on all four cylinders. They said: well our tech drove it and he said it drives like every single other MS3 he's driven. I noticed they drove over 10 miles on my car, so I'm wondering, what he was doing... hot rodding it? How else could he tell if it was missing power?

The tech manager said that if I was losing compression so bad, I'd have plugs fouled out and a CEL. I told him I just recently done a tune up, complete with EGR, MAP, MAF cleaning, new air filter, new NGK plugs, etc etc.

So they say, well, we can do a compression test, but it will cost you $200 for us to do that. I said, well what if the compression is low, do I still have to pay, they said well if it's as low as you say it is, no we will pay to fix it, otherwise you do.

Not sure what to do. I know I've lost power, I've tested the damn compression like 5 times, every single time it comes back 130psi on all 4. But I don't have $200 to spare.

P.s. when I had the shifter fixed, they had it for 4 days and said they no longer offer dealer cars to drive when getting cars fixed. Is this true for all Mazda or just my dealer? I had to borrow a company truck to get around. Not sure if I can borrow it again especially for a long period of time, if they have to replace the engine.

Lastly, does anyone know the EXACT amount of PSI that the car has to be down to before them fixing it? Mine's at 130 which is very low, but is it low enough for them to fix it? The car does run and doesn't throw a cel. The power loss is significant to me, but might not be to them. As it's still a fast car, just not what it was. If the stock car is 264hp, I'd guess I'm down to around 200hp. The torque loss % is probably a tad more than the hp. So it's still fast for most people but definitely not what it was.

Advice please...

[FreeFlyFreak]

Originally Posted by shpankey Advice please...

Pay the $200

[2007speed3]

there is a number for how low compression has to be before they would replace the motor. I want to say 120ish but im not sure...

[cpolly69]

140 is the min i believe - they are also looking for a 40lb difference in between any 2 cylinders iirc