ok, i know there is a difference between a blown motor and a hurt motor. Ive been told I have a hurt motor, it still runs and I can drive it around but it only boosts to 6-7 psi on primary and secondary turbo. Does having a hurt motor lead to not being able to run full boost. I just want to know if im looking at a leak somewhere or if its something to be expected with a hurt motor. it runs like 7-4-6/7 boost pattern.

 

Sounds more like a solonoid issue. What is your vacuum at idle, and have you done a compression check?

 

i have not done any compression checks. im kinda short on cash. at idle its usually between 16-14. it has a lumpy idle but is only rough running at idle. once i blip the gas or get on it it runs fine, except for the low boost .


This all happened after 2 runs at the track like 2 months ago. after it started running rough it still boosted fine. 13-11-13. (i had it turned up a little) then within a week i noticed it going down little by little and now just runs 7-4-7 or 6-3-3

 

Can you please list all your mods? Were you running 13psi on the stock ECU?

 

sure sorry

Brand new (not rebuilt) transmission from Mazda, added B&M shortshifter with MOMO ****.

-Brand new 99 Spec Turbos from Rotary Performance

-ECU upgraded with fully programmable Apex'i PFC

-Suspension - Koni Yellow adjustable shocks, w/ Eibach springs, and RE rear toe-links

-Exhaust - M2 Downpipe and Racing Beat Single Tip Cat-Back exhaust.

-Intake - HKS Racing Suction

-Cooling - Koyo Aluminum Radiator w/ aluminum AST new coolant lines.

-Intercooler - Greddy 2 Row Front Mount w/ Greddy Elbow and J-Spec Y pipe

-Greddy Spec II Boost Controller.

-Greddy pulley kit.

 

its just hard for me to accept i have a broken motor when it runs so fine, ecxept for idling, and the low boost issue. i know rotaries are different than piston engines, but.......i dont know, im in denial.

 

You really need to do a compression check to know whats going on. Just go to any auto parts store and get a regular compression gauge ($20), and do a quick search on here for the proper way to do the test. It will at least let you know if it is an engine issue or not, and you can stop guessing.

 

'hurt' motors are just one step away from 'blown' motors, in reality. It is not like it is going to "fix" itself, you know? But yeah, you can at least drive the thing around, it is akin to a piston engine that has bad rings still being able to run. Not pretty, but it will get you by.

 

i know it wont 'fix' itself. it would be nice if it would though. lol. it just drive so strong. thats all.

 

There have been many "hurt" motors that have boosted just fine. Who told you this?

 

I'm not sure where I see ahurt motor changing your boost if you have fair compression on all faces, I'd suspect a boost leak some where with the turbo's being so new.

 

I'm sure you already know how to do it... just in case or for others that come across the thread.

http://www.fd3s.net/compression_test.html

 

maybe you are having issues with the idle because of removing your airpump? your vac readings are fine. it seems like 2 seperate issues.

it sounds to me like you have a boost leak somewhere. fd3s.net also has an awesome section on how to check for boost leaks and where to start. i feel your pain, i just fixed a boost leak...what a pita.

 

yea. but the air pump was removed before I got the car, didnt start to have issues with the car till 3 weeks later when I took the car to the track.....took it down the 1/4 only twice.

 

Sounds like a chipped corner of an apex seal, usually the result of a forced break, such as a pinging episode. This sort of break usually occurs to relatively new/rebuilt engines where the seals are less worn and therefore stronger. If a higher mile engine encounters this sort of internal force, it usually shatters the apex seal to begin with causing the "normal" total loss of compression on 3 faces because the seal is already worn down quite a bit.

This type of break will reduce compression on 2 faces, and cause a slightly lumpy idle and an idle note that more resembles a v6 piston motor. Any significant reduction in compression is by definition a reduction in exhaust volume, thus the turbos respond a little less.

Continuing to drive this way, the damaged seal will eventually shatter altogether (as they normally do) and destroy the rotor and rotorhousing. There is a good chance that the rotor is currently reuseable. The rotor housing is likely scratched in some place or another, and will probably require replacement.

 

I would start with the basics. Put a fresh set of plugs in, if you haven't done so already.

 

Chipped apex seal...You can drive it for a while but it will fail in a big way after a while.

 

ok less responsive turbos. but would it cause it to boost 6-7 psi less than it should? Am i looking at loss of compress as a culpret or a vac/boost leak? I know its hard to diagnose with out seeing it but just trying to figure it out the best I can before I take it to a show that will just tell me I need a new motor. If thats the case than so be it. but IF i have a 10% chance of it being something else than I would rather try what I can to save myself the money and hassle.

 

COMPRESSION CHECK.

Everything else is irrelevant for now.

What you're doing is like having a car that pulls to one side all the sudden. You start checking the alignment and worrying about whether the differential has gone bad, instead of simply checking to see if all the tires have air in them. One simple test will render all speculation unnecessary. You're missing the forest, looking at the trees.

 

i completely agree with you, im just simply asking if my low boost issues can be a result of bad compression or if im dealing with 2 seperate issues.

 

Quit trying to diagnose anything until you get a compression check. You're just talking yourself around in circles right now...

 

Ask yourself. What drives the turbos? What makes them work?

Exhaust airflow.

Where does exhaust airflow come from?

Combustion.

How is combustion possible?

Compression.

So, lower compression means less combustion force, less exhaust gas volume and velocity, and lack of ability to drive the turbos.

Why is this not simple to see?

 

COMPRESSION CHECK COMPRESSION CHECK... got it.

 

dude are u retarted....ur motor is fucked and all you think about is boosting??? thats why ur motor got fucked in the first place. Turning up the boost is a good way to loose a motor unless you have the mods that can handle it....well good luck on a rebuild, i hope the few runs where worth it! and people call me crazy cause i baby my car like a crazy person...but this is why i do it.

 

wow.....im not concerned with being able to run more boost right now, im just simply wondering if my boost issues were related to the motor situation. thats all. next time read b4 u post.