Won't WOT pass 4K rpm
 

Ok, the car won't WOT pass 4K rpm, but if I lightly tap it it will go up to redline (but quite a lot of back firing, pop pop popopopopopop )

I searched, most people said it has something to do with secondary injectors being clogged, Fuel filter, vacuum leak

I just changed the fuel filter yesterday, So that's not it. how many people actually found out it's the secondary injector that fails ? it's my friends car and he is looking for "the cheaper,the better" fix.

Year car, mods, etc?

What happened between when the car didn't have this problem to now? Engine swap/rebuild? Installed/updated engine components?

As far as I know (and what I was told by the owner), it's an S1, no mods except Mazdaspeed 300 kmh gauge(even the gauge is not fully functional, the rpm needle jumps sometimes, and the odo sometimes just disappears, but i dont think this has anything to do with the issue he is experiencing)

he got the car 3-4 yrs ago, odo shows about 70K

nope, still the same as is, no rebuild/swap whatsoever. owner doesn't know anything about rotary.

Car has been running fine (so he say) and this starting to happen around 4-5 months ago.

Im scratching my head right now, when I floor it, the rpm stuck at around 4K rpm and the engine sounds like it's going to die with lots of backfiring. but if I go slow the rpm goes up, still back fires, just not as much.

something probably failed, i will take everything apart next week and check everything, but if anybody has any idea that will be great, saves me some time :)

check it for codes, if it has a code for anything boost or fuel related, it'll have a fuel cut around 1psi, but under 1psi will run completely fine

if it was a later car, the speedo actually can cause that problem too, but the v1-v3 FD's won't do it

Can you go wide open until 4k rpms and everything is fine? Boost gauge installed? If not, do it asap it will tell you a lot. Doesnt exactly sound like limp mode but hard to say without boost gauge hooked up.

Okie ... blank post ... :lol

anyway, it's a early JDM model. I'm gonna jumper it to get the code this weekend or so. cuz JDM models does not have CEL. so I gotta get my multimeter to get it read.

it does have boost gauge, but it I forgot the exact numbers but it's not making lots of boost.

I have a youtube video uploading. will post link when it's done.

Here u go,

WOT/FLOOR IT : stuck at 4K rpm MAX, it feels like engine is going to die

lightly tap it : rpm goes up, but it has some backfiring.

Took this video right after I changed the fuel filter (it's a bitch ass job, gasoline poured all over my arm and it does NOt feel good :( )

Test the secondary injectors

Will do that this weekend or possibly early next week, thx :)

my car did that too until i changed out/cleaned the secondary injectors

Ok, time for some update , yeah it's been a while, but family/work occupied my ass till yesterday

Anyway, I took everything apart again, tested the 2nd injectors with direct power feed. it clicks like it should, so I think the injectors are still functional as it should.

pull the coils out, Primary reads 0.6 Ohm, both T coils reads 0.8 so it's still within spec.

should I still replace the 2ndary injectors ? I was about to test the wires but it starts raining so I gotta stop. the ECU grounds the injectors so I guess I gotta test the wires and ECU at the same time ?

Iono but it act exactly the same when my car went into limp mode. I was able to lighting accelerate pass 4k. But if I WOT it, it will NOT go pass 4. Same exact symptom.

Check for codes, if no codes are present. Tried disconnecting the battery and resetting the ecu memory.

Restart vehicle and see if that fixes it. If not, then you'll have to get ur injectors cleaned/tested.

-AzEKnightz

Won't WOT pass 4K rpm
 

And the fuel pressure is???

no codes at all, cleared the memory, jump in, test, nope. will not go thru 4K when WOT.

Guess I will just replace the injectors and see what happens. it takes another 30 minutes for everything anyway. Have to order new part because Im not in US right now, and there isn't any place that I know of can do injector cleaning.


no idea. but even if the pressure is low, it shouldn't buck like that.

So there isnt any injector cleaning services where you're at? If so, buying net injectors might be ur best bet. OR simply dip your injector tips in ATF overnight as a last resort if you cant clean the injectors or takes too long for new injectors to arrive.

-AzEKnight

I heard there is, but I really don't trust the locals here.

I will try the ATF trick, but I will order 2 new ones anyway, takes about a week and 1/2 to get here :(

Try the ATF trick. Worked on alot of electronic controlled mechanical components like EGR valve, injectors, power steering pump etc etc. That's what all the cold school mechanics does when something is stuck, not working right. Dip em overnight!

However, this is NOT a permanent fix. Just a bandage.

-AzEKnightz

Before replacing/servicing injectors (which is a good idea if you don't know when they were last serviced), I would suggest investigating the CAS sensors. Make sure the wires aren't cut and/or damaged. Make sure the correct connects are on the correct sensors (if the car was driving fine before, this is not likely a problem but it's good to verify). Make sure there is continuity of the sensors to the ECU.

Well, worth a shot, it's almost free :)

it's weird tho I mean, if it's stuck or dead, there shouldn't be any noise/click when I give it power (direct power fed)

got some GB Reman injectors should be here in a few days, fingers cross.

CAS and wiring works fine. I checked already lol

Before you go nuts try replacing the O2 sensor. It's $45 and u can swap it from the engine bay. It's attached to the downpipe trailing the turbos on the passenger side. That can cause a good amount of hesitation in the range you are talking about

Id say its your secondary injectors. When I bought my FD in 06' it wouldnt rev past that point as well. Upon removing them they were filthy so I switched them out and everything has been perfect since. You might want to check your fuel pump if thats the case as well. The tank can get quite filthy and I have seen the rubber mount for the fuel pump disintegrated.