Ok guys, I need your help. I'm beyond frustrated with my ride. after 8 long years of rebuilding. I finally had the opportunity to put some tire to road a few times this past month but not nearly under the circumstances I'd like. I took her down the street just to make sure her heart is still there but most times , I barely made it back.

I've done many mods and I must say that i'm quite proud of myself since I did every bit of it myself.
Ok here are the current mods that may be a factor:
1. intake and exhaust streetport w/ standard rebuild. (standard 2mm seals and orings, oil jet and thermal pellet mod) Synthetic Castrol 20/50
2. lightweight flywheel with street disc and factory pressure plate incl autotrans counterweight.
3. stock ecu and sequential turbo setup, turbo hose simplification w block off plates (ACV, Airpump freewheels, ACV tube, Split air pipe, AWS, AWS tube,) Kept ICS and accelerated warm up
4. 255 lpm Fuel pump, fuel pump mod w/ dampner removal and regulator replacement with adjustable w/ guage set to just under 40lbs
5. Had MSD but fried it due to bad b+ wire from igniter, turbo II coil, iriduim plugs and Magnacore wires
6. Racing radiator w silicone hoses
7, Dp, Mp, high flow cat and catback, Airbox mod w/ K&N filter, and Pulleys( WP, ALT)
8. Had front mount intercooler but using stock cooler tempry.

ok, now here's my question. I have such a hard time starting her and I think it's because of the extra fuel injected when thermosensor is cold and the missing extra air from the acv being removed so to even get close to "ignition", airbleed screw has to come out 4 complete turns and throttle screw open a couple hairs.
-OR-
maybe a failing waterthermosensor

What cha think. And how do I fix air mixture for cold start in this instance?

FACT.
Plugs get SOAKED, but injectors hold pressure

 

You are running higher fuel pressure than the stock ECU was designed for. I know that is a common setting, but the base fuel pressure is NOT 40psi from the factory! That throws all the stock ECU's fuel calculations off. You can check the water thermosensor resistance but the best way to check IMO is to read the actual water temperature from the computer and see if it makes sense. And unless you have the Mazda's service tool, you can't view the temperature reading on the factory ECU.

Did you block off the ISC valve or the fast idle cam? Those increase air for improved cold starting. You need engine management, PFC most likely because you want to stay sequential. I suppose you could drop your fuel pressure down to I believe 36psi base (I don't recall if that's right for the factory FPR) and that may help. But you are going to have to hit the accelerator pedal to improve starting if you don't have an ISC valve.

 

I didn't block the ISC or disable the fast idle cam but I will double check that I didnt kink a hose or forget to plug something back in. I'll also double check the fuel pressure, I do believe it's something like 36/37 deg. i know how sensitive these cars are. The PFC is definitely on my list but I'm sure that the car has to be atleast drivable. Right now, I cant even get her to start easily. Thanks for your help.
When I drove her the other day, it felt so good after all these years of this rebuild and I can feel that she wants to run but I don't want to hurt her!!

 

just for your own clarification.....AWS is the accel warm up system, you prob meant you still have the Fast idle cam still in place. You can't have a mp and a high flow cat...it's usually one or the other...i assume you have a cat if still on the stock ECU. The ACV has nothing to do with your problems...it is meant for post combustion. The AWS on the other hand is what adds air on the cold start.

What is your idle....if it is too low you will have cold start issues....usually it has to be around 1k rpms to not have problems with the stock ecu.


When you say it won't start easy.....does it just crank and crank and then start or does it crank, sputter and then start?

 

Three things add air on cold start:

The accelerated warmup system, a solenoid valve that is fed by the factory TB elbow. This is on USDM compliant cars only and is not necessary for making the engine start quickly. In fact I'm not even sure if it runs during cranking, it might only run in the post start period.

The Idle Air Control Valve (ISC valve), which goes to max duty during cranking.

The fast idle cam, which mechanically opens the primary throttle plate further until coolant temperature reaches approximately 70 C.

During cold start fuel is batch fired (both primary injectors fire at the same time). The pulsewidth is determined mostly by the water thermosensor reading.

 

I believe the correct fuel psi is 32-36, also how can u removed acv and aws and using stock ecu, without no engine code?

 

I removed the ACV and the AWS including TUBE. the fast idle cam setup is still functional. I'm almost positive that the cat in the midpipe, which was a custom build, is a high flow but i'll have to doublecheck the invoice since it and the catback were a gift.
As for starting, i'll turn the key and she'll crank, she'll spin up like shes gonna start then shell fall off like the fuel has been cut. I have to tap, and sometimes floor, the acc ped for it to catch. this doesnt always work though. I'll have to do the deflood procedure. She seems to be most comfortable with the air bleed out 1/2 a turn from fully closed, the throttle screw almost all the way down, and the fuel pressure reading at 35. but i haven't turned that down but once. I could try lower. And as for how I can delete the ACV and the AWS without codes, well 330 ohm resistors are the perfered method although some people retain the vacuum hose disconnected solenoids.

 

The other weird thing is that even when i do finally get her runnning and after shes warm, since the last time I took her out and barely made it back, whenever I try to drive her, she has absolutely no power she revs great but not enough umfh to move. sure the air mixture has something to do with that though. I had the air/bleed all the way out (4 complete turns from closed) and she had power but now she pops out the exhaust when i give it gas now.

 

Have you measured intake manifold vacuum at idle?

 

no, why? I think my boost guage says about 17 after warm

 

My buddy just told me he thinks its a resonator, not a cat. he's gonna check. I'll post a pic asap but it looked like a cat without the air pipe bung to me. I think that would explain my issues, especially the power issue. I know rotaries need backpressure especially with the stock ecu!!

 

ok heres the most recent develpoment. I got the car started with the air/bleed 1/2 a turn from fully closed. idle set screw was about halfway down. maybe a little less than halfway actually. Well I took it down the street and she had alot of power but after I made a u-turn to head back home about 4 block away, all of a sudden, no power. The engine seem like she wants to stall and dies after I put it in gear. really weird. Almost like the fuel pressure fell off completely. Power was great then not enough to move her!! Whats the deal???? maybe thers a solenoid that comes online after a while which is acting like a vacuum leak!

ANY THOUGHTS???

 

Hey guys, Help me out here if you would cause this is almost more than I can understand.
What would cause the engine to suddenly, after a short run, not have enough power to move itself but still idle fine. I was thinking maybe there's a solenoid that open near or at boost getting stuck open. This solenoid may have some control over the air fuel mixture. or maybe a turbo control is stuck open. i dont get it. Could a compression issue cause this. My compression was fine but I'm wondering if maybe something changed!

 

Next thing I would look at is your ignition system. Put stock coils on and try that. Also, what temp plugs are you running?

Really sounds like you're not getting enough spark.

With your mods, the stock ignition system with all NGK BUR9EQP's should work dandy. Maybe add a Twinpower for more umph.

Dale

 

The ignition system is a second gen turbo II primary coil triggered by an MSD unit. Well it was and will be again after I repair the MSD. The plugs, leading and trailing, are iridium. Im wondering if I should have left the filters on the turbo control solenoid after i did the simplification. Today I went to retrieve her from my unsuccessful test run and
1. She started right up! FTF!! (First Time Fire)
2. Even though the FR tire was flat, she made it home.

Now she was cold. I drove her home Immediately after she started just to see if the power problem was heat related. And since I made it home with no prob. Im leaning towards A turbo solenoid because when she ran the day before, she was warm. She had been ideling for at least 15 mins. I know I shouldn't be driving it at all without some sort of tune; Not to mention an ecu; and definitely don't boost!! well, she hit a little boost on the run. Im hoping that a solenoid needed that filter i removed, and replaced with a vacuum cap, to release a vacuum signal after cutoff. Probably a stretch but other than bad compression, power shouldnt vanish after warmup. When I checked the compression it was great!!! I checked it cold warm.

 

I replaced that filter looking piece on the solenoid. I assume, by studing the diagram, that the filter allows the turbo control to close again after operation by draining negative pressure, ie. vacuum, through it after the voltage is removed!

 

you have a ported engine, removed emission and full exhaust with stock ECU? Stop trying to make it work and buy a Power FC quick or you'll need yet an other rebuild...

 

I understand how "important" the ECU is!!! But from my understanding, The car has to be at least drivable before the PFC can be installed. Now if i'm wrong, then ok, please tell me so. If i'm right, well than, I have to fix these issues. Especially the fact that she has power enough to move when cold but after warm-up there none. I do now think I figured that out With the filter on the solenoid. Was keeping the turbo control actuator door open. If she drives well this afternoon, because I have her ideling in my driveway right now but cant risk a breakdown this morn, then I'll know she ready. I will try not to boost!! The other thing is that I may have to go with a different ecu for now. PFC is just a little out of my price range at this moment.

 

C-mon guys, I just want to make sure weather or not, that the car has to be drivable before the ecu can be put in or not. Somebody's got to know. In the meantime. I'm not sure what to make of this drivability issue. When the engine is cold to just about warm, she drives fine. but as soon as she warms up, the there's no power to move herself properly. Shes running really rich at cold start, (WHEN I CAN GET HER TO START!) smoke out the tailpipe and the plugs are completely black from just a few minutes of running!! I'm "guessing" that the air/fuel mixture is way off but it shouldn't be off so much that I lose drive power when warm. Or am I wrong? Thought it was the turbo control filter on the solenoid but that didn't seem to make any difference after warmup. All I can think is that the ecu is cutting fuel pulse or cycle duration so much after warmup that shes leaning out due to my upgrades. HELP ME GUYS. WHAT DO YOU THINK? AND please easy on me regarding the pfc. I know I need a computer!!! Could an ecu issue really cause my drive problem???

P.S. did another compression test after warm. readings were about 90 to 100 psi on both rotors

 

which irridiums? BR10EIX? Those definitely hurt idle quality without tuning.

 

I do applaud you for trying to get the car running right on the stock ECU. Way too many people see a problem and just start throwing aftermarket parts at the problem. If you can't get the car running right with the stock ECU, you'll have even more problems with a PowerFC.

As long as you're staying out of boost, you'll be fine with the stock ECU.

First step, try a set of stock or near stock (all 9's) plugs like I recommended. It really sounds like an ignition problem to me.

Still not sure why you went wacky with the coil packs - no good reason that I can see. There's a reason MSD stands for My Spark Disappeared, by the way .

The filter on the turbo solenoid (still not sure what you're talking about there) shouldn't mean anything, you're chasing your tail there. Sounds more like a primary engine control problem - fuel pressure, sensor problem, ignition problem. Have you checked for engine codes?

Dale

 

FWIW, I installed a "low mileage" set of coils with my last motor replacement. It seems that they are worse than the original 140k miles coils. On a warm re-start when just quickly moving the car in/out of the garage, it is hard to start and has flooded slightly. My AFRs on start up are very rich. New plugs and new wires. Only change in ignition was the coils.

Don't rule them out.

 

The plugs Im using are ngk brand RE7C's. Those are the leadings. I have to pull the trailings out to get their model no. I will give the original plugs a try.

there are two reasons I changed the coil pack.
1. I researched that the 2nd gen turbo II coil is "BULLETPROOF" and can handel an msd much better than the stock fd coil
2. The msd unit blew up my original leading coil. It may have been due to a faulty wire between the igniter and the original coil pack. Eitherway, that coil is no more!!!!
thats actually the first time I've heard about the msd meaning "MY SPARK DISAPPEARED?"
And I have no codes at all. Thats was a Major PITA to fix as well. The filter on the turbo actuator solenoid was just something I caught while trying to fix the other issues. I wouldn't have cause any issues until I tried to boost. the wastegate door would have just remained open.

Im considering a tuned oem ecu that I saw on ebay just to bridge the gap between now and when I can afford the PFC. but I'll try a few other suggestions you guys have made.

Since I dont have the stock coils anymore, whats a better option? Something aftermarket or oem?

 

Please. I'm begging you. Do not buy an ECU on eBay. Your stock ECU will have to do until you can get an aftermarket unit and have it tuned properly, a "tuned oem ecu" will put your whole project at risk.

It's hard to diagnose something over the internet, so perhaps the best thing to do is start working backwards to eliminate suspects. I think that the problem lies somewhere around your new fuel and ignition mods. Try and reverse what you've done since the last time it ran well, one step at a time. Start with replacing the fancy ignition with a stock OEM unit. Maybe go back to your OEM fuel setup if you have to. (While it's a good mod, consider holding off on the new pump until you get an aftermarket ECU) Labor is cheaper than new parts or band-aids.

If you can reverse back to running well on the stock OEM ECU, enjoy it until you can afford a quality aftermarket unit with a proper tuning for the fuel, ign, etc. It'll be worth it in the long run.

 

i would agree with you with working backwards etc, etc., but I've done so many mods that I'm not really sure where to begin. Remember, no emissions, Lightweight flywheel, stock air box mod, Fuel pump wiring mod, new fuel pump, regulator and dampner mod, etc. I will try because I really don't want the ebay ecu , Im just getting frustrated at this point.
I WANT TO DRIVE MY BABY!!!!!!!!!!!!!!!!!!!!!!!!!!!