Hopefully someone can help me figure this out. The car ran fine in sequential, but I wanted to try out fully non-sequential twins and since I had a spare set kicking around I figured it would be a good learning experience. Now the car is back together completely but I'm having issue with it running. It idles fine, but when on the road if I apply throttle to the point where the boost gauge reads just in front of 0 PSI the car starts backfiring and loses power. As soon as I release the throttle it runs fine again. I can reach any point of the rpm range with minimal throttle application and experience no problems. I changed out the TPS and the same problem persisted. I added another ground to see if that would help and it didn't. What would you check next? and in what order.

When going non-sequential I removed the solenoids and used 330 ohm 1watt resistors. All emissions controls are gone.

 

Sounds to me like the ECU is getting confused when you hit boost.
Have you verified the boost sensor and the connections to it?

 

I have searched for a way to produce error codes. I ended jumping the TEN and the Ground pin in the diagnostics box. Using the following thread thread I came up with these error codes for my car. https://www.rx7club.com/forum/showth...ht=error+codes

28 LL SSSSSSSS EGR Solenoid open or short circuit No

38 LLL SSSSSSSS Accelerated Warmup System Solenoid open or short circuit No

39 LLL SSSSSSSSS Releif 2 Solenoid open or short circuit No

44 LLLL SSSS Turbo control Solenoid open or short circuit No

Are all of these from the rats nest? If so is it possible that the 330 ohm 1Watt resistors require to much juice? Also, does the ECU need to be reset each time after an error? How is the reset done properly, i have seen a few methods but am unsure which is correct?

 

I'm guessing the my car is running in limp mode, which is why it won't boost.

 

Um, are you on the stock computer? You can't just convert your car to non-sequential and keep using the stock computer.

thewird

 

i am using one of those pettit unlimited ecu's. What I have done so far is removed the resistors and put the solenoids back in, but the same codes so far.

 

Was the Pettit ECU tuned for non-sequential?

Check that your TPS voltages are within Spec. They should be...

Mazda's Standards are:
VTA1: closed 0.10 to 0.70. open 4.2 to 4.6.
VTA2: closed 0.75 to 1.25. open 4.8 to 5.0.

Also make sure you hooked up everything including injectors as well as the grounds.

thewird

 

try increasing the boost
also notice if the car hesitates ..to achieve the boost setting u have assigned
if it does
its the ecu
get it tune or change it.... again i am not that experience .. but try it .. it might help u

 

Please do not "try increasing the boost" if the car is backfiring as it enters boost. Find the problem, fix it, then increase the boost.

thewird

 

^^^Recipe for rebuild....


Follow what Marco (Thewird) suggested, he knows his ****...


J.

 

lets increase the boost all together right now ASAP

 

lmao, this guy.

 

You can run non-seq. with the stock computer, the way you did it is fine. Try to reset the computer (disconnect the battery ground cable,pump the brake pedal a few times,re-connect the battery cable), if the codes are gone then your good to go...if not check all your wiring on the resistors.
Check and do what "The Wird" said to do plus go over all the vacuum lines....what ever you do don't over boost the car, if you have a boost controller....turn it off until you have this figured out.

 

ya letsss do it

 

Ive tried to clear the error codes so far. The ecu was not tuned specifically for non-sequential but my understanding was you didn't need to do that. I also switch the ecu out and the exact same codes.
My fear now is that I may have damaged the wiring harness. Does someone know of a way to determine if this is what I have done without replacing it.

 

I guess my fear of the wiring harness being damaged must have be right, I changed it out and the error codes are now gone. A new problem that developed though is, first gear and second gear turn the engine off. With the clutch still in and simply placing the shift stick in first or second causes it to turn off the engine. Third, forth, fifth, and revers work fine. Any ideas on this? Thanks

 

I should also mention that I went from using a North American ECU with a JDM wiring harness and a JDM transmission, and now I have a North American ECU with a North American wiring harness, with a JDM transmission.

 

Every time I repair and issue another one presents itself. I fixed the shifting issue, turned out to be damaged wiring going to the switch.

Now it seems as like one of my fuel injectors is stuck open. Is there a way to check if and which injector is causing me grief. The symptom is the vehicle is flooded every start now, but it seems to be one rotor only. The only way to get the vehicle to run properly is to take the plugs out, followed by turning the engine over to get the excess fuel out, clean the plugs, put them back in and start er up(smokes quite a bit for a while). I found that the vehicle will run with the fuel relay pulled out too, I thought this was strange. I know its not electrical because I unplugged the battery to check and its still flooding the engine every time. Any Ideas?

 

Just have all injectors tested and cleaned if that is the case. Better safe then sorry.

thewird

 

Sorry to bring this thread back to life but I have not solved my problem regarding the flooding of the engine. I was away and busy with work so I had to leave it for now. I have changed out the fuel rails and the pressure regulator and that still didn't help. Injectors are good to go. I find that when I start the car it runs crappy and gets worst from there. I discovered that as soon as I pull out the fuse for the fuel pump the car begins to run much better. Of course i have a smoke show of unburnt fuel, but the the car does not sound like its about to die and it idles at its proper RPM until the fuel pressure has bled off and the car eventually dies. Has anyone encountered something like this?

 

Sounds like one of your injectors is leaking, pull the UIM, have someone turn the key on and have a listen down each LIM runner for a hissing sound, if the sound is present its a injector that is stuck open.

 

Another way to check for a leaky injector that isn't quite as labour intensive is to do a simple fuel pressure leak down test. Hook up a fuel pressure gauge to your fuel system, turn on the key and let it build pressure. Shut the key off and then watch your fuel pressure reading. The residual fuel pressure should hold steady and not drop. A slight slow drop is normal, but if the pressure drops off fairly quickly you have a leak in that fuel system (leaky injector probably).

 

^^ that's tricky and requires experience to know how fast it should drop