well i swapped complete s4 turbo 2 motor and drivetrain into my s4 GXL i only changed the engine harness the dash harness i kept and the alt, started harness that goes on the driver side i kept on there i switched out the stock fuel pump and put an fd one and i also put 680cc secondaries everything else is stock its starts up fine drives smooth but i cant get it to boost im not sure is even boosting im getting a boost gauge soon but im trying to figure out why isnt it building pressure i diconected my actuator and the car felt the same not sure if the door is stuck open or anything else that would cause this im stumped
help please motor came out of an 87 and my gxl is also the same year

 

Turbo ECU/MAP sensor/AFM? or NA versions? If you don't have a boost gauge, you can't really say it's building 0 boost. For now, you're just going by feel/sound.

 

yeah its turbo ecu turbo afm turbo pressure sensors both of them the one under the hood and the other one next to the passenger door, true i am just going on feel and sound but it just doesnt feel like its building boost

 

If it is not building any boost, possible sources are: a BOV stuck open, wastegate stuck open, or a large leak in the intake piping.

Also, running 680cc secondaries on the stock ECU means you'll have a large hesitation around 3800 RPM and excessively rich mixtures under boost. Using an Rtek 1.7 chipped ECU will work a lot better.

 

hmm i c ill check those out and ok do you know where i could possibly get that chipped ecu?

 

http://www.pocketlogger.com/index.ph...age=1&ecu=S4T2

 

ok well i checked for any boost leak none at all i checked the bov and its not stuck open although when i took out the UIM i checked all the plugs on the injectors and primary 1 was a little loose so i pushed it in, replaced everything carefully then noticed the connector to the BAC valve was missing one of the wires in the clip so i stripped it and the black wire was pulled down and so i pushed it back inand connected it now that i put everything back together i took it for a run and i felt boost but not for long i drove on the street and i kept feeling it less and less till it was back to how it was.......im not sure if one of those two i messed with got loose again but would that even affect it to not boost? or could the symptom be something else

 

The BAC won't have anything to do with acceleration/boost, but an unplugged secondary injector could cause fuel cut in the mid-range. If you're uncertain that the plugs are staying on, backprobe the injector wires at the ECU. LG, LG/W, LG/B. LG/R on the small ECU plug are for the injectors. All of them should have 12V with the ignition 'ON'. If a primary injector plug came loose, the engine would just stall or run horribly rough.

I still think you need to get a boost gauge so you have some idea of how much pressure is being produced. If you're on the wastegate spring alone, it will only be about 5-6psi.

 

hmm i c ok ill check out the the wires from the ecu and yeah im picking up a boost gauge this weekend. but again for example i went to food4less went inside then came out not much time i got in my car about the first 5 min i can feel boost and as the engine gets more warmed up i dont feel the boost anymore

 

ok now i got a boost gauge and it is boosting 5.something pounds but the car goes nowhere could it be that my downpipe is clogged??? i got the stock one or could it be the injectors....

 

you might get more help if you write using actual sentences

 

you do know what im trying to say tho, im going to try and get a downpipe and if that doesnt work i will try cleaning the injectors. hopefully that fixes the problem thanks

 

ok ok i still cant figure out the problem, my leading coils arent working could that be the reason why it hessitates????

 

How do you know the leading coil isn't working? You obviously need it functional.

 

...YES. Leading coils do most of the work power wise. You could pretty much just shut off the trailing coil all together and be rather fine (aside from then having no tachometer since its tied to that coil and not the leading coil...why mazda did you choose the trailing coil for the tach?), but leading coils, no. There you have a big problem. Must idle shitty too huh. The little white connector to the leading coil isn't the best. Try cleaning the contacts and then after you clip it back on, take a zip tie or something of the sort and tie the two connectors together really tight so they stay connected. The re-check spark. If still no spark, take a multimeter and check for power at that same white connector with the key on or even running. There should be power to it. Coils go off a ground impulse. Negative, coil charges up. Sudden No-Negative, Coil fires. You could put your multimeter on the negative wire at that connector and the other lead to a positive and then crank the engine and check to see that the numbers or needle jumps rapidly. That would indicate your pickup in your CAS is working. If all checks out there you could do a resistance test on the leading coil and see if its in spec, or plug your leading coil into another known working RX and see if it works in that car, you might be able to plug it into the trailing coil plug (don't quote me on that one) and see if it then works, but if your plug to the coil checks out as fine, then basically signs point to a bad leading coil pack... or severely bad wires and/or plugs.
Fix the leading coil problem first, then notice your increase in power.