help!!! turbo is killing me!, 7afe turbo issues Options

[darkhorse]

ok well.... first off i'm newish here. was on a while back but lost info and kinda stepped away from it all for a while. any-who, finishing up my 7afe turbo build and having minor issues. aka lack of performance.

mind you all its a budget/junkyard build.

96 7afe

list of whats done...

t3/t4
manifold
external waste gate
obx fmu
bov
gm 3bar map
vac and oil lines


just to give a little background i have had my own shop for a while with my sis (who was a frequent on here for a while(had a 7afe show car bagged and all kind of crap done to it candy red paint with airbrushed flames)) and old man. done plenty of turbo systems before and plenty of street tunes but this one is really pushing my buttons. (prob cuz its a build for myself) but a simple build has been a nightmare so far.
long story short......


1 water pump killed motor

2 junkyard motor swapped turbo kit added

3 head gasket bad rods bad turbo shot (should have looked better at it)

4 no car for work week 1

5 no work on car raining! week two

6 2nd junkyard motor 2nd turbo re-fab manifold/header for turbo. works ish...

7 fmu is not rising rate so tuning does not do s....! and horrific breaking up at boost.

8 breaking up solved with plug gap (don't trust pre gap plugs) still no power more than factory

9 fmu swapped out with correct one better vac to 0 range (not flooding) stumbles at 0 to 2 psi and 2 to 7 has factory performance.

10 stumped!!! i have read that factory fuel pump and injectors are ok to the 5 to 7 range. pressure and vac tested piping. waste gate fully functional. bov fully functional. piping removed car runs perfect. turbo spooling perfect (from sound and response) cant adjust timing (spent three hours swapping dizzy guts into a different dizzy housing with the adjustable bolt hole.... didn't do a d.... thing) i have researched posts here from oobe and hurley (prob misspelled) and i didn't notice my issue anywhere anyone have any ideas??? before my wife shoots me???




help!!!!!

[Bitter]

So you have no kind of engine management other than the stock PCM? And you're wondering why you have driveability issues?

[darkhorse]

So you have no kind of engine management other than the stock PCM? And you're wondering why you have driveability issues?

as far as.....

never had to do full electronics on any other vehicle i was merely asking for a few ideas not arrogance and yes factory ecu with the 3 bar map and from everything i have read so far that should be a start point with functionality. i honestly don't have a lot to spend on this project just trying to find a few ideas on why this particular one is being stubborn. if you don't have any advise that's cool. let someone else comment.

thanks

[silverceli]

I would recommend getting a safc and wideband to see where ur afs are...

[Bitter]

So you have no kind of engine management other than the stock PCM? And you're wondering why you have driveability issues?

as far as.....

never had to do full electronics on any other vehicle i was merely asking for a few ideas not arrogance and yes factory ecu with the 3 bar map and from everything i have read so far that should be a start point with functionality. i honestly don't have a lot to spend on this project just trying to find a few ideas on why this particular one is being stubborn. if you don't have any advise that's cool. let someone else comment.

thanks

Uh no, the reason is't not running right is because the ECM has no idea wtf is going on inside the engine and can't run fuel or timing correctly for boost. At all. It will kill itself running lean or running too much timing or both. It may run and make more power than stock but it's not going to do that for very long on strictly the stock ECM. As far as you trying to mechanically retard the timing curve that can only be done with OBD1 vehicles, which yours is not.

I was trying to clarify how you had this thing tuned to make sure I didn't miss something or you didn't forget to mention it. At minimum you need a SAFC type device to add fuel back in and a wideband O2 sensor to know how much fuel to add (or where to take some away). In reality you need boost referenced fuel and timing curves which yes you can only do with 'full electronics'. A 3 bar map sensor does no good if the PCM doesn't know what to do with that signal or what it even means. The PCM assumes the MAP sensor signal is running from full vacuum to atmospheric pressure regardless of range it's actually running across, it has no idea you're cramming in more air under pressure EXCEPT for the O2 sensor feedback showing it that it's running lean for some mysterious reason. It's seeing the MAP signal at say 2 volts which now is under boost (I have no idea, just follow along) but it doesn't know, to it 2 volts is 8 inches of vacuum. Having a 3 bar sensor means nothing if it can't understand that the signal means something different now.

But go ahead, hack away, disregard all this, you do you. Let us know how long it lasts and please post pictures of the burned valves or holes in the pistons.

[huntsmcgee2]

I know this is a somewhat dated thread but I have put about 1500 miles on my new 7afe build. I am using a t25 with safc and wide band. Also I'm running 265cc Miata injectors it's plug and play I turned the dizzy back to 5 degree instead of 10. I have a switch I made to reset the ecu in cabin and that helps keep my safc tune from getting kicked out. The car runs near stock when off boost and has plenty of power. I also had bad misfire until plug gap at .22 but I'm also running at 12-13 psi so might have something to do with it. Anyway if I where you I'd go safc wideband and Miata injectors or safc wideband 320cc supra injectors and 3sgte 2 bar map and if your staying fmu perhaps the begi unit since you can leave fuel alone for the onset of boost. Btw 320cc will run nasty rich on warm up even with safc tuning if running stock map and 320 is not needed unless you plan on 200-220whp. The stock will get you to about 160, the Miata stock 180es.