I won't go into any gory details as to why, but I had an FD in here for a motor swap. When the turbos were removed they were found to be cracked beyond repair. The customer opted to get a T78 kit on his own and have us put it on. The rest of the car is largely stock; factory ECU, factory intercooler, factory injectors, factory fuel pump. Vacuum rail and emissions equipment have been removed. Engine is OE Mazda reman. I advised him I was unsure of the compatibility of the T78 and the stock parts.

The car starts and idles just fine. When driven, however, anything over ~15% throttle and it bogs down as if it were not getting enough fuel. Falls flat on it's face actually. Has anyone else run into a situation similar to this, or know of incompatabilities in his existing setup that could cause this driveability problem? We're not getting into boost at all, this is all during part throttle applications. It acts like maybe a clogged fuel filter.

Thanks
Shane
www.aimtuning.com

 

Did you resistor all of the stuff you removed?

 

Nope, no resistors. We did end up getting codes 35, 43 and 44, all turbo control codes. Is it possible that the ECU is not finding something it is looking for and going into limp home mode? All the standard inputs are hooked up (intake air, coolant temp, MAP, etc...) Unfortunately we've never tried to make one work with the stock ECU so this is all speculation.

Shane
www.aimtuning.com

 

Put the resisters in place and it should fix the problem. He really needs at minumum engine management, intercooler, injectors, and a fuel pump. I exspect that motor to last more than a week or two max with his setup.

 

if the ecu is unsure about boost control or fuel it will, have a cow

mike

 

I agree completely with your assessment of what it needs. The engine and turbo conversion have exceeded his budget, however. This reaffirms my suspicion that the ECU is in limp home mode. He is taking it easy driving the car (no choice really), but I am going to bring it back in for more inspection. I really need to find a solution.

Provided we can get it driveable at more than 20% throttle, our objective is to artificially limit the output from the T78 until he can have the necessary upgrades performed.

For now though, I'm trying to help him find a solution that will not cost much and render the car at least driveable, if not massively powerful.

Presumably then, replacing the missing resistance values would at least let the factory ECU operate somewhat normally and hopefully restore some driveability to the car.

Anyone know on exactly which circuits? Anyone have a list of resistance values handy? C'mon, I'm not asking for much LOL

Time to start digging in The Manual.

Shane
www.aimtuning.com

 

if you pull the codes, and look in the manual they list the resistances for you

mike

 

you can also get a manual boost controller to turnt he boost waaaay down. I think the wastegate spring that comes with the t78 is something like 18 psi.

 

Even the boost controller wont be able to pull the boost down low enough to make that car at all reliable!

The stock fuel system & that turbo setup is a timebomb.

 

A somewhat happy ending to the story. I brought the car back in and plugged in all the solenoids (sans vacuum hoses) and the car is running much better now.

Of course, I advised the customer that he was driving a loaded gun and that his engine would live or die by his right foot until he could afford to get everything it needs!

Thanks for the help guys.

Shane
www.aimtuning.com

 

Take his key and hide it from him like a drunk driver... He might/should thank you later...

When he gets back form rehab(ie: fuel, computer, intercooler, ect.) you can give it back to him in good concience.

 

That cars engine will last seconds with those non-mods. I hope he has a big wallet...

 

hmm my T78 was $3500 everything else to make it work properly was only $8000+ hmmm

 

In addition to that, half ***'ing a modification like this will likely cost more in the end than actually doing it right from the start.

 

well when he blows the engine it will damage the $2000 turbine so yeah it will be even more expensive