89 t2 fuel issue
 

I recently purchased an 89 t2 with a low mile engine. When it starts to build boost it sputters. I don't think the secondary injectors are turning on. The engine has a mild street port,stock turbo,stock boost. It has a rb foam air filter and a rb turbo back exhaust,stock ecu and injectors,fd fuel pump. It also has a wideband o2 and gauge,that reads too lean at 4500rpm. I've been just staying out of boost to save the engine. Any help will be appreciated.

Overboost FCD?


-Ted

I installed a bov and the lean condition went away. I'm suspecting a bad stock bypass valve. It still sputters though when it builds boost. It supposedly has a fdc installed,but I haven't checked yet. I looked under the hood and couldn't find any loose wiring. I did change the plugs,but the old ones didn't look bad.

I'm not sure whats going on. I installed the blow off valve and now it goes way rich. The car has an fd fuel pump,could that cause it to go that rich? Do you think it killed my factory pressure regulator? When the rpm increases,the more rich it goes.

test the car for boost/vacuum leaks. sounds like you got a chinese cheapo BOV that is leaking. the worst part is your OEM BOV probably wasn't even the problem and you will still have the lean issue after you fix the BOV issue you created.

lean issues are usually related to fuel system problems, such as poor engine harness grounding or failing fuel pump/dirty filter. in other cases a bad TPS can cause fuel to cut from the rear rotor(decel fuel cut).

It doesn't have a made in china bov. The engine popped the other day and I'm suspecting boost creep with the stock turbo. It'll be rebuilt soon and I'm porting the wastegate. There will be measures taken to keep it from blowing again.

After trying to figure this issue out, I think it was a victim of the stock unported wastegate.

Sure twasnt.


The stock WG does not cause engine failure.

it was probably your original assumption that a secondary injector wasn't firing.

if it's still together you can check the injector continuity by accessing the ECU, turn the key on and backprobe each of the 4 injector wires to see if they all read close to 12v.

but live and learn, you knew it was running lean but decided to push it anyways. why would you have a wideband but no boost gauge?

The car has a boost gauge, fuel cut defender. The gauge never read over 5psi and I didn't push the car. I never reved it past 4500rpm. My car has a racing beat turbo back exhaust, an fd fuel pump, racing beat replacement air filter. The injectors have professionally cleaned new fuel filters. I will check the voltage to the secondaries.

Waste of time...
All 4 fuel injectors tap off the same circuit for +12VDC.
It's highly unlikely that half of your injectors +12VDC power side suddenly stopped working.
The circuit is completed by a pull-to-ground signal coming off the ECU.


-Ted

S5 ecu will throw limp mode for the omp if its not plugged in.

the ECU plug checks both the voltage to the injectors and continuity through the circuit.

and yes, the brass crimps that hold the 12v wires to the loom can and do fail.


but i'd be more concerned as to why the engine failed at 5psi and under 4500 RPMs, even if it was running extremely lean that criteria would not pop an engine. if the timing wasn't set properly, a secondary injector was not functioning and it was taken slightly higher than that then yes i could foresee it as possible. or the engine already had 1 foot in the grave and the fuel issue is a secondary problem that killed the marginal engine.

I started the removal process friday and found 2 ground wires not grounded to the engine(the stock compression tube on the throttle body). I removed the upper intake to disconnect everything and the rear injector plug was barely on. With the way you had to start it, I'd say the compression was already down. It was on borrowed time.

replace the injector clips, better safe than sorry. also clean and secure all grounds next time around. checking fuel pressure also isn't a bad idea even if it may be a pain to do. you can also have the injectors serviced if they haven't been done in the past 5 years or so.