Hey USMB

 

The Car:

1983 MPFI Turbo Brat -  170,000 miles

2" body lift

5-sp D/R Transmission Swap (originally 3-sp auto)

Water Cooled EA82 Turbo Swap (originally oil cooled)

EA81T

 

The Problem: I am having issues with the brat running rich, with a lot of fuel in the mixture. I have replaced temperature sensors, air flow sensors, the O2 sensor and i am still running into the same issues. as a result, my fuel mileage is around 19 MPG, and i have a strong hydrogen sulfide smell (almost an ammonia smell) coming from the exhaust, especially when i spool up the turbo and bring the RPM's up into the ~3000 rpm range.

 

My concern: The engine was designed specifically for the Oil-Cooled turbo in 1983 (in '84, they were recalled and replaced with water cooled versions), I have a suspicion, because i am running out of options, that the computer for the MPFI was not designed for this specific turbo. As a result, it has mismanaging its fuel-to-air ratio; causing it to dump more fuel in than is necessary because of the extra amount of air volume it is sensing, then calculating.

 

Does this prognosis seem in any way logical to more knowledgable USMB members?

 

 

 

 

 

 

 

 

How are the spark plugs, spark plug wires, coil, cap, rotor, and air filter? Does it have stock fuel injectors or upgraded? Also what psi is your turbo running at? Have you read your codes on the ECM?

I would also look at the ECU codes first.  It is highly unlikely that any changes to the ECU were due to the addition of water-cooling to the turbocharger.

No,that does not seem logical at all.

The ECU meters fuel in proportion to airflow.

Subaru did not change ECUs as part of the recall for oil cooled EA-81T turbos.

My 84 EA-81T runs great w/the water cooled turbo.

 

If you have a heavy throttle foot,you will get poor mileage.

Big tires do not help either.

 

I would check fuel pressure and flow.

Note paticularly the flow rate at 42 psi w/7 psi of simulated boost on the pressure regulator.

 

Timing OK?

How do the plugs look?All the same?

Got good compression?

Ever get this problem figured out?