When the Tuned Port fuel-injection system arrived in 1985, it was asignificant improvement on the throttle-body systems that came before.Much cooler looking and with more power potential, the Tuned PortInjection (TPI) system used a mass airflow sensor (MAF) to determinefuel/air mixture.
The Tuned Port MAF sensor is a sensitive piece of equipment thatincorporates a thin piece of wire that reads air intake and reports tothe computer the current air conditions. If the wire is damaged in anyway, the engine will not run properly, hunting for a rich or leanmixture to keep the engine operating. Regardless, the engine will notmeet performance or pollution requirements.
Our '86 Corvette was running poorly. A diagnostic check netted a MassAirflow Meter error code (number 34). In addition, several of theair-cleaner pieces were broken, including the clips attaching the MAFsensor to the air intake, the air-cleaner element box screw mounts, andthe air snorkel from the MAF to the throttle body had picked up a hole.Any or all of these problems can cause the MAF sensor to misinterpretthe data from the computer.
Parts List
Zip Products: Modified Mass Air Flow Sensor, part number EH-478;Air Filter Housing, part number AC-134; Air Intake Duct, part numberEH-459
K&N: Air Filter Element, part number 33-2014
One call to Zip Products fixed all that. In addition, we improved theflow of the system with a K&N air filter and a Modified Mass Air FlowSensor. The installation took about five minutes, and a recheck of thesystem netted an all-clear by the computer. This is truly a simple fixand one that any novice mechanic can complete. If you can change anair-filter element, you can complete this operation.
The Modified Mass Air Flow Sensor is an excellent changeover to any TPIsystem. The Modified unit allows more air to flow through the sensorinto the engine. As any engine builder knows, the more air your engineingests, the more potential power you can generate. Knowing that theintake system of these cars is already somewhat restricted by theunderhood configuration of the engine compartment, anything thatincreases airflow is a good thing. If you're already changing the MAFsensor, this swap is a good idea.
Follow along as we repair and improve the intake system on our '86Corvette. It's easy.
The basic layout of the intake...
The basic layout of the intake system on our TPI '86 Corvette.Disconnect the battery when performing any engine work.
A check of the diagnostic...
A check of the diagnostic system on our Corvette resulted in a faultyMAF-sensor readout.
Our air-filter housing had...
Our air-filter housing had broken tabs at the point where it was toconnect with the MAF sensor. The new housing was a dramatic improvement.
The air-intake duct had a...
The air-intake duct had a hole, allowing air and debris into the enginebehind the MAF sensor and air-filter element. Bad news.
(above & right) The air-cleaner...
(above & right) The air-cleaner box tab mount (arrow) was broken off, allowing debrisinto the intake system behind the air-cleaner element.
(above & below left) The new...
(above & below left) The new Modified Mass Air Flow Sensor looks like the stock unit on theoutside and mounts in the factory location. When removing the originalMAF sensor, be sure to disconnect the electrical connector.
The one electrical connector...
The one electrical connector that leads to the MAF sensor should becleaned with electrical contact spray, allowed to dry, then reconnected.
With the system once again...
With the system once again together, we rechecked it and received theall-clear sign from the diagnostic computer.