Make My 1990 Corvette Great Again: YUGE
07-24-2016, 02:18 PM
#1
Make My 1990 Corvette Great Again: YUGE
My fellow Corvette fanatics...it starts grim, but this has a happy ending.
My Red 1990 Corvette had reached crisis proportions. At 93K miles, the car was not drivable, and had multiple symptoms and problems.
The car would start up, run a little rough, warm up, and stall repeatedly. Injectors ohm'd out at 12 ohms hot, but at least one was leaking. Fuel pressure was good running, but dropped to zero on turning the key off.
Long story short...
New fuel injectors, Delphi OEM (no 'refurbished' or 'upgrade' injectors, I bought and installed the ones the car was built with and designed and tuned to use).
New plenum gaskets, throttle body gasket, etc.
A new inline fuel filter
New Delphi in-tank pump, also OEM, and new fuel screen.
All this involved a Yuge amount of work.
And once completed, the car ran TERRIBLE. And was overheating.
Yikes.
But, I had an idea of what was causing it.
The car was behaving like it was over-enriching the fuel mixture. As though the computer thought it was always in cold start and warm up mode. Also, the car would do 40 mph foot off the gas. And if shut off hot, was very hard to restart. To start it after it would stall, I had to floor the accelerator, as if the car was flooded. All this pointed to too much fuel in the air fuel mixture...
Back in the winter, the car threw a few Coolant Temp Sensor codes, but that had stopped. I recalled this, and bought a new CTS to install, along with a complete flush and fill of fresh 50/50 coolant, and of course a new thermostat, 195 like the car was supplied with and designed to run with. I also tweaked the Throttle Position Sensor, which wasn't off by much but is now right on.
Well, this time the change was truly YUGE. The car is Great Again.
It now runs like new. Immediate start. Low steady throaty idle, no searching, no missing, no surges, just rock solid low steady idle. And off idle, crisp immediate throttle response, gobs of low end torque and rocket like mid range power. I can't remember the last time the car was so responsive, powerful and smooth, across all operating ranges.
All this took about a month, and had plenty of frustrating moments. good notes, pictures, and the factory service manual helped. Kudos to whoever suggested putting all the removed bolts into a flat piece of cardboard - made reassembly go much easier.
Hope all this helps anyone else who faces similar problems.
My Red 1990 Corvette had reached crisis proportions. At 93K miles, the car was not drivable, and had multiple symptoms and problems.
The car would start up, run a little rough, warm up, and stall repeatedly. Injectors ohm'd out at 12 ohms hot, but at least one was leaking. Fuel pressure was good running, but dropped to zero on turning the key off.
Long story short...
New fuel injectors, Delphi OEM (no 'refurbished' or 'upgrade' injectors, I bought and installed the ones the car was built with and designed and tuned to use).
New plenum gaskets, throttle body gasket, etc.
A new inline fuel filter
New Delphi in-tank pump, also OEM, and new fuel screen.
All this involved a Yuge amount of work.
And once completed, the car ran TERRIBLE. And was overheating.
Yikes.
But, I had an idea of what was causing it.
The car was behaving like it was over-enriching the fuel mixture. As though the computer thought it was always in cold start and warm up mode. Also, the car would do 40 mph foot off the gas. And if shut off hot, was very hard to restart. To start it after it would stall, I had to floor the accelerator, as if the car was flooded. All this pointed to too much fuel in the air fuel mixture...
Back in the winter, the car threw a few Coolant Temp Sensor codes, but that had stopped. I recalled this, and bought a new CTS to install, along with a complete flush and fill of fresh 50/50 coolant, and of course a new thermostat, 195 like the car was supplied with and designed to run with. I also tweaked the Throttle Position Sensor, which wasn't off by much but is now right on.
Well, this time the change was truly YUGE. The car is Great Again.
It now runs like new. Immediate start. Low steady throaty idle, no searching, no missing, no surges, just rock solid low steady idle. And off idle, crisp immediate throttle response, gobs of low end torque and rocket like mid range power. I can't remember the last time the car was so responsive, powerful and smooth, across all operating ranges.
All this took about a month, and had plenty of frustrating moments. good notes, pictures, and the factory service manual helped. Kudos to whoever suggested putting all the removed bolts into a flat piece of cardboard - made reassembly go much easier.
Hope all this helps anyone else who faces similar problems.
07-24-2016, 07:39 PM
#2
booyah
nice work mon amis.