TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
Welcome to ThirdGen.org!
Welcome to ThirdGen.org.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!
I have a 1985 L98 from a Corvette. It has been swapped to Speed Density, running the '730 ECU and a TPI chip from Larry's Electronics. I recently had some issues where the engine wouldn't idle and through trouble shooting have found that it's running very rich. The engine is currently in my Jeep after sitting for a couple years well protected in my garage. As far as I know, the engine is all stock.
The plugs are all fouled. The exhaust smells like gas and most recently, I was getting black smoke on startup.
After letting the engine warm up and hooking it up to TunerPro at idle I get the following info:
Throttle Position - .78
TPS % - 0
Coolant Temp - 87.5* C
Startup Coolant Temp - 20.75* C
Battery Voltage - 13.7 V
Fuel Pump Voltage - 13.5 V
Vehicle Speed - 0 MPH
Engine Speed - 700 RPM
Map Volts - 1.6 V
Map kPa - 40.24 kPa
Manifold Air Temp - 65.24* C
Target AFR - 14.73
O2 Sensor - Sweeping up and down
Integrator - 129
BLM - 156 (read as high was 160, as low as 144)
Block Learn Cell - 4 (this changes while driving)
Injector Pulse Width - 2.55 ms
I ohmed out all the injectors with them all ranging from 23 - 29 and one at 42. From what I've read that is pretty high.
The opinion I've gotten from a few people is that I've got leaking injectors. I pressured the system, clamped off the fuel and return lines and it does leak down to around 10 psi in 15-20 minutes. I used a thermometer to measure the exhaust manifold at each cylinder and there weren't any huge differences.
Does anyone have any insight? Does this sound like bad injectors?
If you have the means to do it, perform an injector power balance test. That should reveal a leaking injector. My 91 Z28 is running a wee rich as well, and I've already checked the fuel pump and pressure regulator. My O2 readings sweep all over like yours, and my integrator is at 128. A quick test you can do is unhook the O2 sensor once warmed up, and jump the harness connector to ground and see if your O2 millivolts goes to around .350, that way you know that your ECM and wiring is good. If the O2 sensor age is unknown, a new one is about $20 at autozone, i would try replacing that because a contaminated or weak one will affect how much fuel the engine gets. According to the 91 service manual, O2 milivolts must be at or above .750 for 30 secs before a rich condition code will set. It can run close to there and be rich and still not throw a code.
Also the manual says as part of the diag for this to unhook the MAP sensor electrical connector and see if that improves it.
I have a 1985 L98 from a Corvette. It has been swapped to Speed Density, running the '730 ECU and a TPI chip from Larry's Electronics. I recently had some issues where the engine wouldn't idle and through trouble shooting have found that it's running very rich. The engine is currently in my Jeep after sitting for a couple years well protected in my garage. As far as I know, the engine is all stock.
The plugs are all fouled. The exhaust smells like gas and most recently, I was getting black smoke on startup.
After letting the engine warm up and hooking it up to TunerPro at idle I get the following info:
Throttle Position - .78
TPS % - 0
Coolant Temp - 87.5* C
Startup Coolant Temp - 20.75* C
Battery Voltage - 13.7 V
Fuel Pump Voltage - 13.5 V
Vehicle Speed - 0 MPH
Engine Speed - 700 RPM
Map Volts - 1.6 V
Map kPa - 40.24 kPa
Manifold Air Temp - 65.24* C
Target AFR - 14.73
O2 Sensor - Sweeping up and down
Integrator - 129
BLM - 156 (read as high was 160, as low as 144)
Block Learn Cell - 4 (this changes while driving)
Injector Pulse Width - 2.55 ms
I ohmed out all the injectors with them all ranging from 23 - 29 and one at 42. From what I've read that is pretty high.
The opinion I've gotten from a few people is that I've got leaking injectors. I pressured the system, clamped off the fuel and return lines and it does leak down to around 10 psi in 15-20 minutes. I used a thermometer to measure the exhaust manifold at each cylinder and there weren't any huge differences.
Does anyone have any insight? Does this sound like bad injectors?
sounds like leaky injectors. Pull one or all of the plugs, if the cylinder/cylinders are wet, then you have one or more leaky injectors, besides the ohm readings are WAY to high.
sounds like leaky injectors. Pull one or all of the plugs, if the cylinder/cylinders are wet, then you have one or more leaky injectors, besides the ohm readings are WAY to high.
They were wet.
I ordered new injectors today from FIC. Hopefully that fixes things.
