- City
- Biloxi
- State
- MS
I wanted to post up some questions/comments/concerns to see if anyone can help me out
I am running a TBI 5.7 (350) that came out of a 1990 Caprice Classic, in my 1984 Scrambler. It also has the 700R4, 4.10 axle gears, 33" tires.
The engine always starts right up, accelerates smoothly/linearly, shuts off with no "dieseling", and has plenty of power. No bogging, stumbling, cut outs, stalls, etc. Basically, I am pretty happy with it. Runs good, very reliable.
As far as I know, the engine is bone stock. I changed the valve stem oil seals, water pump, thermostat (195 degree), some hoses, etc. The engine came with a brand new TBI unit from "Turbo City", so the injectors and all TBI mounted sensors are new. When I first started the engine up, I got a code for a bad MAP sensor. I changed this sensor, good to go. I also recently changed the coolant sensor with a new one, and mounted it directly into the stock hole in the intake manifold. Before I changed this sensor, it was mounted in a metal block extension coming off the intake, and it would only read 130 degrees with the engine warmed all the way up running at 200 degrees.
My "complaint": The first few highway trips I drove the Scrambler on, if I drove 65-70mph, I was getting between 18-19mpg!!!!!!! Now, I get 11-12. The MPG drop happened before the coolant switch change. The other issue - at idle, the exhaust is slightly stinky. It smells ever so slightly rich, but not bad. It mainly just smells "extra exhausty", if that makes sense My red Scrambler with MPI smells "clean" when idling, the tan Scrambler with TBI smells "extra exhaust" at idle. Neither Scramblers have cats.
Here is a bunch of operating data from the code reader, engine fully warmed up and idling. No MIL, no stored codes:
RPM = 525-550 (seems a bit low????)
Coolant temp = 185 -190 (when driving down the road, it stays between 200-210)
MAP = 1.74 volts at idle (that is correct I believe)
O2 Sensor = around 450 mVolts, constantly moving (below 500 is lean, which is what I am showing)(pre-convertor O2 range 100-900 mVolts)
TPS = .6 volts (0-5 volt range, low at idle, should be good)
IAC Steps = 22-23 (0-255 steps total, should be good here)
Integrator = 128 (this is what it should be if air/fuel ratio is correct, should be good here)
Block Learn = 123 (under 127, fuel being subtracted, so this shows a slight lean??)
Closed/Open Loop = it always goes into Closed Loop when running, at idle it will sometimes go back into open, then closed again
Knock Sensor = shows 18 at idle (assuming this is OK)
Clear Flood Mode = OFF (this will only show ON if key is on, engine off, gas pedal floored)
Learn Control = DISABLED (this should be off if block learn is OK???????)
Async Mode = OFF (this just shows if extra fuel added during WOT operation, out of sync with injectors??)
Rich Lean Flag = constantly alternating (I assume it should do this in closed loop when the O2 sensor constantly adjusts A/F ratio?)
When driving down the road:
TCC Status = ON (this shows the TC is getting the signal to lock up) I am POSITIVE the TC is locking. If you unplug the harness off of the transmission, the TC will not lock. You can see the RPM increase, and feel the performance difference. My TC will lock in 2, 3, and 4 (OD). You can watch it on the Scan tool, see the RPM drop, and "feel" it.
Vehicle Speed = Works (it matches the speedometer/GPS)
Other Notes:
I have an operational charcoal canister system. I am using an "early" TBI set up - canister with a line from the fuel tank, single purge line directly to ported vacuum on the TB. Works fine, no gas smell, no weird gas cap issues. My computer/harness does not support the solenoid activated purge system.
EGR system - I have the stock EGR, and the stock EGR solenoid. Everything is wired/plumbed up like it should be. I "assume" it is working correctly. The solenoid portion does not have any error codes. I will check the valve and solenoid with a vacuum gauge to verify it is working. I do not have the "typical" bad EGR symptoms, but maybe their is a problem?
Fuel Pressure - I have not checked this, it is a PIA to check on the TBI. I am pretty sure the pressure is OK. You can hear the injectors cycling back and forth, see the "cone mist" of fuel coming out. However, it "looks" like a droplet of fuel comes out of each injector, too. The throttle plates just stay "damp" at idle, no fuel puddeling, no black smoke. Spark plugs have a real nice, perfect tan color. If you pinch the return line shut, the engine starts to stumble/run rough. I will need to verify pressure to rule out regulator/fuel pump problems, but I think they are OK.
One other note - When the engine was averaging 18-19 MPG, and it was not stinky at idle, I had the heater hoses ran incorrectly, and the engine was running between 215-220 degrees. From what I researched, this is the acceptable operating range for these engines? With the heater hoses ran the way I had them, the coolant switch was reading engine operating temperature. When I re-ran the heater hoses, I don't think the sensor was submerged in coolant, so it would only read 130 degrees. I am hoping that since the new sensor is reading the correct coolant temperature, this might help fix part of my problem. I "assume" if the computer thinks the engine is only at 130 degrees, it will "rich" up the fuel mixture, like it is in a constant warm up mode?
I plan on driving the Scrambler some more, take it on a highway drive, and see if the MPG has gotten better.
I look forward to any comments/criticisms/suggestions
I am running a TBI 5.7 (350) that came out of a 1990 Caprice Classic, in my 1984 Scrambler. It also has the 700R4, 4.10 axle gears, 33" tires.
The engine always starts right up, accelerates smoothly/linearly, shuts off with no "dieseling", and has plenty of power. No bogging, stumbling, cut outs, stalls, etc. Basically, I am pretty happy with it. Runs good, very reliable.
As far as I know, the engine is bone stock. I changed the valve stem oil seals, water pump, thermostat (195 degree), some hoses, etc. The engine came with a brand new TBI unit from "Turbo City", so the injectors and all TBI mounted sensors are new. When I first started the engine up, I got a code for a bad MAP sensor. I changed this sensor, good to go. I also recently changed the coolant sensor with a new one, and mounted it directly into the stock hole in the intake manifold. Before I changed this sensor, it was mounted in a metal block extension coming off the intake, and it would only read 130 degrees with the engine warmed all the way up running at 200 degrees.
My "complaint": The first few highway trips I drove the Scrambler on, if I drove 65-70mph, I was getting between 18-19mpg!!!!!!! Now, I get 11-12. The MPG drop happened before the coolant switch change. The other issue - at idle, the exhaust is slightly stinky. It smells ever so slightly rich, but not bad. It mainly just smells "extra exhausty", if that makes sense My red Scrambler with MPI smells "clean" when idling, the tan Scrambler with TBI smells "extra exhaust" at idle. Neither Scramblers have cats.
Here is a bunch of operating data from the code reader, engine fully warmed up and idling. No MIL, no stored codes:
RPM = 525-550 (seems a bit low????)
Coolant temp = 185 -190 (when driving down the road, it stays between 200-210)
MAP = 1.74 volts at idle (that is correct I believe)
O2 Sensor = around 450 mVolts, constantly moving (below 500 is lean, which is what I am showing)(pre-convertor O2 range 100-900 mVolts)
TPS = .6 volts (0-5 volt range, low at idle, should be good)
IAC Steps = 22-23 (0-255 steps total, should be good here)
Integrator = 128 (this is what it should be if air/fuel ratio is correct, should be good here)
Block Learn = 123 (under 127, fuel being subtracted, so this shows a slight lean??)
Closed/Open Loop = it always goes into Closed Loop when running, at idle it will sometimes go back into open, then closed again
Knock Sensor = shows 18 at idle (assuming this is OK)
Clear Flood Mode = OFF (this will only show ON if key is on, engine off, gas pedal floored)
Learn Control = DISABLED (this should be off if block learn is OK???????)
Async Mode = OFF (this just shows if extra fuel added during WOT operation, out of sync with injectors??)
Rich Lean Flag = constantly alternating (I assume it should do this in closed loop when the O2 sensor constantly adjusts A/F ratio?)
When driving down the road:
TCC Status = ON (this shows the TC is getting the signal to lock up) I am POSITIVE the TC is locking. If you unplug the harness off of the transmission, the TC will not lock. You can see the RPM increase, and feel the performance difference. My TC will lock in 2, 3, and 4 (OD). You can watch it on the Scan tool, see the RPM drop, and "feel" it.
Vehicle Speed = Works (it matches the speedometer/GPS)
Other Notes:
I have an operational charcoal canister system. I am using an "early" TBI set up - canister with a line from the fuel tank, single purge line directly to ported vacuum on the TB. Works fine, no gas smell, no weird gas cap issues. My computer/harness does not support the solenoid activated purge system.
EGR system - I have the stock EGR, and the stock EGR solenoid. Everything is wired/plumbed up like it should be. I "assume" it is working correctly. The solenoid portion does not have any error codes. I will check the valve and solenoid with a vacuum gauge to verify it is working. I do not have the "typical" bad EGR symptoms, but maybe their is a problem?
Fuel Pressure - I have not checked this, it is a PIA to check on the TBI. I am pretty sure the pressure is OK. You can hear the injectors cycling back and forth, see the "cone mist" of fuel coming out. However, it "looks" like a droplet of fuel comes out of each injector, too. The throttle plates just stay "damp" at idle, no fuel puddeling, no black smoke. Spark plugs have a real nice, perfect tan color. If you pinch the return line shut, the engine starts to stumble/run rough. I will need to verify pressure to rule out regulator/fuel pump problems, but I think they are OK.
One other note - When the engine was averaging 18-19 MPG, and it was not stinky at idle, I had the heater hoses ran incorrectly, and the engine was running between 215-220 degrees. From what I researched, this is the acceptable operating range for these engines? With the heater hoses ran the way I had them, the coolant switch was reading engine operating temperature. When I re-ran the heater hoses, I don't think the sensor was submerged in coolant, so it would only read 130 degrees. I am hoping that since the new sensor is reading the correct coolant temperature, this might help fix part of my problem. I "assume" if the computer thinks the engine is only at 130 degrees, it will "rich" up the fuel mixture, like it is in a constant warm up mode?
I plan on driving the Scrambler some more, take it on a highway drive, and see if the MPG has gotten better.
I look forward to any comments/criticisms/suggestions