if your not looking for something to boost your performance its always good to go as close to original as you can.

 

Bosch 0280155703 are EV6

 

I know very little about fuel injection. I know nothing about the stock ECU pulse widths, injector timing, fuel ratios, etc. From reading forums and listening to experts, picking a good replacement is almost a trial and quessing process. eg I had these on the self and they seem to work. I may be a bit paranoid or too much of an engineer, but without a calculation to select replacements I get an uncomfortable feeling.

I guess I need to learn a bit more about injectors and fuel systems

 

Just go for a good set of stock replacements. The originals lasted how many years? Yeah, they are a 'pencil-beam' type injector, but, the idea there is, the injector is pointed at the back side of the (very hot) intake valve, so, when the fuel stream hits it, it flashes to vapor. I seriously doubt anyone would be able to tell the difference between them, and the assorted four hole injectors..... just by driving it. Of course, if your current injectors are bad, then ANY change will likely be an improvement.

That said, if you get injectors that are 'close' to the stock flow rating, the computer will figure them out pretty quick. That's what O2 sensors are for. Just keep in mind, that they NEED to be "close", else other problems will present themselves.

 

Thanks, agreed on getting something reliable.. I don't want to do this again 6-12 months because of junk parts. There's been no luck finding NOS injectors, they've been out of production since '96/'97. All matching, available EV1s found are rebuilt. I've had pretty poor experiences with rebuilt parts in the past, so I'm looking for new injectors from a known reliable manufacturer. I think I'll be forced to move to EV6s. If I need to move, I may have as well move to a 4 pin injector because 1) they are lower cost and 2) more available than 1 pin.

The reason I'm changing them out is the truck didn't pass emissions, plus power/mileage has been pretty poor. There is a big push in Colorado to reduce emissions and been tightening the screws on older trucks. Changing the timing chain helped, but didn't push it over the line. I'm already at 5500ft, which loses 10%-15% power than at sea level. I went to buy a new 2500, the price is outrageous. Anything on the lot is $93K+ unless I wait a year to have it built. I've paid less $$ for houses with 5 acres of land and a barn. I'm going to check out Mississippi and Louisiana for better pricing.

In the past 2 months, I've had 3 notes left on my truck asking if I was interested in selling, one note was left when I was at the dealer.. I'm thinking it may be worth restoring if it can pass emissions. It's a bunch lower cost than a new 2500.

 

The new ones are plain ugly! You probably have more issues going on not passing emissions than injectors. They rarely ever go bad but occasionally do. If you have one sticking open that would cause it. Plenty of people have 300K with the original injectors. You could find used ones in the junk yard from a vehicle with low miles and save some cash.
What's this telling you? Keep the second gens on the road!

 

Before starting this thread, I did look at salvage yards and craigslist, ebay, this and other forums looking for parts. No luck. My truck passed emissions 3 years ago, but new emission standards are pushing older vehicles off the road. The state keeps extending the age of "vintage vehicles" with higher emissions standards. Dealers are pushing electrics and hybrids which I'll never buy. The big selling point for EV trucks is high torque, but with a range of 150-200 miles they do me no good. More importantly, the electrical infrastructure in my area cannot handle all the new electric vehicles purchased. Worsening things, Xcel Energy has increased the cost of electricity about 20%, making the per mile cost of electric vehicles about equal to gasoline vehicles. New vehicle batteries last about 10 years. For a truck, it's a $25K replacement cost, or about $2,500/yr and cost of batteries are increasing 5%-10%/yr. Maintenance for EVs is said to be $200 lower annual cost without battery replacement. Once battery replacement is rolled in, EV operating and maintenance annual costs are $2,200 more than gasoline trucks.

Talked to my brother in Dallas area, used trucks prices are skyrocketing because you just cannot buy new trucks under $60k. Considering my EV rant above, if I throw $6K at this truck, including paint, it'll be like having a new daily driver with conventional steering so I can feel the road.

 

That’s my take also… you can do an awful lot of 2nd Gen restoration for $60k, knowing you’re good for another 100k minimum.

 

I'm honing in on replacement selections. The major concern I have is whether the new injectors operate correctly with the oem ecu's open loop mode.

Just because a substitute injector works near sea level, it may not work correctly 5500 ft. At 5500 ft there is 20% less oxygen, the engine needs 20% less fuel than at sea level. Until the engine warms up or while starting, accelerating, decelerating, wide open throttle, the ECU's operates in open loop mode where throttle position sensor, coolant sensor, MAP, manifold temp sensor and injector flow rates to assure proper fuel mixture. Meaning the the injectors flow rates and ecu needs to be calibrated to provide the correct-ish open loop fuel mixture. A rich fuel mixture accelerates CAT clogging/failures, high exhaust temps and higher rates of engine valve failures. Once the engine warms up and only while "Cruising" and "Idling", O2 sensors inputs are used to adjust fuel trim.

In other words, the injector flow rates must be properly matched to the obd-1 ecu. As altitude increases, flow rate matching seems to be becomes more important to prevent rich mixture during every mode of operation outside of warmed up idle and cruising.

FSM pg 8D - 7:
When the engine is cold, the PCM will operate in the Open Loop Cycle. I t will demand slightly richer air-fuel mixtures and higher idle speeds, until normal operating temperatures are reached. Refer to Modes Of Operation in Group 14, Fuel System for a description of Open and Closed Loop operation. On the 3.9L V-6 or 5.2/5.9L V-8 engines, the sensor is installed in the intake manifold near the thermostat housing (Fig. 17).

FSM pg 14 - 51/52
OPEN LOOP/CLOSED LOOP MODES OF OPERATION
As input signals to the powertrain control module (PCM) change, the PCM adjusts its response to the output devices. For example, the PCM must calculate different injector pulse width and ignition timing for
idle than it does for wide open throttle (WOT). There are several different modes of operation that determine how the PCM responds to the various input signals.

MODES
• Open Loop
• Closed Loop

During Open Loop modes, the powertrain control module (PCM) receives input signals and responds only according to preset PCM programming. Input from the oxygen (02S) sensor(s) is not monitored during Open Loop modes.

During Closed Loop modes, the PCM will monitor the oxygen (02S) sensor input. This input indicates to the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the 02S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance.

The fuel injection system has the following modes of operation:
• Ignition switch ON
• Engine start-up (crank)
• Engine warm-up
• Idle
• Cruise
• Acceleration
• Deceleration
• Wide open throttle (WOT)
• Ignition switch OFF
The ignition switch On, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes. The idle and cruise modes, (with the engine at operating temperature)
are Closed Loop modes.

IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following actions occur:
• The powertrain control module (PCM) pre-positions the idle air control (IAC) motor.
• The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
• The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy based on this input.
• Intake manifold air temperature sensor input is monitored.
• Throttle position sensor (TPS) is monitored.
• The auto shut down (ASD) relay is energized by the PCM for approximately three seconds.
• The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately one second unless the engine is operating or the starter motor is engaged.
• The 02S sensor(s) heater element is energized through the fuel pump relay. The 02S sensor(s) input is not used by the PCM to calibrate air-fuel ratio during this mode of operation.
• The up-shift indicator lamp is illuminated (manual transmission only).

ENGINE START-UP MODE
This is an Open Loop mode. The following actions occur when the starter motor is engaged.
The powertrain control module (PCM) receives inputs from:
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Starter motor relay
• Camshaft position sensor signal
The PCM monitors the crankshaft position sensor. If the PCM does not receive a crankshaft position sensor signal within 3 seconds of cranking the engine, it will shut down the fuel injection system.

The fuel pump is activated by the PCM through the fuel pump relay.

Voltage is applied to the fuel injectors with the PCM. The PCM will then control the injection sequence
and injector pulse width by turning the ground circuit to each individual injector on and off.

The PCM determines the proper ignition timing according to input received from the crankshaft position sensor.

ENGINE WARM-UP MODE
This is an Open Loop mode. During engine warm up, the powertrain control module (PCM) receives inputs from:
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
• Park/Neutral Switch (Gear indicator signal—auto, trans, only)
• Air conditioning request signal (if equipped)
Based on these inputs the following occurs:
• Voltage is applied to the fuel injectors with the powertrain control module (PCM). The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off.
• The PCM adjusts engine idle speed through the idle air control (IAC) motor and adjusts ignition timing.
• The PCM operates the A/C compressor clutch through the clutch relay. This is done if A/C has been selected by the vehicle operator and requested by the A/C thermostat.
• If the vehicle has a manual transmission, the upshift lamp is operated by the PCM.
• When engine has reached operating temperature, the PCM will begin monitoring 02S sensor(s) input. The system will then leave the warm-up mode and go into closed loop operation

ACCELERATION MODE
This is an Open Loop mode. The powertrain control module (PCM) recognizes an abrupt increase in throttle position or MAP pressure as a demand for increased engine output and vehicle acceleration. The PCM increases injector pulse width in response to increased throttle opening.

DECELERATION MODE
When the engine is at operating temperature, this is an Open Loop mode. During hard deceleration, the powertrain control module (PCM) receives the following inputs.
• Air conditioning request signal (if equipped)
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
• Park/Neutral switch (gear indicator signal—auto, trans, only)
If the vehicle is under hard deceleration with the proper rpm and closed throttle conditions, the PCM will ignore the oxygen sensor input signal. The PCM will enter a fuel cut-off strategy in which it will not supply battery voltage to the injectors. If a hard deceleration does not exist, the PCM will determine the proper injector pulse width and continue injection.

Based on the above inputs, the PCM will adjust engine idle speed through the idle air control (IAC) motor.

The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.

The PCM opens the ground circuit to the A/C clutch relay to disengage the A/C compressor clutch. This is done until the vehicle is no longer under deceleration (if the A/C system is operating).

WIDE OPEN THROTTLE MODE
This is an Open Loop mode. During wide open throttle operation, the powertrain control module (PCM) receives the following inputs.
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
•• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
During wide open throttle conditions, the following occurs:
• Voltage is applied to the fuel injectors with the powertrain control module (PCM). The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off. The PCM ignores the oxygen sensor input signal and provides a predetermined amount of additional fuel. This is done by adjusting injector pulse width.
• The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.
• The PCM opens the ground circuit to the A/C clutch relay to disengage the A/C compressor clutch. This will be done for approximately 15 seconds (if the air conditioning system is operating). If the vehicle has a manual transmission, the upshift lamp is operated by the PCM.

 

You are over-thinking this. Get some stock replacement injectors, or equivalent, and be down the road. The open loop tables tend to run a bit rich in any event, as long as the injectors are 'pretty close', they'll work.