Ok, got a little deeper into it last night. The ECM is requesting 3100 RPM on start-up then idle at 825 RPM. The engine cranks, eventually starts, barely runs at 400-450 RPM then dies. If I feather the throttle (and watch TPS voltage) it does nothing until I let off and the TPS voltage goes back to .56 then the RPM jumps up. Once the ECM enters the Closed Loop mode it seems to idle closer to what the ECM is requesting and run a little better. O2 voltage is 4 not 400 but 4.

It has fuel and fuel pressure. It has spark. All the grounds for the ECM are good. I have ruled out vaccum leaks. I have a DFI computer for it however I'm afraid to add something else into this equation as I can't figure this one out.

I have checked the EST wire and its voltage. I have checked the spark-time-out wire during the cranking phase. The ignition module. Each plug wire for spark at each cylinder. The thing I don't know how to check is the actual injectors. The new Accel injectors do not "click" like the factory units, these seem very quite. The engine runs considerably worse since I swapped injectors. I went from 24# to 26#. I'm running a TPIS Level VI prom which was set-up for the 24# units. Being that the car has a MAF sensor, I don't think the injector size increase is what is causing the problem. The engine is running extremely lean. This is the reason I believe for the delayed throttle action and the extended starting. Too much air, not enough fuel.

Any ideas? Anyone want to make some money working on an IROC? After last night I remember why I took a year off!

 

Bad gas
Clogged fuel filter
Bad injectors (I doubt all of them went bad but some maybe??), Chip work.

I have the opposite problem at start up. I'm so rich It burns my eyes. I wish I could see the ECU but I'm still stuck at getting my laptop to link on my car.

 

Yeah, I've gone completely through the fuel system. What I thought was a rich condition turned out to be a lean condition. When she's running very lean it will produce the same type of burning eye smell. Can you see the exhaust? Is it really rich or does it smell rich? Mine has no exhaust plume, just stinks!

 

I can't see any exhaust. But when I go to the back and sniff the bumper I have a psychodelic experience.

So your saying a lean condition would do the same. My digi O2 guage is pegged if that helps. It mellows out in closed loop and last night it was just fine at 70 in 5th. My pressure is only getting to 46 psi were as before I was getting 52 PSI at WOT.
I need a FP and new AFPR first before I start wiggin.

 

You have to change the injector constant. There is really no way around that. The ecm thinks the injectors are smaller than they really are, and its flooding the engine with fuel, at least it should be.

I'm not following what you say the TPS is doing. Do the volts increase as you open the throttle? The startup RPM before the engine fires up is ok, thats normal.

 

Just a observation:
If the injectors were flowing too much fuel, wouldn't the O2 sensor see the air/fuel ratio and decrease the injector pulse width?

Being that the chip I have was burned for 24# and I now have 26# injectors, coupled with the fact that the engine is a 383, do you think that an increase of 2# is enough to make the engine barely run?

The other observation is the O2 sensor readings. Normal closed loop O2 readings at idle should be in the 350-440 MV range, higher numbers being richer, lower numbers being leaner respectively. My O2 reading at idle is 4. That is way lean.

The delayed starting of the engine. Check this out: If I crank the engine it takes a good 5 seconds to light off. If I bump the key several times without fully cranking it over, then crank the key it starts right up. I'm thinking there is more air than fuel which is why it doesn't start right up. The several bumps of the key fill the cylinders with fuel so when it does fully crank it starts right up.

The TPS sensor: At idle (even tough the engine won't) the TPS reads .56, if the throttle is depressed the TPS increases up to 4.0 +. When the engine is barely running and I press the throttle open the RPM does nothing, it doesn't respond at all. After the throttle blades close and the TPS voltage comes back down the RPM jumps up. It is like a total delayed reaction. Again, I'm thinking more air than fuel.

Going back to when the original problem started, it was a slow degredation. At first is was only a starting problem (delayed start). Then it became a poor running engine until closed loop was entered. Now it is all the time although a little better in closed loop. The car cannot be driven.

I think that it's starving for fuel, in open loop the ECM is at a pre-set parameter for the amount of fuel to inject. What ever the problem that is starving the engine for fuel is restricting (?) the fuel supply however when closed loop is entered the block learn multiplier and cell integrator increase the pulse width to tryand compensate the lack of fuel, hense making it run better.

I have installed a new fuel pump, filter and injectors to no avail. Idle psi is around 36, WOT is around 49. Is it possible to have enough PSI but not enough volume? Do I have a fuel supply problem? How do I check? How can I check the amount of fuel leaving the injectors? What should I do next? I am truly lost on this one! I used to think a huge vaccum leak was causing the low O2 readings and the delayed start. That Super Ram is sealed tight as a drum. The creek is deep and I have no paddle!

 

Just a observation:
If the injectors were flowing too much fuel, wouldn't the O2 sensor see the air/fuel ratio and decrease the injector pulse width?

Yes, but in open loop (when you fire the car up) the o2 is not affecting what the computer is doing, its not ready. Theres a minimum 3 minute 'timeout' where it does squat. In closed loop, the ecm can only adjust so far before it runs out of space to make adjustments.

Being that the chip I have was burned for 24# and I now have 26# injectors, coupled with the fact that the engine is a 383, do you think that an increase of 2# is enough to make the engine barely run?

Not really, but I think you have more than one thing going on, and thats what is really screwing it up.

The other observation is the O2 sensor readings. Normal closed loop O2 readings at idle should be in the 350-440 MV range, higher numbers being richer, lower numbers being leaner respectively. My O2 reading at idle is 4. That is way lean.

Dunno what to tell you about that, maybe it is that lean once the o2 takes over.

The TPS sensor: At idle (even tough the engine won't) the TPS reads .56, if the throttle is depressed the TPS increases up to 4.0 +. When the engine is barely running and I press the throttle open the RPM does nothing, it doesn't respond at all. After the throttle blades close and the TPS voltage comes back down the RPM jumps up. It is like a total delayed reaction. Again, I'm thinking more air than fuel.

Quite possibly. This is where you have to play with the MAF tables, something that TPIS does little if any of to their chips, as I understand it.

Going back to when the original problem started, it was a slow degredation. At first is was only a starting problem (delayed start). Then it became a poor running engine until closed loop was entered. Now it is all the time although a little better in closed loop. The car cannot be driven.

I've had cars do this before, with no seemingly reasonable explanation. Best advice I have is get the computer straightened out first and go from there.

I think that it's starving for fuel, in open loop the ECM is at a pre-set parameter for the amount of fuel to inject. What ever the problem that is starving the engine for fuel is restricting (?) the fuel supply however when closed loop is entered the block learn multiplier and cell integrator increase the pulse width to tryand compensate the lack of fuel, hense making it run better.

Have any idea what the block learn and stuff is in closed loop?

I have installed a new fuel pump, filter and injectors to no avail. Idle psi is around 36, WOT is around 49. Is it possible to have enough PSI but not enough volume?

Possible, but very unlikely.