Where does the engine get air from? The inlet air temperatures (IAT) are extremely high - 144-degF when it stalls. At the same time the O2 sensors go lean. Appears it may be so hot under the hood that the fuel may be vaporizing. I have a feeling that with very high IAT temperatures the PCM starts to pull timing. Advance was showing as low as 15-deg at idle, against a typical programmed value of 20-deg. There are tiny amounts of knock retard, and the PCM drops the advance down to 10-deg, knock retard goes higher, and then it stalls.

More questions:

Has A/C been deleted? (not important, just allows me to delete columns in the data log. Program out?

Is the AIR pump functional - relay shows it is turned on at cold start, but there is no evidence of air flow at the O2 sensors. Program out?

 

The air intake is under hood i mine making a scoop for outside air. it has no a/c and no air pump it should be program out. i got new ect from gm finely go put it un run test , do u want me run test with a second computer to see different, when test was done i had no pressure in rad toke cap off did nor blow out running carmro rad

 

Based on the data log the coolant temp sensor is working fine. The DTC 14 code could have set when you pulled the harness off to verify 5 volt reference voltage between the harness connector pins. Leave the coolant temp sensor alone for now.

Describe your fuel pump setup:

- Is the fuel pump in the tank or outboard?

- If outside the tank, how close is the pump suction connection to the tank - how long is the section of line from the tank to the pump? What size is it?

- If outside the tank, Is the pump suction at/below the bottom elevation of the tank? If not, how far above the bottom elevation of the tank is the pump suction?

- Where is the fuel filter located?-

- What size is the line from the pump discharge to the engine fuel rail? How long is that line?

- Do any of the fuel lines get real close to the exhaust system, exposed to high heat?

- Are you using the stock LT1 fuel pressure regulator?

- What size is the return line from the fuel pressure regulator to the fuel tank?

I'm looking for weak points in the setup that may be leading to vapor lock.

 

my fuel set is outboard inline fuel pump rated at 60lbs max ,pump is about 15 inch above tank. Bottom elevation, has 3ft from tank to pump, the filter is up front by motor on inner fender well . 3/8line from pump to fuel rail 7ft of line. i keep lines away from all exhaust system not exposed to high heat, I'm using stock lt1 regulator, the return line is 5/16 from regulator to tank thank you doug

 

Having the pump above the bottom of the tank can result in cavitation in the suction line, where the fuel can flash to vapor. Is the pump suction line connected at the bottom of the tank? What size is the line from the tank to the pump? I had an outboard pump drawing off the the bottom/rear of the tank on my 94, and we used a -10AN (5/8”) line to the pump inlet to avoid excessive pressure loss in the line. I wouldn’t recommend anything smaller than that.

Filter is better in the back, away from engine compartment heat.

 

ok will do thank you

 

You missed this part:

What size is the line from the tank to the pump?

Also, what is the air temperature like right now, where you are located in Canada (Alberta?). The IAT temperatures you are seeing is what I would see here in NJ on a 90+-deg day, stopped in heavy traffic, with the A/C on.

Is your IAT sensor in a stock elbow right in front of the throttle body?

 

The line from tank to pump is 3/8,
the air temp is 62 F right now, west coast bc
the IATis in stock elbow in front throttle body

I'm moving fuel pump to frame it will be below fuel tank and change to 5/8 from tank to pump
the air intake was close to upper rad hose putting spacer in getaway from heat and new air intake from outside

tk doug

 

Too small. That plus the 15" lift above the fuel tank is prone to causing the fuel to vaporize in the suction line. Add a lot of hot fuel (heated up in the engine compartment) being returned to the tank, and it makes it even worse.

Seeing 144-degF IAT with that ambient temperature seems to point to an excessively hot engine compartment. Pulling hot air from that engine compartment is costing you HP. The IAT sensor in the stock location in the F-Body engine compartment is prone to heat soak, reporting an even higher than actual temperature.

Looking at the data log, the engine seems to be running pretty well, right up to the 11.5 minute mark. Then all of a sudden IN A MATTER OF 0.72 SECONDS, both O2 sensors go full lean, the RPM starts to drop, the PCM opens up IAC valve to try and hold the 600 RPM target idle, MAP increases, the MAF sensor sees the increased air flow, the PCM bumps up the injector pulse width to provide more fuel, but the O2 sensors stay dead lean. Too late, it stalls.

Not something I have ever seen before, but to me it is pointing to a sudden loss of fuel supply. Attributing this to vapor lock is just speculation, but I can't think of anything else, short of a fuel pump failure, that would cause that sequence of events.

 

thank you ,I'm doing all that u recommended know, will rerun test .what you said about 11.5 min mark is true , then when try to restart it run like **** , pings ,miss, then out blue she revers up by it self. then idle fine .doug

 

OK re done all changes u wanted run new test.
on road
test stalled when turning around .
sound like it was pinging some times
stalled when git back
started it again so u can see it how it was running
thank you doug

 

Seems my suggestions did not solve the problem. Seems to be beyond my capability to sort out. There are things going on in the logs that I can't explain.

We know there are 6 codes due to missing components, and maybe there is something in one of those codes, or some combination of codes that is turning on the coolant fans at random temperatures for example. The fans are both running when the coolant is only 74-deg. This does not seem to be a stock program. Something in the conversion, that I can't figure out.

The fuel seemed logical at the time, and there definitely were errors in the way the pump and filter were configured. But in the long run the fuel system changes can only help. Unfortunately didn't solve the problem. I apologize for that. In the first log, just before it stalled the O2 sensors went dead lean. In the first file above, in the entire log the O2 sensors are reading very rich, and while they lean out a bit at the stall, only the right bank goes very lean. On the other hand, you still have knock retard and the PCM is raising the injector pulse widths to add more fuel.

If you are still interested in my help, I need to understand why there are 5 data logs. I opened the first one, and it's 45 seconds of idling. Is this the restart after the first stall? Appears from the time stamp it is.

I'll open the 4 additional files, but it's going to take a while. Two of them appear from the time stamps to be duplicates of the same file. It would have been easier if you just repeated the process I requested you to follow, and that you used to generate the file you attached in post #6. If you can describe what the other 4 files are, it would cut down enormously on the amount of time I have to spend sorting them out.

 

the fuel pump changes made a different as for re starting when hot it did not act up like it did before and run good ,
the first log was when i got back and it stalled i did that so you could see what it was doing .
no2 was at start up when battery in computer die
no 3&4 i save when i was turning around and stalled big finger hit twice
no5 was return run i didn't know which ones were want .
i really appreciate your help thank you doug
i will rerun test '

 

Did it stall at the end of log #2? Appears it did. The target idle RPM is 600. It was idling a bit above that, and in a period of about 1.5 seconds RPM drops to 117 and then 0. And, the 600 RPM target idle speed is NOT a stock value. This PCM appears to have been altered. Did you pull the engine and PCM out of a junk yard car? You've also mentioned two different PCM's. What was "done" to them?



When I asked about the coolant fans running at very low temperatures, you responded:

Quote:

factory programmed pcm no switch wired from shbox site

Just doesn't match a "factory programmed pcm". How do you know the programs in the two PCM's you have are stock? Why do you have two PCM's? Why did you "wire" the coolant temp sensor? Wouldn't that wiring have been art of the harness you bought from Painless?

You indicate you hear "pinging" sometimes. You have MASSIVE knock retard every time you get heavy on the throttle. The knock sensor picks up the sound of knock (detonation) and the PCM pulls out ignition advance to eliminate the knock. If you actually hear knock, it's because it is beyond the capability of the PCM to pull enough timing to prevent the knock. The stock programming allows the PCM to reduce the timing advance by 15-degrees maximum. There are points when you go 100% throttle that the PCM max's out at 15-degrees retard. If the engine is knocking that bad, there's a chance you are damaging the engine. There are no signs of it running lean when this happens. Coolant and inlet air temperatures are not excessive. I wonder if this is somehow tied to the fact you deleted the EVAP system, but it's still in the PCM. Generally, when you get heavy on the throttle, the PCM is commanding 100% duty cycle on the EVAP system, and that's when you get the knock retard.

Have the heads ever been off the engine? Do you know if the compression ratio may have been increased by shaving the heads, or replacing the pistons with smaller valve reliefs, or even a dome? What grade (octane) fuel are you running?

I still haven't opened the #3 file. These files are very large, and take a lot of time to format and manipulate. What I "wanted" was a single file, from cold start, driving normally over a wide range of throttle and RP conditions, ending when it stalled. Just was I outlined in post # 2, and the same as you attached to post #6.

 

i bet he is not running premium gas. i could not get away from using premium gas, even tried on a freeway trip and my car didn't like at all!