Engine Cuts out and stumbles under boost...HELP PLEASE! `

[Nero328]

Thank you gentlemen...

I wish that is all it was but I do appreciate the thought, I am not the smartest man in the world and it is likely something simple like that but it is not the TPS. Unfortunately it is on correctly...

 

[Ttype6]

I wish that is all it was but I do appreciate the thought, I am not the smartest man in the world and it is likely something simple like that but it is not the TPS. Unfortunately it is on correctly...

And it doesn't do anything odd in the logs. In fact we see other odd things happen while the TPS is at a steady value.

 

[Street Lethal]

So Nick Micale set it up, broke it in, and all was good. The battery was changed because it sat for awhile, and now the engine sputters and misfires under boost only, is this the gist of it? I didn't read all these pages, but I can only assume the basics were checked like all sensor data reading correctly, spark plugs wires not arcing, spark plugs gapped appropriately, and ICM not too weak nor overheating...

I guess I could say it again. In this case,there is not an insufficient amount of fuel being delivered to the fuel rail. This is exactly what I stated earlier. Nothing else. The problem is that the computer is dispensing the fuel to the cylinders in an erratic fashion because it is receiving bad information.There is no fuel delivery problem meaning the fuel pump,lines, filter,regulator,and voltage are not the problem. The computer is making bad decisions because it is receiving bad information. Corrupt information is the cause of the problem,not fuel supply...

But how exactly was the fuel pressure confirmed?

The oxygen sensor is delivering low numbers because it senses high amounts of oxygen in the exhaust stream. There is a lot of oxygen in the exhaust stream because of the computer commanding less on time for the injectors and incomplete combustion/misfires.

Low numbers regarding air/fuel? That would indicate rich, not lean, unless you're referring to BLM of course. Remember the original complaint, it only happens under boost. If you're suggesting that the computer is pulling fuel due to skewed information, and if the O2 sensor has proven to be good, then the problem is either in the chip calibration, or the MAF sensor. Again, battery was pulled, fuse might have been blown, or something might have happened inadvertently...

Wow, you not only have a reading comprehension issue, but also a writing comprehension disorder.

Do you recall that there are three fusible links coming off the power feed from the starter? And that they deteriorate over time... It is very possible that there is an issue with one or more of these fusible links.

RemoveBeforeFlight

Are you having fun with all of this Bob lol...?

 

[Nero328]

So Nick Micale set it up, broke it in, and all was good. The battery was changed because it sat for awhile, and now the engine sputters and misfires under boost only, is this the gist of it? I didn't read all these pages, but I can only assume the basics were checked like all sensor data reading correctly, spark plugs wires not arcing, spark plugs gapped appropriately, and ICM not too weak nor overheating...



But how exactly was the fuel pressure confirmed?



Low numbers regarding air/fuel? That would indicate rich, not lean, unless you're referring to BLM of course. Remember the original complaint, it only happens under boost. If you're suggesting that the computer is pulling fuel due to skewed information, and if the O2 sensor has proven to be good, then the problem is either in the chip calibration, or the MAF sensor. Again, battery was pulled, fuse might have been blown, or something might have happened inadvertently...



Are you having fun with all of this Bob lol...?

Fuel pressure was confirmed with a gauge at the rail...

I have not replaced the O2 sensor yet...that is what started that argument, LoL...we all get a little invested in these issues.

 

[Street Lethal]

Fuel pressure was confirmed with a gauge at the rail...

I have not replaced the O2 sensor yet...that is what started that argument, LoL...we all get a little invested in these issues.

You tested fuel pressure at the rail under boost pressure? What was the fuel pressure reading when the engine began stumbling and misfiring, and at how much boost pressure?

 

[achalmersman]

You tested fuel pressure at the rail under boost pressure? What was the pressure reading when the engine began stumbling and misfiring, and at how much boost pressure?

This is all in the thread, in the logs, and has been discussed in detail.....

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

You tested fuel pressure at the rail under boost pressure? What was the fuel pressure reading when the engine began stumbling and misfiring, and at how much boost pressure?

No, I confirmed that the gauge in my car is accurate and therefore the reading on the PowerLogger log is accurate. Have you been able to look at the log? I can't answer that question off the top of my head and I am not near my computer right now to look it up however I would guess around 48 PSI just from my very vague memory. There are 4 logs in the thread...

 

[achalmersman]

Post 252 i posted the numbers

He already did and it looks to be stable. Not exactly 53 psi at 10psi boost, but its stable and not dropping off. Showing 49psi at 10psi boost, and 53psi at 13 psi boost. <br /><br />No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

So Nick Micale set it up, broke it in, and all was good. The battery was changed because it sat for awhile, and now the engine sputters and misfires under boost only, is this the gist of it? I didn't read all these pages, but I can only assume the basics were checked like all sensor data reading correctly, spark plugs wires not arcing, spark plugs gapped appropriately, and ICM not too weak nor overheating...



But how exactly was the fuel pressure confirmed?



Low numbers regarding air/fuel? That would indicate rich, not lean, unless you're referring to BLM of course. Remember the original complaint, it only happens under boost. If you're suggesting that the computer is pulling fuel due to skewed information, and if the O2 sensor has proven to be good, then the problem is either in the chip calibration, or the MAF sensor. Again, battery was pulled, fuse might have been blown, or something might have happened inadvertently...



Are you having fun with all of this Bob lol...?

Also, one more thing to clarify...I wouldn't necessarily call what Nick did "breaking it in" essentially he drove it around a few times and built up the boost to 18 PSI and apparently had no problems. I showed up 6 days later to pick up the car and began to have trouble on the very first test drive. The battery was changed when I got there because my battery was dead and wouldn't take a charge so Nick loaned me a battery for his testing and I brought a new battery with me when I came to pick up the car. Yes, all of the normal culprits, sensors, ignition module, coil module, ECM...all checked with known good parts while I was in Phoenix at Nick's place.

 

[mikestertwo]

All the grounds on the back of the head are clean and tight...correct?

 

[Ttype6]

Also, one more thing to clarify...I wouldn't necessarily call what Nick did "breaking it in" essentially he drove it around a few times and built up the boost to 18 PSI and apparently had no problems. I showed up 6 days later to pick up the car and began to have trouble on the very first test drive. The battery was changed when I got there because my battery was dead and wouldn't take a charge so Nick loaned me a battery for his testing and I brought a new battery with me when I came to pick up the car. Yes, all of the normal culprits, sensors, ignition module, coil module, ECM...all checked with known good parts while I was in Phoenix at Nick's place.

Did the car act up when Nick drove it with his battery?
When you drove it and it acted up did it have your new battery in it?

 

[Street Lethal]

Post 252 i posted the numbers

He already did and it looks to be stable. Not exactly 53 psi at 10psi boost, but its stable and not dropping off. Showing 49psi at 10psi boost, and 53psi at 13 psi boost. <br /><br />No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

If the fuel is there pressure wise, injectors are flowing cleanly, and the sensor data including the MAF data is correct, then it sounds like a timing issue during boost that the ECM is trying to compensate for by pulling fuel. We had a similar issue like this with a turbo powered SBC on another board, he was running a Megasquirt and it turned out it was SA related in the bin he was using...

 

[Nero328]

Did the car act up when Nick drove it with his battery?
When you drove it and it acted up did it have your new battery in it?

According to Nick it ran perfectly all the way up to his 18 PSI test and he stopped there...the car is built to go to 30 PSI. Yes, we changed the battery out as soon as I got there and that is when I drove it. My battery tested fine and the voltage on the PL log shows a solid voltage even through the problem area.

 

[Nero328]

If the fuel is there pressure wise, injectors are flowing cleanly, and the sensor data including the MAF data is correct, then it sounds like a timing issue during boost that the ECM is trying to compensate for by pulling fuel. We had a similar issue like this with a turbo powered SBC on another board, he was running a Megasquirt and it turned out it was SA related in the bin he was using...

"SA related in the bin he was using"...can you educate me here please? I am not a newbie however these are terms that I am not aware of.

 

[Nero328]

"SA related in the bin he was using"...can you educate me here please? I am not a newbie however these are terms that I am not aware of.

One thing I have not done is send these injectors off to be flow tested however they are new and were only the in other motor for a few months and were run less than 100 miles and had race fuel in them so I wouldn't expect them to be gummed up. I bought these injectors from Eric and they are 80#. I could take them to my guy here in Houston however that is another $150 to clean and flow test them. I don't see the data that tells me that could be an issue but if I am wrong and anyone think's that this is something I should do please let me know.

 

[Nero328]

All the grounds on the back of the head are clean and tight...correct?

Yes...again I wish it were that simple.

 

[Ttype6]

According to Nick it ran perfectly all the way up to his 18 PSI test and he stopped there...the car is built to go to 30 PSI. Yes, we changed the battery out as soon as I got there and that is when I drove it. My battery tested fine and the voltage on the PL log shows a solid voltage even through the problem area.

Next time you get a chance to drive the car disconnect the connector on the oil pressure switch before driving it. Something to try that costs nothing.

 

[TurboTGuy]

Good wishes for you and your family. Concentrate on that.

The car will still be there when all the family issues settle themselves.

Looking at it with a clear mind and new perspective might just help you solve your problem.

 

[Nero328]

Next time you get a chance to drive the car disconnect the connector on the oil pressure switch before driving it. Something to try that costs nothing.

The oil pressure switch is already disconnected.

 

[Ttype6]

The oil pressure switch is already disconnected.

That's too bad. Why is your oil pressure switch and your trans connector disconnected.