Engine died during dyno and won't restart!
07-28-2009, 10:48 PM
#1
Engine died during dyno and won't restart! Got on the dyno for the first time with my new motor last Sat. Made a couple of pulls, tuner was working on the tune, then... car dies after the third pull and won't restart.
Car will crank but not fire - AND - the PCM won't communicate with LS1edit. Other electronics are working, i.e. lights, chimes, etc. I'm thinking that the PCM ground may have come disconnected.
Also, before the car died the fuel pump was doing some funny things, almost like voltage spiking. I'm thinking that the ground was coming loose, then came completely undone and killed the power.
Where is the PCM ground? Thanks!
Car will crank but not fire - AND - the PCM won't communicate with LS1edit. Other electronics are working, i.e. lights, chimes, etc. I'm thinking that the PCM ground may have come disconnected.
Also, before the car died the fuel pump was doing some funny things, almost like voltage spiking. I'm thinking that the ground was coming loose, then came completely undone and killed the power.
Where is the PCM ground? Thanks!
07-29-2009, 07:21 AM
#4
Yup at especially in the LT's, I havent had that happen with the LS's, Dam I shouldn't of said that!!. Anyway I was the tuner, First off its not the PCM, I tried another and still the same results, No start, No communication. Also what is happening is there is no fuel pressure, At first I thought it was the fuel pump, but I decided to read the pcm and no luck so I thought the same, Dam pcm fried that is why I installed the other PCM. After all that the Dyno operator told me on the last pull when it was coming down to an idle the engine just shut off. ( I didnt know that until the end). Now this is what the car did. There was a rich dip at app the 4000-5000 RPM range, in the low 11's, the rest was good at app 12.9 across. so I leaned it up a little just in that area and the next pull was around 14.2 across the board, thats when the car died....And yes I did check the fuses for the PCM and Lighter...Thanks for any advice...
07-29-2009, 07:43 AM
#5
Yup at especially in the LT's, I havent had that happen with the LS's, Dam I shouldn't of said that!!. Anyway I was the tuner, First off its not the PCM, I tried another and still the same results, No start, No communication. Also what is happening is there is no fuel pressure, At first I thought it was the fuel pump, but I decided to read the pcm and no luck so I thought the same, Dam pcm fried that is why I installed the other PCM. After all that the Dyno operator told me on the last pull when it was coming down to an idle the engine just shut off. ( I didnt know that until the end). Now this is what the car did. There was a rich dip at app the 4000-5000 RPM range, in the low 11's, the rest was good at app 12.9 across. so I leaned it up a little just in that area and the next pull was around 14.2 across the board, thats when the car died....And yes I did check the fuses for the PCM and Lighter...Thanks for any advice...
This weekend I'll check the ground on the back of the head. I'd had been messing around back there addressing a suspected manifold leak, maybe I inadvertantly loosened something up?
07-29-2009, 10:19 AM
#7
I forgot to ask, did any DTCs pop up during the dyno runs that could shed any light?
This weekend I'll check the ground on the back of the head. I'd had been messing around back there addressing a suspected manifold leak, maybe I inadvertantly loosened something up?
This weekend I'll check the ground on the back of the head. I'd had been messing around back there addressing a suspected manifold leak, maybe I inadvertantly loosened something up?
Nope, No codes at all...
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07-29-2009, 01:47 PM
#9
Hey Moe,
The PCM tanking that I witnessed happened during a write and the tuner guy knew it as soon as it happened (error msg I assume, as the room was filled with colorful language
)
I had a car battery totally die out of the blue on the dyno a few years back and act somewhat similar.
The PCM tanking that I witnessed happened during a write and the tuner guy knew it as soon as it happened (error msg I assume, as the room was filled with colorful language
)I had a car battery totally die out of the blue on the dyno a few years back and act somewhat similar.
07-30-2009, 06:55 AM
#10
Hey Moe,
The PCM tanking that I witnessed happened during a write and the tuner guy knew it as soon as it happened (error msg I assume, as the room was filled with colorful language)
I had a car battery totally die out of the blue on the dyno a few years back and act somewhat similar.
The PCM tanking that I witnessed happened during a write and the tuner guy knew it as soon as it happened (error msg I assume, as the room was filled with colorful language
)I had a car battery totally die out of the blue on the dyno a few years back and act somewhat similar.
07-30-2009, 10:55 AM
#14
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You might also want a spare fuel pump relay, if you
dropped to low enough line that it was chattering
the pump load current might've burnt the contacts.
Maybe see if jumpering the contacts, makes the
pump go. That would narrow you down to relay guts
or intention (coil drive, VATS or PCM).
Bus / comms misbehavior might have also messed
up the VATS - PCM, with a working PCM try the
"relink VATS"?
Bus hangs can sometimes be recovered by pulling
PCM fuses, I don't remember which one (there are
two) did it for me, back when.
dropped to low enough line that it was chattering
the pump load current might've burnt the contacts.
Maybe see if jumpering the contacts, makes the
pump go. That would narrow you down to relay guts
or intention (coil drive, VATS or PCM).
Bus / comms misbehavior might have also messed
up the VATS - PCM, with a working PCM try the
"relink VATS"?
Bus hangs can sometimes be recovered by pulling
PCM fuses, I don't remember which one (there are
two) did it for me, back when.
07-30-2009, 01:50 PM
#15
You might also want a spare fuel pump relay, if you
dropped to low enough line that it was chattering
the pump load current might've burnt the contacts.
Maybe see if jumpering the contacts, makes the
pump go. That would narrow you down to relay guts
or intention (coil drive, VATS or PCM).
Bus / comms misbehavior might have also messed
up the VATS - PCM, with a working PCM try the
"relink VATS"?
Bus hangs can sometimes be recovered by pulling
PCM fuses, I don't remember which one (there are
two) did it for me, back when.
dropped to low enough line that it was chattering
the pump load current might've burnt the contacts.
Maybe see if jumpering the contacts, makes the
pump go. That would narrow you down to relay guts
or intention (coil drive, VATS or PCM).
Bus / comms misbehavior might have also messed
up the VATS - PCM, with a working PCM try the
"relink VATS"?
Bus hangs can sometimes be recovered by pulling
PCM fuses, I don't remember which one (there are
two) did it for me, back when.
Yup, Man were stumped, I checked all of the fuses, swapped out relays and still nothing....??? Just cranks with no fuel pressure..
