Turbo 5.3 idle issue.
04-17-2018, 11:07 PM
#1
Turbo 5.3 idle issue. My setup is a 67 chevelle with a forged 5.3, 80mm turbo, Siemens Deka 80# injectors, 102mm cable driven TB, stock pcm with stock harness that I reworked, dual electric fans, th400 10” TC, 3.25 gears. I have to fuel pressure reg set to 40psi at idle.
Today, finally got my driveshaft delivered and installed it. I was able to drive the car today which was nice after months of building...
I am having issues with the idle. Seems like when the engine is warmed up, it idled okay. Doesn’t surge... but when I put it under load (ie in reverse or 1st gear) the rpms start to dive and it chokes and dies.. I literally have to hold the throttle a little to keep it from dying or I have to stab the throttle fast. I can hear the TB open (the air sucking sound) and the engine dies for a second and I’m able to gas it to keep it from dying.
When im cruising it’s fine. Coming to a stop it’s fine. Everyone once in a while my wideband goes to - - - (like its super lean).
I had my local tuner shop flash the Pcm to remove VATS and also get it pretty close to what I need to break in the motor.
I will contact them to see if they can help me out as well.
thanks
Today, finally got my driveshaft delivered and installed it. I was able to drive the car today which was nice after months of building...
I am having issues with the idle. Seems like when the engine is warmed up, it idled okay. Doesn’t surge... but when I put it under load (ie in reverse or 1st gear) the rpms start to dive and it chokes and dies.. I literally have to hold the throttle a little to keep it from dying or I have to stab the throttle fast. I can hear the TB open (the air sucking sound) and the engine dies for a second and I’m able to gas it to keep it from dying.
When im cruising it’s fine. Coming to a stop it’s fine. Everyone once in a while my wideband goes to - - - (like its super lean).
I had my local tuner shop flash the Pcm to remove VATS and also get it pretty close to what I need to break in the motor.
I will contact them to see if they can help me out as well.
thanks
04-18-2018, 06:15 AM
#2
Restricted User
Is it a cheap 102mm throttle?
That sucking sound is probably the IAC. The hole in those for the IAC is so small that it can't react fast enough to save a falling idle.
That sucking sound is probably the IAC. The hole in those for the IAC is so small that it can't react fast enough to save a falling idle.
04-18-2018, 07:59 AM
#3
My setup is a 67 chevelle with a forged 5.3, 80mm turbo, Siemens Deka 80# injectors, 102mm cable driven TB, stock pcm with stock harness that I reworked, dual electric fans, th400 10” TC, 3.25 gears. I have to fuel pressure reg set to 40psi at idle.
Today, finally got my driveshaft delivered and installed it. I was able to drive the car today which was nice after months of building...
I am having issues with the idle. Seems like when the engine is warmed up, it idled okay. Doesn’t surge... but when I put it under load (ie in reverse or 1st gear) the rpms start to dive and it chokes and dies.. I literally have to hold the throttle a little to keep it from dying or I have to stab the throttle fast. I can hear the TB open (the air sucking sound) and the engine dies for a second and I’m able to gas it to keep it from dying.
When im cruising it’s fine. Coming to a stop it’s fine. Everyone once in a while my wideband goes to - - - (like its super lean).
I had my local tuner shop flash the Pcm to remove VATS and also get it pretty close to what I need to break in the motor.
I will contact them to see if they can help me out as well.
thanks
Today, finally got my driveshaft delivered and installed it. I was able to drive the car today which was nice after months of building...
I am having issues with the idle. Seems like when the engine is warmed up, it idled okay. Doesn’t surge... but when I put it under load (ie in reverse or 1st gear) the rpms start to dive and it chokes and dies.. I literally have to hold the throttle a little to keep it from dying or I have to stab the throttle fast. I can hear the TB open (the air sucking sound) and the engine dies for a second and I’m able to gas it to keep it from dying.
When im cruising it’s fine. Coming to a stop it’s fine. Everyone once in a while my wideband goes to - - - (like its super lean).
I had my local tuner shop flash the Pcm to remove VATS and also get it pretty close to what I need to break in the motor.
I will contact them to see if they can help me out as well.
thanks
Is your regulator boost referenced? If so, unplug the vacuum line to it (plug up the hole to avoid high idle), let the vehicle idle and adjust to 58 psi then re-install vacuum line.
If it isn't boost referenced, just adjust to 58 psi
Unless you are boost referenced and 40 psi is where it is under vacuum load, but I'm not sure what the psi would show at idle if you have it set to 58 psi
Also, are you running a MAF? If so, make sure the MAF is between the BOV and the throttle body. If BOV is between the throttle body and MAF, you're gonna have a bad time
Another thing - you said the tuner 'got it close' so you could break it in, if fuel pressure regulator WASN'T set to 58 psi when he did this, this may have some side effects
Last edited by TXjeepTJ; 04-18-2018 at 08:10 AM.
04-18-2018, 09:37 AM
#4
Fuel pressure regulator should be set to 58 psi
Is your regulator boost referenced? If so, unplug the vacuum line to it (plug up the hole to avoid high idle), let the vehicle idle and adjust to 58 psi then re-install vacuum line.
If it isn't boost referenced, just adjust to 58 psi
Unless you are boost referenced and 40 psi is where it is under vacuum load, but I'm not sure what the psi would show at idle if you have it set to 58 psi
Also, are you running a MAF? If so, make sure the MAF is between the BOV and the throttle body. If BOV is between the throttle body and MAF, you're gonna have a bad time
Another thing - you said the tuner 'got it close' so you could break it in, if fuel pressure regulator WASN'T set to 58 psi when he did this, this may have some side effects
Is your regulator boost referenced? If so, unplug the vacuum line to it (plug up the hole to avoid high idle), let the vehicle idle and adjust to 58 psi then re-install vacuum line.
If it isn't boost referenced, just adjust to 58 psi
Unless you are boost referenced and 40 psi is where it is under vacuum load, but I'm not sure what the psi would show at idle if you have it set to 58 psi
Also, are you running a MAF? If so, make sure the MAF is between the BOV and the throttle body. If BOV is between the throttle body and MAF, you're gonna have a bad time
Another thing - you said the tuner 'got it close' so you could break it in, if fuel pressure regulator WASN'T set to 58 psi when he did this, this may have some side effects
04-18-2018, 11:16 AM
#5
TXjeepTJ has it for the win. Hopefully that will fix it.