Hello All,
I’ve been chasing a rough starting issue on my 1997 US Spec 80 series along with a random P0172 code for weeks now… and I’m pulling my hair out here! Let me explain: I go out to start the 80 early in the morning (truck has sat all night) and when I start it, it fires up but stumbles, hardly runs and stalls. I restart it and similar response. If I apply throttle while it’s trying to start- there’s little to no response (if anything it makes the hesitation worse). After a time or two of trying to get it running, it finally idles on its own and runs but you can’t move it under its own power (put it in “D” or “R” and it will stall out). If I let it warm up to say 170*F or so it’s completely fine and the rest of the day it runs like a champ except an occasional p0172 code. After the truck is warmed up for the day, it will start every time, just as it should for the rest of the day (zero issues) but let it sit overnight and the starting issue returns like a bad dream.
Now about the code. The P0172 code will randomly come on, sometimes 2-3x a day sometimes only once in 3-4 days. ???
After using “search function” and FSM I’ve gotten nowhere. Per my search & FSM I changed both O2 sensors with New Denso units, changed both Engine Temp sensors (dash and ECM with new OEM units) cleaned Mass Air Flow sensor 3x, changed all vacuum lines with OEM units, new OEM TVV, new OEM Fuel Pressure Regulator, new OEM fuel pressure resistor & fuel pressure relay. When I rebuilt the engine (roughly 25k miles ago) I replaced practically everything with OEM parts. I added New OEM fuel injectors, OEM intake tube and a new OEM Toyota engine wire harness. I’ve cleaned the idle air control valve and new PCV. Even a new break booster valve and lines. The truck runs Amazing as soon as it’s warmed up (it’s my daily driver and it’s driver roughly 5k miles per month). I’ve double checked the torque on manifolds and down pipe/ exhaust manifold, even used a “smoker” to look for intake/vacuum leaks, everything seems fine! What am I missing??
At first it seemed to be related to ambient air temperature; if it was cold outside, say mid 30s it would act up but now it’s upper 80s in the morning when I go to start it and same issue.
Any suggestions? What am I missing?
Thanks!!
Cheers
I’ve been chasing a rough starting issue on my 1997 US Spec 80 series along with a random P0172 code for weeks now… and I’m pulling my hair out here! Let me explain: I go out to start the 80 early in the morning (truck has sat all night) and when I start it, it fires up but stumbles, hardly runs and stalls. I restart it and similar response. If I apply throttle while it’s trying to start- there’s little to no response (if anything it makes the hesitation worse). After a time or two of trying to get it running, it finally idles on its own and runs but you can’t move it under its own power (put it in “D” or “R” and it will stall out). If I let it warm up to say 170*F or so it’s completely fine and the rest of the day it runs like a champ except an occasional p0172 code. After the truck is warmed up for the day, it will start every time, just as it should for the rest of the day (zero issues) but let it sit overnight and the starting issue returns like a bad dream.
Now about the code. The P0172 code will randomly come on, sometimes 2-3x a day sometimes only once in 3-4 days. ???
After using “search function” and FSM I’ve gotten nowhere. Per my search & FSM I changed both O2 sensors with New Denso units, changed both Engine Temp sensors (dash and ECM with new OEM units) cleaned Mass Air Flow sensor 3x, changed all vacuum lines with OEM units, new OEM TVV, new OEM Fuel Pressure Regulator, new OEM fuel pressure resistor & fuel pressure relay. When I rebuilt the engine (roughly 25k miles ago) I replaced practically everything with OEM parts. I added New OEM fuel injectors, OEM intake tube and a new OEM Toyota engine wire harness. I’ve cleaned the idle air control valve and new PCV. Even a new break booster valve and lines. The truck runs Amazing as soon as it’s warmed up (it’s my daily driver and it’s driver roughly 5k miles per month). I’ve double checked the torque on manifolds and down pipe/ exhaust manifold, even used a “smoker” to look for intake/vacuum leaks, everything seems fine! What am I missing??
At first it seemed to be related to ambient air temperature; if it was cold outside, say mid 30s it would act up but now it’s upper 80s in the morning when I go to start it and same issue.
Any suggestions? What am I missing?
Thanks!!
Cheers