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Hi all, this is a crosspost from tacomaworld, just trying to get more attention to my concern apologies if you have already seen this!
I've got a '99 5VZ-FE and I'm looking to get some help with an issue that has been plaguing me for a couple of months...a dreaded P0172 that won't go away mixed with intermittent P0130/P0133 codes.
Bit of back story...
When i first bought the truck, I had a misfire (P0303) and rough idle. I swapped out coils, plugs, and wires (all OEM). The misfire went away but the rough idle stayed. A couple weeks later the misfire returned (P0303).
I then purchased some matched re-manufactured flow tested fuel injectors (figured it may be a failing injector, why not swap em all), cleaned out the throttle body, replaced the IAC, and replaced the fuel pressure regulator. The misfire went away but the P0172 still remained. I swapped out the MAF and both O2 sensors and the code still stays.
When cold, the engine will surge to about 1500 RPM for a quick second and then go down to about 1100-1200 RPM. Acceleration is fine while cold, however after warmed up (ECT reading ~180F) I will get random hesitation while accelerating. It will last if I keep pushing the gas, however if I back off and ease into it, it will accelerate alright (still lacks power). At times if I do not ease off, the engine will backfire.
My long term and short term fuel trims are both at about -20%...both O2 sensors are reading 0.9V.
Photo attached - when I disconnect the "vacuum hose" circled in red, my STFT cycles between +/-5% and my LTFT goes to about 0 or so.
This video (https://streamable.com/jr9c1) is the sound inside my air box while the engine is running. I removed my air filter and stuck my phone in the air box and it sounds like the engine is missing at times...
Any thoughts??? I have sprayed carb cleaner on hoses to check for vacuum leaks but nothing has surged...
Maybe the coolant temperature sensor?, but sounds like something else is going on, all the teeth on crank still there for the crank sensor to pickup. Wouldn't hurt to look harder for intake leaks, but your running rich not lean so maybe the coolant temp sensor, maybe a timing issue or a combination of issues.
Last edited by Malcolm99; Mar 18, 2020 at 10:31 PM.
Maybe the coolant temperature sensor?, but sounds like something else is going on, all the teeth on crank still there for the crank sensor to pickup. Wouldn't hurt to look harder for intake leaks, but your running rich not lean so maybe the coolant temp sensor, maybe a timing issue or a combination of issues.
I considered that as well and I have a new one that I purchased, as it's basically the last thing on the list of possible causes...thing is, my current temp gauge is reading and sending info...temps are sitting at a reported 180*-183*. Those are normal though, right?
There are 2 sensors for coolant temp, the one on the back of the engine is for your gauge, the other in the front of the engine communicates with the ECU and adjusts fuel trims accordingly.
Last edited by Malcolm99; Mar 19, 2020 at 08:49 AM.
And normal coolant temps are 200*, most japan made stuff runs best at that temp for optimal operating conditions, it would make sense that if your running rich the temps would be low. And I should add the ECU uses the MAF, O2's, and Coolent Temp to adjust fuel trims/timing, so there is a lot of data being processed.
Mar 18, 2020 | 10:07 AM
