AntleredRuin
New member
Hey guys, so I got a CEL this morning, a P0125. 1999 Limited, non-Cali emissions, 5vzfe engine. Of course a CEL when inspection is due next month. Here's hoping it's an easy fix.
I know that this can point to a couple different things; Dirty MAF, Stuck t-stat, bad A/F sensor, bad coolant temp sensor, etc.
I've not really taken a look at anything yet, but I wanted some opinions before I started tearing things apart.
1st: On my drive to work, I was monitoring my temps with Torque, and never got above 196. I did my TB/WP about 2 months ago, and installed a new t-stat (I kept the old one, just in case). I did install it at 6 o'clock, but my temps actually rose compared to my old t-stat (also installed at 6 o'clock). It used to sit at 188 regularly, now it hovers around 194, and caps around 196. I've also noticed that my heater does not seem as hot except for when it's cranked to full 'HOT'. It used to be pretty hot starting around 80, but now feels pretty cold in comparison. Coolant is topped off
Because of this, I assumed a t-stat problem with the new one and was going to swap the old one back in when I had some time.
2nd: Due to a bunch of bullshit a couple weeks ago, I cut my catalytic converter out and ended up clamping it back in. (would have bet hard money that that crazy clattering was a bad cat, but ended up being a u-joint. **** me) I may or may not have an exhaust leak, and I may or may not have messed the cat up in the process. I've not taken it to a muffler shop yet to be properly welded back in. I know the A/F sensor is Bank 1 Sensor 1, which is near where I'd suspect a leak due to the way I had to clamp it.
(If I have to replace the cat, I may go with https://www.ebay.com/i/282016231885?chn=ps Probably cheaper than getting someone to weld it, good seller reviews and 30 day warranty.)
3rd: I'm using an aftermarket MAF. It was my backup MAF because I somehow spoiled my original when I was changing my valve cover gaskets about 6 months ago. I have the original one still that I'll clean again and try to swap in. I'll try cleaning the aftermarket one as well. You never know.
4th: Final piece to the puzzle: I have noticed for about a month (not all the time; it's come and go) that I've had some weird symptoms at cold startup, like sitting overnight. Pretty much, the idle wavers a lot for about 20-30 seconds.
It doesn't idle hard at all; it still feels smooth, with no vibrations, but it just bounces a lot, like I'm revving it. It sounds very odd, as the fan clutch is still trying to grab due to being cold, but the engine can't make it's mind up.
It bogs down if I put it into drive before it evens out, which normally isn't an issue. I usually start the truck, then get the GPS going, etc, then start driving. I usually let it sit for about a minute at cold start anyways.
I was thinking MAF, IAC, or TPS for this issue, so maybe it's related to this (potential) MAF issue? I did try to pull codes for this, but this P0125 is the first code I've gotten.
Anyways, a bunch of puzzle pieces. Anyone have an idea where to start first?
I know that this can point to a couple different things; Dirty MAF, Stuck t-stat, bad A/F sensor, bad coolant temp sensor, etc.
I've not really taken a look at anything yet, but I wanted some opinions before I started tearing things apart.
1st: On my drive to work, I was monitoring my temps with Torque, and never got above 196. I did my TB/WP about 2 months ago, and installed a new t-stat (I kept the old one, just in case). I did install it at 6 o'clock, but my temps actually rose compared to my old t-stat (also installed at 6 o'clock). It used to sit at 188 regularly, now it hovers around 194, and caps around 196. I've also noticed that my heater does not seem as hot except for when it's cranked to full 'HOT'. It used to be pretty hot starting around 80, but now feels pretty cold in comparison. Coolant is topped off
Because of this, I assumed a t-stat problem with the new one and was going to swap the old one back in when I had some time.
2nd: Due to a bunch of bullshit a couple weeks ago, I cut my catalytic converter out and ended up clamping it back in. (would have bet hard money that that crazy clattering was a bad cat, but ended up being a u-joint. **** me) I may or may not have an exhaust leak, and I may or may not have messed the cat up in the process. I've not taken it to a muffler shop yet to be properly welded back in. I know the A/F sensor is Bank 1 Sensor 1, which is near where I'd suspect a leak due to the way I had to clamp it.
(If I have to replace the cat, I may go with https://www.ebay.com/i/282016231885?chn=ps Probably cheaper than getting someone to weld it, good seller reviews and 30 day warranty.)
3rd: I'm using an aftermarket MAF. It was my backup MAF because I somehow spoiled my original when I was changing my valve cover gaskets about 6 months ago. I have the original one still that I'll clean again and try to swap in. I'll try cleaning the aftermarket one as well. You never know.
4th: Final piece to the puzzle: I have noticed for about a month (not all the time; it's come and go) that I've had some weird symptoms at cold startup, like sitting overnight. Pretty much, the idle wavers a lot for about 20-30 seconds.
It doesn't idle hard at all; it still feels smooth, with no vibrations, but it just bounces a lot, like I'm revving it. It sounds very odd, as the fan clutch is still trying to grab due to being cold, but the engine can't make it's mind up.
It bogs down if I put it into drive before it evens out, which normally isn't an issue. I usually start the truck, then get the GPS going, etc, then start driving. I usually let it sit for about a minute at cold start anyways.
I was thinking MAF, IAC, or TPS for this issue, so maybe it's related to this (potential) MAF issue? I did try to pull codes for this, but this P0125 is the first code I've gotten.
Anyways, a bunch of puzzle pieces. Anyone have an idea where to start first?
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