CEL...p0172 and another problem

4

4Runner93

New member
On the way to school, CEL came on. Just threw the code P0172, something about rich bank 1. I just googled it and the first couple pages didn't really help me diagnose the problem, so I need some assistance!

It came on after the engine had heated up and hit the halfway on the gauge. Then, something else happened. After sitting in my parking lot at school, I started it and let it idle to warm a little. All of a sudden, the engine starts to...pulsate I guess. The RPM's dip down to about 500 then up to 1000 and it did this for about half a minute. And it shook the car side to side pretty good too every time it pulsated.
 
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I think the same thing is happening to me, same CEL code and I get pulsating on cold starts.

I cleared the code and the cold start problem "went away". After few days later the CEL came back on (same code) and the cold start problem started again.

I talked to my mechanic, he thinks it's a temperature sensor of some sort. He is going to cold start it while hooked up to the scanner tomorrow or Monday (depends if I get it to him tomorrow or not)

I don't think you need to be immediately concerned, my problem first started a few weeks ago and it still drives strong, my mpg's have taken a hit though. I'll update when I know more.
 
same happened to me, my MPG is down the crapper. 220 miles on a tank and a half...

THis happened when we first bought it about 4 months ago, and we thoughtit was the TPS sensor so we had that replaced. The pulsing stopped but now it's back
 
For me the pulsating starts 30 - 60 seconds after starting (when cold) and lasts for maybe another 30 - 60 seconds. When it was really cold (-20 F) a few weeks ago it actually stalled because of it, started right back up with no further problems that day.

I have not noticed any other symptoms besides the CEL and mileage.

I hope to have this checked in the morning, so hopefully I'll have some info soon.
 
Mechanic played with his scanner and thinks it's the TPS sensor. He's going to dig into it deeper on Monday. The ground for the TPS sensor (which is shared with the MAF sensor) could be a problem as well. Cleaning the throttle body won't hurt either.
 
replaced tps sensor, cleaned throttle body and replaced spark plugs.

Already seems to drive better, scanguage immediately started averaging +1-2 mpgs
 
The day after I replaced the sensor (Tuesday) I had pulsating on cold starts both times I started the truck and it wasn't a particularly cold day.

I have not had pulsating since and it's been significantly colder. I am hoping the computer just had to make an adjustment and has fixed the fuel ratio on cold starts, but we'll see.
 
alright, looked back on the repair and found out it was the Air Idle Sensor we replaced. So it sounds like replacing the TPS didn't really help?

btw, filled up on gas last night, haven't driven differently or anything other than it's about 30-35 degrees here. 17 miles on my Trip A and it's on the 3/4 line :(
I'm only in high school, I can't keep affording this!
 
hmm, well guys, it has returned

shaking and CEL, so they're definitely connected somehow, but I have no idea what could cause it. Anyone have any ideas to throw out?
 
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