Tracking down P0171

Post by **jtp** » 19 Jan 2013, 20:20

Swapped out to a different IAC I had sitting around tonight. Old one was clean though. No stumble when I started it so that's promising since it's been doing that. Real test will be when the motor is ice cold tomorrow. Negative cable off to drain it and reset LTFT (thanks again to regent!!!).

Have been suspecting a broken fuel pump check valve but I pushed the schrader valve after shutoff and fuel shot out hard, so I think I'm set there.

Smoke test is on the menu for tomorrow.

echase76 · Post by **echase76** » 19 Jan 2013, 21:07

Pump the brake a few times and that drains it pretty good and then let it sit.

How are you doing the smoke test? do you have a home method?

Post by **jtp** » 20 Jan 2013, 05:15

Smoke Pro Total Tech. Went in on a used one with my brother. If you are down in my area and want to give it a whirl just let me know.

Post by **jtp** » 20 Jan 2013, 05:38

No stumbling at all on an ice cold start this morning. That's definitely new with the other IAC motor in. Promising, but I'm not getting my hopes up.

Post by **regent** » 20 Jan 2013, 07:32

I have seen issues with unmetered air from a sticky IACM (similar to vac leaks). Let's hope you've found the culprit.

Post by **jtp** » 21 Jan 2013, 19:24

Alright. So yesterday I noticed the that the vacuum line from the fuel pressure regulator wasn't quite kinked coming out of the regulator but was turning pretty steep. I put a longer line there and routed it with wide turns.

Also noticed two of the vacuum "caps" on the vacuum tree were cracking (6 months old, way to go autozone). Replaced those.

Between these two things and the new IAC the code did not pop up tonight on the way home from work like it should have based on before.

Too early for me to consider the issue done but really promising.

Post by **jtp** » 21 Jan 2013, 20:36

One more thing I did in case anyone is looking at this in the future. The tube from the PCV the plugs into the top of the valve cover was a little loose. I tightened that down.

Thanks again...

echase76 · Post by **echase76** » 21 Jan 2013, 21:57

jtp - love the Uncle Rico avatar. Hope you got your problem solved! My car also ran great today. Maybe it was because I pulled and opened the fuel pump relay last night. Or maybe it was the weather. Who knows.

Anyway, anyone know where can you find good vacuum caps? Everywhere I have tried locally has crap that cracks within a year. Seems like there is a market for silicone vacuum caps.

gswede · Post by **gswede** » 21 Jan 2013, 22:27

My PO171 was tracked down to a faulty TCV. Replaced it, deleted code. Have been running great ever since.

Post by **jtp** » 22 Jan 2013, 09:29

So it popped up again just now. Definitely took longer to come back this time, which seems odd.

I'll test for vacuum leaks today. It's just so stinking cold outside. All my vacuum leaks have always been p0172 though, and this is p0171.

Tracking down P0171

Re: Tracking down P0171