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Discussion Starter · #1 ·
Sorry if it's a repost guys but I looked through a bunch of TPS (Code P0122) threads and can't find what i'm looking for.

For reference this is an 02 TJ, 4.0L.

So first I got the code, had it read, and on the way back it started sputtering and such under acceleration.

So I took off the electrical connector and cleaned that up, I was unable to unbolt it from throttle body due to a frozen bolt and I managed to strip the head. So I couldn't clean up that side of it, but that's a headache for another day.

The good. After a reset, the Code hasn't been back yet, drove it around for a bit under varying acceleration, and it seems to be fixed. Time will tell, probably only put around 5 miles on it since I cleared the code. Also it seems to pull a little harder now than I remember it.

The bad. And this is where I need some advice. Now when you start it, it jumps up to 2,000 RPM idle, and slowly comes back down over about 10 seconds to 1,000 RPM where it seems to stay. It has idled closer to 500 since I have had and never jumped up to 2,000 before on start.

***For you guys that have had these things since brand new. Is it supposed to start and idle like that? Maybe this thing was idling wrong before and now it is fixed. I've had it around 2 years and it has always behaved completely different on start up.***

Another thing that may or may not be related to this. I also disconnected the intake hose to see if the throttle body was dirty too while i was at it. When putting it back on I noticed the Vacuum hose, i think that's what it is, was cracked at the end. The little rubber hose that goes off of the air intake tube into the front of the engine. Don't know if that happened when i was pushing stuff around or if it was always like that. But since parts store was closed I wrapped it tightly in electrical tape temporarily and reconnected it. Maybe the seal on this is messing stuff up.
 

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Maybe the seal on this is messing stuff up.
Any vacuum leak that allows air to leak into the intake manifold will cause an increase in idle rpm. The ECM, via the IAC, can compensate up to a certain point. You need to fix the vacuum leak and see where that leaves you.
 

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Discussion Starter · #3 ·
That was a next step regardless. Electrical tape is hardly an acceptable repair. So that is definitely getting fixed asap.

I was mostly curious if anybody can tell me if my jeep was idling/starting right before or after the repair so I have a starting place to go off of.

I do appreciate the input though. Definitely going to start going through all the electrical connections and cleaning them up after this little incident. I just hope this is the fix and I don't have to actually replace the TPS. Seeing as how one of te bolts is stripped It's going to be a fun time getting it out. And hopefully Crysler dealer has a replacement bolt as well.
 

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Discussion Starter · #4 ·
Anybody know what that particular hose is called?
 

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Is that rubber hose you're asking about the one that connects between the air intake and the connector on top of the valve cover? If so, that hose won't cause any problem like that even if disconnected, let alone just leaky. It is only for crankcase ventilation and is thus called the Crankcase Vent Valve Tube. Nearly any neoprene hose will work, you should be able to get the same size at nearly any well equipped hardware or automotive parts store. It might be difficult to find a new factory replacement hose with the factory bends in it.
 

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Any vacuum leak that allows air to leak into the intake manifold will cause an increase in idle rpm. The ECM, via the IAC, can compensate up to a certain point. You need to fix the vacuum leak and see where that leaves you.
Except the front CCV hose is BEFORE the throttle body and not connected to the intake manifold...

OP, on cold start up RPMs should start out just above 1000 and drop down as the engine warms up. For me ~700 RPM is normal idle, that's at altitude. I would suspect you do have a vacuum leak (unrelated to the leaking CCV hose) or the idle air controller is acting up or the TPS is acting up.
 

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Except the front CCV hose is BEFORE the throttle body and not connected to the intake manifold...
In which case, it isn't a vacuum hose after all. And there is no vacuum leak to fix.

All a broken upstream CCV hose is going to do is allow unfiltered air into the crankcase. By my standards, that's a problem.
 

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Discussion Starter · #8 ·
Well after about a week. It has started idling like before. So I don't know what is going on. But at least the light didn't come back. Still gonna replace the hose though
 

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Not to reopen if the issue is gone, but you definitely want to get the TPS bolts replaced now, so you're not stuck doing it in a bind.

Remove the throttle body ( careful on the gasket) and you can drill out and remove the stripped screw. I replaced mine with hex-drive cap screw so that I can use a small Allen wrench to get in the tight space between the TB, brake master cylinder, and firewall. Get a stainless steel if you can. The screw size is M5 x 25mm long. A hex or pan head screw won't fit in the boss recesses on the actual TPS.
 

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Discussion Starter · #10 ·
Ended up replacing the sensor. Fixed the light, but it still idles really low, like 4 or 5 hundred rpm. Just doesn't feel right.

But yeah, I ended up having to take off the throttle body and multiple tools later, a pair of vise grips finally managed to budge that bolt. Luckily sensor came with new bolts, but they were oem style, not stainless
 

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Is it a steady idle, or does it fluctuate around? Also, does it feel like the engine is about to cut out while idling?
 

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I'm about to go do the same replacement. My acceleration gets rough at sustained 70mph and then bucks and then throws the TPS code. My normal idle however (since massive cleaning, 4 hole injectors, throttle body spacer ( no flame please) and new plug) has been 1000 then slowly down to the 500 range. It's super smooth and doesn't feel like cutout is even close.

My question. Where did you get your TPS? And is the autozone / pepboys replacement as good as the original one?
 

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Discussion Starter · #14 ·
Steady, just so low rpm it feels like its gonna cut out and idle is rough sometimes.

As far as aftermarket ones, couldn't tell you. I got an oem sensor. No more jumpy throttly or CEL.
 

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On start up when cold the idle RPM's should be around 950 - 1050, then after warming drop slowly to around 550 - 650, depending if you have automatic trans and if you have A/C.

Mine, when cold starting will jump to 1000 RPM's then slowly drop when warming to around 600 RPM's. 5sp manual transmission and no A/C.
 
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