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TPS ( i think ) please verify my diagnosis


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ok here is the deal. I'm the proud new owner of a 1988 Jeep Comanche 2wd 4.0 with auto tanny EFI

 

think would not go in to any gear but reverse and 1/2

 

disconnected the TCU under the glove box and now i can manually shift

 

it stalls alot but that may just be because there is no exhaust on it at the moment. i'll deal with that later...

 

Sounds to me like the tps based on my research here. i believe i have located the tps please verify pic

 

here is the jeep

 

also whats this?

and should it go here?

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Haven't tore into a Renix motor in a while, but i'm pretty sure that what you're pointing to is the Idle Air Controller (IAC). This may also be part of your stalling issue. The other pick is your PCV valve which should have a vacuum line on it if i remember correctly

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Haven't tore into a Renix motor in a while, but i'm pretty sure that what you're pointing to is the Idle Air Controller (IAC). This may also be part of your stalling issue. The other pick is your PCV valve which should have a vacuum line on it if i remember correctly

 

 

i thought that was the PCV.. its getting oil thru it so i need a new one i guess... i believe that the AIC is next to (to the left) of where I'm pointing...

 

anyway how about the diagnosis?

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OP is right, the IAC is on the left, TPS is what he's pointing to.

 

Yes, the elbow in the VC is supposed to be connected to that hose.

 

However, I wouldn't even think of blaming anything on the TPS until you put an exhaust on it. How much of an exhaust do you have? Please tell me you at least have a manifold.

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So you can buy more tools, haha. Could the missing pcv hose cause a problem w/the vacume?

You own a jeep, you should most definitely have a complete set of torx sockets.

 

It shouldn't cause it to run rough, maybe a high idle.

 

You should also check out a FSM for the 4.0L Renix and learn which sensors the computer uses to control the engine at idle, then make sure they're all in working order.

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also the "PCV" is not a pcv at all.. its just an elbow joint... is that bad? wrong? there es a hose connecting that elbow to the air filter box (looks like the original hose broke and this was installed in its place)

No, that's not wrong. It's part of the CCV system and allows the crankcase vacuum to suck fresh air from the airbox. The other elbow in the valve cover should go to manifold vacuum and suck crankcase fumes into the intake to be burnt. The elbow to the airbox should suck into the valve cover if indicating everything is working properly.

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ok well here is an update

 

**************UPDATE***************

 

Drilled out the down-pipe/manifold bolts and bolted on the new exhaust.

tested the tps with a dmm

 

RESULTS

 

a+b = 5v

c+b= .011v

 

as you see the offset voltage is wrong so i need a new tps. does everyone agree with that assessment ??

 

Autozone has the sensor for 60 bucks

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If you look closely at your TPS, you can see that one(might be both, don't remember) of the screws sits in a slot, not a hole, so you can adjust where the TPS is relation to the arm from the butterfly shaft in the throttle body.

 

One of the electric gurus on here can better explain it or find you a DIY link. Not saying your TPS is shot, but adjusting it may be able to save you $60... especially since you'd need to adjust a new one after installation anyway.

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