156 tps sensor - Alfa Romeo Forum
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(Post Link) post #1 of 6 Old 4 Weeks Ago Thread Starter
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156 tps sensor

Hello


My 156 2.0 twin spark idle is rough. There seems to be a problem with the tps sensor- Is there a way to fix it or is just better to get a new one? Thanks in advance for your replies
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(Post Link) post #2 of 6 Old 3 Weeks Ago
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Hi, I note your location so I can work out relevance. I think Because the TPS is screwed on and easily replaceable, a new one is best.

That said, a TPS has 2 resistance tracks on it. If one is value A, then the other should be value B. The ECU is programmed to expect that. If that is not so, the ECU would know that. In that case, the EML/MCSF would come on and the car would go into limp mode and only 25% of maximum throttle would be available (if it is a CF3).

My point is it is unlikely to be the TPS at fault. Try cleaning the throttle body with carburettor/throttle body cleaner thoroughly. If that doesn't work, it may be the breather valve at fault. This valve is between the cam cover and throttle valve. It is not the bit which feeds into the main induction hose. This valve regulates crank case gas blow-by from pistons and lets it go through the throttle body. The idea is there should be a gentle suction in crank case and in cam cover air space. If the valve malfunctions, it tends to case engine idle issues. Cleaning this valve may help. I'd try that before getting new parts.

Last edited by Fruity; 3 Weeks Ago at 09:35.
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(Post Link) post #3 of 6 Old 3 Weeks Ago Thread Starter
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Thanks Fruity for your reply

The problem with idle is that revs goes down when stop and the car almost stalls
The breather valve checked ok, the throttle body cleaned.

I forgot to mention that i will be heading to europe in two weeks (spain,sweeden) so i could get spares there

I have checked the TPS , opened it and cleaned the tracks with big improvement, still not perfect. But i noticed that one of the "forks" that contact the tracks does not move (this is kind of weird isnīt it?) The one on the short track is frozen

is this normal?
Please let me know what you think and thanks in advance
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(Post Link) post #4 of 6 Old 3 Weeks Ago
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My GT JTS does idle hunt sometimes. I don't know what to try next, I already tried TB cleaning, checked the air induction (again), checked the hoses around the PCV and the valve itself. For good measure, I want to change the valve, but its nowhere to be sourced. Been at the dealer with no luck, I checked breakers and found what was even in worse state than mine. Running out of ideas.
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(Post Link) post #5 of 6 Old 3 Weeks Ago
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TPS is part of throttle body

@Hernando , I've not opened up the TPS but what you describe is strange. I cannot answer that. It seems that the TPS is part of the throttle body though. I think I can get a part number for the valve but disconnecting the hose and blocking the part going into the throttle body should be a good test to see if it is the valve.

@Bsrgt , try the above yes to see if that sorts it. Probably difficult given you have an intermittent fault. In any case, your car may have something to do with carbon deposits. If you could try to get an engine compression test when idle is poor and normal, it may show low compression from a valve not shutting fully (if your JTS is coked up but not in the Ozzy Osborne kind of way).

Last edited by Fruity; 3 Weeks Ago at 09:39.
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(Post Link) post #6 of 6 Old 3 Weeks Ago
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The fault shows maybe once a month, revs shoot up to 1.5k - 2k.. tap the throttle a bit, revs calm down and fall to 850ish. Thats why I am thinking throttle body, as the fault is not permanently there.
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