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Throttle Position Sensor cross reference part?


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HEY ALL!

Does anybody know if the following symptoms are indicative of a defective/worn tps? Or might it be some other problem?

I have a 94S4 which seems to have a flat spot at right about between 20% throttle and 40% throttle (and most noticeable between 3000 rpm and 4500 rpm). The symptoms are that when I drive at a constant speed (at any speed between 30mph and 70 mph) like when I am on the freeway, just cruising with traffic, and I start to notice that the power feels flat, so I very very slightly put pressure on the gas pedal, and I don't accelerate.... In fact it almost seems like there starts a slight missing, with no power gain, and I see the boost start to climb. Then, If I release the throttle a little bit (back it off slowly) all of a sudden, the power surges on, and the car gets power to the point that it does accelerate slightly, and the boost backs off. It doesn't do this at higher (above 50% throttle, the car pulls very hard), but last week on the dyno, the car seemed to be running erratic, with unusual puffs of black sooty exhaust going off one or two times a second, then a couple of seconds of smoother exhaust, then once again puffs of black smoke, almost like a misfire.

I'm suspecting that there are other things going on besides the tps, but I was wanting to start with one thing at a time, and eventually go through the injectors, spark plugs, etc.

Does anyone know what the GM part was for that tps? I'm hoping it is an easily sourced part here in the USA.

Also, any suggestions on these symptoms would be greatly appreciated!

All the best

Paul

94S4

85TE

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Yes it's a classical problem, to the point that some ECU chips have been designed among other things) to help with this problem !

Have a look at PUK chips descriptions for example:

www.pukesprit.de

--

Vince

Edited by troutrou
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Yep, I'm aware of the problem with the flat spot, but this is a LOT more than that. Also, I already have Johan's high power chip in, which already took care of that issue, so whats' going on seems a lot more serious, not to mention it didn't do this at all last year while driving. It's a fairly new symptom. It's got to be something else, I think. Any advice is appreciated!

Paul

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Don't know the part, but watch out because there are some which look similar but are designed to rotate in the opposite direction (give 100% reading when ours need 0%), Malc homes had some of those AFAIK.

You could check out your existing sender unit using freescan and simply advance the throttle very slowly, watching to see the ECU registers an increasing throttle position.

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Another item that can cause problems are the rubber vacuum elbows used in the MAP sensor lines...one at the manifold, and another on the sensor itself...they are poor quality and crack....if you are leaking pressure it can cause weird symptoms. They are also used in the HVAC lines....anywhere one of those plastic capillary lines are used.

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Yup . . . 95% of the GM TPS "look" like they will fit but actually rotate the reverse direction to the Esprit one.

These 2 sources rotate the right way and "should" bolt right in and work.

1) 1988 to 1993 Pontiac Lemans (front wheel drive car from Korea) also sold as the Passport Optima and the Asuna GT but these might be in Canada-only names for all I know

Either the 1.6 litre engine or 2.0 litre . . . they have the same TPS

2) Olds Quad 4 engine (years made are unknown to me)

Really common in auto wreckers where the part would be $2 or $4.

AP

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