Check Engine Light...no idea

NewMStang

New Member
Oct 5, 2004
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Though i would start a new post to make things more organized...

So i recently installed a Accufab 75mm Throttle Body, Plenum, and JLT CAI and soon after my car threw a check engine light and had an issue of when driving th e car, when i accelerated to around 30-40mph the car would kind of bog and the rpms would drop down to around 1100-1200 and the car wouldn't really accelerate. Or if i accelerate quickly, let off the gas and try to flore it the car won't really accelerate...but on my drive to work this morninig the same issue as i stated in the message right above(It seems like the car just won't go higher then 1000-1500 rpms.) Well driving to work this morining sometimes when i even hit 30, it would seem like the rpms would just die down and drop to 1100 or so and not reaccelerate.

So I had the code scanned and it said it was the throttle position sensor, I went ahead and changed it and the light went off temporarily but came back on this morning. Does anyone have any idea what the issue could be, if the code states it's an issue related to the throttle position sensor, shouldn't have changing it done the trick? or where would the next best place to look be?

Somethings that I'm thinking might be an issue/stood out to me:

--When i reinstalled the throttle body position sensor I may have accidentally moved the throttle body positin slightly...(i may not have, not really sure if i did)

--I noticed after the install when i had the car turned off and was pressing down on the throttle body(spinning the throttle body plate) the throttle body cabel would kind of stutter/bounce back when i released the throttle (i don't remember if this was normal or not, meaning should the throttle body cable just go back smoothly in one motion when releasing the throttle body?). I mean it looks like it's installed properly.
 
Pull the codes again, since it could be something completely unrelated to the TPS. Did the new TPS solve the issues you were having with part/WOT hesitation and they have returned along with the check engine light?
 
http://forums.stangnet.com/645245-please-read-before-you-replace-adjust-tps.html

There is also a trick to installing the TPS. At least there was for me.

Use your pinkie to rotate the pins inside the TPS and see which way it manipulates the pins the most. You may have to slide the pins onto the TB blade at a bit of an angle to make sure they are making contact. Otherwise, if you install it and the throttle blade move inside the pins before it manipulates the sensor the computer may have issues with the readings. As the link above says as the car is started the voltage is read and assumes closed throttle. Anything after that is the reading it uses to determine throttle position.
 
Pull the codes again, since it could be something completely unrelated to the TPS. Did the new TPS solve the issues you were having with part/WOT hesitation and they have returned along with the check engine light?

I'll try to get the codes scanned again tomorrow, and no the new tps didn't solve the part/WOT hesitation issue or the check engine light issue.
 
Not sure if this helps but...

The specific error code was: PO122

The autozone reciept said the following....

Throttle/Pedal position (TP) sensor circuit low.
Explanation: The TP sensor signal 1 circuit has reported an open low voltage.

Probable cause:
Open or short circuit condition
Poor electrical condition
TP sensor error (already changed the sensor)
 
Have you hooked a volt meter up to the sensor to see what its acutally doing?

I haven't had a chance yet/ i don't have votl meter.

On a tangent....

So this morning on made sure to monitor the rpms and they do seem a bit off:

When the car is in...

Park: 1100
In Drive: 600
At a roll in Drive: 600-700 (i don't remember to well)

Side Note:
I noticed that at WOT from a stop, the car doesn't seem to shift to 2nd(i have an auto if you couldn't tell yet), i need to get of the gas for the car to shift to 2nd. I noticed the car was at around 4000rpms when i was driving about 35-40. After the first shift the car shifts fine. I'm hoping that's all related to the idle screw

I'll adjust the idle screw after work today and let you know what happens. Thanks for everyones input so far.
 
The idle screw has nothing to do with shifting... Unless maybe its holding the blade open all the way. Get a volt meter and manually check your tps. That way you will know if its sensor related, or if its in the wiring/puter somewhere. Stop chasing ghost and do the right test.
 
Find an Ossiliscope and find out whether its signal is digital or analog, this will show what the TPS is doing while you open and close your throttle, it should have what a normal scan looks like for the make model and year of car, you will have to peirce the wires to read them though. Dosn't sound like the TPS is malfunctioning though, check the wiring harness to the tps, you might not have all of the wires connected or some might be loose. Your Idle air control and the air intake would malfuntion your Idle. I'm glad its not serious though!!!