mattdott

My 88 formula 350 started to throw a code for high tps voltage. I tried to test and adjust the voltage and it got zero volts on the middle wire. I bought a brand new tps from auto zone. When I try to adjust the voltage I cannot get over. 27 volts. Where I press the lever to wot, I only get 2.75 volts. I have 4.98 volts coming in on the third wire.
What can cause this?
Is my new tps bad?
I search the forum and all I can come up with is someone saying I need a new ecm. This doesn't are sense to me since a tps is basically a resister. The voltage out shouldn't have anything to do with the ecm. It's only sending voltage to the ecm. Am I right on this?

Tuned Performance

iTrader: (92)

Your right sounds like a bad tps. The ecm feed the tps almost 5v on the grey wire and the ecm feedback is the blue wire so at wide open throttle there is verry little resistance .

mattdott

I'm glad some agrees. I'm going to take the tps back today and see if that makes a difference.

mattdott

Ok, new tps. Best at rest is 0.41, wot 3.01. What the hell could be going wrong? I could bend the arm a little to get to 0.54 where I need to be but that doesn't help the wot.
I'm stumped.

TTOP350

iTrader: (8)

What does your TPS holes look like? are the slotted or just a drilled hole?

Tuned Performance

iTrader: (92)

sounds like you keep getting crud tps if the grey wire has 5v ref or your issue is with the ground splice or behind the cylinder heead.

mattdott

Slotted holes. I have even went so far as to dremal out the holes longer. Now I have 0.54 at rest, and 3.27 wot.
So I take it for a test drive and get a code 21 for high tps voltage. Maybe my meter is off?

mattdott

Any suggestions before I go buy another meter?

mattdott

Voltage verified on another meter. If I smash the throttle, the engine almost bogs to a stall. What can I check?

TTOP350

iTrader: (8)

If your getting 5volts in you should be able to get it out.. Weird.

mattdott

The real funny thing is I can't get more than 3 out but I'm getting a code 21 high tps voltage when I floor it. And also it bogs out.
If I slam on it from a dead stop, it takes of sluggish . No tire spin. If I hit it half throttle, the tires spin... Wtf?

TTOP350

iTrader: (8)

Going to need to data log it and see whats up

mattdott

How do I data log it?

mattdott

ok, I got part of this figured out. I checked my iac and it was way off. After setting the minimum rpm to 450 as in the tutorial on this page, it idles at almost 2k rpm when plugged in.
I am not able to set the tps right though, but the wot voltage is still low.

Bad IAC?

Tuned Performance

iTrader: (92)

You can always check the resistance with the tps in wot. If the voltage drop from 5v to 3.27 you would have 3k Ω through the tps grey wire and the blue wire at pin c13 of the ecm. You can hear the pointless of the iac seating when the aldl is jumpered from a to b before you unplug the iac to set the minimum air speed adjustment.

Tuned Performance

iTrader: (92)

See post #50 for testing your iac

https://www.thirdgen.org/forums/tpi/...my-305tpi.html

mattdott

k guys i really want to apologize for most of this. My meters have three volt range settings. 1.5v , 9v, and 12v. I was using 9v because i was testing between .3 and 5 volts right. Well when i switch to 12v I ready higher. 0.34 on 9v setting 0.69 on 12v. I use the 12v setting and everything works great for the tps.

Once again sorry for wasting your time.

But.... this still doesnt fix the high idle when i set my iac. I follow all the steps perfect. I can here the iac clicking and making noise when th aldl is jumped. I set it to 450 rpm and the shut off the car. Plug back in the iac, start car, idle jumps to 2000 rpm.

Now if i back the torx screww back the whole way to where it doesn't even touch the throttle, reset the tps to match, i can get it down to 1200 rpm at idle. still not low enough and its not set properly. If i unplug the iac in diag the car wont even start untill i screw in the throttle screw alot, something is not working right.

Tuned Performance

iTrader: (92)

Having a scanner to view iac steps is nice, did you have any high idle issues before this code 21 issue ?

mattdott

Well yes. The tps issue is fixed. And my idle has always been about this high with the idle screw all the way out. That's how it was when I bought the car.
Now that I know how to set the iac correctly I want to do that. But if I set it correctly at 450 rpm with the plug unhooked I'm at 2000 rpm. I have to screw the idle screw the whole way out to achieve a drivable rpm and reset the tps accordingly.
It's drivable now but it's just not right.
I'd like to get this iac thing figured out. I'm going to have to order a cable to hook the car up to a laptop I guess.
I have plans of doing some engine mods but I want to get these bugs out first.
I'm coming from the Honda boost scene, converting to American muscle. I'm definitely not a noob to engine building, boost, and tuning. I
I have a lot to learn on these v8's.