Bob1985z51

Hey guys I recently got a scanning tool and my tps doesn't want to go to .54 volts and it doesn't show 5 volts at wide open! I've been having a issue with running rich lately I rebuilt my motor (heads cam and ported intake) I got a chip burned from ed wright so I don't think it's in the tune but I'm not sure.anybody know what the factory service manual has to say about tps and resetting them?
Ps also my iac is at 144! I've heard it's suppose to be at 30.

DanielRicany

What does your TPS read? Also open your hood and with the engine off, push the pedal all the way down and look at the engine and see if the throttle linkage is opened all the way. I had this problem on mine, I fixed that by switching the cables around at the throttle body. Also I'd imagine your TPS voltage being more than 0.54v if it's running rich at idle. Do a minimum idle reset procedure.

MrWillys

Sounds like the throttle blade screw may need to be adjusted bringing the tps back in line, and fully warmed iac counts between 20 to 80 with 40 to 60 being best. I'd set the tps at .60 to get a slight extra pump shot. What do your blm counts read?

Bob1985z51

The throttle is wide open
How do I do that procedure?

Bob1985z51

I'll it's rich at idle then I just relized I was reading the wide band wrong it goes from 12.4 or so to over 18.0 and my wide band maxes out badly and it stops revving and just pops
I'll have to get back to you on blm I can't start my car past 8 it sets off all car alarms within 50 feet haha

gerardvg

If you have a multimeter you can measure the top two wires, i usually push the probes into the harness connector following the wires.

Turn ignition on and Loosen the screws holding the tps sensor a little and adjust the TPS, (pulling the end the connector upwards will raise the voltage).
Set it to 0.54 volts DC, check you get 4.5 volts with full throttle.
Secure the TPS sensor by tightening the screws and confirm it has not changed, now you are good to go.

If the voltage does not go to 4.5 volts dc at full throttle then replace the TPS.

Check your fuel pressure, the 85 has the 24 lb injectors so the fuel pressure is lower around 35 psi.
Some add an adjustable fuel pressure regulator so they can adjust the fuel pressure, i would not go over 45 psi.

Injectors are they leaking not shutting off?
You can do a leak down test, this is done by removing the connector from the injector and applying 12 volts and a ground directly from the battery for a couple of seconds. Note what the fuel pressure stays at, if you find one that bleeds down or your fuel pressure will not stay at 30-40 psi then you have either a leaking injector or fuel pump not holding pressure.

Good luck

Bob1985z51

Well I replaced my tps still doesn't want to sit at .54 and only reads 4.27 at full throttle.
I now have 30lb injectors

MrWillys

Mine scans key on engine off .56, and 4.31 at WOT. Running rich is a programming issue, and not caused by TPS being off slightly. What do your BLM counts read?

Cliff Harris

You say it doesn't want to go to .54. What DOES it go to? You never told us that.

If you suspect that the TPS is bad you can take it off the throttle body. It should read roughly zero volts.

4.27 is OK. The ECM considers anything over 3.5 volts to be WOT.

That sounds too big for a relatively stock engine. Not surprising that you're running rich. Did you change the injector constant in the tune to 30 lbs? If not then the ECM thinks you've still got 24 lb injectors and you'll run very rich, especially when you're in open loop mode.

IAC count is 144? Is that at idle? Hot or cold? The ECM will start off with the IAC at 144 to simulate a "fast idle" when the engine is cold. It should drop down to around (very roughly) 50 when warmed up. It sounds like the ECM is trying to compensate for the big injectors by adding air.

Did you do the minimum idle adjustment, as previously suggested? Here's the procedure:

http://forums.corvetteforum.com/1570563689-post1.html

Bob1985z51

It is NOT stock the only thing stock about it is my plenum on the induction and that's ported to big mouth gaskets, the computer has a chip from ed wright. It's rich at idle and lean everywhere else(just got use to the wideband)
The tps does not want to read at .54 it skips and goes right to .53 or .55
I checked from a cold start to closed loop it always read around 144 give or take 2

65Z01

That TPS setting of value .54 Vdc is at base idle of 450rpm. At normal idle of say 600rpm the TPS will read around .65 Vdc. I like to set mine so it reads ~.73 Vdc at normal idle. If it gets a little too high the ECM will throw a code and then you can back it off a little till no code is set.

Don't worry about the TPS absolute reading value at WOT so long as it's above .4 Vdc. Just tweak the setting for the highest value possible while maintaining the idle setting.

If it's running rich at part throttle you will see that in the BLM counts since the ECM is trying to pull fuel.
If it's running rich at WOT you will see an O2 value well above .92.

DanielRicany

No You Don't Want To Set Your TPS That High. Mine Slipped And Caused My Engine To Idle At 1500 RPMs And Run Very Lean, 22.4:1. TPS Voltage Was .73 And It Ran Like Crap Until I Adjusted It.

Also, To The OP, What I Think Is, You Need To Set Your Fuel Pressure Back To Stock And Put 24 Lb Injectors Back In.

Then Come Back With Any Problems.

AGENT 86

It's not an exact science. The service manual says .54v +/- .075v, so if you are between .46 and .61, it's is good enough.