For example today's cold start up... right after the car starts running voltage and % go right up and cause the car to idle high and eventually pull timing.
Wires to the tps are Blue, Black & Grey According to my haynes manual wiring diagram Blue is the Right fuel level, Black is ground, and grey is 5v feed.
With the KOEO
Blue .011v
Black .015v
Grey 5.03v
It never crossed my mind to do it with the engine running so tomorrow I will do it and see what the numbers are.
Last edited by SmokedOutZ28; 05-16-2014 at 08:30 PM. Reason: Adding more info
Have you reset your tps? When I got mine I went through a reset procedure. I forget the exact procedure, but something along the lines of unplugging it, starting it, plugging it back in, off then starting again. I am sure you could do a search on that one.
Yeah I've done the reset a few times.Originally Posted by sarg
I am going to try and inspect the ground wiring back to the pcm and ohm it out for high resistance.
When I started the car and checked the ground wire for the tps at the connector I had .60v
So I checked the ground wire for continuity from the connector at the TPS and the computer. I went through all the pins on both red and blue connectors to the harness and found I had continuity at
Red Side #36 (Brown wire) (Air pump relay control)
Blue Side #20 (Orange Wire) (Bat. Pos. Volt)
Blue Side #42 (Drk green) (Engine Cooling Fan 1 relay)
Blue Side #57 (Orange) (Batt. Pos. Volt)
Blue Side #60 (Black) (TP Sensor Ground)
Now I know what the pins are but what I can't understand is why a ground wire for a TPS that should go straight back to the pcm would close a circuit if I touch other pins but #60 which is for the tps.
Does anyone have a 99+ harness laying around where they can test the resistance of the - wire for the TPS and maybe do there own checking to see what results they get?
The blk lead is the gnd for the TPS.
The gray is the reference voltage. 5v is correct.
The blue wire is the actual TPS voltage the PCM reads. If you were to operate the throttle by hand, you would see that voltage change from near 0 to +5v.
Rather than answer over on LS site. Continuity typically means 1-2 ohms or less with one lead on the TPS connector and the other on that same wire at the PCM.
Modern DVM's auto range and sometimes 1k ohms looks like 1 ohm at a glance. So if you are checking to those other leads, it's prob not a low resistance.
I'm not trying to give you an ohm meter lesson. Sorry if it's coming off that way. :-) this stuff is easier to talk through rather than type through.
You can also data log the TPS volts as well as TPS position with HPT.
I have a 99 Camaro harness in my nova that I modded. In my car, KOEO TPS volts is .59v at 0% TPS. I verified that both with the volt meter and HPT. Seems like your volts at the blue wire is too low? You can adjust it btw.
The PCM grounds to the engine at the back of the drivers side head. There are 2 lugs under 1 bolt.
Might check that for tight. But your gnd volts at the TPS seems correct.
before fans fuse tps.hplThanks for your reply. I have been logging tps v & % and today verifed them with the meter, I did a full sweep of the TPS by hand before doing anything else and it seems all my voltages with KOEO are correct.
Here is something I found interesting..... I checked my tps ground wire against those pins at the PCM harnness with the respective fuses / relay out and did not have any continunity except for pin #60.
if my math is correct 2% throttle increase will show 0.1v increase at the tps (.02 x 5 = 0.1) I am thinking that my ground is shitty that no matter what I can't get clean voltage. If you look at my log with the KOEO I am working the throttle by hand and my voltage out changes everytime I open and close the throttle it never stays the same.
I picked up a new tps connector to splice in and replace my old one and at that point I am going to bypass the computer and go straight to the battery. Clean in vs Clean out = good signal to pcm?
Ok, we are on the same page. Good!
I see that in your log. Sometimes it's .49v, then .51v
The TPS goes to .39% when the V says .51v.
Interesting, because mine does the same! I asked about that in a post here.
Although I don't see any issues in how mine runs.
It doesn't increase over that whether it's running or not.
Hmmm. There are areas in the idle stuff that have to do with min TPS? I've not messed with them.
Is your system voltage ok when it's running? About 14v or so?
Also, what happens if you force the throttle closed by hand when it's running?
See what happens when you give it a solid gnd at the TPS.
Last edited by RonSSnova; 05-20-2014 at 01:38 AM.
Y2K C5 A4 Coupe (10.78 @ 127) Cathedral port 6.2
S476 L33 5.3 69 Nova 8.76 @ 158 Drive to the track street race car
06 Cobalt SS bought new
I have had problems with inconsistent tps voltages/readings with some aftermarket throttle bodies. The problem I have seen is that the bore that the tps goes into is smaller than a factory throttle body and puts a squeeze on the tps and causes erratic operation. The throttle itself feels fine opening and closing. I have had success using a small file and dressing down the tps alignment tabs (ever so gently) until it slides into bore and seats fully without binding. I don't know if this is what you are fighting but might be worth a check.
I thought about that but I don't think my issue will be solved with another tb this goes way beyond that I wish it was that simple.. I started logging ignition voltage and found that during start up my voltage would drop as low as 7v and the tps voltage would drop down as well too..... SO I replaced the battery since it was BAD and now the voltage drops 9-10v at cranking but still the tps voltage will drop.
BUT now I found that when my high speed fan (aftermarket) is engerized my % and voltage jumps to 2-3% and 0.02v - 0.04v even with the TPS UNPLUGGED it does it so I have pretty much ruled out the tps sensor and the throttle body being the issue.
Right now I am at the point that I give up. My plan is to find a know good harness and start from there, once I secure it I am going to probe, pick and dismantle my current harness to find out what and why this happened.
If anyone has any idea's I am open to trying things now I am out of idea's. So far I have done these things:
Replaced TPS
Replaced Battery
Replaced TPS Connector
Ran Independent TPS ground
Verified Voltage (5v) & Refrence wire
Replaced Computer
Check all grounds
*Side note* if you remove the ground from the tps the voltage and % on scanner shoot up to 100% and 5v
Info on the logs..... "Crazy voltage drop" is during start up how the tps v drop and the ignition v drop.. replaced the battery.
"Unplugged tps" is the car running tps unplugged and me turning on and off the high speed fan at random, notice the Voltage change with tps.
"Cooling fan tps" is after the battery swap and me turning on a off the high speed fan through PCM controls tps is plugged in and installed.
Last edited by SmokedOutZ28; 05-21-2014 at 10:09 PM.
I think you are getting close.
In your log with the engine running. The movement from 0 to .39% is normal.
It takes even less than .02v to cause that. The A to D converter in the PCM is just that sensitive to minute TPS volt change.
I was messing with mine today because I fixed a vacuum leak at the TB to intake manifold the other day and I've had to go back through all the idle setups.
Just pushing the TB lever harder onto the stop would shift from .39 to 0%.
Your test with the car off and turning your fan on and off is pretty revealing.
The 5v on one side of the TPS is a regulated supply from the PCM. It will always be 5.0v if you measure it using a gnd at the PCM.
Even if the ign voltage you measured moves around.
Leads me to believe you have a ground issue.
So, where does the +12 to your fan come from? Are you using a relay? And where is it grounded?
Batt in your car is in the stock location? Does the batt ground right to the engine?
I'd check and clean all grounds. And check and clean all the main supply leads as well. Relays etc. If I'm not mistaken, Camaros have a relay block up front somewhere? pull em all out and put back in.
See what you find.
Ron
Y2K C5 A4 Coupe (10.78 @ 127) Cathedral port 6.2
S476 L33 5.3 69 Nova 8.76 @ 158 Drive to the track street race car
06 Cobalt SS bought new
You could change(up the %) the values in dynamic airflow for the idle zone tps and idle tps max to see if it goes into the idle zone. Here is a picture.
The fans are connected to the stock harness so they ground with the relays and pcm like the factory fans do.
The battery is in the stock location and all the connections look good and are corrosion free. I pulled all fan fuses and relays they are clean and free.
I haven't went any further then ordering a new harness. I plan to get back into the garage and pull the fan fuses, relay's and go from there.
gagliano7- I've read about changing the pcm tune to make up for the issue but it didn't always work for people.
So today I pulled the Cooling fan #2 relay and all the voltage and % Jumps stopped with KOEO of coarse but now I need my cooling fan, So I cut the ground wire @ pin 60 and ran a new ground from the TPS connector to Pin 60 everything seemed to be fixed KOEO.
Fire up the car still have a voltage jump but now 6% and 0.86v. That problem would not be fixed until I grounded the wire I cut in my harness Why?!? I don't get. So I grounded it straight to the battery and now only get 1% but I still have the 0.00-0.02v fluctuation and sometimes a shitty idle due to that 1%. So clearly something in that stupid ground wire that should only go from the tps to the computer is talking to the PCM when I unhook it from ground the % and voltage both spike like the TPS was unplugged and then plugged back in.
I went ahead and pulled all cooling fan, ABS, TCS fuses and relay and nothing seem to control that 0.02v even with the TPS unplugged it was still jumping around.
I am not going to give up until I find this! but the new harness will be here Friday then I am going to focus my attention on replacing it!
Anyone reading got any more thoughts or some more places these grounds intersect?
Two days ago I pulled every fuse and relay I could that wouldn't stop the scanner from working, Unhooked the ABS module, TCS module/motor and still had a 0.02v fluctuation in my tps voltage so I decided to walk away from the car for a few days and just get a fresh start.
I got the new harness yesterday but I will not install it until it's my last resort.
Does anyone reading have the Ground locations & Power splices for 01 F-body?
Reply With Quote