bmfonda

hi everybody, iv searched this problem for months now but i still cant figure out the problem. when im WOT for more than 2 seconds in any gear it goes from open loop to closed loop no matter what gear or rpm im at, iv done 3rd gear pulls from 2k-5k, 5th gear, and 6th gear pulls and its always when im WOT for more than 2 seconds. my tuner doesnt know what the problem is and he forced it into permanent open loop as a safety measure. i had an error code for high voltage reading on TPS and i just recently replaced that sensor so idk if itll come back but the problem is still happening. no other relevant codes are present, just evap. im wondering if there is a short or overload somewhere, maybe at the fuel pump. maybe faulty primary O2s? i thought it could be a fuel pressure leak but it doesnt seem like a physical problem, more electrical to have the ecu switch tables. but i dont see why the computer would ever lean out as a safety measure, it would get richer if anything went wrong.

my car is a 1996 240sx with an ls1 from a 2001 camaro SS, walboro 255 pump, stock ecu, no secondary O2s, stock motor. i have a wideband hooked up and a scan tool to see open loop/closed loop so i can test if a certain fix works without a dyno.

please help i want this fixed, its been too long

2xLS1

iTrader: (25)

Make sure the TPS problem is fixed. get a datalog of it doing it and post it. Only way you will get help

bmfonda

Ok I'll try to get a log of throttle position and open /closed loop, I hope my scanner can log fuel status. I put in a new tps and it's still doing it. Code hasn't come back and I drove it a couple hours since I changed it

2xLS1

iTrader: (25)

Use a voltmeter and see what the TPS voltage is at WOT on the blue wire.

bmfonda

At closed tps reads .90 volts and at wot it reads 5.07. From what I've read this is a bit high. At rest the throttle is 0.8% open. Idk if that would be causing a higher reading or if that is within allowable specs. My scanner doesn't let me graph fuel status but I'll take a video of the data stream and try to post it tomorrow.
Also, the tps high voltage code came back under pending codes even with the brand new ac delco sensor

2xLS1

iTrader: (25)

What kind of throttle body? .9V closed is too high. Usually anything over 4.7V WOT causes the HV code. Measure voltage between black wire on TPS and Battery -. When measuring those voltages what are you using for the ground reference on the meter?

bmfonda

Stock throttle body, idk what size. Could I rig up a throttle stop/block and fix the problem? Or would the tps never read wot if I did that? I heard I can rotate the tps to get the closed and wot readings down.
What do you mean "ground reference"? Like where I'm setting the ground probe on the meter?

2xLS1

iTrader: (25)

Where are you grounding the meter when measuring TPS voltage? It can make a difference on what you read for TPS voltage on the blue wire. Stock TP sensors are not really designed to be clocked. They have a locating tit on them. Has the throttle body bump stop been altered?

With KOEO probe between the black wire on the TPS plug and Battery -. See if there is any voltage between the two points. Should be as close to 0v as possible. Use the smallest range on the meter that doesn't over range.

MontecarloDrag

iTrader: (3)

That's your problem. I find hard to believe your tuner has not fixed it. Any competent tuner does know that.
At closed throttle the TPS must be below 0.67V, between 0.500 and 0.650 is optimal. At WOT it should not go above TPS high fail threshold. 4.5 to 4.7V is ok. Measure this values with the scanner, a multimeter is good for troubleshooting but you need to know what the PMC sees to adjust.

If the TB opens a lot and makes the TPS go past 4.7, you need to adjust the stop screw to limit the opening.
If the TPS trips any DTC or goes out of range at WOT it will cause all kinds of problems including transmission issues. It's one of the things that bothers the PCM the most.

2xLS1

iTrader: (25)

Where is this WOT stop screw on a stock throttle body?

bmfonda

Ya I just put a screw in the throttle body bump stop which is limiting the voltage at wot to 4.8 and that seems to have fixed the problem for now. I did around 10 pulls at wot lasting up to 5 seconds or so and it stayed in open loop the whole time. Idk if the bump stop was tampered with but it didn't have a screw so it was able to go back all the way.

2xLS1

iTrader: (25)

The .9V at closed throttle is not correct. And that WOT bump stop is not stock. It has been ground down. I still think you have a ground problem somewhere. Still don't know how you are coming up with those voltages. But fix it how ever you want.

bmfonda

I'm just putting the ground for the multimeter on a chassis bolt. I'm gunna adjust the lower bump stop down once the wd40 seeps in because it's stuck for now.
I'm very open to more ideas and I did think this could be a short or lack or ground somewhere like you said and I'll test where you wanted me to when I have time next.
I'm gunna keep trying to trigger the problem every time I drive it and see how long a certain "fix" lasts

MontecarloDrag

iTrader: (3)

If the TB doesn't have a stop screw you can install one, piece of cake.
The other way to adjust it is slotting the TPS mounting holes so you can turn it.
Your actual range is from 0.9 to 5.07 V (4.17V). I think you need to rotate the TPS a lot to make it work from 0.5 to 4.67V but it's possible.

jimmyblue

iTrader: (11)

There is no WOT stop screw on a stock TB, just a cast
stop-tang which is usually too fat to let the blade fully
open. Aggressive hogging here can let you go over the
top. But before you get to wrapping the tang with foil
tape have a look at the 5V reference that drives the TPS,
reading 5.07V at WOT means the reference may be out-
of-spec high.

Measure everything right at the TPS, do not use unrelated
chassis sheet metal points; the TPS ground returns directly
to the PCM and that is the reference that matters.
of spec high and bending the TPS output everywhere
(idle=0.9V is kooky too).

bmfonda

I tested the voltages again now with using the black wire from the tps as the ground and at closed its .820, open with throttle stop is 4.8, and open with no throttle stop its 4.98.
Voltage from black tps wire to battery ground is 89mV, so basically zero.
I'm gunna drive the car today after work and see if the problem happens or not

bmfonda

I got in my car today an drove around the block and I noticed the fuel status said "CL_fault" and it wouldn't go into open loop under acceleration. I took it home and parked it. I think I have a grounding issue somewhere? I noticed I don't have a grounding cable for the bank 2 side of the motor so I'll put one and check for loose grounds throughout the whole car. What do you guys think it could be? Also now I'm throwing a code for low tps voltage instead of high

bmfonda

update: i just put in new O2 sensors because of the "CL_Fault" fuel status and its still saying the same thing. idk what this could be but i dont think my tps and this fuel status fault are related. i now have two pending codes for both my secondary O2 sensors that i dont remember having but iv never had secondary O2s since the car has been running.
what do you think?