Adjusted TPS to 0.54, now idles at 1300 - Page 2 - CorvetteForum - Chevrolet Corvette Forum Discussion

Notices
C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Adjusted TPS to 0.54, now idles at 1300

Old 05-23-2018, 11:02 AM
  #21  
aklim
CF Senior Member
 
aklim's Avatar
 
Member Since: Jul 2004
Location: Hartford WI
Posts: 14,932
Thanked 727 Times in 713 Posts
Default

Originally Posted by JasBass View Post
Yeah, all times I checked it, max was 2.6. Even looking this morning, blades wide open only got 2.6. Wouldn't surprise me if it was bad, or even if that was the right TPS on there. I cannot understate enough the years of bad mechanic work and poor maintenance i've had to undo on this car
Make sure you have the lever in the right position with the other lever on the TB. Ask me how I know
aklim is online now  
Old 05-23-2018, 11:30 AM
  #22  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by aklim View Post
I know mine does use initial voltage as 0% throttle but I think previous TPS units HAVE adjustable slots. Mine does not have slots Just 2 holes. I think the changes came with the switch to speed density

Could be the TPS is bad but maybe the reference voltage is not 5V?
The MAF cars still did take a 0% value to account for small variation in the reference voltage - I had started my car back when it was MAF with my foot barely on the gas, and it ran terribly. Key off, key on, and back to normal. Plus, the shop manual gives a range of voltages that is 'acceptable' for a 0% value, and shifts where the WOT is based on that initial value.

And I agree, OP should check the reference voltage. If the reference voltage was at 2.3, then 2.3 is all he will get from the TPS. In addition, his '0' mark would be off if the reference was half of what it should be.
TheBlaster9001 is offline  
Old 05-23-2018, 12:11 PM
  #23  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Originally Posted by aklim View Post
Make sure you have the lever in the right position with the other lever on the TB. Ask me how I know
The lever arm coming from the TPS sits nicely against the lever arm from the TB. I don't see any other way it could be possibly oriented?? I can check tonight to see if I manually move the tps lever if I can get to 5v.


Originally Posted by TheBlaster9001 View Post
The MAF cars still did take a 0% value to account for small variation in the reference voltage - I had started my car back when it was MAF with my foot barely on the gas, and it ran terribly. Key off, key on, and back to normal. Plus, the shop manual gives a range of voltages that is 'acceptable' for a 0% value, and shifts where the WOT is based on that initial value.

And I agree, OP should check the reference voltage. If the reference voltage was at 2.3, then 2.3 is all he will get from the TPS. In addition, his '0' mark would be off if the reference was half of what it should be.
Yessir, confirmed it is getting 5v. Everything is leading to the TPS being bad. Seems to account for why I had crummy mid range throttle response (3-4500)
JasBass is offline  
Old 05-23-2018, 10:45 PM
  #24  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

2.8 was all I could get out of it. And that was depressing the TPS lever, not just tb lever. Picking up a new TPS tomorrow and we'll see how it turns out. Tune should be here tomorrow as well.
JasBass is offline  
Old 05-23-2018, 11:04 PM
  #25  
aklim
CF Senior Member
 
aklim's Avatar
 
Member Since: Jul 2004
Location: Hartford WI
Posts: 14,932
Thanked 727 Times in 713 Posts
Default

Originally Posted by JasBass View Post
2.8 was all I could get out of it. And that was depressing the TPS lever, not just tb lever. Picking up a new TPS tomorrow and we'll see how it turns out. Tune should be here tomorrow as well.
If you have 5V reference and 2.8V by depression of the TPS lever, we are done with the the TPS. Ebay special Slightly used
aklim is online now  
Old 05-24-2018, 02:38 AM
  #26  
LWesthaver
CF Senior Member
 
LWesthaver's Avatar
 
Member Since: Dec 1999
Location: Columbia MD
Posts: 766
Thanked 39 Times in 26 Posts
Default

Maybe this will help: TPS diagnostics
LWesthaver is offline  
Old 05-25-2018, 08:21 AM
  #27  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

So, picked up a new BWD TPS and installed it last night. Odd thing here is, still only getting 2.2V at WOT. Getting 5V at at bottom battery input. I cleaned the connector terminals, no corrosion was present. At this point, I'm stumped
JasBass is offline  
Old 05-25-2018, 10:07 AM
  #28  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Possibly getting resistance through ground?
JasBass is offline  
Old 05-25-2018, 10:13 AM
  #29  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post
So, picked up a new BWD TPS and installed it last night. Odd thing here is, still only getting 2.2V at WOT. Getting 5V at at bottom battery input. I cleaned the connector terminals, no corrosion was present. At this point, I'm stumped
That's no good. You get 5 volts measured bottom wire to ground wire? How about bottom wire to a ground anywhere else (frame, header bolt, etc). I'm thinking that someone or something has gone all 'amateur electrician' on your wiring harness.

When I had accidentally hooked my MAP sensor up backwards, the TPS input would not pick up until about half throttle, and wouldn't get above 2 volts. I used the same ground for TPS and MAP. So power went into the ground on MAP, then from the power on map, to the same ground wire as TPS.

Nothing got broke, but sensor input for both sensors was garbage. I don't know the way your car is wired, but I imagine you have several sensors sharing the same ground coming back in to the ECM - my car did. I wonder if there is a short/bad conection somewhere in the harness, or if a sensor that is also on that ground is acting up.

Try this, if you can - get a wiring diagram for your ECM, and ideally, a 5 volt power supply of some kind. I suppose you could jumper from another sensor, but a run from an external supply would be ideal.

First, start off by disconnecting the other sensors that share a ground with the TPS, one by one, and then all at the same time. All different combos of disconnected sensors that are on that same ground. Check TPS signal voltage each time.

If a certain sensor appears to be at fault, it may be bad. If that test ends up being inconclusive, then we know the power/ground wiring to the TPS is not shorted by another sensor.

Next, I'd try hooking a 5 volt supply up to the TPS, attaching the signal wire, and measuring signal voltage again, just to check.

I'd then repeat this at the ECM, only you will need to take the pins for TPS voltage and ground out, and hook them to the supply. What's the signal voltage do then?
TheBlaster9001 is offline  
Old 05-25-2018, 10:14 AM
  #30  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post
Possibly getting resistance through ground?
That's quite possible, it could be a bad connection in the wiring harness, or at the ECM
TheBlaster9001 is offline  
Old 05-25-2018, 10:35 AM
  #31  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Im definitely getting 5v at reference, so strange. Iíll have to look up the ground path in my FSM and check it. On the bright side, I installed the tune in the car and wow, completely different car. Actually has some go now haha. Cant imagine how it'll feel when this gets sorted out
JasBass is offline  
Old 05-25-2018, 05:48 PM
  #32  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Did a quick check of the TPS connector. Top wire ground will complete the 5v circuit coming from the bottom supply. The culprit seems to be the ECM reference wire. Once again, it only reads .40 at rest and WOT 2.2V. So, thinking maybe a connector issue? Loose at the point of the connector. Visually, the wire is intact until it enters the harness firewall passthrough. And the part I can see entering the ECM visually passes the test. I'd hate to think it's a bad ECM, but between the connector, the ECM reference wire, and the ECM, these seem to be the culprits.
JasBass is offline  
Old 05-25-2018, 05:55 PM
  #33  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post
Did a quick check of the TPS connector. Top wire ground will complete the 5v circuit coming from the bottom supply. The culprit seems to be the ECM reference wire. Once again, it only reads .40 at rest and WOT 2.2V. So, thinking maybe a connector issue? Loose at the point of the connector. Visually, the wire is intact until it enters the harness firewall passthrough. And the part I can see entering the ECM visually passes the test. I'd hate to think it's a bad ECM, but between the connector, the ECM reference wire, and the ECM, these seem to be the culprits.
I don't think the ECM would be to blame, unless it was shorted out and putting a voltage out on the TPS sensor input pin

Last edited by TheBlaster9001; 05-25-2018 at 06:06 PM.
TheBlaster9001 is offline  
Old 05-25-2018, 06:04 PM
  #34  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post
Did a quick check of the TPS connector. Top wire ground will complete the 5v circuit coming from the bottom supply. The culprit seems to be the ECM reference wire. Once again, it only reads .40 at rest and WOT 2.2V. So, thinking maybe a connector issue? Loose at the point of the connector. Visually, the wire is intact until it enters the harness firewall passthrough. And the part I can see entering the ECM visually passes the test. I'd hate to think it's a bad ECM, but between the connector, the ECM reference wire, and the ECM, these seem to be the culprits.
Try this for me - can you de-pin the middle wire, then hook the TPS up to the connector? I just wonder what it'll do with the middle wire absent.

Last edited by TheBlaster9001; 05-25-2018 at 06:05 PM.
TheBlaster9001 is offline  
Old 05-25-2018, 06:07 PM
  #35  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Originally Posted by TheBlaster9001 View Post
Try this for me - can you de-pin the middle wire, then hook the TPS up to the connector? I just wonder what it'll do with the middle wire absent.
I'll hit it either later tonight or in the morning! Is there a way to check resistance of the ECM reference wire?
JasBass is offline  
Old 05-25-2018, 06:11 PM
  #36  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post
I'll hit it either later tonight or in the morning! Is there a way to check resistance of the ECM reference wire?
You could measure resistance of the wire itself by taking a multimeter and going from the TPS to the ECM connector. Make sure you don't test resistance there with the ECM plugged in, that could hurt it.
TheBlaster9001 is offline  
Old 05-25-2018, 06:26 PM
  #37  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Originally Posted by TheBlaster9001 View Post
You could measure resistance of the wire itself by taking a multimeter and going from the TPS to the ECM connector. Make sure you don't test resistance there with the ECM plugged in, that could hurt it.
Oah yeah, duh lol. Its been a long week man. Iíll pull the pin number from the FSM and test it
JasBass is offline  
Old 05-25-2018, 07:49 PM
  #38  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post


Oah yeah, duh lol. Its been a long week man. Iíll pull the pin number from the FSM and test it
I feel ya, sounds good.
While you've got the ECM pin pulled, you could reconnect the ECM minus that pin, and then measure the voltage with the wire off of the ECM - that way you can find out if the issue is the ECM or not

Last edited by TheBlaster9001; 05-25-2018 at 07:51 PM.
TheBlaster9001 is offline  
Old 05-25-2018, 09:42 PM
  #39  
JasBass
CF Senior Member
Thread Starter
 
JasBass's Avatar
 
Member Since: Jun 2017
Location: NC
Posts: 318
Thanked 11 Times in 10 Posts
Default

Originally Posted by TheBlaster9001 View Post
I feel ya, sounds good.
While you've got the ECM pin pulled, you could reconnect the ECM minus that pin, and then measure the voltage with the wire off of the ECM - that way you can find out if the issue is the ECM or not
Damn, I wish I had checked this before I did that. I ohm'd the ECM reference wire from connector to c13 as per FSM and got 0.00. I used the tables in the web link one of the members here posted for the Ohms of the TPS, confirmed all the specs within 0.5-1. Hooked power back up and probed power input and top ground and got 5v.

The facts as the lay now:
TPS is receiving 5v.
TPS top ground wire holds 5v and has no resistance to ground.
ECM reference wire itself has 0.00 ohm resistance.
When power supplied, TPS connected, probed and checked, ECM reference wire at rest is 0.30v now and WOT is 2.12.

At this point, the finger is pointing to the ECM... Frustrating if this is the only thing wrong with the ECM, but really, it's kinda a big thing lol.
JasBass is offline  
Old 05-25-2018, 09:46 PM
  #40  
TheBlaster9001
CF Senior Member
 
TheBlaster9001's Avatar
 
Member Since: Apr 2018
Posts: 349
Thanked 52 Times in 51 Posts
Default

Originally Posted by JasBass View Post
Damn, I wish I had checked this before I did that. I ohm'd the ECM reference wire from connector to c13 as per FSM and got 0.00. I used the tables in the web link one of the members here posted for the Ohms of the TPS, confirmed all the specs within 0.5-1. Hooked power back up and probed power input and top ground and got 5v.

The facts as the lay now:
TPS is receiving 5v.
TPS top ground wire holds 5v and has no resistance to ground.
ECM reference wire itself has 0.00 ohm resistance.
When power supplied, TPS connected, probed and checked, ECM reference wire at rest is 0.30v now and WOT is 2.12.

At this point, the finger is pointing to the ECM... Frustrating if this is the only thing wrong with the ECM, but really, it's kinda a big thing lol.
Does the pin have 2.2 volts at WoT? Check it with just the pin, if it is 5volts on the pin with the pin not connected to the ECM, then the ECM is at fault.
TheBlaster9001 is offline  

Thread Tools
Search this Thread
Quick Reply: Adjusted TPS to 0.54, now idles at 1300


Sponsored Ads
Vendor Directory

Contact Us About Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: