can someone tell my why my car runs better with the TPS unplugged?
 

I've had some major bucking issues lately with my 00 Civic d16y8. I have on ongoing thread on my ordeal. If you want to read it for me in depth info you can find the link below. I had the car dyno tuned a little over two years ago and everything has been fine until recently.

https://honda-tech.com/zerothread?id=2239760

Mods done to my D16y8.

*Crower stg2
*OBD2>OBD1
*chipped P28 ECU
*I/H/E

Replaced the following.

*stock TPS with a Blox TPS (.5 closed 4.5v WOT)
*whole dizzy
*plugs
*wires
*cap/rotor less than 6 months ago
*fuel filter less than 6 months ago
*cleaned IACV
*cleaned TB
*swapped a known good chipped P28 ECU

Why does my car run "normal" (CEL on and crappy mileage) with the TPS unplugged? Could it be the Blox TPS or a bad plug? I'm about to throw in the towel and take it to a dealer and have them diagnose it for me then I'll fix it.

Thanks,

Jeremy





Modified by gimmezell at 5:19 PM 4/29/2008

Re: can someone tell my why my car runs better with the TPS unplugged? (gimmezell)
 

In a case like yours, I would go as far as to run completely new wires to the TPS and to the ecu, because you have ruled out everything in between.

If you swapped a known good ecu and it still did it, and put in a new TPS (which was sourced from ebay?!) My guess is that assuming the TPS is good, which you have said it is, then the only thing between the tps and the ECU is the wiring..

Re: can someone tell my why my car runs better with the TPS unplugged? (sanimalp)
 

The simplest answer is often the one overlooked. If everything is in spec and it runs better "running rich" with the TPS unplugged and CEL on... perhaps you're running lean or too advanced (Chipped ECU) when everything is plugged in. Get it tuned properly.

It is tuned properly. I had it dyno tuned a little over two years ago and everything has been good until recently. No major mods since then.

Re: (gimmezell)
 

Well something is going on. You have a wideband to be sure? Have you checked to see that the voltage changes properly as throttle is given?

Re: (HRTuning)
 

Nope, no wideband. I don't have access to an oscilloscope to test the voltage of the TPS. I only have a voltmeter and I can't see any voltage spikes when I manually open the throttle.

Re: (gimmezell)
 

Are you running closed loop with a stock o2? Does it run ok WOT?

Re: (HRTuning)
 

Do you know if your CEL/MIL or any sensors are disabled on your ROM? If your not sure, the person who tuned your car would know. Ask them to be sure, you could have a CEL condition that's not showing.

Re: (HRTuning)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HRTuning &raquo;</TD></TR><TR><TD CLASS="quote">Are you running closed loop with a stock o2? Does it run ok WOT?</TD></TR></TABLE>
I've replaced the stock O2 with one from Rywire.com and from what I can tell it runs decent at WOT. I say decent only because it doesn't feel as smooth as to when I disconnect the TPS. This maybe all in my head though (placebo effect).

Re: (GhostAccord)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GhostAccord &raquo;</TD></TR><TR><TD CLASS="quote">Do you know if your CEL/MIL or any sensors are disabled on your ROM? If your not sure, the person who tuned your car would know. Ask them to be sure, you could have a CEL condition that's not showing.</TD></TR></TABLE>
I have two BIN's and I can't remember which on is on there now. I don't have access to a Moates until Friday.

The 1st BIN just has the knock sensor disabled and the second BIN has the knock sensor, ELD, atmospheric pressure sensor and injector test circuit disabled. I'm 95% sure I have the 1st BIN on the chip.


Modified by gimmezell at 1:01 PM 4/30/2008

Re: (gimmezell)
 

What does your car run like if you swap the TPS and MAP sensor connectors?

Re: (gimmezell)
 

If it runs well WOT it could have something to do with closed loop and your o2. You could try disabling closed loop and see if that helps.

Re: (GhostAccord)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GhostAccord &raquo;</TD></TR><TR><TD CLASS="quote">What does your car run like if you swap the TPS and MAP sensor connectors?</TD></TR></TABLE>
I can guarantee that the connectors are in the correct location.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HRTuning &raquo;</TD></TR><TR><TD CLASS="quote">If it runs well WOT it could have something to do with closed loop and your o2. You could try disabling closed loop and see if that helps.</TD></TR></TABLE>
I'll have to give that a try on Friday when I get my buddies Moates burner. If it does run better what will that tell me? Bad O2 sensor or connector?

Re: (gimmezell)
 

That it could be the o2, but disabling closed loop makes it run a little richer anyway, so it could be anything in your fuel system causing less fuel to get through.

Re: (HRTuning)
 

for the past few months i've ran 2 different omni tps's and both did not work out for me. after about 1k miles on each, it would start hesitating and bucking again. so i left it unplugged for a while also. and today i finally got a used oem tps with low miles and installed it. it's running great. so much smoother. i hope it stays that way. i've been dealing with this shit for over a year now. it's so annoying. maybe try a good used oem tps OP and see what happens.

Re: (HRTuning)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HRTuning &raquo;</TD></TR><TR><TD CLASS="quote">If it runs well WOT it could have something to do with closed loop and your o2. You could try disabling closed loop and see if that helps.</TD></TR></TABLE>
I disabled the oxygen sensor within Crome and it runs fine. It runs the same as if I unplugged the TPS.

Re: (gimmezell)
 

https://honda-tech.com/forums/images/smilies/emwink.gif

Re: (HRTuning)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HRTuning &raquo;</TD></TR><TR><TD CLASS="quote"> https://honda-tech.com/forums/images/smilies/emwink.gif </TD></TR></TABLE>
By disabling the o2 sensor I didn't fix anything did I? I mean it's ran with the o2 sensor just fine before the problem.

It's back. I took an hour drive and the bucking is back. All though it's not as bad.

So disabling the o2 sensor did nothing I guess. Any more ideas HRTUning?

Re: (gimmezell)
 

Did you disable the "o2 sensor" or did you disable closed loop like I mentioned? Completely separate things. Disable closed loop.

Re: (HRTuning)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HRTuning &raquo;</TD></TR><TR><TD CLASS="quote">Did you disable the "o2 sensor" or did you disable closed loop like I mentioned? Completely separate things. Disable closed loop.</TD></TR></TABLE>
I think I just disabled the "o2 sensor". I don't see a specific option in Crome to disable closed loop. I'm not too familiar with Crome so maybe it's hidden somewhere.

Re: (gimmezell)
 

There should be one somewhere. All you disabled was the heater circuit. Closed loop would still be acting based on the o2 voltage.

Re: (HRTuning)
 

When you open your ROM in Crome and look in view/options there are 3 O2 options.

1. Disable Oxygen Sensor (Open Loop)
2. Disable Oxygen Sensor Heater
3. Debug Mode (Disable O2 and more)

So I would assume that if you are to check the disable O2 (open loop) check box. That would disable closed loop IIRC.

Re: (GhostAccord)
 

got a friend who has same problem. car bucks when coasting in gear when foot is off the gas, but runs fine on the highway. hope u figure it out.

Re: (all-in)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by all-in &raquo;</TD></TR><TR><TD CLASS="quote">got a friend who has same problem. car bucks when coasting in gear when foot is off the gas, but runs fine on the highway. hope u figure it out.</TD></TR></TABLE>

That's not even close to the same thing. That has to do with the fuel cut, or lack thereof.