Just thought I'd share..

My accelerator cable was slack, my 'trusted' midas shop said it was normal.. its not!

I have got MPG's of before & after to show slackness... but no where to host

from this pic you can see I have no adjustment thread left, my cable is about right but a bit tighter would be good... Red arrow shows where it was.



I don't think I was seeing wide open throttle before, going to remove the bits in front of throttle body (oil separator etc) and make sure it does fully open this weekend.

Its well worth checking yours to make sure its hitting the WOT

 

how do i do this??? mine is loose as hell and i dont know how 2 fix it

 

WOT is actually detected by the TPS - so your butterfly could be wide open, but if the TPS is incorrectly calibrated, the ECU won't know you are at WOT. On the other hand, you could have a scenario where the ECU things you are WOT even if the TB isn't fully opened (same thing, TPS needs adjustments).

 

If you look near the red arrow you see 2 bolts...1 either side of the bracket holding accelarator cable. the one on the left is the Adjustment nut, the one on the right is the lock nut.

I loosened both, lifted cable to remove slack and then tightened them both, its pretty simple when your looking at it too see which way to turn the bolts to elimiate the slack.

 

Huh so are you saying the slack was normal and its my TPS that needs adjusting? Or do both cable and TPS?


With the Slack cable.. its quite possible that the cable wasn't been pulled tight enough to bring the rocket arm round to fully open the throttle + you need to push gas more for it to engage

 

The cable definitely needs to be adjusted to take up the slack from stretching over time. I was just clarifying that WOT is really detected by the TPS (based on movement generated by the cable/gas pedal). It wouldn't hurt to check the TPS for calibration - I know mine is slightly out of spec, and I'll adjust it the next time I have the air intake off - I couldn't get a good angle to break the screws free.

 

Cool, I'll be doing the same

 

Slack in the line is normal and I doubt tightening it up makes a differnece in final throttle postion. It would have to be really, really loose for the throttle plate not to open all the way and keep the TPS from reaching the correct voltage. The TPS voltage does not have to be exact either for open loop to occur. IIRC 4 volts is spec but I am fine with 3.7 at WOT

 

Mike - good info.. just a correction, I think you mean kilo-ohms not volts... when I measured mine this weekend it was like 0.7 k-ohms closed and 4.5 k-ohms wide-open.. do you know what the acceptable tolerance is?

 

Whats "TPS", "WOT" and whats the effect of tightening the cable and fixing the TPS??

 

throttle position sensor & wide open throttle....benefits are prolly better acceleration

 

Interesting that my max has two cables for the throttle vs one as in the pic above. I was going to adjust mine on my 99SE cause I know it's slack. Anyone know why I have two to adjust?

 

One is for the cruise control and one is for the accelerator pedal.

 

yup your cruise would be on the left if i remember, and throttle on the right

 

no, mike was right, it is supposed to be volts. and you can hardly go pass 4 volts. it's the potential difference we are talking about. when you measured 4.x ohms, that's resistance you are measuring. in a way, they are related, because the greater the resistance, the greater your voltage will build up between the two ends. however, this is just a measure of the throttle signals for the ecu. so both potential differences and resistance readings can be used collected. however, in our factory specs, the tps is simply a potentiometer that measures by volts. resistance is related but not used by the ecu to determine the throttle positioning.

 

Strange - the Haynes manual specifically instructs you to check for resistance between two of the TPS terminals...

 

hm, i may be wrong, because when i took electonics, tps is a potentiometer that measures in volts.

besides, many orgers here who are doing their own check ups are doing it in volts, too. i know for sure stephen max has his in volts, and he has trouble getting the tps to read more than 3.5 volts at wot.

it is strange. however, like i said, the two values are directly proportional.

this is the simple Ohm's law:

V=IR

V=voltage
I=current
R=resistance

from the equation, setting current as a independent constant, voltage varies directly with resistance. so both make sense...

 

I am also an EE - so I know all about ohm's law... but I wasn't sure how much current (in Amps) is flowing through the TPS - so it wasn't clear to me what voltage range to expect across the terminals... 4V at 4kohms = 1ma of current.

 

good, so you know exactly how it works since you are in EE. that's great.

from Ohm's law, if we can measure both the potential difference and the resistance from the tps, then we will figure out what the current is. of course, we all know this current may be varied due to many factors, but the idea is to get a current reading and set it a constant so we can figure out the range of other readings. Now, combining your resistance and my voltage at WOT:

4.5kohms and 3.96volts
current would be V/R= 0.88 mA

so for voltage reading, factory spec WOT kicks in at 3.7 volts. then we go back and do the math, R= v/I= 4.2045kohms. so in resistance terms, WOT occurs at 4.2045kohms

i'm in ME, not EE; however, we have to take a few EE classes, and I turned out pretty good at them.

 

We're on the same page... strange that the Haynes talks only in terms of resistance... I wonder if the FSM talks about voltages.. I'll have to take a look when I get home. Where did you find the factory spec for WOT voltage? Is there one for idle too?

 

well, i don't remember much about idle voltage, but this default 3.7 volts comes from my findings in reading many posts from i30tmiked, stephen max, and some others. they mostly post about this topic in the force induction topics, and those guys are big time and legit in terms of credibility on the org...

so i take their word in seriously.

 

As do I.

 

arent we suppose to adjust it at 60k miles?

 

good deal modi, coming down to baton rouge for a spar at the track? it'll be fun. there are many maxima guys liking to hang out together once in a while. it' pretty cool, too.

 

wish i could - not sure the family would approve HA HA! plus it would be quite a road-trip from Chicago.

 

hey modi, just returning from reading the post from stephen max. i got it wrong, i do apologize. WOT kicks in at 4 volts, not 3.7. Stephen Max writes that he car barely make it up to 3.75 volts. so that's what it is. well, mine WOT's at 3.96, that's very close, i guess during an acutally drive with alternator running and everything, it's possible that mine would sit on 4 volts for a WOT AFR. so i stand corrected on this one. sorry, i was just talking straight out of my bad memorization.

 

No apologies needed... it was a discussion - we both learned something.

 

yeah, thanks alot. what a cool guy you are. see, there are so many flammers over here trying to ***** an extra post by storming others. that's why i don't like to discuss much on the org. we rather have maxima meets every thurs night and exchange our innovative learnings. this discuss is the first to be so constructive. good job buddy, we need to keep this kind of discussion on the org.

 

No, I mean volts. We may be testing different types of sensors. Different year and different tranny style maxima/I30's have different types of set ups. I have just the one TPS sensor with the WOT incorporated into it. Some are two seperate sensors. But I know it is volts. I have messed with that thing alot when I did the Pathfinder TB way back when.

 

All you basically want is to stay as close to 4 volts as possible while still keeping a decent idle speed.

 

Thanks Mike. Mine has the two seperate connectors... that explains it.