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post #16 of 46 (permalink) Old 11-08-2012, 06:38 PM
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You've got the beginnings of a Puttstick in reverse. LOL!
I know, I need to find my printout, pull the drivers seat and lay in there underneath and hopefully it's just the one wire! LOL
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post #17 of 46 (permalink) Old 11-11-2012, 08:39 AM
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...If you're up for that, so am I. But I don't want to start it if we aren't going to agree take it to completion.
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Peva, I'm all in...
OK. So that commitment lasted, what, 12 hours?
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post #18 of 46 (permalink) Old 11-14-2012, 05:50 PM Thread Starter
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Yeah sorry. Car has been parked. I had the one spring cup on my strut break. The result was me smashing into a curb head on. Broke the strut and ruined my 18s. I'm not real happy about it. I haven't been able to even check the car out to see if any other damage was done. So till I get time to fix it, this has to wait.
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post #19 of 46 (permalink) Old 11-14-2012, 07:36 PM
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Understood. Sorry to hear that - but glad you're OK.

This is the second instance of that exact thing occuring in the last 3 weeks that I've read about: http://300mclub.org/forums/viewtopic...292472#p292472

Last edited by peva; 11-14-2012 at 07:38 PM.
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post #20 of 46 (permalink) Old 11-14-2012, 08:50 PM
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It would involve adding 2 variable resistors (potentiometers) - one in series with the ground wire, and one in series with the +5 volt wire going to the TPS. Stay with the TPS you have in there now if you want to.

But before you add the variable resistors, you would make some measurements. They would be:

1. With the TPS installed but the connector disconnected, measure the following on the TPS itself:
**a. Resistance from ground pin to +5V pin.
**b. With throttle at idle position, resistance from center (wiper) pin to ground pin.
**c. With throttle held to WOT position, resistance from center pin to ground pin.

2. With the TPS installed and the connector connected and the ignition on, measure the following on the wires going to the TPS:
**a. Voltage from ground wire to +5V wire.
**b. With throttle at idle position, voltage from ground wire to center wire.
**c. With throttle at WOT position, voltage from ground wire to center wire.

You would provide me with those numbers and the WOT voltage that causes the CEL/limp mode. Then we would agree on a value for the WOT voltage - one that would be just below that CEL/limp mode value - based on the 4.64 volts you mentioned in your OP, maybe go with 4.55 volts as a safe value - i.e., close to the max., but with some reasonable margin so the CEl/limp mode doesn't get tripped by small system variations (due to temperature, vibration, etc.).

From all of that information, I would develop the formulas to calculate the values of resistance to dial into the two variable resistors which would at the same time give any desired idle position voltage and the safe high WOT voltage.

IOW - you would end up with a table that would have 3 columns. First column would be a list of idle position voltages, starting with the unaltered idle position voltage that you measured before putting in the variable resistors, and then values increasing in, say, 0.05 volt increments up to, say, 1.2 volts. Then columns 2 and 3 would be the values of the ground wire variable resistor and the +5V wire variable resistor, respectively, to achieve the desired idle position voltage and the high safe (i.e., non-CEL) WOT voltage.

From there, it would be up to you to adjust the two resistors according to the table for different idle position voltages for experimenting. As you moved it further up, you would eventually hit an area of idle position voltage in which the performance/fuel mileage would start decreasing. Then you could dial it back down to the sweet spot.

Beyond that, you could either leave the variable resistors in for further experimenting, or you could replace them with optimum value fixed resistors.

If you're up for that, so am I. But I don't want to start it if we aren't going to agree take it to completion.
Well you can count me as interested.

We have long known that the "off the shelf" aren't a good option but that doesn't mean tinkering through external manipulation can't be done.

I've got some questions that I need to sort through, but I'll get to that later tonight.
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post #21 of 46 (permalink) Old 11-14-2012, 11:52 PM Thread Starter
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Understood. Sorry to hear that - but glad you're OK.

This is the second instance of that exact thing occuring in the last 3 weeks that I've read about: http://300mclub.org/forums/viewtopic...292472#p292472
It was the spring seat on top, the plastic one. The bearing had been going since not long after I installed it. It broke earlier in the day. At night on the way back, I let my focus from the road go for a second to take a drink(of water) and hit the curb. The strut bearing being broke can make the car pull. I'm pissed I ruined my expensive 18" tire. I have a spare matching rim. And yeah, could have been a pole or something there.
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post #22 of 46 (permalink) Old 11-15-2012, 01:13 AM
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So after reading through the jeep thread it looks like the MAP sensor is indeed the only thing that matters as far as the ECM is concerned at 80%+ throttle, which if you're going for making the car faster is what really counts.

What about the rest of the range though. The ECM reads O2 to decide fuel, so how does the TPS play into the equation in the ECM? I'm all for remapping the fuel curves, but I feel like there is a hole here in this method that we aren't talking about.
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post #23 of 46 (permalink) Old 11-16-2012, 11:15 PM Thread Starter
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The TPS is more for timing advance and shift points. It uses the TPS along with the MAP to know how much air is entering the engine and the load demanded.
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post #24 of 46 (permalink) Old 11-17-2012, 06:52 AM
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It was the spring seat on top, the plastic one. The bearing had been going since not long after I installed it. It broke earlier in the day...
Oh. So this is due to the aftermarket design problem, not a factory part rust-thru.
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post #25 of 46 (permalink) Old 12-19-2012, 01:12 PM
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Any word on where this idea ended up?
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post #26 of 46 (permalink) Old 12-24-2012, 11:50 AM Thread Starter
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Yes, I did do some of this. With some issues arising still. Got the "MAP Enhancer" installed. Found out some weird stuff about it. I thought I had to richen up the fuel mixture. Turns out its not the case exactly.

I initially did raise the voltage from the stock 5.01v(about 5v exactly) to 5.5v. Great improvement power wise. Though I smelled fuel at idle. Then I went to town going up and down with voltage driving it around. At just shy of 6v, it was a rocket!!! I had to keep the steering wheel 90 degrees to counter act torque steer. It spun tires till 3rd gear! I was amazed. But it seemed to lag on the lower throttle and smelled awfully rich at idle. It was the first time I've ever had the car spinning both tires from a stop going straight.

Then I went the other way. And finally got settled to around 4.5v. Has great power till half throttle. Takes off with no effort and maintains speed like a dream. I have to keep letting off and tapping the pedal to maintain any speed up to 80mph. But now it falls even more short at higher to full throttle.

I tried putting the TPS down to near stock voltage and was around .65v. Had horrible shifts. The trans shifted way early and was slipping between gears. But it did smooth out power through the entire range more. I put it back to where I had it at .87v to correct shifting.


I'm a little lost at it all. I don't have a wide band O2 to really see whats going on. I'm listening for detonation and smelling for gas. But from what I gather, it seems like I need larger injectors to really get it tuned for what I've done. Seems like I'm flowing too much air through for the stock programming to compensate for. I'm not going to dish out $$$ for tuning a ECU in a car I'm only going to drive through till spring(have the new car and a 3.2 to put in it).

Anyone help on what the stock injectors are supposedly? I've found mixed results searching. How about higher flowing ones? Any other ideas what might be going on?

Could it be my fuel pressure regulator is bad and pressure is too high? Maybe causing it to run rich at idle and low? Its not leaking through the vacuum. But with out adapters to test the rail for pressure, I don't really have a way to test fuel pressure. I've seen bad ones that don't leak.

Last edited by Dirdy; 12-24-2012 at 11:57 AM.
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post #27 of 46 (permalink) Old 12-24-2012, 11:56 AM Thread Starter
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Okay, cant seem to edit my post right now.

There is no CEL codes for lean or rich. But I do have the infamous "IM DYING" code p0601. Maybe it wouldn't show anymore codes regardless. I'm swapping computers today anyways.
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post #28 of 46 (permalink) Old 12-24-2012, 02:18 PM
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You've added a variable that would be beneficial - that is, the supply voltage, or Vref. It is likely that to get the optimum tuning that you are in the process of determining, to get the upper end TPS voltage, you would need a negative resistance added between the top of the potentiometer and Vref. Since we know there is no such thing as a negative resistor, your jacking up of Vref is the perfect solution. From there, the real value resistors could be determined.

Fortunately I anticipated that when I built the formulas - I made the Vref as one of the variables, so all that would be required would be to pick a Vref voltage that is determined to be high enough, and go from there. That would allow you to raise the idle voltage and the WOT voltage at the same time using the variable resistors at both ends at settings determined from the formulas.

For your experimenting, it would probably be easier to set a fixed voltage for Vref determined to be high enough for a range of possibilities, and put in adjustable resistors on both ends - then dial in the bottom and top end TPS voltages by setting the variable resistors according to the formulas. That way you can quickly experiment with different settings of the two ends simultaneously across all operating conditions - not just trying to optimize bottom, top, and middle in separate test runs. Just a suggestion.


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post #29 of 46 (permalink) Old 12-24-2012, 02:48 PM
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For injectors, I believe the 3.2/5 injectors are bigger and should bolt in.
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post #30 of 46 (permalink) Old 12-24-2012, 04:18 PM Thread Starter
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Now the way I have it currently is raised voltage at idle. The top end(full throttle) is cut down by not letting the throttle open all the way. With it the way it is now, I'm lean on the top end still. With what your saying to be done, I can't make the top voltage any higher for the WOT. I understand what your saying, about getting the low voltage where it needs to be and then the high voltage, but it seems like I already hit a wall with that. I'm lean with a maxed out TPS signal on a throttle body that isn't open all the way yet. Its cut down to about 85-90% now. I think the throttle body is too large. I do have a smaller 60 or 65mm to try out.

If I can't get this done here soon and have it set correctly, I may just put the stock 2.7 intake back on and just tweak the MAP sensor alone. I love the extra low end kick, but the hit in mileage just isn't worth it to me. I was only getting 21-22mpg with the way I ran it for a long time. With just turning the MAP's vref down alone, I'm back to about 26mpg. And thats with winter fuel. Before I tore into the engine I could get 30+.

If it was easy to take the MAP's vref and have it lower on the low throttle and higher on the high throttle, I would do that. I'm just not that knowledgeable to design something like that myself.

If I can do the above, I will fix the TPS voltage how you say. But I need to fix the fuel issue first. Know how to build a variable 5v circuit ran off the TPS signal?
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