ctandc

I just recently swapped in a 5 speed in my 85 IROC. It also had a '87 L98 TPI 350 instead of the factory LB9, so I'm sure the stock PROM in the'870 ECM is confused, but here's a WEIRD one...


When I 1st fired the car up after finishing the 5 speed swap, it idles WAAAY up ( outside temp was like 65 degrees so that wasn't a factor ) and it didn't want to idle down at all. So, being that I was TIRED and obviously NOT THINKING straight, I just turned the idle screw down at the TB... ( I know I know ).


So fast forward, I'm driving it now, and it seems to have trouble idling only after going into closed loop, almost dies at stoplights, surges / hunts etc... ( I'm doing the min AIR and IAC today )....I figured the 5 speed swap had something to so with it at.....


Turns out, the reason it idled up when I 1st fired it up after the swap, was the fact I'd removed the TV cable, since the T5 of course doesn't need it, and the TB lever wasn't "springing" back to closed as there wasn't anything pulling it back like the TV Cable had. I installed a carb return spring to see if it helped, and it did, but the throttle was too stiff etc, but I had it on there for about 5 days of driving, and I took it off last night and it seems fine now, as far as not sticking open.


ANYWAY.....so I got WinAldl running, 10k resistor in place, all data was available ( as much as the 870 gives anyway ) and everything was working...then I clicked on the DASH function in WINALDL so I could use the larger reading of the TPS so I Could make sure it was set right, since the ECM threw a "high TPS voltage" code at one time ( it went out while driving ).

The dash function has a TPS Voltage reading...it was reading -2 volts....NEGATIVE 2 volts at idle.... WTF?!?!!? So I loosened the TPS and tried to adjust it....got it to .7V at closed throttle, and it seemed okay. Then as it idled, the reading would change....WTF???!?! Then I turned off the DASH function and just looked at sensor data, and it was showing .5V for the TPS at closed throttle and all seemed okay while running with more pedal etc......voltages looked fine.

Open the dash function, same WEIRD readings again??!?!?


Anyone have any ideas? I'm resetting the IAC / min AIR today anyway, and I'm swapping in a 165 ECM VERY SOON, but this is still a WEIRD one......


Any ideas?



Thanks

V8Astro Captain

iTrader: (1)

You need to configure WinALDL to your TPS voltage. Don't screw with the TPS itself, now it's all messed up and you need to put it back where it was.

Try running it without the 10k resistor. I know on the 747 you don't need the resistor...all it does is puts it in this stupid ALDL mode, which includes a 1000 rpm idle.

ctandc

HUH?

The 870 ECM is selected w/ TPS voltage being .54V closed throttle 4.5V WOT


If the 870 ( like the 165 ) ECM does NOT have the 10k resistor in between A-B, it don't work...period... ( tried it numerous times )


I had used Winaldl before plenty without this weird problem...




Chris
Can't wait to drop kick the 870 in the next week or so... :P

kevm14

The dash function of WinALDL does NOT show TPS voltage! It shows percentage. And that percentage isn't the same percentage that you'd see on, say, an XP240. It's simply calculated by the following formula (I assume):

(TPSvolts - TPSmin) / (TPSmax - TPSmin)

where
TPSvolts = current TPS voltage
TPSmin = "TPS Voltage for 0%" setting in WinALDL
TPSmax = "TPS Voltage for 100%" setting in WinALDL

Whenever I scan a different car, I always calibrate the TPS % first, so I have a useful reading from the Dash display (I like it, too). Simply turn the key to 'ON,' get a reading of true TPS volts from the Sensor Data tab, then floor the gas to it's buried-in-the-floor position and get that reading. Put these values into the respective areas in WinALDL and bingo - proper TPS percentage. You may find that since WinALDL reports TPS voltage to 2 significant figures, you will have to play with the hundreths position of the "TPS Voltage for 0%" and 100% to get the percent read out to be exactly 0% when it should be (I've also never seen it hit 100%...).

HTH

ctandc

That's weird.......mine reads Volts, not percentage.

Is this because I'm using a 870 ecm?

Like I said, same ECM, same laptop, same Winaldl, only diff was the cable, and I set the TPS by the dash readout......

Hmmm.......I'll look at it closer this weekend.


Thanks for the input

Chris

kevm14

I suppose that's possible...weird, but possible. You're talking about the Dash mode, right?