ccguy;1894685 said:
That feeling would be wrong. Try again. And stop focusing on resistance. The ECU doesn't deal in it.
help stumble 7mgte!!!
- Thread starter ccguy
- Start date
That feeling would be wrong. Try again. And stop focusing on resistance. The ECU doesn't deal in it.
Did you monitor your Vf signal yet, just to see what the ecu is doing? http://www.well.com/user/mosk/Vfsignal.htm
Did you temporarily disconnect the O2 sensor, just to see if there is a difference in how your engine runs?
Did you temporarily disconnect the AFM, just to see if there is a difference in how your engine runs?
When checking for faulty sensors there's a rule of thumb when you temporarily disconnect a sensor and nothing changes in your engine behavior, most of the time the sensor has gone bad.
Be sure to understand what sensor you are disconnecting and what behavior to expect before doing that.
Did you temporarily disconnect the O2 sensor, just to see if there is a difference in how your engine runs?
Did you temporarily disconnect the AFM, just to see if there is a difference in how your engine runs?
When checking for faulty sensors there's a rule of thumb when you temporarily disconnect a sensor and nothing changes in your engine behavior, most of the time the sensor has gone bad.
Be sure to understand what sensor you are disconnecting and what behavior to expect before doing that.
ok the voltage going to the ecu from the hac is 3.04.
does that sound about right for 6500 ft elevation (if anyone knows)?
that is some good info and i will give it a shot tomorrow.
there is NO difference if i unplug the O2 sensor. nothing.....?
if i unplug the tps or the afm it wont run for crap.
here is a video driving. notice at the end where it accels when i barely have the throttle cracked.....could that be my iacv sucking in air past the tb?
when i say it "bucks" it feels like as if you would pop the clutch or wot then let off. feels like it is going to break a u joint or motor mount
http://www.youtube.com/watch?v=eDLr4Hk-zXU&feature=youtu.be
also i was thinking about the hac. as the altitude gets higher it tells the ecu there is less o2 so it reduces the amount of fuel sprayed (right?) so in theory if it is a lean fuel issue pluggin in the hac would farther confirm that due to it cutting the amount to be sprayed.
hopefully the fuel pressure gauge will get here within the next 2 days.
with the pressure gauge could i put it on before the fuel rail? basically just before the dampener or should i try it on the rail like off of the cold start inj?
i will probably try both just to see how it fluctuates
does that sound about right for 6500 ft elevation (if anyone knows)?
that is some good info and i will give it a shot tomorrow.
there is NO difference if i unplug the O2 sensor. nothing.....?
if i unplug the tps or the afm it wont run for crap.
here is a video driving. notice at the end where it accels when i barely have the throttle cracked.....could that be my iacv sucking in air past the tb?
when i say it "bucks" it feels like as if you would pop the clutch or wot then let off. feels like it is going to break a u joint or motor mount
http://www.youtube.com/watch?v=eDLr4Hk-zXU&feature=youtu.be
also i was thinking about the hac. as the altitude gets higher it tells the ecu there is less o2 so it reduces the amount of fuel sprayed (right?) so in theory if it is a lean fuel issue pluggin in the hac would farther confirm that due to it cutting the amount to be sprayed.
hopefully the fuel pressure gauge will get here within the next 2 days.
with the pressure gauge could i put it on before the fuel rail? basically just before the dampener or should i try it on the rail like off of the cold start inj?
i will probably try both just to see how it fluctuates
Did'nt the vf signal change after unplugging the o2?
Leave the hac alone, it's not your (main) problem.
I believe pressure can be read before the fuel rail and if so, the fpd spot will work but don't quote me on this.
An enginerauto-revving at idle is indeed a vacuum leak somewhere. In addition to your iscv,check your throttlebody gasket.
Leave the hac alone, it's not your (main) problem.
I believe pressure can be read before the fuel rail and if so, the fpd spot will work but don't quote me on this.
An enginerauto-revving at idle is indeed a vacuum leak somewhere. In addition to your iscv,check your throttlebody gasket.
>>the voltage going to the ecu from the hac is 3.04. does that sound about right for 6500 ft elevation<<
As per the manual (you have one right?) it should be 3.6 vdc @ 750 torr, 2.8 vdc @ 540 torr, and 1.2 vdc @150 torr.
Torr is mmhg with 0 msl being 760.
As per the manual (you have one right?) it should be 3.6 vdc @ 750 torr, 2.8 vdc @ 540 torr, and 1.2 vdc @150 torr.
Torr is mmhg with 0 msl being 760.
i dont have a revving idle. and vacuum is around 16-18 at idle.
only manual i have is a haynes and the turboninjas online fsm for a 87.
so 750 torr = 750 mm hg.
750 mm hg = roughly 358 ft elevation = 3.6v
540 mm hg = roughly 9150 ft ele = 2.8v
so 6500 ft ele = 620.5 mmhg = ~3.1059 v
i wish i could find someone with a turbo mk3 here in my town of 30,000 but i have not seen one yet. would be nice to swap parts and scratch heads together....you guys are doing a great job helping me and i do appreciate all of the wisdom. thanks.
i ran out of time today to do the vf tests on that link but they will be a job for tomorrow.
i installed a fuel pressure gauge. with just the walbro running at idle the fuel pressure before the dampener is crazy bouncy like 32-36. with both of the pumps running at idle (walbro and in-tank pump) the constant pressure is 38 psi. and it goes up to 42 ish with higher rpms.
with just the intank pump running the pressure is constant 34 psi and up to 40 when revved.
only manual i have is a haynes and the turboninjas online fsm for a 87.
so 750 torr = 750 mm hg.
750 mm hg = roughly 358 ft elevation = 3.6v
540 mm hg = roughly 9150 ft ele = 2.8v
so 6500 ft ele = 620.5 mmhg = ~3.1059 v
i wish i could find someone with a turbo mk3 here in my town of 30,000 but i have not seen one yet. would be nice to swap parts and scratch heads together....you guys are doing a great job helping me and i do appreciate all of the wisdom. thanks.
i ran out of time today to do the vf tests on that link but they will be a job for tomorrow.
i installed a fuel pressure gauge. with just the walbro running at idle the fuel pressure before the dampener is crazy bouncy like 32-36. with both of the pumps running at idle (walbro and in-tank pump) the constant pressure is 38 psi. and it goes up to 42 ish with higher rpms.
with just the intank pump running the pressure is constant 34 psi and up to 40 when revved.
32 to 34 psi @ idle is stock.
Be sure to use a gauge that's filled with liquid so the needle moves smoothly.
it's normal for the psi to rise when you rev the car.
Be sure to use a gauge that's filled with liquid so the needle moves smoothly.
it's normal for the psi to rise when you rev the car.
waiting for new coil packs....if they ever come in, they were to be here today so i dont know.
here r some videos of drive by's. when it bucks in the first video i am holding the petal steady. when it hesitates it does that with the petal steady and if i push down it is just like n the video of reving it by hand and it not going above the hesitation.
http://www.youtube.com/watch?v=RAVWI79i0Ak&feature=youtu.be
http://www.youtube.com/watch?v=XaZRQyf-lpQ&feature=plcp
when it is stumbling the petal is steady and on the drive back by the petal is steady and it just comes out of the stumble and accells fine.
here r some videos of drive by's. when it bucks in the first video i am holding the petal steady. when it hesitates it does that with the petal steady and if i push down it is just like n the video of reving it by hand and it not going above the hesitation.
http://www.youtube.com/watch?v=RAVWI79i0Ak&feature=youtu.be
http://www.youtube.com/watch?v=XaZRQyf-lpQ&feature=plcp
when it is stumbling the petal is steady and on the drive back by the petal is steady and it just comes out of the stumble and accells fine.
Did you also check you spark plugs?
A crack in the ceramic part can also cause hesitation of your engine.
A crack in the ceramic part can also cause hesitation of your engine.
coil packs made it a little better but still heavy stumble.
if the ground going from the metal coil pack bracket is not hooked up it runs just the same. then if i ground it, it still acts the same. i think i remember reading if it does not have a good ground it will not run right. so what am i missing????
if the ground going from the metal coil pack bracket is not hooked up it runs just the same. then if i ground it, it still acts the same. i think i remember reading if it does not have a good ground it will not run right. so what am i missing????
i installed a 20 ohm resistor and used a 25 ohm rheostat to make the voltage divider so i could adjust the volts going to the ecu from the hac sensor plug.
the idle changes as i change the volts from 2.8 to 3.8.
seems that when i turn it towards 2.8v the stumble is worse and when i turn it up towards 3.8 it is less noticiable but still there.
SO i am thinking it is something to do with the fuel injection for sure.
the tps readings at the ecu plugs (with it unplugged) are out of spec when the hac is plugged in and when the hac is unplugged it is perfect as it is at the tps.
so ......... and it runs better without the hac plugged in.
i have swapped out the tps and reset it in the past with a new one form az. it acts the same if i use either of the 2 tps sensors i have.
the idle changes as i change the volts from 2.8 to 3.8.
seems that when i turn it towards 2.8v the stumble is worse and when i turn it up towards 3.8 it is less noticiable but still there.
SO i am thinking it is something to do with the fuel injection for sure.
the tps readings at the ecu plugs (with it unplugged) are out of spec when the hac is plugged in and when the hac is unplugged it is perfect as it is at the tps.
so ......... and it runs better without the hac plugged in.
i have swapped out the tps and reset it in the past with a new one form az. it acts the same if i use either of the 2 tps sensors i have.
The HAC just trims the AFM signal, nothing more. By increasing the voltage you are simulating a lower altitude, which adds fuel, but since idle should be in closed loop it will just get trimmed out by the fuel trim control logic.
In post #22 you were asked about VF and also if your O2 is cross counting. Now that you've finished wasting your time replacing the coil packs and HAC sensor, you can get back to troubleshooting the problem. Let us know your results from the tests outlined in post #22.
In post #22 you were asked about VF and also if your O2 is cross counting. Now that you've finished wasting your time replacing the coil packs and HAC sensor, you can get back to troubleshooting the problem. Let us know your results from the tests outlined in post #22.
-ok so i just checked the tps at the ecu with it running.
-vta at idle is .48 volts
-the stumble starts at .74 volts. (also at 2500 rpm)
-once the stumble starts if i press down on the petal it increases in volts to the ecu up to ~3.7v.
-so i am back to thinking it is a boost/egr/vac leak or something like that.
when the throttle is depressed past the .74 v quickly to say 1.2v it revs up like no problem or stumble.
then when the rpms are still up if i rev it again it will rev like a normal engine. i can hear the bov once i let off of the petal and the throttle body is closed.
i plugged in my spare cps and pulled the fuel pump fuse. turned the ign on and put a spark plug in the end of the #1 plug wire and grounded it to the body. as i turned the spare cps gear the plug would spark the same time the injector would click/fire. so i know my wiring and ecu are seeing the cps signal and telling the injectors to fire and the coil as well.....
________
-vta at idle is .48 volts
-the stumble starts at .74 volts. (also at 2500 rpm)
-once the stumble starts if i press down on the petal it increases in volts to the ecu up to ~3.7v.
-so i am back to thinking it is a boost/egr/vac leak or something like that.
when the throttle is depressed past the .74 v quickly to say 1.2v it revs up like no problem or stumble.
then when the rpms are still up if i rev it again it will rev like a normal engine. i can hear the bov once i let off of the petal and the throttle body is closed.
i plugged in my spare cps and pulled the fuel pump fuse. turned the ign on and put a spark plug in the end of the #1 plug wire and grounded it to the body. as i turned the spare cps gear the plug would spark the same time the injector would click/fire. so i know my wiring and ecu are seeing the cps signal and telling the injectors to fire and the coil as well.....
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Excessive "anal"-lyzing without an understanding of how something actually works is an equation for frustration. I'd take the thing to a competent mechanic if I were you.
i would rather waste time than money.
learning how things work through gaining knowledge and info through experimentation and form written documents and otherspersons is how you figure things out....just as all of the mechanics and all professionals ever became who and what they are.
thanks.
learning how things work through gaining knowledge and info through experimentation and form written documents and otherspersons is how you figure things out....just as all of the mechanics and all professionals ever became who and what they are.
thanks.