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Car runs rough with MAF plugged in (a known good MAF)

CAFIFTY

Active member
Joined
Feb 17, 2013
Messages
27
Location
Kzoo, Michigan
I changed the ISC with another one with the same results. I also pinned both out as described on VFAQ and they were both good.

Unfortunately the logger cable i made was a COM style and my new laptop doesn't have that so i am waiting for mine to ship dsmcables.com

But I have since:
replaced the coolant temp sensor. (still surges)
replaced the TPS sensor (still surges)
reaplaced the 02 sensor (still surges)
Swore at car (still surges)

While replacing all this i did notice that unplugged my TPS sensor doesn't seem to affect my car. It runs the same (poorly). Wondering if the wires could be bad. Just looked the wireing diagram up. Going to make sure pin 1 (gr) reads 5v, that pin 4 (gb) is ground and i am assuming pin 2 reads somewhere between 0-5v based on pedal position....


To top things off my ECU decided that it was time for the capacitors to fail. It was the original VR4 one I have a spare but i am not sure what year it came out of. I will be sure to look it up.
 

tektic

Well-known member
Joined
Dec 19, 2012
Messages
1,497
Location
ronkonkoma, ny
Set your isc as per the vfaq. It successfully fixed my idle surge problem

edit: sorry meant biss. Get your scan tool it should tell you in 2 seconds whats out of spec.
 
Last edited:

CAFIFTY

Active member
Joined
Feb 17, 2013
Messages
27
Location
Kzoo, Michigan
ISC can't be set? It can be tested. Or am i not understanding something.

I did set my TPS, BISS, and base timing via the methods listed on VFAQ.COM


I am planning to visually confirm my ISC is cycling like DSMISC shows
 

CAFIFTY

Active member
Joined
Feb 17, 2013
Messages
27
Location
Kzoo, Michigan
If i were to pin out the TPS at the ECU what voltages should i see when at closed throttle and open throttle. I am guessing closed throttle should be close to 0v and open should be around 5v?
 

CAFIFTY

Active member
Joined
Feb 17, 2013
Messages
27
Location
Kzoo, Michigan
Looks like i should have searched first

http://www.ecmtuning.com/wiki/dsmlinktpsadjustment


"The ECU wants to see 0.63v from the TPS sensor when your foot is off the throttle and greater than, say, 4.6v when you're fully on it. You can datalog TPSvolts to see what the ECU is really getting. The value at idle (foot off the throttle) is probably more important than the value at wide open throttle. A value that's too high at idle can prevent the idle switch from activating or it will prevent the “simulate idle switch” functionality from working properly."
 
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