Hey guys,

I have a '93 Del Sol with a boosted D16Z6.

I am having a rough idle problem and cannot pinpoint it.


I have searched and have found nothing to follow what I am going through.

I have checked for vacuum leaks - NONE
I have cleaned the IACV screen, and made sure the power for that and the PCV were not crossed - DONE
I am not throwing any codes, except for code 36, which I am told is JDM VC (w/e that is)

Now, I was tinkering around with it, doing odd stuff here and there to try and figure it out.




If I unplug the MAP sensor while the car was idling, the car would die.

I leave the MAP unplugged and try turning the car over, it doesn't start.

I plug the MAP back in and start the car. Magically the car idles 100% perfect, problem is solved. However, it obviously is throwing a MAP sensor code now (Code 3)

I reset the ECU, leave the MAP plugged in, and start it. It returns to a rough idle (bouncing from 400-1K RPM, sputtering, dies sometimes)

Also, a COUPLE times, the car actually RAN with the MAP sensor disconnected.


What am I dealing with here guys? Faulty MAP sensor?

Car is running boost basemap, trying to get it figured out so it can be tuned. Car used to idle fine, with same basemap, than it sat for a bit.

Any help is appreciated


Thanks guys!

 

You would get a lot better help with this problem by posting in either the Forced Induction or Tuning forums...if you want this thread moved, let me know via PM and I will do that for you...

EDIT: Got your PM and i moved it for ya

 

Thnx!

Ok guys, what you thinking?

Is this a faulty MAP or am I wayyyyy off?

 

I think you should try and new map sensor. wat management system are you running?

 

What map sensor are you using? Is it the stock one? Code 36 is JDM Traction Control I think. Also what computer do you have and what engine management?

 

It is a chipped P28, it has just a turbo basemap. I never had idling issues before it sat for a bit.

It is using the stock MAP sensor.

No Engine Management as of yet.

I'm trying to get this idle resolved so I can bring the car in for a full tune.

Thanks.

 

When it sat for a while how did you try and start it, with Ether? (starting fluid) OR Did you just get in and crank it over? If you used Ether then you probably fouled your plugs so I would check them. Also did you change your injectors out?

 

No starting fluid was used.

The car runs perfect while driving.

It is simply the idle that is rough, surges. But DOESN'T when I did that little MAP sensor thing.

That leads me to believe it is a faulty MAP, but I wanted a second opinion before I went out and got another one.

Thanks.

 

For anyone wondering,

greddy 15g Turbo
450CC DSM injectors

 

OK as I asked above, now you have 450cc DSM's into the mix. Was the "turbo base tune" made to run with those injectors? Also are you running a resistor box?

 

Yes the basemap was for the 450cc injectors.

Because it is a basemap, there is a small overage of fuel to prevent leaning out.

Yes, it has an EF resistor box.

Like I said, the car used to idle perfectly fine, with everything the same on it now, that was previous.

I am leaning towards the MAP because of the troubleshooting I did in my first post.

Again, everything on the car now, is the same as it was when the car idled fine.

Thanks again :D

 

Perhaps the small amount of fuel overage caused the MAP tof ail? IS that possible? I"m not a guru when it comes to sensors lol.

 

No that would not cause a map sensor to go bad. Either way I would still pull your plugs and see if they are fouled, something as simple as that could cause your car to have your descibed symptoms. If all else fails replace the MAP then go from there.

 

fouled plugs will cause idle surge?

Even when the MAP is disconnected and throwing a code, it runs perfect. no hesitation, no sputtering, runs perfect.

I await you reply to that, than I will go forth.

Thanks.

 

check the TPS voltage at idle should be around .5 volts no higher than .65V

 

im having a problem wit my car too a friend is telling me its my MAP causing... in the middle of a drive my check engine light sometimes comes on andif i hit an incline the car starts to die down i down shift but nothing its like the cars not getting enough fuel or something could that be cause by the MAP?...any thoughts?

 

TPS reads 0.48V @ idle.

 

hows the valve clearance?

 

Everything mechanical is PERFECT.

The car ran GREAT, than it was parked, and nothing was touched on it.

now it idles rough.

I put a diff MAP sensor on it today, and it idled GREAT for about 10minutes, than the rough idle returned.

I know it's running rich, cause of the basemap, but is it possible to foul a MAP sensor? that quickly?

 

K fixed it.

Turns out, whoever put the TB on the car, used RTV, and plugged the MAP passage on the TB, that made it better.

Also running to rich caused the ECU to try and correct it, but it catn cause the amount of fuel.