lee101315

Installed a M-tune today, everything was better. My start ups were no longer super rich, and it idled far better than it ever did with the Mafterburner kit.

The idle is a bit high to start, 1100 rpm with the throttle adjustment and idle speed screw fully closed. No big deal I thought.

I drove it around and enjoyed a much smoother response. A few minutes later, I shift into neutral for a stop light, and my idle is 4000 rpm. I shut the engine down, started it in gear, and drove back to the garage.

I pulled the idle speed hose off of the inter cooler hose and tried running the engine with it plugged the hose up to see if maybe the idle speed valve was causing the problem, but it isn't.

Anyone else have this issue?

refresh951

I have not seen this issue with the MTune. Can you get to 4K with a throttle plate fully closed and the ISV plugged? Could it be a sticking throttle plate?

lee101315

The throttle doesn't seem to be sticking, everything moves fluidly without sticking, and I recently rebuilt it. Actually, everything in the engine is kinda new. The engine has less than 1500 miles on it, everything that is rubber has been replaced, and I replaced every wire possible in the wiring harness using Lindsey Racings kits.

I loosened the throttle adjustment, but there was only a 1/4 turn of pressure on the throttle plate.

It seems to idle at 1100 when the engine is cold, and after a few minutes of driving, the idle shoots way up there.

I'll pressure check the intake system again to see if any hoses came loose...

944s just love to stay broken...

gruhsy

I've got some funky idle issues also. My car is also hitting overboost protection between 5-9psi.

Double checked my idle as per procedure. No real change. Still need to do some more troubleshooting.

I also swapped from the mafterburner.

Rogue_Ant

So, with the ISV plugged, your engine is idling at 4k...? The only way this is possible is if air is getting into the engine past the (assumingly) closed throttlebody...

If your throttlebody is truly closed, then you have a vacuum leak - and it must be a pretty big one.

Rogue_Ant

Generally this indicates that the DME is not getting a good MAP sensor signal. So, it will try to keep the car from getting into much boost.
Need to verify the MAP sensor signal is good (you also removed the resistor in the DME, correct?).

gruhsy

resistor removed 5volts on red wire. borrowing a better fluke today from work. I may have a vac leak on my intake banjo fitting in the intake. Gotta do some more checking

Definitely impressed with the off boost response and the fact I can back out of the garage right after firing it up. I could not do that before until warm.

Tiger03447

Since it occurs after the engine warms up, you might want to check the temp sensor that runs to the DME..Just sayin'

gruhsy

(edit) re-reading the wires do not tie in together they are just bundled together.

I think I found an issue with DME pin 28

I have the lindsey racing Idle stabilizer harness.

I'm guessing you have this also.

I found my instructions for this harness.

DME pin # 13 yellow, DME pin # 28 brown and DME pin # 5 brown all tie in together on the LR harness.

If this is an issue how can we change this?

stock wiring is:
#5 is reference sender grounding
#13 is NTC II (water)
# 28 is ground

map sensor red wire is around 5 Volts
map sensor green wire is 0.126 Volts
Using a Fluke 79III multimeter from work which is properly calibrated...as in used on equipment that needs very high accuracy

mtnman82

So in STOCK configuration, coming out from the DME pin 28 there SHOULD be a wire going to ground.

To install the MAP sensor, you cut this wire to ground leaving two ends - one to ground and the other to DME pin 28 (along with cutting the resistor in the DME). You need to connect the output from the MAP sensor to the wire end going to DME pin 28 (pin 28 was an unused A/D converter channel Rogue is now taking advantage of). The MAP sensor also needs power and ground so Rogue suggests tapping into (don't cut, splice into) DME pin 9 for +12v and then using the 'other' end of the wire you cut (non-DME end, which goes to engine ground) for the sensor ground.

http://roguetuning.com/map_sensor_installation

When all is working properly, idle will be on the high side without using the tuner to adjust (waiting patiently for my tuner package to do just that, amongst some other adjustments).

gruhsy

For me I've installed everything as per Rogue's and LR instructions.

lee101315

Somehow the throttle adjustment screw worked its way down a bit during the test drive ( I left the nut loose a few turns while setting the idle and didnt think it would move during the test drive )

Man, I feel dumb. But the car is running excellent! No more rich idle, poor cold starts, or any more hesitation. I'd highly recommend this to everyone.

Rogue_Ant

Glad to hear you found the issue!