Idling weird, cutting out, dying

Ok, so my car idles all normal and then out of noware just cuts out and dies, did it about 3 times tonight, i was under the hood watching my fuel pressure, and as it was dying the fuel presssure was going up!(less vaciuum press up) because i though it was my fuel pump cutting out. Now i thing it's my ISC it usually doesnt just cut out, only when i come off high rpm and let off it dies, and only when its hot, this time it was cold and did it just sitting there. What do you all think? is it the ISC?
thanks
John

 

Not much help here, because mine is also doing a strange idle. after the car is warm, it will idle steady at 850 and then after less than a minute, the idle will seem to cut out and try to catch itself at about 5 or 600 rpm and then stumble a few more times, sometimes dying. If I give it a little gas for a few seconds, it goes back to great 850 idle. I have recently added AFC and Blaha MAF w/o flapper and run 800rpm band a bit rich to compensate...?
Caps were replaced sometime ago and will be doing fuel filter hopefully this weekend.

 

you didn't mention your ECU capacitors, but replacing them is a given if not yet done.I think there are 4 windings in the ISC, which means an inconsistent fault condition can certainly occur if 1 winding is failing. Its easy to remove the ISC & measure winding resistance. The manual has the specs, if 1 winding is off or infinite resistance, then you know for sure. There's a big o-ring where the ISC mates into the throttle body, be careful that it doesn't fall out.Don't overlook a pressure test on the intake tract. There's a million places where leaks can occur, & in my experience the car is extremely sensitive to uncounted air getting in. Although, a vac leak that causes it to idle fine then just die seems unusual.

 

Well, on mine, I have a logger and can display the ISC counts, but don't know how to interpret that data or if it's useful (not sure if: the ECU sends the signal to the ISC and logger counts this regardless of whether ISC is operating correctly)As mentioned in mine: caps were replaced long time ago, recently - plugs and wires.I'm pretty sure my ISC is and has been worthless for sometime. Since the summer before last it has not pulled the rpms up with a/c on etc, BUT still never manifested this idle issue.Sorry for the hijack Khadiyev. Hoping something comes up to help us both off topic/ Mr Ed - start the cyclone project yet?

 

Those counts are probably how many steps the ISC has been instructed to take, & I bet they're counted even if the motor isn't responding. I think a step is 1/4 or maybe 1/2 turn of the pintle on the threaded doo-dad.When my ISC died it was apparently at a non-idle position. I suppose if it dies while at a different position you might not stall but you have no air-bypass adjustment as the engine warms up.I can email the relevent manual pages for testing the ISC out of the car if you want. I think I once read about someone rebuilding an ISC by re-winding a bad coil.A leak test won't hurt- my car "came" without the ISC o-ring (former owner=moron) hell I drove for 2 years with that massive TB leak before doing a pressure test. Original throttle plate shaft seals are leaking now, there's VFAQs with info on sourcing the seals.The cyclone will have to wait until warm weather next spring, but I'm psyched! Cheers, -Ed

 

Now I feel I have completely hijacked the thread sorry...
I've had my ISC's out before and swapped it with the wifes (when her's still worked and kicked the idle up for the a/c) and still didn't show any improvement. Tried to test it per the manual...wasn't showing anything negative and gave up. Adjusted the BISS in the summer to not let it die when AC kicked on.
The ISC doesn't control cold idle speed does it? (my cold idle is fine)

 

O my god, Thats a trip. I have the same problem and I have been on a never ending journey to fix by bad idle. I have the exact problem as GVR1643. Some people told me its a vac leak, others told me its the vented BOV, I have tried all of that, and sum.I have done almost all the VFAQ on bad idle,excet the test on the ISC. Mine gets realy bad when its at night time, and I turn on my lights. I dont care about power anymore I just want decent idle. I am out of ideas guys. Whats left

 

[ken inn]

if it happens when you turn on the lights, try stepping on the brakes, too. if that makes it worse, it sounds like your electrical system is marginal. maybe alternator, or battery. get a load test done on the charging system, and clean the terminals real good.

 

vacuum leak sounds like the problem. I had a car that ran fine during start up then after it warmed up, the idle would be around 400-600 rpms and would stall sometimes. A smog tech should be able to diagnose if there is a vacuum leak. Bring the car to a smog check repair facility. The smog guy fixed the vacuum leak and replaced the egr solinoid. A little history of this car. I had no clue what was wrong with the car. It had new distributor, rotor, timing belt, water pump, both axles, new exhaust gaskets, new intake gaskets, air filter, timing adjusted, valve adjusted, new valve cover gasket, new air filter, new fuel filter, new head gasket, new alternator belt, new power steering belt, new oem spec spark plugs, O2 sensor, new thermostat and used housing. So with all this replaced I could not figure out the reason it idled bad.late
need a vr4...

 

[ken inn]

quote:Originally posted by Damn, I need a VR4:
vacuum leak sounds like the problem. I had a car that ran fine during start up then after it warmed up, the idle would be around 400-600 rpms and would stall sometimes. A smog tech should be able to diagnose if there is a vacuum leak. Bring the car to a smog check repair facility. The smog guy fixed the vacuum leak and replaced the egr solinoid. A little history of this car. I had no clue what was wrong with the car. It had new distributor, rotor, timing belt, water pump, both axles, new exhaust gaskets, new intake gaskets, air filter, timing adjusted, valve adjusted, new valve cover gasket, new air filter, new fuel filter, new head gasket, new alternator belt, new power steering belt, new oem spec spark plugs, O2 sensor, new thermostat and used housing. So with all this replaced I could not figure out the reason it idled bad.late
need a vr4...if you have a distributor, you dont have a vr4

 

If you have a vacuum leak, it would most likely idle poorly all the time. Always pressure check your intake system. Chances are, you have small leaks anyway. That will eliminate a bunch of variables.I would second Ken's assessment of a basic charging/electrical issue. Usually the car will stall when you apply the brakes while approaching a stop light. Also, you may notice your headlights dip in brightness with your turn signals or when you apply the brakes.

 

Ok, I found out that the pump i have is the buschur style, 160lph/43psi. Do you all think that's enough for a 400whp aplication?
thanksJohn

 

quote:Originally posted by ken inn
if you have a distributor, you dont have a vr4so galants vr4 are DIS?

 

[ken inn]

yes and no. there is a cam angle sensor, it sits behind the intake cam, and is used to set base timing. actual timing and idle speed is controlled by the ecu.

 

quote:Originally posted by ken inn
yes and no. there is a cam angle sensor, it sits behind the intake cam, and is used to set base timing. actual timing and idle speed is controlled by the ecu Its a distributorless ignition system (DIS).With my story I forgot to mention the solution to the weird idle was due to a vacuum leak.

 

[ken inn]

DIS also can be direct ignition system. which is what is used on german cars, and now is known as digital motor electronics, or motronic. to me, a dis system is one that you CANNOT adjust base timing, which you can on the vr4.

 

Khadiyev,
that doesn't sound like enough of a pump, but I'm not 100%. There's got to be a formula for figuring this, but I wouldn't know it... I think I'll be going with a 190lph pump with a target of 300whp at stock fuel pressure.On the Vac leaks...would a vac leak really let it idle rock solid at 850 for 20-30 seconds and then drop? I'm guessing fuel or ignition. I replaced the fuel filter this w/e in hopes of bring my a/f up some to no avail. Next is rewire and/or bigger pump.

 

Thanks, that's what I was thinking, I bought a Walbro 255lph (high pressure) for $129 from Slow Boy racing yesterday.
Hope that helps.John

 

Using an estimated BSFC of .55, you would need to burn about 140 liters/hr of fuel. Part of the equation has to be what your base fuel pressure will be and how many pounds of boost you will run, because the pumps flow less at higher pressures. At 58 psi, the Walbro 190 only flows about 130 lph at 58 psi (38 base + 20 lbs boost). With a rewire, the Denso 165 upgrade will flow about 170 lph at 58 psi.
This leads me to believe that the Walbro 190 is only good up to about 370 HP at .55 BSFC. You are REAL safe with the Walbro 255 or Denso Supra pump.
Jeff O.
#1886/2000

 

quote:Originally posted by ken inn
DIS also can be direct ignition system. which is what is used on german cars, and now is known as digital motor electronics, or motronic. to me, a dis system is one that you CANNOT adjust base timing, which you can on the vr4. Ahh yes, DIS system is where you cannot adjust timing. There are a lot of cars out that are DIS and its relatively old technology, just like AWD but its up in the hype for consumers. How would I be able to adjust base timing for the vr-4 with no distributor? Pictures would help. Need a vr-4