crappy starts...

MX-3 Money · Post by **MX-3 Money** » October 13th, 2005, 5:34 pm

Every time I start up my car after it has been sitting for a couple hours the starts are really bad. Sometime it stalls and i have to restart. But always the rpms are around 200 or so...very low. Then after about 30 seconds everything goes back to normal and i don't have any problems. Any ideas?

jschrauwen · Post by **jschrauwen** » October 13th, 2005, 6:30 pm

Try checking the resistance value of the ISC. It's the small cylindrical unit at the bottom of the TB. It's purpose is to sense the temp of the coolant that resides in the bottom half of the TB. Based on that temp it accordingly assists in the step up of the idle until normal engine temps are approached and gradually lessens the idle to the normal 700rpm. Resistance values should be 10.7 to 12.3 ohms @ 20c. Mine's toast as it's at 12.6 ohms so I just disconnected it but now on initial start up I don't get the high idle kick down but rather a very low idle until she's warmed up a bit. Hope this helps Brad.
*John*

dewthis · Post by **dewthis** » October 13th, 2005, 7:41 pm

Maybe a FPR issue. Do you get in and turn the key all the way to start?
Try turning the key to the "on" position and give the fuel pump a minute to prime the fuel system. This is a common problem after swapping the stock FPR for a after market unit.

MX-3 Money · Post by **MX-3 Money** » October 13th, 2005, 8:43 pm

John I tried unplugging it and the engine would just die, maybe I have the wrong thing. If you remember I have been having a high idle problem for awhile so maybe mines toast too. Now I'm not very good with electrical things but how do you measure that resistance. I know its with the muti meter, but where do you stick the 2 plugs to measure it. I know I know, newb question....but i've never been told or shown lol. Please don't judge me lol.

MX-3 Money · Post by **MX-3 Money** » October 15th, 2005, 3:10 pm

tried leaving the key in the on postion to let the system prime itself and still the same thing happens.

mitmaks · Post by **mitmaks** » October 15th, 2005, 3:51 pm

vacuum leak somewhere?

em-ex-3 · Post by **em-ex-3** » October 15th, 2005, 4:16 pm

Have your spark plugs been replaced recently?

MX-3 Money · Post by **MX-3 Money** » October 15th, 2005, 5:47 pm

I can't find a leak, and I put new plugs in a couple months ago.

hgallegos915 · Post by **hgallegos915** » October 15th, 2005, 6:18 pm

do this...first open up your idle screw... and screw that valve under the tb.. disconnect it... as a temo fix you can control your idle via the screw WITHOUT that valve. Thje exact same thing happened to me. Got crappy idle at starts excepot i would get high idle, i dosconnected that valve and it dies on me..but i pened up the idle screw alot, and now car idles fine. That valve is useless in my setup. Everyone says its necesarry but i just drove over 200 mines without it and no effect on gas mileage whatsoever. Ill replace it later on.. what it will do is if you turn on your ac your car may die if you set your idle at around 700. I got this oinformation from probetalk and mx6.com and well i confirmed it myself. Our set ups may be different..i got a kfze and a kf ecu. Im sure fi you chujeck codes you will get that valve code.

jschrauwen · Post by **jschrauwen** » October 15th, 2005, 8:33 pm

MX-3 Money wrote:John I tried unplugging it and the engine would just die, maybe I have the wrong thing. If you remember I have been having a high idle problem for awhile so maybe mines toast too. Now I'm not very good with electrical things but how do you measure that resistance. I know its with the muti meter, but where do you stick the 2 plugs to measure it. I know I know, newb question....but i've never been told or shown lol. Please don't judge me lol.

Hey no worries Brad. Like you I had high idle issues which I believe the ISC was a partial contributer. It's understandable that the idle may drop but not to a point of stalling. The ISC is a 2 wire connector. Just connect your multimeter to both pins on the ISC and set meter to resistance (ohms). That's it!!! Let us know what reading you get. Re-start problems could also be attributed to the PRC solenoid not being hooked up correctly. There is a current thread running right now dealing with that with pics. I've made a few posts in that thread so give that a try too. G/L Brad.
*John*

MX-3 Money · Post by **MX-3 Money** » October 15th, 2005, 9:56 pm

PRC? where abouts in that post?

hgallegos915 · Post by **hgallegos915** » October 15th, 2005, 10:55 pm

trust me man, unplug that white connector under the throttle body and set the idle screw to idle higher, its only used for cold starts. I confirmed it right now i went to start the car and it dies but i started again and left pedal depressed just a bit and it idled..immediatelly it was able to idle at 8k rpm. My idle is steady and soft, acceleration and fuel consumption was not affected. Ignore that orc solenoid.

jschrauwen · Post by **jschrauwen** » October 16th, 2005, 1:40 am

MX-3 Money wrote:PRC? where abouts in that post?

http://www.mx-3.com/phpbb2/viewtopic.php?t=46138

Here's what's in that post that may be of benefit.

That item attached to the side of the airbox with 2 vaccum lines is the PRC Solenoid. Basically a solenoid used in conjunction with the fuel pressure regulator that assists in hot re-starts by enriching the mixture for a set short period of time. There's a 2 wire connector IIRC that goes to this unit the traces back to the same wire bundle as the VAF. This is controlled by the ECU which will tell itif the engine is hot or not and will according allow or stop the vaccum that's connected to it from reaching the fuel pressure regulator. Like I said this is regulated by the ECU to last for a short duration (120 seconds) on warm engine re-starts. FWIW, it may have been better that Mazda called it the FPR Solenoid rather than the PRC (Pressure Regulator Control) Solenoid. Shop manual jargon can sometimes be confusing. Hope this helps Brad.

MX-3 Money · Post by **MX-3 Money** » October 16th, 2005, 4:14 pm

oh now i know what you mean, and I don't have that anymore. Took it off when I put on my cai. I asked and someone on here said its useless, so i just took it off.

hgallegos915 · Post by **hgallegos915** » October 16th, 2005, 9:00 pm

it is useless... disconnect that valve unde rthrottle body and adjust idle..TRUST ME