I was running an Accel 300+ ignition box on my car but it crapped out on me, don't get them they suck. Anyway when I had the box on there it would usually idle somewhere around 600-700. But without the box once it goes into closed loop the car tries to idle below 500 and almost stalls and then kicks up before trying to drop down again to 600, 550, 500, then it repeats, its not a loping idle like a vac leak or EGR, the ECM really is trying to idle it that low. Any ideas? All ignition components are MSD and have been on there for about a year. The plugs are TorqueMaster plugs, if you don't have them, get them, they are great. http://www.TorqueMaster.com

Thanks.

 

ignition module good?? idle air control sensor?? throttle sensor --forgot what its called, ...black thing on the pass side of the tbi, 3 wire circular harness is connected to it....other than that maybe a fuel filter.....check your timing as well, and the ecm for trouble codes....then report back

 

Well I replaced the cap and rotor, they were way worn, oops. That made the idle alot smoother but still really low. My track time was with the new ones on there. There aren't any codes in the computer, so that rules out anything sensor related. The ignition module is in fine shape, still looks as new as when I put it in there last year. Fuel filter is also new. I'm stumped. Best I can figure my ECM is just getting lazy and doesn't feel like idling very high right now.

 

did you search the ecm for stored codes??? try resetting the computer by disconnecting the batt for 1-2 mins ,then try, ....it MAY be your throttle position sensor gone bad, ...its could seriously be alot of thing, ..MAP sensor, idle air control sensor, Engine temp sensor --driver side on the head between #1 and #3 plugs--- a wire? a plug? pull the plugs, check em, even if you think or even KNOW they are good, ....hate to see ya replace 100 bucks worth of stuff and it be a plug. after that, check the fuel pressure, ...check for vacuume leak, any unplugged wire harness, COULD be a o2 sensor now that i think about it. but start at the plugs ,.....does the car run real rough?? or just idle real low? check the plugs for a good spark by unplugging the injectors, take a plug out, lean it againts a good ground with the plug wire attatchd to the plug, and hav someone turn th engine over a couple times....any more questions, just ask, ill be here and have gone through many problems like this before...


sean

 

Tada

Despite the appearance of the ignition module it is indeed bad. I was driving today and a code 42 showed up, which is the module. I wont be able to replace it until probably Sunday, I've gotta work so I hope it'll hold out until then. Thanks for your help.

 

lucky.... my car idles at 1100-1300... well I think so... I'm pretty sure that my tach is off ... it says 3500 at 75 MPH with 3.08 gears, ANY IDEAS GUYS

 

A trick for checking the accuracy of the tach/speedo is this:

If you are going 70 in your 1:1 gear then the RPMS will be your rear gear ratio, ex:

70MPH = 3230RPMs then you have 3.23 gears and everything is accurate.

For your case you'd be looking for 3080RPMs at 70MPH. Our tachs are electronic reading off the ignition system, so if the tach is off in its readings something is shorted out or crossed in the (seemingly) miles of wire that run from the distributor to the ECM and to the tach. Or the tach itself is bad, I'm not the ignition system expert so I hope that that at least gives you something to go off of.

 

lucky , i cant figure out why my car is backfiring like a shot gun on decelleration..ive checked it alllllllll

 

lucky , i cant figure out why my car is backfiring like a shot gun on decelleration..ive checked it alllllllll

 

Maybe something in the injectors is leaking fuel? I'm really reaching here but if you are off the gas and there is too much fuel going into the motor then unburnt fuel will hit the hot cat/other exhaust parts and explode causing backfiring?

 

I wouldn't go as far as saying the ecm is trying to idle down so low. That initial "stall saver" is built into the ecm code.
Too much timing will have the ecm stumble when in gear (if an auto). It'll be able to chug a while in a gear but it'll stumble and almost stall. How long does it take the car to idle down and does it take about the same time for it to stumble from a normal idle down low as it does when it recovers? A TPS adjustment might be in order.
Does it do this happen when in park/neutral or just when in gear?