ok...narrowed down the rpm drop problem

00VERT GT

00VERT GT

New Member
Jun 30, 2003
376
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0
SW Florida
#1
My rpm for the past year have been dropping really low when i put the car in drive or coem to a stop light and a few times the car has stalled. I have replaced IAC and cleaned MAF. This morning it died again while in reverse, BUT i noticed that i was rolling down the windows at the same time i was in rev and it killed the car. So i did it again, rolled down windows and put car in rev and foot on the brake....bam dead. So what is it? Battery going? Alternator going? Something is drawing power or something isn't gettgin enough power and the car is dying.

EDIT: nevermind it is doing all the time now again for no reason. good times.
 

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#3
00VERT GT said:
My rpm for the past year have been dropping really low when i put the car in drive or coem to a stop light and a few times the car has stalled. I have replaced IAC and cleaned MAF. This morning it died again while in reverse, BUT i noticed that i was rolling down the windows at the same time i was in rev and it killed the car. So i did it again, rolled down windows and put car in rev and foot on the brake....bam dead. So what is it? Battery going? Alternator going? Something is drawing power or something isn't gettgin enough power and the car is dying.
Click to expand...

I have a 5 speed and mine does something very similar especially when it's first been started and hasn't been warmed up all the way, but it does it after it's been warmed up sometimes. When I'm coming to a stop and I am on the brakes good or trying to stop while going down a hill, i.e. giving decent pedal pressure it bogs down real low, and if I am trying to roll down the windows, or the heater fan is on or the radio is up at all, it trys to stall or does stall on me. I bumped my idle screw on the throttle body up a little and it has helped alot, but it still does it sometimes, or just bogs down real low rpm now instead of stalling. Maybe it is time for a new battery, but It's hard to imagine that something as small as rolling down the windows put's enough strain on the battery to kill it, but yet it still starts perfectly fine and the headlights don't dim, etc. Everything else says the battery is fine, but your right, the stalling does seem like it comes from a electrical failure.
 
#5
Have you been to AutoZone and got your alternator tested.. ?
You could get an Optima battery. It would help even with your system you have..
How many watts you have going to the 2 W3s 400-600? plus the stock 460w ?
thats alot on your battery..
1 more thing just to check.. do you have underdrive pulleys?

Matt
 
#6
What does your voltage gauge look like? I have a problem with my electrical system where the alternator will not come on until the car is warmed up. you should have someone get in your car and try to get it to do it again as you read from the positive post on the battery to a good ground. When you do this don't get run over and see what your voltage drops to. Your battery might be bad if your alternator is not charging it. You should read at least 14vdc. If you have a aftermarket sound system check all those wires as well.
 
#10
Have exact same problem. RPMs drop below 500 during hard braking and it stalls once in a while. It stalls even more often when hard braking is acomponied with sharp turns. This problem presisted from day one I owned this car, almost four years now. I took car to dealer a few times. They give me lame crap, such as "ohh this is very common occurance with performace engines".
 
#11
This is a Ford bug, I think to do with the computer engine management (but maybe IAC related)... and I don't think they have a clue how to fix it. Whatever it is, it isn't right.

My old SVT Focus (and many other SVT Focuses) had the same issues and no resolution from Ford. Dipping idle and occasionally the system fails to compensate enough to bump it back up to avoid a stall. Could happen out of the blue and at really bad times.

Interesting that you relate it to your electrical, because it happened on my Focus (since new) even with no accessories turned on, but more frequently with the AC running.

I'd point my finger at their strategies to lower emissions on their high output motors. Of course pumping up the idle helps avoid the stall, because the RPMs have further to fall before being caught by the system to prevent that.

My Mustang has been fine so far though.
 
#12
I've had my '03 for over a year, but only has 5k miles. I don't think its a problem with bad/dirty parts because its done this since it was new. Its always random though. Sometimes its cold, and sometimes its after its been driven. I was worried the first time it did it coming to a stoplight on a highway. Then, later when I got home I found out on here its fairly common.
 
#13
well it's nice to see i'm not the only one. Yeah i kinda knew it wasn't the MAF or iac since this car has been doing it since i bought it. Had and still has very low miles. The best part is that sometimes when the rpm's drop real low and the car tries to punch it back up the car will actually surge forward or backward depending on direction im' going.

ah well no car is perfect i guess i was just hoping that there was a fix. :notnice:

Also yeah when i turn the wheel the rpm's drop rapidly. And yeah i've brought it to ford about 4 TIMES. each time they tell me it's common and send me on my way.
 
#14
I was just about to post a similar thread when I ran across this one. I have a similar problem but I am almost certain it is not accessory/electrical driven. I am on my 4th Mustang and I have experienced similar problems in what you guys are describing with idling issues. Ford has told me the same thing...especially with the power steering problems they have.

My car has just recently started stalling when cold. It has really only stalled twice but there have been other times where it was going to stall and I gassed it to bring up the RPM's. I think this may just be a tune up issue ie plugs, wires, fuel filter etc. Anyone have any other suggestions on what to check for with these symptoms? Any help would be great. Thanks.
 
#16
00VERT GT said:
well i'm going to go and get my alt and battery tested to see if they are running ok. I'll keep bumping this thread to see if anyone has found a solution.
Click to expand...

What helped mine the most was adjusting the screw on the throttle body up a little. It has just about completely cured my stalling and low bouncing idle completely. I have been adjusting on it for a couple months now and finally got it perfect a couple of days ago. If It's adjusted too low, the the computer/IAC can't catch it fast enought when the idle drops quickly. If it's adjusted too high, you get the notorious hanging idle where it sticks at like 1100-1200 RPM for a few seconds before it drops to idle. It's just a matter of patience and time to get it adjusted right. Just never turn it more than a 1/4 of a turn at a time and get some good driving time in before you adjust more. It doesn't take alot of turning on that screw to make a big difference.
 
#17
slvr00gt said:
Have exact same problem. RPMs drop below 500 during hard braking and it stalls once in a while. It stalls even more often when hard braking is acomponied with sharp turns. This problem presisted from day one I owned this car, almost four years now. I took car to dealer a few times. They give me lame crap, such as "ohh this is very common occurance with performace engines".
Click to expand...

Mine is doing the exact same thing. What caught my eye about this post was that it only happens whencombined with braking and turning. I replaced the IAC (at 53,000 miles) and it still does it, but perhaps not as often. Was wondering about replacing the Throttle Position Switch?

The 95 GT that I had was doing the same thing, and the idle was hanging from time to time as well. The guy I sold it to said that he replaced the MAF at AutoZone and it cured both problems. I'm not ready to go that route with less than 55,000 on the original MAF.
 
#18
00VERT GT said:
I think a lot of people do. every week there is a "MY RPMS ARE BOUNCING AT IDLE" thread but yet no one has any real solutions.

MGT if you find anything out before i do about how to fix this problem lmk.
Click to expand...

U Bet.. I just had to buy a new intake manifold..found out mine was warped and I had a BAD vac leak.. i'm waiting on install
 
#19
Marine One said:
Mine is doing the exact same thing. What caught my eye about this post was that it only happens whencombined with braking and turning. I replaced the IAC (at 53,000 miles) and it still does it, but perhaps not as often. Was wondering about replacing the Throttle Position Switch?

The 95 GT that I had was doing the same thing, and the idle was hanging from time to time as well. The guy I sold it to said that he replaced the MAF at AutoZone and it cured both problems. I'm not ready to go that route with less than 55,000 on the original MAF.
Click to expand...

well.. I have thus far replaced: IAC, TPS, EGR, PVC, cooling sensor, & MAF.. I just purchased a new Intake manifold and i'm waiting on install for that.. I'll post results. I'm leaning toward the electrical side since i've replaced so many mechanical parts..there's not much left :shrug:
 
#20
MGTConv00 said:
well.. I have thus far replaced: IAC, TPS, EGR, PVC, cooling sensor, & MAF.. I just purchased a new Intake manifold and i'm waiting on install for that.. I'll post results. I'm leaning toward the electrical side since i've replaced so many mechanical parts..there's not much left :shrug:
Click to expand...

That's exactly what i didn't want to start doing...replacing things one part at a time.
Sorry for the ignorance but where is the screw that you guys were talking about to adjust idle?
 
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