[Wilkins]

I dont know where to start. Ive never really dealt with FI engines before so im a little lost. any insight would be greatfully appreciated!

1) Its got a really nasty cam and sounds amazing at about 7-800 rpm, but at idle, the car will stay at about 800 rpm for a few seconds and then rev up to 1100 for a few seconds for no reason at all and then back down to 7-800. This one has got me baffled

2)Crusing down the highway, the temp stays at about 180-185. But if you have to stop at a light for too long or go through the drive through, it will easily get up to 210-215. But 2 mins of driving will cool it right back down. But the fan is spinning. If i hold it at 1500 while at a red light, i can maintain my temp.

3)Car isnt charging correctly. Battery gauge never goes over 11v-12v, even at 3000 rpm. It has a brand new high output alt and a optima red top battery.

So i cant turn it off or else it might not start again. Cant leave it running or it gets a little warm.

HELP!!!!

[dr.gonzo!]

1. sounds like a vacuum leak. what year is your car?

2. you might want to flush the cooling sytem and see if that helps

3. these cars a pretty bad when it comes to charging. there is something called the 3rd gen swap where you modify your car to accept a 3 gen alternator. Fox Mustang Alternator - Easy Alternator Upgrade - 5.0 Mustangs & Super Fords Magazine

[BLUE91GT]

You can also look at the August 2008 issue of muscle mustangs & fast fords, they have a good article on charging. They put a PA performance 130 amp 3g in their test car, and it put out 80 amps at idle. Mark

[Wilkins]

Im going to have to see what alt i have. Ill check it out and let yall know. Im pretty sure its a nice one

[BLUE91GT]

Just because it's a high out put doesn't mean it has a lot of amps at idle, make sure you find out what it is at idle. Just my 2 cents! mark

[fogged306]

Dont trust the stock battery gauge. Get a multimeter and see exactly what the voltage is at while running. You may just have a bad gauge and everything else is fine. Or you could possible have a blown fusible link on the charging wire. If you don't have the 13-14v at the battery that you're supposed to while running, check it at the alternator itself and see if it is actually outputting correctly, if so it's a bad link.

[fogged306]

Originally Posted by BLUE91GT Just because it's a high out put doesn't mean it has a lot of amps at idle, make sure you find out what it is at idle. Just my 2 cents! mark

Amps and Volts are 2 different things. Even though it probably doesn't have a whole lot of amperage at idle, it still should be putting out the correct voltage of between 13.8 and 14.4

[BLUE91GT]

Originally Posted by fogged306 Amps and Volts are 2 different things. Even though it probably doesn't have a whole lot of amperage at idle, it still should be putting out the correct voltage of between 13.8 and 14.4

Let me explain this a little different! You car runs on altenating current hence altonator. If you look back at older cars they had a amps guage, this was a not so good way to measure what you altonator was putting out due to you had to have a wire that ran from their to the amp guage that carried that currant. Then came the volt guage which is direct currant, and you can measure this with out the nasty wire with all the ac currant running through it. All cars run on alternating current, and a volt guage is just a different way to measure that.

I hope I am explaining that right!!!! Your altonator needs to be able to supply enough amps to run the entire car, ie pw pb stereo ect ect. So if you go adding a big stereo, electric fan you need to adjust your idle amps to accomadate the entire electrical system so you have 13.8 to 14.4 volts at idle. Mark

[Bigfatts]

The rolling idle could also be a TPS on it's way out. My notch does it some times, just haven't gotten around to replacing it yet. Does your's do it all the time or just sometimes? Next time it does it, shut it off. Let it sit for a second and start it back up, if it runs fine after that it may be the tps. Also, give the inside of the throttle body a good cleaning, that fixed my wife's old Camaro of the problem.

2 could be the thermostat. Do you know what's in it? When I first got my Capri it did the same thing. Swapped it out and had less of a problem. Could also be that your fan isn't powerful enough. Is it the belt driven fan or an electric?

[Hunt_chevs]

Originally Posted by Bigfatts The rolling idle could also be a TPS on it's way out. My notch does it some times, just haven't gotten around to replacing it yet. Does your's do it all the time or just sometimes? Next time it does it, shut it off. Let it sit for a second and start it back up, if it runs fine after that it may be the tps. Also, give the inside of the throttle body a good cleaning, that fixed my wife's old Camaro of the problem. +1 2 could be the thermostat. Do you know what's in it? When I first got my Capri it did the same thing. Swapped it out and had less of a problem. Could also be that your fan isn't powerful enough. Is it the belt driven fan or an electric?

+1

[1989Gt.]

i get 13.6 or so with every gauge on my fog lights my two amps in the back 750 and 400 and my lights turn signal radio blasting..... off of a summit one wire alt. 100 amp

[fogged306]

Originally Posted by BLUE91GT Let me explain this a little different! You car runs on altenating current hence altonator. If you look back at older cars they had a amps guage, this was a not so good way to measure what you altonator was putting out due to you had to have a wire that ran from their to the amp guage that carried that currant. Then came the volt guage which is direct currant, and you can measure this with out the nasty wire with all the ac currant running through it. All cars run on alternating current, and a volt guage is just a different way to measure that. I hope I am explaining that right!!!! Your altonator needs to be able to supply enough amps to run the entire car, ie pw pb stereo ect ect. So if you go adding a big stereo, electric fan you need to adjust your idle amps to accomadate the entire electrical system so you have 13.8 to 14.4 volts at idle. Mark

Not even close. Please don't take this as a personal attack, but someone has given you some misinformation.

Cars run on DC (direct current). The alternator is an AC electrical device, true, but there are diodes in them to eliminate the negative voltage in the AC current and effectively convert it's output DC current. AC is what powers your home, DC is what powers your car.

[BLUE91GT]

Originally Posted by fogged306 Not even close. Please don't take this as a personal attack, but someone has given you some misinformation. Cars run on DC (direct current). The alternator is an AC electrical device, true, but there are diodes in them to eliminate the negative voltage in the AC current and effectively convert it's output DC current. AC is what powers your home, DC is what powers your car.

None taken, thats how you learn!!! Mark

[flyin ryan]

Originally Posted by Wilkins 1) Its got a really nasty cam and sounds amazing at about 7-800 rpm, but at idle, the car will stay at about 800 rpm for a few seconds and then rev up to 1100 for a few seconds for no reason at all and then back down to 7-800. This one has got me baffled 2)Crusing down the highway, the temp stays at about 180-185. But if you have to stop at a light for too long or go through the drive through, it will easily get up to 210-215. But 2 mins of driving will cool it right back down. But the fan is spinning. If i hold it at 1500 while at a red light, i can maintain my temp. 3)Car isnt charging correctly. Battery gauge never goes over 11v-12v, even at 3000 rpm. It has a brand new high output alt and a optima red top battery. So i cant turn it off or else it might not start again. Cant leave it running or it gets a little warm. HELP!!!!

1. Sounds like a vac leak.. listen for a hissing and check the voltage of your TPS.. it maybe not be kicking the idle up when it's suppose to so you might want to try resetting the idle as well.

2 and 3 are most likely due to the fact that you have underdrive pullies.. the water pump pulley is larger thus the waterpump and fan which is attached to the water pump isn't spinning fast enough at idle anymore so check to see if you have underdrive pullies and get rid of them

[gotn20]

re set your idle per the sticky on the main page to eleminate rolling idle

[jjperl]

what should the base idle RPM be set at, in order to get it to stop a high rolling idle?

[lone5oh]

could be water pump getting old, when you go faster your wp spins faster when at stop it slows down and you get less flow. just my 3 cents worth. probably is one of the other things mentioned above though.

[jrh_1980]

1. I would check the tps voltage and possibly adjust your base idle. There is a good sticky with that info.

2. fan clutch may be going to shit. How does the Fan shroud look? if it's broke it may be the problem. without it, the air isn't being pulled directly through the radiator and will cause the car to run hot but when your moving down the road the air is being pushed through it and it cools down.

[Smirnoff]

my car overheated like that when it had a bad thermostat in it. eventually it stuck and blew all my antifreeze out of the overflow and onto my car made a huge mess.

[95blackbeauty]

I had a rolling idle like that and it would go up and down then die. My problem ended up being insufficient Fuel injectors, went to 24# injecs and its been fine ever since.