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Jump or Push?


thewheelman

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Got ready to head to work yesterday and the GT 500 was dead as a hammer. I suspect the GPS being left on in the car for a week was the culprit as I had the battery checked later in the day and it was fine. Hasn't failed to start since. Thankfully my son was still at home when it happened and we jump started the car with no problems. However, before we chased down a set of jumper cables, he said, get it straight and I'll push you (by hand). Can you push start these cars? One, there's a lot of engine to turn over (he's used to push starting his Fiat) and second, there's a lot of electronics that have to be functional..........:headscratch:

 

Not that I plan to make a habit of it or anything, but is push starting possible with these cars?

 

Thanks!

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Should be no problem, just make sure your on blacktop and not gravel, otherwise the tires will just slip when you pop the clutch.

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I've/we've push started my a few times... I tend to leave my lights on at the track... doh! So, YES. You can.

 

 

Not with a *dead* battery, you won't.

 

Your EFI control system works on a 5 volt reference signal so you need at *least* 5 volts to get your EFI to work.

 

Your Electronic Ignition needs 9 volts to operate.

 

You have a alternator on your car and a alternator needs to be "excited" for it to start charging. The old Generator systems had Permanant Magnets in them therefor you could push the car to get the Generator to start charging, which would in turn give you enough voltage to fire your ignition system. An alternator does not have Permanant Magnets it it, it uses voltage applied to the rotor to create the Electro-magnet which in turn produces a voltage in your Stator. But in order to get the EM to work, you need the "exciter voltage" I wrote of above.

 

If you were able to push start your Electronic ignition, Electronic Fuel Injected car you did *not* have a dead battery. You had at *least* 5 volts left (which is just BARELY enough to excite your alternator rotor field) and the Alternator put out the remaining voltage to fire the Electronic Igntion system.

 

 

And THAT'S.....the rest of the story,

Phill

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Not with a *dead* battery, you won't.

 

Your EFI control system works on a 5 volt reference signal so you need at *least* 5 volts to get your EFI to work.

 

Your Electronic Ignition needs 9 volts to operate.

 

You have a alternator on your car and a alternator needs to be "excited" for it to start charging. The old Generator systems had Permanant Magnets in them therefor you could push the car to get the Generator to start charging, which would in turn give you enough voltage to fire your ignition system. An alternator does not have Permanant Magnets it it, it uses voltage applied to the rotor to create the Electro-magnet which in turn produces a voltage in your Stator. But in order to get the EM to work, you need the "exciter voltage" I wrote of above.

 

If you were able to push start your Electronic ignition, Electronic Fuel Injected car you did *not* have a dead battery. You had at *least* 5 volts left (which is just BARELY enough to excite your alternator rotor field) and the Alternator put out the remaining voltage to fire the Electronic Igntion system.

 

 

And THAT'S.....the rest of the story,

Phill

 

 

Excellent write up. But not necessarily true. I left my lights on at the track no less than 3 times (seriously, I know) each time with the voltage gauge just inside the "L" mark. I'd try to start it and it would barely turn over and then give me the dreaded rapid clicking noise. And each time, I got her rolling down the grade and jump started her. Off I went and after the drive home it charged up fine and wasn't a problem again (until I left the lights on again). Maybe it wasn't 0 volts, but it was dead *enough* not to start and did with a push start.

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Excellent write up. But not necessarily true.

 

LOL....I can't believe this. You're arguing with a California BAR Certified Auto Tech Instructor who specialized in Engine Managment Diagnosis (EMD) and taught courses starting with BASIC ELECTRICS and all the way through to Electronic Fuel Injection AND the California Clean Air Car/CACC (i.e. "Smog") course that allows field techs to take the test to get their Smog License.

 

So...."not necessarily true"??? ROTFLMAO!

 

No, it is exactly true.

 

 

I left my lights on at the track no less than 3 times (seriously, I know) each time with the voltage gauge just inside the "L" mark. I'd try to start it and it would barely turn over and then give me the dreaded rapid clicking noise. And each time, I got her rolling down the grade and jump started her. Off I went and after the drive home it charged up fine and wasn't a problem again (until I left the lights on again). Maybe it wasn't 0 volts, but it was dead *enough* not to start and did with a push start.

 

The fact that it would "barely turn over" means it had about 9 volts left stored in the battery (9.5v is the minimum before we condem a battery).

 

A fully charged battery has 12.6 volts (2.1 volts PER CELL). 9 volts would mean your battery was about 75% of a full charge. That's FARRRR from "dead".

 

Read my "write up" again and see what I say about voltage requirements for the IGNITION SYSTEM and the ELECTRONIC FUEL INJECTION SYSTEM.

 

No, it WASN'T "0 volts" otherwise you would NOT have been able to push start your car, no matter how far you pushed it. You could push it a million miles and if there is no electricity to allow your ELECTRONIC ignition and/or ELECTRONIC fuel injection to work.....it ain't gonna start.

 

EDIT: If you have/had a car with a GENERATOR on it, you CAN push start it with a totally DEAD battery in it.

 

Yes, it is true that there was not enough potential voltage stored in the battery to allow the starter motor to crank the engine over with but it was certainly charged enough to allow the EFI (5v) and the EE (~9v) to work.

 

 

Phill

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I use reverse to pop my clutch....best gear for roll starts. I sometimes have to let my car roll out of the garage before I start the car, and its just easier popping the clutch to start it up.

 

 

Generally, reverse is a very low gear ratio. It spins the engine over faster but you stand more of a chance of locking up the tires. If you have good traction (concrete or asphault) AND you can get the car moving fast enough, reverse is GREAT (due to the faster spinning engine).

 

It's kind of like using 1st gear headed forward. I try and use the HIGHEST gear I can, for the speed I can/will attain due to the hill I'm on or how many "Friends" I found willing to help push a car! LOL (having a GT500 assures you WILL suddenly have more "friends").

 

Oh yeah, and to add to my last post regarding the guy that is able to "barely crank the motor over"...since you have about 9v (maybe as low as 7 or 8) you DO have the needed electricity/voltage to "excite" the field (rotor) and get the alternator to start charging, which will give you MORE than the available battery voltage (at the time). So in his case, pushing the car at a good rate of speed will also help due to the Alt. spinning faster and producing more of a charge (to run the electronic and electric systems).

 

But as I said in my ORIGINAL POST on this issue....NOT if you have a DEAD battery, you won't (key word: DEAD).

 

For what it's worth, I very much enjoy sharing my knowledge & experience because when you have a group of people, you will learn 10 things back for the 1 thing you shared!

 

I'm hoping I did not come off too "strong" to the poster that said "not necessarily true". I don't mean to be personal but my credentials are long and I do take it personally when someone (basically) says I'm wrong, don't know what I'm talking about, etc.

 

Mia culpa,

Phill

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Generally, reverse is a very low gear ratio. It spins the engine over faster but you stand more of a chance of locking up the tires. If you have good traction (concrete or asphault) AND you can get the car moving fast enough, reverse is GREAT (due to the faster spinning engine).

 

It's kind of like using 1st gear headed forward. I try and use the HIGHEST gear I can, for the speed I can/will attain due to the hill I'm on or how many "Friends" I found willing to help push a car! LOL (having a GT500 assures you WILL suddenly have more "friends").

 

Oh yeah, and to add to my last post regarding the guy that is able to "barely crank the motor over"...since you have about 9v (maybe as low as 7 or 8) you DO have the needed electricity/voltage to "excite" the field (rotor) and get the alternator to start charging, which will give you MORE than the available battery voltage (at the time). So in his case, pushing the car at a good rate of speed will also help due to the Alt. spinning faster and producing more of a charge (to run the electronic and electric systems).

 

But as I said in my ORIGINAL POST on this issue....NOT if you have a DEAD battery, you won't (key word: DEAD).

 

For what it's worth, I very much enjoy sharing my knowledge & experience because when you have a group of people, you will learn 10 things back for the 1 thing you shared!

 

I'm hoping I did not come off too "strong" to the poster that said "not necessarily true". I don't mean to be personal but my credentials are long and I do take it personally when someone (basically) says I'm wrong, don't know what I'm talking about, etc.

 

Mia culpa,

Phill

 

 

Easy there Phil. I never discredited you. All I said was that, for what I believe the purpose of this thread was in the first place, is that YES, if you run your battery to the point where it will not start... such as leaving your lights on, or a GPS unit plugged in... you CAN possibly push start your car. I also complimented you on the write up, didn't I? I fully believe your knowledge to be true and greatly appreciate it. But again, a car that will not start after having some sort of electrical draw, can be restarted by pushing, rolling, etc. No offense intended.

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The fact that it would "barely turn over" means it had about 9 volts left stored in the battery (9.5v is the minimum before we condem a battery).

 

A fully charged battery has 12.6 volts (2.1 volts PER CELL). 9 volts would mean your battery was about 75% of a full charge. That's FARRRR from "dead".

 

Read my "write up" again and see what I say about voltage requirements for the IGNITION SYSTEM and the ELECTRONIC FUEL INJECTION SYSTEM.

 

No, it WASN'T "0 volts" otherwise you would NOT have been able to push start your car, no matter how far you pushed it. You could push it a million miles and if there is no electricity to allow your ELECTRONIC ignition and/or ELECTRONIC fuel injection to work.....it ain't gonna start.

 

EDIT: If you have/had a car with a GENERATOR on it, you CAN push start it with a totally DEAD battery in it.

 

Yes, it is true that there was not enough potential voltage stored in the battery to allow the starter motor to crank the engine over with but it was certainly charged enough to allow the EFI (5v) and the EE (~9v) to work.

 

 

Phill

 

 

Holy crap, I didn't even see this post. Sensitive much? Relax. The point of this thread, as I understood it, was someone who had run their car to a low voltage (not necessarily DEAD) wanted to know if they could potentially restart it via roll/push starting. And the answer is yes, it it possible. Am I wrong? If my car is low enough to not start, to me, it's dead. And in the all the cases I've tested the roll start theory, it's worked. Sorry to have insulted you.

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Whoa guys, yeah, you answered my question......in spades! Geez, I just wanted to know if we could push start it. My driveway is virtually flat so we're not going to get up a great head of steam. I'll just keep the jumper cables handy and flag down a neighbor if I'm home alone!

 

Thank you everyone for you informative, if impassioned, responses!

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Whoa guys, yeah, you answered my question......in spades! Geez, I just wanted to know if we could push start it. My driveway is virtually flat so we're not going to get up a great head of steam. I'll just keep the jumper cables handy and flag down a neighbor if I'm home alone!

 

Thank you everyone for you informative, if impassioned, responses!

 

 

Cool, ya as often as I run mine "dead", I keep one of those booster boxes handy. Speaking of... This thing is remarkable. I've had it for 4 years... charged it once. How is that possible? I've used it to jump start cars no less than a dozen times and it still keeps kickin'. Well worth the $30 or $40 I paid for it.

 

And Phil, seriously man, I'm sorry. I really didn't mean to insult your knowledge. I literally just meant that in many cases the roll start is an option if your car will not start from an electrical draw. Honestly, no offense was intended. I do ALWAYS value the knowledge of other folks on this and other forums. Thats the beauty of them. You can gain MASSIVE amounts of great knowledge from people, like you. Cheers.

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