Why is my car harder to crank when it is hot?

94gts · Dec 7, 2006

Right now my car has been sitting over night. If i were to go outside and start it, it would crank nice and stong and start right up.

BUT.......

If i were to go on a 20 minute drive (or any amount for the car to heat up), shut it off then try to start it 5 minutes later, this is what it does......It cranks, but it is very weak. Its similar to if the battery barely has enough juice to start it. I have to hold the crank for several seconds. hitting the gas pedal helps a little. The car has done this since May right after i finished putting together the h/c/i.

Labora · Dec 7, 2006

Your starter could be getting hot and be on it's way out.

94gts · Dec 7, 2006

Labora said:
Your starter could be getting hot and be on it's way out.

that was my first thought, seeing how thats what leads me to think there is a problem. the dam thing has 123k on it lol. i just didnt want to replace it and everything be the same

1slow95 · Dec 7, 2006

Starter. The heat from the exhaust kills the stock ones pretty quick.

Labora · Dec 7, 2006

Also it is easier to start when it is cold because the car doesn't make as much compression. Once it warms up it makes more compression...

94gts · Dec 7, 2006

does it make sense that it would last for 7 months and 10k while like this?

HISSIN50 · Dec 7, 2006

It can also be a power cable issue with IR.

I'd get it hot (where it will crank slow). Grab a jumper cable and run it from the negative battery terminal to the motor. Then try from the motor to frame. If you have a weak cable, the jumper cable will augment it and the car will crank strong.

If that doesnt help, then I'd hit the starter like everyone said (I agree that the starter can be it but it's easier to test grounds than the starter). A parts store can load test the starter. I've had it done for dead spots but not for hot start issues, so I'm not sure if they can mimic a hot condition.

Good luck.

final5-0 · Dec 7, 2006

Kyle

Are you saying it turns over at a slower rate when hot
or
Does it turn over at the same rate as when cold
but
It just takes longer to fire

Grady

95cobraguy · Dec 7, 2006

kyle, did u load test the battery? start with the basics first!

AaronG · Dec 7, 2006

My car does the exact same thing. I have a really old battery and my terminal wires suck, so I'm gonna replace those things and see if that helps first... Then again my car does have 139,xxx miles on it. ::::

Aaron

94gts · Dec 7, 2006

final5-0 said:
Kyle

Are you saying it turns over at a slower rate when hot
or
Does it turn over at the same rate as when cold
but
It just takes longer to fire

Grady

turns over at a slower, weaker rate

94gts · Dec 7, 2006

HISSIN50 said:
It can also be a power cable issue with IR.

I'd get it hot (where it will crank slow). Grab a jumper cable and run it from the negative battery terminal to the motor. Then try from the motor to frame. If you have a weak cable, the jumper cable will augment it and the car will crank strong.

i gotta try that. what exactly does IR stand for?

and eric, ill test the battery tomorrow. but, im sure it is good.

if i could guess now i would say a weak ground but why would it be fine when cold but not when hot? ill check that tomorrow too.

final5-0 · Dec 7, 2006

94gts said:
turns over at a slower, weaker rate

I understand now

I looked at your sig and did not see inj size

I was gonna say maybe it was too fat at startup due to ? larger ? sized inj's.

But that ain't it

Seems funny it started doing it ever since you did the h/c/i thing

Makes me think it was something that happened during the project

Grady

94gts · Dec 7, 2006

i have 30's

the car is untuned and is rich. but would that contribute to a weak starter?

final5-0 · Dec 7, 2006

94gts said:
i have 30's

the car is untuned and is rich. but would that contribute to a weak starter?

NO!

Thats how come I said ... "that ain't it" ... above

Grady

HISSIN50 · Dec 7, 2006

When a cable gets hot, it becomes more resistive. As it gets more resistive, it builds more heat (this is the IR stuff). Eventually you have a great big snowman at the bottom of the hill and a car that wont crank.

A cable can be barely adequate when cold but when hot, it no longer cuts it. That's why I was thinking that the cables are worth checking out. If you place the jumper in parallel with some cable and now the car cranks awesome, add another cable across that pathway and clean up the existing cable. I wonder if you wont find your motor to frame ground is bad. I chose to add an auxillary 4 AWG cable from the passenger side of the motor to the frame to assist degrading OEM cables. 5-10 bucks well spent.

And having a hosed motor ground from having the top end apart is quite possible.

Good luck.

reddy351 · Dec 7, 2006

I think the ECM pulls timing when starting, maybe it's not. The computer uses a signal from the starter solenoid. (Right?) Maybe the wire came loose while you were doing the HCI. That would make it harder to crank. What is your timing set at? Having the timing too far advanced can also cause this.

mo_dingo · Dec 8, 2006

I experience the same thing as you. But IMO it's a tuning issue not a mechanical one.

final5-0 · Dec 8, 2006

What would there be in the pcm that would make your car crank with a slower rate at normal operating temp than when cold

Grady

ProKiller · Dec 8, 2006

my first thought was a hot start fuel issue due to a tune like Grady said. but since you said it just cranks slower, that shouldn't be it.

i say check what hissin said, then if everything is good from that, it means your starter is on the way out IMO

Why is my car harder to crank when it is hot?

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