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So as the title says I just recently replaced my alternator. After replacing it I started the car up and it sounded good. I looked at the rpms and it was chilling at 500. Which, after a little researching, I know is too low. Also when doing a quick rev on the engine it sounds like it's going to die then gets up past 1k rpms and runs just fine. If I do a nice gradual rev it sounds fine as well. Also when doing the quick rev it sounds like one of my belts is rubbing (a squealing noise) . But I checked and there was no rubbing that I could see.

I asked my friend what he thought and he said he had the same problem on his cavalier and that it might be my TPS if I remember correctly.

I however think it might have been because when doing the alternator swap, I made the belt too loose/tight. Or something else.

It ran fine before the swap, before the alternator went out anyways.

So could this be because the alternator requires a break in period, the TPS is off, I incorrectly put the belt back on, or something else entirely?

I appreciate your guys' thoughts ahead of time. I'm kind of new to cars, as I'm sure some of you guys noticed just by reading my post, but I'm willing to learn.

Also I don't think there were any codes being thrown. I could be wrong however, and I won't be able to check 'til I'm off work.
 

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pulling the EFI fuse or disconnecting the battery will make your ecu forget about the table it learned from the engines conditions, it should start to run better after some time idling and adjusting it injection table and whatnot

however if it is really related to your alternator...
 

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Well if you are correct then I guess it's just a waiting game. How long would I have to let it sit there idling before it corrects itself? On average. I ran it for a good 3-5 minutes with no change...

If it is related to the alternator what could be causing this? I've never done a swap on one before. So, I don't really know some of the things that come with the swap.
 

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Discussion Starter #5
So I just used my good friend Google and it said that for the stock alternator it put out 70 amps. This new one puts out 70 amps as well though. Could it be that it puts out too little? Or even too much?
 

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Maybe the new alt isnt spinning as freely. But this would make more sence if the charge was higher then your previous. Unless the new alt has been sitting on the shelf for years and years or what.

Turn on the car and read your amp gauge and let us know where the needle is. Should be clearing 12v mark completly. My 86.5, the needle is like a quarter of an inch above the '12v' background image from the drivers seat point of vue. But I remember the shop guy asking me if I wanted more amps since I was running a stereo system. Im idling about the same 500rpm when hot sometimes.
 
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pulling the EFI fuse or disconnecting the battery will make your ecu forget about the table it learned from the engines conditions, it should start to run better after some time idling and adjusting it injection table and whatnot
This guy is right if i reset my ecu my car runs like crap and idles at 500 on a cold start,
you need to drive it around for awhile takes me around 2-3 days to get my car to fire up
and run around 1300-1500rpm on a cold start and idle around 650. Dont think anything is wrong here.
 

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Discussion Starter #9
pulling the EFI fuse or disconnecting the battery will make your ecu forget about the table it learned from the engines conditions, it should start to run better after some time idling and adjusting it injection table and whatnot
You, my good sir are, one smart cookie. I was able to go check on my car today (It's at my gf's house at the moment) and it started up and idled like a champ. So the low idle thing has been solved.

However There is still a squeaking that comes when i do a quick rev and it kind of hesitates and feels rough for a split second after I push on the gas. Could this be the TPS? I'm sure the squeaking is coming from the belt. Did I maybe make it too tight? Or does that happen when it's too loose? I've never had to deal with belts before now...

Thank you for all your help guys. I really appreciate it.
 

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misadjusted TPS will cause that kind of thing, also it would be worth a dime to reset your timing properly, it helps rules out things. once those two things are done, it should rev quicker and without hesitation.

If you have access to a shop who can clean your injector for cheap (because stealership charge you like it's a pound of gold for that service) it might help
 

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^ As shipkiller said.


OP when you floor it, does it only pull at 3800 more then anyother time?


My car use to idle at 500 and it ran like total shit^. I just did my distributor/timming and im ideling at 1k now and the motor is as awake is it ever was. Turn motor for cylinder 1 to be at top dead center and take out your timming and install it according to spec all over again. Here is the steps http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=IG&P=17

I have an 86.5 as well. For 2. b) on re-installing the distributor, (There was no prostrusion marking on the drive gear on my 86.5) I lined up the housing to the hole that is drilled into the shaft and installed it according to the following provided steps. Now my car wips out sideways in corners in first/second gear no problem.
 

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Discussion Starter #14
Thanks boosted mk3 supra I'll try tightening that up today.

Shipkiller I'll adjust the TPS today as well. I'll have to look up how to do that though...

87supramario I actually haven't driven the car since the swap for fear of damaging something. But most likely I'll be bringing it home today so I'll let you know later.
As for the timing thing, I'm confused about how to do that. From what I can tell all I do is turn the cylinder to top dead center and install the timing? Do you mean the timing belt, the distributor timing (didn't know there was one 'til now), or something else? Sorry for the noob question...
 

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Discussion Starter #15
So I adjusted the belt and there was no more squeaking. So thanks boosted mk3 supra! And the hesitation seems to have gone away. So I didn't mess with the TPS.

As for the timing though, I'd still like to know how to do that cause it would be good to do.
 

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Did the battery die when the alternator went out? If so, a low battery would cause your hesitation. And with the time between the swap and now would have given it time to charge.
 

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His low idle has nothing to do with timing or the TPS. A low battery (ie driving on a bad alternator until the damn thing dies) will cause these issues. Low voltage makes for a weak spark meaning loss of power, and low RPM. Come on guys.
 

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he mentioned his low idle problem went away after the ecu had a bit of time to relearn about the engine conditions, he was asking how to fix the slight hesitation when stomping on the throttle.

come on
 

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^ What engine condition? Weak spark? All he did was swap the alternator lol. Tell you what, leave your lights on for a few hours to run your battery down and tell me what happens when you get it started. It'll do the same thing. Doesn't matter, his problem is solved.

OP, take a look at your spark plugs and tell us what they look like.
 
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