97 shuts off when coming to a stop

[Big Mike 74]

My 97 idles fine when you start her drives great but when in drive and coming to kind of an abrupt stop or stopping and turning the wheel....she shuts off please help!

 

[stephen newberg]

Stumbles to a stop or stops almost instantly?

pax, smn

 

[zoomlater]

I'm only familar with Gen II's, but is the battery or cable moving such it causes an open circuit during a sudden stop or turning the wheel
I also once had a battery cable making contact with the accessory belt during acceleration (engine movement) and causing the engine to stumble

 

[Big Mike 74]

Stumbles to a stop or stops almost instantly?

pax, smn

Well the back story is I had got an act tuner with custom loaded Tunes on it by a registered sct dealer who actually has a 98 Sho with the same Tunes on it and his runs great, anyway...as I was tuning the car yesterday (sct 4 device) it was writing the stock tune to the device and as it got to the end of doing that before it put the performance tune on it a memo came up on the screen and said car battery not strong enough to continue tuning, charge battery or replace .....so I didn't start the car at all because it probably wouldn't have started, I raced to Autozone to get a new battery swapped it in and continued with the tune, after the tune was in place I decided to set the car "back to stock" after I did this I took the car out and it was running okay except for every time I came to an abrupt stop it would shut off, and when I would start it after sitting for a few hours it would fire up and shut right off then I would start it again and it would stay on and idle fine.....I drove it about 20 miles yesterday and it has stopped shutting off when I come to a stop or make a slow turn it idles as it should, and this morning I started it before I went to work and it fired right up and idled fine.....no check engine light, I'm wondering if I should load a performance tune on it again or leave it as is in case the computer had to re learn everything... I'm a nervous wreck I've owned the car for 10 years and it has been in the family since brand new and always ran great.....cams are welded

 

[stephen newberg]

Hmm. Sounds like it was the interrupted tune attempt that was the problem. If you do not have to use the car, that is it can be a backup for a while with some other car getting you to work, you could try running the tune again, now that you have a good battery and the entire thing would go in in a single attempt. But if you do not, I would not try it until you have a number of days off to be able to recover the car from on and off cycles. For what it is worth, there is pretty good data that none (zero) of the tunes available for the Gen III cause any increase in performance, and some cause decreases. The better ones do, from what people that have them say, improve 'drive-ability', though I have never been exactly sure what that means, and there is in any seat of the pants judgement the problem of confirmation bias. The car is pretty drive-able from the factory, IMO, considering it is a 20 year old design at this point.

pax, smn

 

[Big Mike 74]

Hmm. Sounds like it was the interrupted tune attempt that was the problem. If you do not have to use the car, that is it can be a backup for a while with some other car getting you to work, you could try running the tune again, now that you have a good battery and the entire thing would go in in a single attempt. But if you do not, I would not try it until you have a number of days off to be able to recover the car from on and off cycles. For what it is worth, there is pretty good data that none (zero) of the tunes available for the Gen III cause any increase in performance, and some cause decreases. The better ones do, from what people that have them say, improve 'drive-ability', though I have never been exactly sure what that means, and there is in any seat of the pants judgement the problem of confirmation bias. The car is pretty drive-able from the factory, IMO, considering it is a 20 year old design at this point.

pax, smn

Yea I haven't been driving it to work I have a brand new battery in it now just been driving it around the block when I get home from work.....it gets better everyday last night it was pretty much back to normal, I think the tuner said he made it shift higher and stiffer but I'm not sure if that's good for the car anyway....I've decided to leave her be.....is it possible that the car just had to relearn itself that's why it seems to get better everyday I get home and take it for a spin.....so far only 28 miles

 

[E1]

What CPU is in it? JJK2. AWL1 or AWL2?

I have found the 1996 computers to be as dumb as a box of rocks (JJK@ and some AWL1) They take forever to start when they are inexperienced, and then run like a scalded dog when you floor them.

I think Stephen is right about a partial down load. Try it over again one more time. I know there is a training protocol for the early CPU's, too. Like start car, put in reverse, turn on AC, etc.... stuff like that. I just can't find it on V8SHO.com

I have a good deal of experience with X Cal 2 and X Cal 3 controllers, but zero with X Cal 4's. There also may be something else afoot.

 

[rubydist]

When a new tune is loaded, or when the battery has been disconnected for some time, one of the things the pcm must guess at is how much pulse width is required on the iac to keep the engine running at idle. Depending on a whole bunch of factors, this initial guess may be close or may not be. After some driving, it will learn the actual pulse width it takes to keep it running at the right speed. I have had a similar symptom after changing a sticking iac - the one that tended to stick open took a very small pulse width, and the new one took a larger pulse width and so it would on occasion make the engine stumble or die when dropping to idle speed. On one car, it took nearly 2 weeks of daily driving to get the pcm dialed in on the necessary pulse width. From your symptoms and their improvement, I would say that is all that is going on in your case.