My car is stalling, I don't get why.

[BlackSunshine]

Hi
I need some help. I have a 97 Talon TSi AWD. I was having a problem with a loud squeal from the alternator / belt, the revs bottoming out and it occasionally stalling. I tested the alternator and it was only putting out 12.5 volts. So, I replaced the alternator and belt.

Now the car doesn't stall as often, but it still stalls on occasion. When I put the clutch in and let the revs drop, the TAC will drop down to 200 revs, sometimes down to zero and it will occasionally stall. This is the same behavior as before I changed the alternator, but the stalling is less frequent now.

I have had the car on a scope and the codes were the Throttle Position sensor was 2.4% at closed throttle (spec is 0% - 2%), which I adjusted to be back in spec. One O2 sensor is showing a voltage spike and the cat is showing low flow. So, I need a cat and an O2 sensor. A cat that is a little plugged up and a dying O2 sensor should not cause the revs to bottom out or the car to stall.

Why is the car still stalling (This is not my first manual, I know how to drive a stick)? Why are the revs still dropping down below idle speed? Why do I still have a squeal, even though it is not as loud as before?

If anyone has any suggestions as to what could be causing this, let me know. I would appreciate any help you guys can give me.

Cheers,
lz (aka BlackSunshine)

 

[RadDsm]

Could a boost leak cause this? and of course the obvious, are you venting your BOV?

 

[slowstang]

Could a boost leak cause this? and of course the obvious, are you venting your BOV?

Thats what came to my mind first. It sounds like your running a little rich when your let off the gas. What RPM does your car idle at, given it doesn't stall out. It could be that your base idle is set too low. I know my car does dip down a little before it finds idle when I let off the gas and it's tuned properly. If your idle is set to 400-500 I could see it dipping down to 200 before it finds idle (or stalls) especially if it's not tuned properly.

 

[AlaskanDsm]

Check your battery, its possible your battery may be bad or has gone bad. At least it would put that worry out of the way and its an easy check.

 

[cali]

could be a number of things; start with the simplest...

how are your battery cables? vacuum leak? venting bov?

 

[RayBan GST]

Check for any Boost leaks or let us know if u have a vented BOV ? check if the hose that connects the BOV to the intake is properly conected and does not have any leaks.

maybe your idle is set too low then its possible that it could dip down to 200 before it finds idle

try to set your idle a bit higher try adjusting the BISS screw


let us know

 

[tsiturbotalon]

an easy check is the base idle like slow stang said i believe it should be around 800, if its lower than that that could be an easy fix to your problem.

 

[N1te]

How much was your alternator? I'm about in need of a new one too.

 

[93DE-EZ-UM]

I have the exact same problem as you. My voltage is ranging from 12.7V to 13.6V according to the pocketlogger. I would tighten the tension on the alternator and the squeek will go away but never notice the low battery voltage until last night. I'll have to see if tightening the tensioner will result in better voltage readings. I have tried new ISC (ohm out correctly according to the spec.), whole new throttle body includes new throttle switch,new FIAV. I do have a tiny leak near the throttle body area which I have not yet fix. That will be next item to do on my list. The BISS does not leak. One weird observation I notice was that when I ground out the timing plug to check the base timing and left the pocketlogger in the diagnostic port under the dash at the same time, my idle will surge. When I disconnect the pocketlogger cable from the diagnostic port under the dash but left the plug near the battery under the hood grounded, the car idle solid. According to the manual, you only have to ground the plug near the battery to check your base timing but I read some where in these forums that the procedure was to ground both locations. If you look in my profile, you'll see that I have lighten flywheel and balance shaft eliminated. I don't know if these mods have anything to do with my problem or not. Most people said it has nothing to do with it.
I'll keep you posted on my findings.

 

[eDeclpse92]

my car does kind of the same thing. when i coast above 30-35 mph, my car will try to find an idle and occassionally die on me. what i found out from other members is to not to coast. bassically engine braking. i tried it and my car has not died and idles perfect everytime i put it into nuetral. if im going 50 mph or somewhere around there and i will leave it in 5th gear and slow down with that until i hit a little above my idle and then i put it into nutral, my rpms are fine. then never dip or surge. i only do it when my car is warmed up though. try it and see if that works for you, becasue i still haven't found a reason why it happen to me. good luck.

 

[Burtismaximus]

just a quick question that could partailly affect it is do you have a light weight flywheel???

 

[93DE-EZ-UM]

I have a lighten flywheeel and balanced shaft removed. I was told by other members that this shouldn't affect it because some of them have the same set-up and does not have this issue.

 

[hubz91talontsi]

Alaskandsm is right..its the damn battery
100percent sure

 

[BlackSunshine]

Hey Guys
Thanks for all your responses. Here's what I know so far and a few other things I forgot to mention in the first post.
The battery is less than a year old and is unlikely to be the issue. I never had an issue with starting the car when I had the bad alternator, so I'm pretty sure it's good, but I'll check it anyways, you never know. You get an engine light if the cables are not securely connected. I know this because I got an engine light on and all I had to do to fix it was tighten one of the battery cables. I'm pretty confident that they are ok, but I'll check it anyways, you never know.
When the car is cold (a few degrees below freezing tonight), she idles around 1000 – 1200 revs. Once she reaches running temp, idle drops to around 500. The car is always at running temperature when it stalls. I don't think the turning the idle screw will do anything but mask the underlying issue. When I put the JDM engine in on the May long weekend, I had it idling at 800 and that was its idle speed until the alternator issues started showing up. I was expecting the new alternator to fix the idle and stalling issues. I haven't touched the idle since I put in the engine, so the idle setting should be fine. I'll probably adjust it if I can't find another reason why the idle changed.
I don't think it is a vacuum leak. I had a vacuum leak on a Mustang I owned and it's not like that. All the hoses were in good shape when I changed engines in May 08, but I'll check.
I spent a month or two screwing with the tension on the alternator belt and replaced the belt twice. The first belt I bought was a cheap one, so I figure that's what you get for cheaping out. The alternator was screwed. I turned it by hand after I took it out and you could feel it.
I got the alternator from UAP/NAPA. They have two, one has a 3 year warrantee, and the other has life time. I get a pretty sweet discount there because my old man is service manager at a heavy truck shop. I pay shop price, so I got the life time warrantee one for $250 Canadian. It puts out 75 amps. It was only $50 more than the other one, so no brainer.
The flywheel has not been lightened / shaved / turned. I still have the balanced shaft in place, or at least I didn't remove it.
This is my first car with a turbo, so I never thought of the BOV or a boost leak. I put on a new Injen Intake when I put in the engine in May 08. The hose for the BOV was tight, I will double check it. I did a little homework and I don't think the BOV is vented or seized shut. If it was vented, I wouldn't get any boost. I get boost, the car runs fine as long as revs are 1000 or higher. If the BOV was shut, I would notice it accelerating; the car would run like shit because it can't vent the pressure. The car runs fine and has good power. If the BOV is sticking a little bit, that might cause the issue.
I'm going to change both O2 sensors next time I can get it into my old man's shop and I'll test / retest all the stuff I mentioned above. Hopefully, it will be this weekend. Does anyone know a good test for a sticky BOV? I have never tested one before, so I got some more homework to do.
Again, thanks for all your help. If what I've written has sparked any more ideas, please let me know. I'll let you know how all the tests come out.

Cheers,
lz