[RESOLVED] Motor dies after I've disconnected the battery

[LKWTSI]

Every time after I reconnect the battery, the car will run fine, but come to a stop or shift, it dies. It won't idle and after I run it for a while and it cools down, it seems to run fine. I've not had any other idle problems other than this. I've read about the BISS leaking and all sorts of leaks and such, this doesn't seem to be the problem. Like I've said, once I've run it and let it cool it seems to be back to normal.

Anyone out there suffering the same deal?

90 TSI AWD

 

[Hollywood77]

You just do any major work that required you disconnecting the battery (for safety purposes)? Clutch work? Sometimes after you have the car sitting with the battery disconnected for some time, it can take the ECU a lil bit a time to "re-learn" things.

 

[No_Skillz]

You just do any major work that required you disconnecting the battery (for safety purposes)? Clutch work? Sometimes after you have the car sitting with the battery disconnected for some time, it can take the ECU a lil bit a time to "re-learn" things.

1Gs have a memory board on their ECU that retains previous settings even if the ECU is disconnected.

 

[1991TSiGFORCE]

Similar problem. I'm pretty sure you probably read about all the leaks but just wanted to give a shot at it. did you check your intake manifold gaskets from tbe to tb and check your throttle cables if its loose? found out i had a leak from my gaskets from intake manifold.

 

[steve]

1Gs have a memory board on their ECU that retains previous settings even if the ECU is disconnected.

Only if you have a 1G DSMLink and that only applies to the DSMLink settings. The ECU still has to relearn the fuel trims and ISC parameters just like a stock ECU.


And I don't see DSMLink in the OPs profile.

 

[turboglenn]

Why are you disconecting the battery? I'm confused on that one. If it's to test the alternator, not all cars will run anymore with out the battery due to some of the electronics and the battery completing a circuit.

I can't place teh connection between your title and teh content text of the post... i don't know why i'm missing it but a little more info about what you're doing with the battery and such would help

 

[steve]

i don't know why i'm missing it but a little more info about what you're doing with the battery and such would help

From what I read the OP is having issues with his idle after any time the battery needs to be disconnected. Like for example changing the clutch or replacing the alternator.

I thought when reading the title that he might be disconnecting the battery while the car was running but he doesn't seem to be making that mistake.

 

[LKWTSI]

Why are you disconecting the battery? I'm confused on that one. If it's to test the alternator, not all cars will run anymore with out the battery due to some of the electronics and the battery completing a circuit.

I can't place teh connection between your title and teh content text of the post... i don't know why i'm missing it but a little more info about what you're doing with the battery and such would help

I may have misled some of you, I apologize, but the problem stems from having the battery disconnected due to some repairs that have been carried out. As some of you who responded, the problem is the ECU doesn't seem to remember how to idle, once the work has been completed and the battery reconnected. I have had 2 instances of having major work done and the battery was disconnected for the reasons of safety and conserving the battery while the work was carried out. The car runs fine, but when you come to a stop the engine dies. Like I said in my first post, I seem to cure the problem by running it until it's up to operating temperature, then shutting it off and letting it cool. Once the car has done this at least twice it appearently cures itself. I was curious if this was normal or like someone quoted " the ECU has to relearn", and if so is there something that can be done to get past this, so I don't have to deal with it everytime the car is worked on with the battery offline. ALSO what is a DSMLink ?? I'm new to the DSM circuit, but have been around many different cars and know my way around the engine bay (used to rally back in the UK) , but I'm still learning about the DSM's. Which I have found to be a lot of fun and look forward to spending some time on the track with my Talon in the next few months.

Thanks for the replies.

 

[steve]

I may have misled some of you, I apologize, but the problem stems from having the battery disconnected due to some repairs that have been carried out.

As some of you who responded, the problem is the ECU doesn't seem to remember how to idle, once the work has been completed and the battery reconnected. I have had 2 instances of having major work done and the battery was disconnected for the reasons of safety and conserving the battery while the work was carried out. The car runs fine, but when you come to a stop the engine dies.

Like I said in my first post, I seem to cure the problem by running it until it's up to operating temperature, then shutting it off and letting it cool. Once the car has done this at least twice it appearently cures itself. I was curious if this was normal or like someone quoted " the ECU has to relearn", and if so is there something that can be done to get past this, so I don't have to deal with it everytime the car is worked on with the battery offline.

ALSO what is a DSMLink??

DSMLink is modified software for the Factory ECU that allows the user realtime logging and tuning. It requires a EPROM version of the ECU so that the modified software can be installed. DSMLink Homepage

The car dieing at stops is usually caused by the incorrect adjustment of the Basic Idle Speed Screw (BISS) or a bad ISC/IAC (same thing just 1G name and 2G name). There are other possible causes but check these first.

The car shouldn't die while it's relearning the trims. That makes me think your BISS is bottomed out or the ISC is having problems stepping.

 

[steve]

Mine was the isc witch caused mine to do almost the same thing

Idle Position Switch? Not telling the ECU that the throttle was closed?

Or

ISC which caused it.

 

[LKWTSI]

Thanks for the DSMLink info, I'll have to look into that as I progress with the mod's. As for the ISC, I have checked it per the steps outlined in VFAQ, so I suspect I may have a BISS problem, which I haven't checked yet. The strange thing is though, that it only did it for a little while, then disappeared. I very very occasionally get the thing to die, if I've been going hard on the throttle and then come to a stop, it'll drop to about 500rpm go to 750rpm then die. I'll start it back up and it'll idle fine. I'll look into dealing with a BISS leak from the forums unless someone wants to reply with the quick fix for it.

Thanks for the input folks.

 

[No_Skillz]

Only if you have a 1G DSMLink and that only applies to the DSMLink settings. The ECU still has to relearn the fuel trims and ISC parameters just like a stock ECU.


And I don't see DSMLink in the OPs profile.

I haven't worked with a DSM with stock ECU in so long... my bad.

 

[Nayr747]

Sorry to bring this back, but I've had this exact same problem for soooo long and I want to get rid of it! I installed a complicated alarm myself, so I had to take the neg battery cable off dozens of times. But if I took it off for more than about 2-3 minutes the car would "forget its idle" as the OP said.

Since I had to deal with this so many times I tested it out a lot. I found out that it will idle fine if you just start it up, but if you put any load on the engine (almost any amount) i.e. move forwards/backwards, once the clutch is released the RPMs will continue to drop past idle to zero and die. It will do this pretty much every time at first, but if it doesn't die it will always drop to almost zero for a second and try to rebound again and again. (I'm not sure on this but I think turning the wheel significantly or possibly even moving without any engine load (coasting down a hill) may cause the idle to lower or possibly die as well.)

The ONLY way to get the car to "re-learn" the idle was to move forward/backward so that the RPMs went at least a little above idle (maybe 300 or more above), then put it in neutral and wait at least 2-5 minutes of idleing (if it doesn't die), and then repeat. I once got this down to two times of doing this process for it to re-learn once. But most times it would take about 10 minutes of doing this annoying process. If it dies once you push in the clutch rather than just drop almost to zero then bounce back (usually a couple times quickly) then you have to repeat the process; starting it back up and idling after it dies without putting a load on it doesn't seem to really do anything. You can tell when it's learning by the way the RPMs will drop almost to zero, then rebound, then it will do it less and less extremely, then it will settle around idle and move very slightly to different RPMs as if it settles on an RPM then moves to a different one after a certain amount of time.

The weird thing is, it will NOT learn at all from just normal driving. You could drive all the way around the world and nothing would change (unless you sat at lights for 2-5 minutes a lot). The first few times I experienced this problem I drove around normally hoping it would learn by that. I probably drove 30 miles, on the highway and some city, trying to make it go away. When I would come to a stop light I would have to somehow press all three pedals at the same time, pressing the brake hard with the top of my right foot and the gas soft with the bottom side. If I shifted gears too slow, the RPMs would just continue to zero and I would be coasting, .

It also does not seem to learn if you perform this proceedure (load, then push clutch in and wait in neutral) if you are coasting or turning the wheel. Like when I would come to this stop sign on a steep long downhill, I would drive off from the sign down the hill then put it in neutral and see if it would learn while I was actually getting to where I was going. But it didn't seem to at all.

Other than rare occasions, the car has absolutely no problem with idle/dieing (unless the battery had been removed). So it is not a problem normally.

So does this happen to everyone else, and if not does anyone have any info on why it does it and how to fix it? I know the BISS and a couple other things have been suggested, but does anyone have any other insight?

 

[deank1]

Im not sure about the idling, however if your alternator is bad, then your car will keep dying and all your electronic stuff will stop working. If you wait a while you battery will regain its juice a little and re run everything however I would say test your alternator.

 

[Nayr747]

Im not sure about the idling, however if your alternator is bad, then your car will keep dying and all your electronic stuff will stop working. If you wait a while you battery will regain its juice a little and re run everything however I would say test your alternator.

Thanks. I guess I'm gonna be making a trip to the auto parts store to have them test it then.

OT: Defiant, or whoever the mod is, I don't think this topic is really resolved at all yet. Could you maybe change it from Resolved?

 

[deank1]

so what was the verdict?

 

[99redgst]

I have experienced similar symptoms when using lightweight flywheels. Never had an issue of stalling with a stock flywheel. Normally took 15-20 min of stop and go driving before it relearned.