325 Stalling issues after battery change

[cornershop]

Folks

Had a none starting episode yesterday on my 1988 325 Auto after none use for two weeks. Tried starting and nothing - dash lights dimmed slightly but engine didn't turn at all.

Bit drastic, but replace battery with a new Bosch item (always change battery on new-to-me old cars as matter of course anyway)

New battery fitted, car fired fine and idled perfectly - blipped the throttle after 2-3 mins, engine spluttered and died. Started again, but died straight away. Same again on 3rd attempt.

Left for 4hrs or so thinking i'd flooded it, fired up ok so took it for a spin. On slowing at first t-junction, could feel the revs dropping slightly but did not die. At subsequent stops, feel the same thing - engine struggling but not dieing. Then stopped at some lights, engine cuts out. Starts, but cuts out. Starts again, just, so i continue home.

Stop in side street once home, put in Reverse, engine dies. Try again, just starts, I stop once reversed into position, engine dies.

Quick bit of research suggests:

TPS - where is this?
DME relay - is this the orange relay under the cover?
ICV - will look to get this cleaned
Multi pin connector - not looked for this yet, easy to reach from above?

Finally, also read that the ECU goes in to learning mode once battery is disconnected - is this true? Could this be related?

Apologies for all the questions, just don't want to spend loads replacing bits not related to above symptoms

Cheers in advance

[Brianmoooore]

Just disconnecting a battery doesn't usually cause problems, but trying to start a car that has a nearly flat battery tends to scramble the ECU's idle settings.
Can't explain why it initially idled OK, but try driving it some more, but maintain the idle with the throttle, and see if things improve.

[Morat]

I got this a lot when I had a dud battery and fell into a bit of a routine that only took 10 minutes. Just start it, and as Brian said hold the idle on the throttle. It should relearn how to idle. Once it idles with your foot off the accelerator try letting the revs drop from about 3000rpm to idle with 0 throttle. If it stalls, try again and catch it at idle with the throttle.
Then I drive off and when it has warmed up take it to the redline at part throttle and then full throttle. It should soon smooth out throughout the rev range and you're done.

[cornershop]

Thanks for the quick response chaps, appreciated.

Morat - when you say drop revs from 3k > 0 - are you holding revs at 3k for a period of time before dropping, or just a blip to 3k?

Will give it another try this week - plugs are new, but will give leads/dizzy/rotor a check too and give a quick coat of WD40.

Cheers

[Morat]

I was trying to replicate dropping the clutch as you come up to a junction, the classic place for the engine to stall as it coasts down to idle from whatever revs you were doing before you slowed. The idle control can be a bit slow, resulting in a dip below idle revs and then a bounce back up to idle - or a stall if the ECU/ICV/whatever doesn't catch it.

My car also tends to misfire/stumble for a second at about 3.5k rpm when accelerating if the ECU has lost it's settings. Once I've driven through it a couple of times it doesn't happen again. I've no idea if yours will be the same but the problem soon clears up if it is.

[HJG-E30]

Common problem I find. Plus makes you look a right idiot when you're trying to turn around in a tight space, stall, start, stall, start

[cornershop]

Now sorted, largely following Morat's advice

Had the car idling on the throttle for at least 20mins with no joy. Found the trick was to get the car to idle as low as possible (500rpm) for 5-10 mins enough for the Ecu and presume Idle valve to work in harmony.

Took for it a blast once idling back at 650-700 ish, now running like a champ

Thanks all

[5six7eight]

I've just used this method to sort my car out. Have had battery problems for a while with it finally giving up this weekend. Put a new battery in this afternoon and then hit this problem with it not idling and needing revs to stay going, albeit lumpy as hell.

So, went out and started the car, used a bit of wood between the seat and pedal to hold it at around 1500rpm. The car was coughing and spluttering, it sounded real rough. Locked it up and left it running for 15mins. When I went back out it was revving steadily and removing the wood let it drop back to just under 1000rpm.
Then, with Morats final tip I took the car out and up to the redline at part, then full throttle. All sorted!

Cheers Morat. This really is the most helpful forum I have ever come across!