Hi!
Im new here but have been reading for years. I have a strange problem. Whenever my battery dies or I disconnect it, The car will struggle to run. It will crank but not stay running. I have to keep pressing the throttle pedal to keep it running until it finally can stay running on its own, which is about 20 minutes. After I get it running again, for the next 3 to 4 days, the initial acceleration seems to kinda bog down. After the 3 or 4 days, its like back to normal. This also happens if I remove the 25 Amp fuse under the hood (which hopefully wont ever happen again as I have replaced the connector and relocated the fuse). I have 2 codes on my OBD, one is for MAF and the other is for O2 sensor. I tried a new MAF from ebay but the car will not even start with it installed so I reinstalled my old one. I cant change the O2 until I can get a new exhaust line installed. But still, this is so super strange. Can someone please help me to understand what is going on? I have a few other issues that I like to ask about but I wont do it on this post. Its my everyday driver and it serves me extremely well. Any help would be greatly appreciated!

Here a link to my car on YouTube:

 

the car won't run without a good battery. that 25A fuse is the main power for the entire fuel injection system, so it won't run without that, either.

it sounds like a whole bunch of problems are stacked up, starting with a bad MAF (get a good replacement, not a bad used one).

 

how much gas do you usually keep in the tank? if your in tank pump is not working it helps to keep
more than 1/2 tank at all times.

 

I have a new battery. The MAF was new too but the car will not start with it installed so Im using my old one. I noticed the problem when I changed the fuse and holder, then my battery died. After charging it, i had this issue again. Got a new battery. the same issue. After 20 minutes, the car will run fine and continue to run fine until i disconnect the battery....FOR ANY REASON.

 

I keep it full all the time. I love gas!

 

is the alternator charging your battery when the engine is running? what is the voltage reading across the battery when engine is idling?

 

Yes, the alternator is charging the battery. 14.3 to 14.4 with the engine running. If I disconnect the battery right now, ill have the problem. If i never have to disconnect the battery, ill never have the problem. Strange! Only when the car has 0 volts.

 

if the 'new' MAF won't run, then its a bad MAF

 

that voltage is too high it should be around 13.8 after it has been idling for a while. you may have an over charging situation
going on. i would double check that reading.

 

Ok. This morning it was 19 degrees outside. I started the car (with no issues), and ran the heat on low "(1)". After 15 minutes, the voltage was at 13.8. I dont believe that the charging is an issue.

 

yes 13.8 at idle is normal. so, you are disconnecting the battery to avoid it discharging when the engine is off? or for some other reason?

 

The only time Ive had to disconnect the battery was when I had to replace it and when I reworked the 25 amp fuse holder. The old one wouldnt keep a charge so I had to jump it off several times until i was able to replace it. Every time I had to jump it, the issue I explained appeared. Ive had the new battery for a month. A few nights ago I accidentally left my parking lights on and ran the battery down. The issue reappeared. Its been 5 days since and the car has been fine. Whatever is happening only happens when either the battery voltage is low, or disconnected, OR that 25 amp fuse is removed.

 

well it seems at least on the surface the charging system is working properly and should keep the new battery
charged. you could do a load test but if the engine starts and runs reliably then probably not necessary.
perhaps you can just watch it for now. btw i love your "anti-theft" starter switch

 

Well, its fine at the moment. 100% confidence that it will start and run as it should. But in the back of my mind, I know if I disconnect that battery, Im going to have this problem. Its like the ECU loses communication with all the sensors or something or forgets theirs values or.......whatever. A true nuisance. And thanks about the switch. Its a nice mod.

 

That is how it was explained to me way back when I was still taking my 240 to the dealer. Usually, after installing the battery and running for a while, the ECU will compensate somewhat for a bad MAF and the car will run and drive pretty much normally. Under these circumstances it will throw a code as you have mentioned.

I think your MAF is dying and the cheap aftermarket (non-Bosch) are junk as far as what I have read. Try to get a Bosch unit. I usually pick them up in the junkyard for about $35 when I see them there (getting harder to find). It has to be off of a '89 or later model including 740's or 940's (same engine).

 

I just happen to have a 94 940 that I bought from my brother in law for $100. I just haven't gotten it's too my house yet. I'm going to try switching the MAF. See if that is the problem. I have a new O2 sensor I'd like to try too but I'd never get it out. Id twist the pipe. The car runs a little rich at times. I can smell the unburned fuel. But it's not all the time