Thanks me too! There is the "day of the dead" I hope today will be the " day of the dead misfire" The weekend saw a very polished Mini and the exhaust rattle fixed.
Well folks. The Mini won again! I got to borrow a car to go fit the sensor about an hour ago. Same problem. Which leaves me with no clue to what the issue is. With the Tmap plug off the engine runs fine but a little rich With the plug on the misfire is between 2500 to 3900rpm with the plug on another Tmap not in the intake the engine runs rough and very rich but no misfire. The new Tmap does not show 4 volts on pin #4 like the others. The 4 wires from the Tmap only go to the ECU. If the ECU was the problem then this issue would have been present when they had the ECU on the donor car at the repair shop. I did think the problem could be the ECU ground so I cleaned all those grounds over the weekend, unless I'm missing one?. The mystery is why I don't have 4 volts on pin 4 and why the engine runs fine without the Tmap.
Maybe the intake is leaking? I have disco fog machine so I might blow some fog through the intake pipe
I think you can forget about the bigger hammer now Chris. I'd start thinking small shaped charge! :deadhorse:
If'n it can only be the ECU do you have any doubts that whoever checked out your ECU is totally correct with their prognosis ??
The thing is they ran my ECU/EWS on a R50 they had in the shop. The engine ran fine. They stop/started the engine several times, they sent me a video because like you I had doubts about their abilities. So I'm sure the ECU is ok.
Here's what i'm thinking which is not much but anyways: The Tmap is showing less airflow than actual at that rpm range. The mixture gets to lean and that lean mixture is the actual cause of the misfire. Vacuum leak in the intake might be the reason for all of it.
The lack of voltage on pin 4 could distort the way the ECM interprets the sensor, give the false airflow reading and be the reason for all that mess as well. Whatever the reason you must be getting close, man.
I would go back to basics. Re check all mechanical parts, I think checking for a vacuume leak is a great idea. Didn't this start with the bad gas?
Thanks for the suggestions last night I tried the fog machine down the intake which didn't do much because the throttle butterfly is closed. So I pulled off the intake and sealed it off at the throttle body,then I blew down the valve cover pipe to listen for leaks but unfortunately there were none. Anyway not getting the voltage on #4 pin must have something to do with the issue so I thought about cutting the sensor ground wire to the ECU and run it directly to the chassis to see if the voltage appears to #4 pin, worse case is I would fry the sensor. Yes the problem started after the bad fuel but the engine runs way better than it did because the misfire was worse back then. Now the misfire just happens in a small rpm range.
I've read a ton of stuff on Tmaps for different cars today and they all say I should have an input of 5V and an output of 1.2 V at idle and 4 V at full throttle or 4v ignition on/engine off. I get nothing which says the Tmap is bad but seeing as this is the 4th Tmap I doubt the sensor is the issue or the ECU. Has to be the wiring, I suppose there is a chance the harness I fitted is bad too.
Here's the latest: I got the Tmap voltage working fine by cleaning the plug pins with a file. However when starting the engine the problem was still there but seemed to take longer to happen So I did an electrical test on the pre 02 sensor, this was 12v key on/engine off but at idle the reading should be 6v I have the going up and down from 3.68 to 7.89v If I have to buy 2 more 02 sensors that'll have to wait until January.
Maybe if you drive it for a while it'll correct itself now that you have the T-Map working properly. The ECU could still be trying to compensate for the erroneous readings you were getting before. Then again, I don't know that much about these cars. Maybe a new condenser and clean the points.
Reseting the ECU might help. Is the engine still running a bit rich but OK with the tmap disconnected?
I did a test last night. Same as before. The engine runs fine although a little rich with the Tmap plug off, also I tried the plug on the new Tmap with the old Tmap in place. The engine runs really rough and very rich but no misfire. The Tmap somehow sends some message to the ECU sensing the misfire. I even tried plugging in the other 02 sensor but not fitted to see what happens. Same issue. I can do the reset tonight. At this point I've thrown enough money at this problem to buy another used Mini R50!
ah yes, the experience is..........buy a Subaru rally car next time LOL Anyway I thought maybe the crappy fuel gummed up the cylinders. Does Seafoam work? Sea Foam Sales Company