My dad snagged a 1986 735i (E23) automatic with a cranks but does not run condition. It had sat for 10 years or so. It has ~70k miles and was previously owned by a lawyer.
We found that some numbnut had replaced the main relay with a relay a standard relay. That meant the DME was on when the key was off and vice versa. Since the crank sensor plugs had been smashed, we also installed new crank sensors.
We replaced the main relay, put some gas in it and it fired and ran.
It ran rough, but was ok for driving around Small Town, USA while figuring out what was wrong with it.
Suddenly it wouldn't shift out of first. We mistakenly thought that this was a governor problem, since that's what the internets said was typically the problem when a 4HP22 stayed in first.
It also needed a new front exhaust section and simultaneously tore the CSB loose inside its mount.
We pulled the driveshaft and replaced the CSB. While the driveshaft was out, we pulled the tailshaft housing off the transmission and find, duh, that since it's an *ELECTRONIC* transmission, there is not governor. BUT the output shaft speed sensor electrical connector had backed off. We replaced the speed sensor anyway and did a preventive service of the transmission. The fluid was BRIGHT red, so we suspect that it had been manifesting this problem intermittently and the prior owner had it serviced preventively. We also added an inline filter to the trans cooler return line.
We put it back together with a Bosal front exhaust section, and it started up again, although still ran rough. We decided that, due to the old gas in the tank that had only been diluted about 4:1 with new gas, we should preventively replace the fuel filter. We did that and it ran better, but still rough.
I left for the week to go to work, and my dad was using the car to drive around town. Then it wouldn't start. We've double checked everything we can find in the book and can't figure it out.
Things we've checked:
->Spark? None.
->Fuel pressure? None.
->Jump the fuel pump relay to hot wire the pump. [Edit:] Have fuel pressure, but engine still will not start
->Thea above items indicate the DME isn't doing anything.
->DME always on power? Good.
->DME key on power? Good.
->DME crank signal? +10V while cranking, but that should be ok, right?
->Ohmed out the crank sensors from the DME connector. They're within spec.
->Exchanged crank sensors. No change.
->DME voltage measurements were relative to the ground pin in the DME connector, so the ground is good.
->Tried another DME from my dad's (wrecked ) '85 635CSi. No change.
We found that some numbnut had replaced the main relay with a relay a standard relay. That meant the DME was on when the key was off and vice versa. Since the crank sensor plugs had been smashed, we also installed new crank sensors.
We replaced the main relay, put some gas in it and it fired and ran.
It ran rough, but was ok for driving around Small Town, USA while figuring out what was wrong with it.
Suddenly it wouldn't shift out of first. We mistakenly thought that this was a governor problem, since that's what the internets said was typically the problem when a 4HP22 stayed in first.
It also needed a new front exhaust section and simultaneously tore the CSB loose inside its mount.
We pulled the driveshaft and replaced the CSB. While the driveshaft was out, we pulled the tailshaft housing off the transmission and find, duh, that since it's an *ELECTRONIC* transmission, there is not governor. BUT the output shaft speed sensor electrical connector had backed off. We replaced the speed sensor anyway and did a preventive service of the transmission. The fluid was BRIGHT red, so we suspect that it had been manifesting this problem intermittently and the prior owner had it serviced preventively. We also added an inline filter to the trans cooler return line.
We put it back together with a Bosal front exhaust section, and it started up again, although still ran rough. We decided that, due to the old gas in the tank that had only been diluted about 4:1 with new gas, we should preventively replace the fuel filter. We did that and it ran better, but still rough.
I left for the week to go to work, and my dad was using the car to drive around town. Then it wouldn't start. We've double checked everything we can find in the book and can't figure it out.
Things we've checked:
->Spark? None.
->Fuel pressure? None.
->Jump the fuel pump relay to hot wire the pump. [Edit:] Have fuel pressure, but engine still will not start
->Thea above items indicate the DME isn't doing anything.
->DME always on power? Good.
->DME key on power? Good.
->DME crank signal? +10V while cranking, but that should be ok, right?
->Ohmed out the crank sensors from the DME connector. They're within spec.
->Exchanged crank sensors. No change.
->DME voltage measurements were relative to the ground pin in the DME connector, so the ground is good.
->Tried another DME from my dad's (wrecked ) '85 635CSi. No change.
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