E38 740il no power to the pedal

[Bowenmatt20]

Hey guys I’m new here so bare with me. I just bought a 1998 bmw 740il from a private owner. The car runs well but when you put it in gear and press the gas, it will move but only go up to about ten miles an hour. There is no response to the pedal at all so it’s only moving when you take your foot off the brake. Owner stated that all of the sudden he went to drive it one day and that was the case and was told by two mechanics that it was the fuel pump. I changed the fuel pump with a brand new one and it still did the same thing. The car is slightly leaking engine oil and transmission fluid possibly. At one point someone use jb weld on the valve covers along with old gaskets so I’m sure there is a leak somewhere up there. I plan on
-changing engine oil and filter. Hasn’t been changed in years
-Transmission fluid flush and filter and possibly replacing the temp sensor under the filter.
-testing around the valve covers to see how bad it’s leaking and find the oil/possible transmission fluid leak
-check for vacuum leaks
-checking pvc(ccv?) valve to see if it is stuck

What else should I check to point me in the right direction? Any help at all would be appreciated this is kinda the deepest I’ve dove into an old car and want to make sure I’m not overlooking something. I also would like to point out that there are no dash lights on and the car runs fine at idle and if in park an neutral you can rev the car up fine with no strange noises

Thank you
-matt

[Sundaycruzer]

Drive by wire problem? Need to have a proper scanner used to determine if pedal and throttle are working. Also check dme plug for corrosion. That’s all I can think of.

[Bowenmatt20]

Drive by wire problem? Need to have a proper scanner used to determine if pedal and throttle are working. Also check dme plug for corrosion. That’s all I can think of.

Is that part of the ecu?

[jclausen]

No, certainly the ecu knows what the position of the gas pedal and throttle body to process the right info back to the engine controls. When you press the gas pedal it makes the throttle body plate move, this is done electronically with motors. You need to check for faults. All so there are two connectors on the intake manifold the could be reversed meaning the the wrong connections get made, I don't know if something like that happened

[Sundaycruzer]

I’m thinking more of corrosion at dme. Pedal and throttle are unrelated. I would check to see if throttle actuator is moving first.

[Bowenmatt20]

No, certainly the ecu knows what the position of the gas pedal and throttle body to process the right info back to the engine controls. When you press the gas pedal it makes the throttle body plate move, this is done electronically with motors. You need to check for faults. All so there are two connectors on the intake manifold the could be reversed meaning the the wrong connections get made, I don't know if something like that happened

I honestly don’t know if someone could have switched them up. That is possible given the state of the car. I have Not checked that the throttle body actually moves when I hit the pedal. Will check that today. Like I said in neutral it will rev as high as you want. But in gear nothing happens. If someone did switch those connections is it ok for me to try and flip flop them without causing damage?

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I will check that too but need to locate it. Is that in the trunk?

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I’m thinking more of corrosion at dme. Pedal and throttle are unrelated. I would check to see if throttle actuator is moving first.

I will check that too but need to locate that. Is that in the trunk?

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Also is there a way to accurately check the transmission fluid while still in the car?

[Mayorchuck]

How are your cluster pixels? Are there any errors showing up there? The car will act similar if it is in Trans failsafe.

[Bowenmatt20]

How are your cluster pixels? Are there any errors showing up there? The car will act similar if it is in Trans failsafe.

Pretty sure it’s not in trans failsafe. No red light. The pixels aren’t all there though

[Timm]

Certainly worth a throttle reset using the following procedure:

Get in the car and shut the doors
Turn the ignition key to position II - but don't start the car
Press the throttle to the floor and keep it there for 5 seconds
Turn the key to the off position but do not remove the key
Let go of the throttle pedal
Wait 2 minutes without fiddling with anything

You are now ready to go, start the car and see if all is well.......

[Bowenmatt20]

Certainly worth a throttle reset using the following procedure:

Get in the car and shut the doors
Turn the ignition key to position II - but don't start the car
Press the throttle to the floor and keep it there for 5 seconds
Turn the key to the off position but do not remove the key
Let go of the throttle pedal
Wait 2 minutes without fiddling with anything

You are now ready to go, start the car and see if all is well.......

Thanks Tim I’ll try it tomorrow. One thing I didn’t mention is the traction control light flashes when I hit the gas. No power just traction control light flash

[Bowenmatt20]

I’m thinking maybe the wheel speed sensors have gone bad. Or even the abs module. Going to order the front wheel speed sensors and replace to see if anything changes

[Gilly32]

the traction control flashing while in gear and trying to move tells me its something with the ABS or a bad module. it is on any other time? go away when youre in park?

make sure you try Timm's procedure too.

[acspecialists]

The DSC light would be a good tidbit to start with. If the wheel speed doesn't match up the DSC will cut the throttle input. For example when I was driving in the snow I could not go more than 10mph no matter how much I pushed on the pedal. Get yourself a laptop set up with INPA so you can check codes and sensor feedback otherwise you are just spinning your wheels. Well I guess not in your case.

[Bowenmatt20]

Going to try Tim’s procedure tomorrow as well as replace the front two wheel speed sensors. And no it’s only when I press the throttle does the abs light flash non stop. If I don’t press it goes away. One observation I had is that on the passenger rear in the little box where the sensor is mounted, there are two sensors. But on the drivers side there is only one. Can someone confirm for me that is normal?

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The DSC light would be a good tidbit to start with. If the wheel speed doesn't match up the DSC will cut the throttle input. For example when I was driving in the snow I could not go more than 10mph no matter how much I pushed on the pedal. Get yourself a laptop set up with INPA so you can check codes and sensor feedback otherwise you are just spinning your wheels. Well I guess not in your case.

Yes that’s exactly what I think is happening. Either the sensors are bad or the module needs to be rebuilt. Is there any way I can test the module to see if that’s the problem? What if I unplug it and try to drive the car

[Bowenmatt20]

It is only when I hit the throttle that the abs light flashes. Not while just in park. Hell even in drive it doesn’t flash until you hit the gas. I inspected the wheel speed sendors and they look awful. Very brittle. I also noticed the rear passenger side has “two” sensors in the box where it’s mounted, while the driver side only has one? Is this normal? Also if it is the abs module how do I test if it’s bad? Can I unplug it and try to drive the car?


[QUOTE=acspecialists;30238342]The DSC light would be a good tidbit to start with. If the wheel speed doesn't match up the DSC will cut the throttle input. For example when I was driving in the snow I could not go more than 10mph no matter how much I pushed on the pedal. Get yourself a laptop set up with INPA so you can check codes and sensor feedback otherwise you are just spinning your wheels. Well I guess not in your case

I’m goung to replace the front two sensors. Try to drive it. And if that doesn’t work then I’ll replace the rears. If that doesn’t work I’ll have to check the abs module but is there a way to check the module to see if it’s bad?

[Mayorchuck]

Going to try Tim’s procedure tomorrow as well as replace the front two wheel speed sensors. And no it’s only when I press the throttle does the abs light flash non stop. If I don’t press it goes away. One observation I had is that on the passenger rear in the little box where the sensor is mounted, there are two sensors. But on the drivers side there is only one. Can someone confirm for me that is normal?

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Yes that’s exactly what I think is happening. Either the sensors are bad or the module needs to be rebuilt. Is there any way I can test the module to see if that’s the problem? What if I unplug it and try to drive the car

Yes. That is the brake wear sensor. One on each axle. Just the opposite on the front.

[Bowenmatt20]

Yes. That is the brake wear sensor. One on each axle. Just the opposite on the front.

Ok thanks for confirming!

[Bowenmatt20]

Can anyone give me any info on if there’s a way to test the abs module?

[Sundaycruzer]

Can anyone give me any info on if there’s a way to test the abs module?

You haven’t scanned the car for codes? I’d stop throwing parts at the car that probably won’t fix it. You need to have the codes from dsc to know if it’s failed or if it’s a sensor. Considering I’ve had 3 dsc fail in the 4 e38’s I’ve owned, you might want to diagnose it like a professional would, then replace parts.

[Bowenmatt20]

You haven’t scanned the car for codes? I’d stop throwing parts at the car that probably won’t fix it. You need to have the codes from dsc to know if it’s failed or if it’s a sensor. Considering I’ve had 3 dsc fail in the 4 e38’s I’ve owned, you might want to diagnose it like a professional would, then replace parts.

I haven’t been able to get anyone to come scan it yet. I have a guy coming. If it is the abs/dsc who would you reccomend for a re build?

[Sundaycruzer]

Module masters is one source. I’ve used an indie shop to send mine out. I’ll have to ask them where they sent mine.

[Timm]

I've just realised this is a pre-vanos engine - and I bet you the problem is that the connectors for the main throttle position sensor and the ASC throttle position sensor have been swapped around as they are exactly the same pattern. This causes exactly the problem you are having.....

[Bowenmatt20]

I've just realised this is a pre-vanos engine - and I bet you the problem is that the connectors for the main throttle position sensor and the ASC throttle position sensor have been swapped around as they are exactly the same pattern. This causes exactly the problem you are having.....

Timm can you tell me where these are located please?

[Sundaycruzer]

I believe he’s referring to these.

[Sundaycruzer]

Or these