My poor zed (2.0i) dropped into limp mode :(

[Jason Goldschmidt]

Afternoon all,
It's fixed! It was a faulty throttle body causing the problem.

I am not sure how it failed, I might disassemble it to find out more.

After replacement my average mpg has shot up. I must have managed well over 40mpg on a long motorway run.
Performance and fuel economy have both greatly improved; very happy.

 

[DomBulfin]

Hi Jason,

I think I’m experiencing the same issues you had last year with my ‘58 plate Z4 2.0i.

Haven’t plugged the car in yet, but the symptoms match.

I have the EML light, throttle limited around 2000rpm struggling to idle and sounds like it isn’t running on all cylinders.

I would also say for some time I’ve questioned whether the throttle response is really there for a zed. Feels just a bit sluggish and I’m sat at around 30mpg average. Sounded like your fix improved all these issues.

How easy a DIY job was the inlet manifold etc replacement you did? I’d consider myself a half decent DIYer (give me a step by step or a YouTube video and I can probably get the job done but have limited mechanical knowledge) - is this something I can probably do myself or is it best I drop the car with a mechanic?

I’m having the car plugged in first thing so hopefully I’ll know a little more tomorrow.

Thanks in advance.
Dom

 

[Jason Goldschmidt]

Hi Dom,

Welcome to the forum and sorry to hear you are having issues with your Zed.

My first suggestion would definitely be to get your car plugged into either a good code reader or ISTA/ INPA diagnostic software. The fault codes present should give us a much better idea of what is going on.

The mechanical work I did to solve this issue was very simple and well within the skill limits of most DIY mechanics, I only had to replace the throttle body in the end. It was the diagnostics that really took the time and patience.

There are many issues that can present similar symptoms, hence why I chased my tail on this one for so long. I am more than happy to offer my opinion on the issue you are having; post the codes up here and hopefully we can help

 

[DomBulfin]

Hi Jason, thanks for your reply.
I dropped the car at the garage today to pull the codes and got the following:

2A67 - VVT - Activation
2D07 - DME - Throttle valve potentiometer
2CF8 - DK Pot sensor.

I’ve not had a chance to look those codes up yet. My mechanic cleared the bottom 2 codes. The first won’t clear.

I was going to take the car away and put a few miles on it to see if anything came back up but to both our surprise the car was dead as a dodo. Wouldn’t start, wouldn’t even try to start and the roof which I’d had down for the drive wouldn't budge either. So I left the car with him and 5 minutes later he rang me to tell me it was now fine. Very odd! I’m sure someone on here knows exactly what that was about but it was a mystery to me.

I’ve left the car with him as I had a few jobs on the to do list for his electrician anyway, but I’m keen to work out what to do to sort the codes to save myself paying for the mechanic’s time working through the problem!

Any assistance would be greatly appreciated.

 

[Faf680]

Add me to the list of answer seekers. Was doing 60 mph on the highway, on an off ramp on a 75 degree day last week when my 2003 Z4 3.0 E85 suddenly lit up a ton of lights on the dash and acceleration disabled. The radio remained on, all electronics on, but the engine would not respond. I was almost killed and fortunately waved my hands frantically with top down to prevent getting rear ended.

Once stopped, I placed the car in park, it seemed okay, but would not resume throttle response. I turned it off, turned it on, and all codes cleared. I did not have a code reader handy anyway. The engine purred like the feral cat it is and I was off again on my way.

I parked it outside my place, jumped out and tried to process nearly dying.

I then turned the car on again a few days later, drove it around the block revving as I went and trying to get into a high gear to try and replicate the issue. NOTHING. It drives perfectly.

Took the car to a mechanic, who noted the oil was overdue a change. He checked the codes, the only one that was stored being a loose of faulty battery connection. He tightened the terminals, the code cleared. Oil change was performed.

We have test driven the car five times. No codes, no replicating of the issue.

I love my Z4, however, I am too young to die.

Thoughts?

 

[DomBulfin]

Can't offer any help right now, but if the auto electrician can shed any light on my car's hissy fit I'll share on here.

In terms of my codes, it's clear I have VVT motor and throttle body issues- still waiting to hear from my mechanic/electrician what the plan of action is.

 

[gookah]

I had this issue when my voltage regulator died on the alternator, Into limp mode had a job to get the engine to rev and every type of light lit up, due to the battery running extremely low,
New Voltage regulator was about £25 off eBay, no issues since.


Loose connections to and from the battery could also be a cause

 

[Faf680]

I had this issue when my voltage regulator died on the alternator, Into limp mode had a job to get the engine to rev and every type of light lit up, due to the battery running extremely low,
New Voltage regulator was about £25 off eBay, no issues since.


Loose connections to and from the battery could also be a cause

Thank you for the input. I'm an industrial engineer so I like to know how things work. Do you have any further details on how a loose connection to or from the battery could cause a car travelling 60 mph to suddenly have zero throttle response?

 

[Faf680]

Thank you for the input. I'm an industrial engineer so I like to know how things work. Do you have any further details on how a loose connection to or from the battery could cause a car travelling 60 mph to suddenly have zero throttle response?

Sorry also, how did you know your voltage regulator had died? Did it throw up a code for you?

 

[gookah]

no codes for that, just lots of others from the aftermath of a very low battery,

I got a second fully-charged battery to use to get me home, just 5 minutes away.
Once home, I put a meter on the battery posts and it read about 11 volts with the car engine running. It should read almost 14v, with the normal output from the alternator to charge the battery.
The 11 volts was what was still left in the second battery but that had already started depleting from it's 12 volts when I put it on, the battery I took off had about 9 volts in it.

With no output from the alternator the car will just suck the power out of the battery until there is not enough to keep all the systems going, which then all start to go into fault mode.

A loose connection may not be able to pass all the current through it that the car requires, it may also get hot as the resistance becomes very high.

 

[Faf680]

no codes for that, just lots of others from the aftermath of a very low battery,

I got a second fully-charged battery to use to get me home, just 5 minutes away.
Once home, I put a meter on the battery posts and it read about 11 volts with the car engine running. It should read almost 14v, with the normal output from the alternator to charge the battery.
The 11 volts was what was still left in the second battery but that had already started depleting from it's 12 volts when I put it on, the battery I took off had about 9 volts in it.

With no output from the alternator the car will just suck the power out of the battery until there is not enough to keep all the systems going, which then all start to go into fault mode.

A loose connection may not be able to pass all the current through it that the car requires, it may also get hot as the resistance becomes very high.

First, thank your this is a really solid explanation. I ask this follow up because I really don't know the answer.

In my case the car lost acceleration. I turned it off, it turned back on without issue and kept chugging along. If the voltage regulator been faulty and depleted the battery to the point of failure as you mentioned . . . wouldn't that same battery have failed to turn on the car again?

It's funny you mention this because the car had been idle for a few months. I thought the battery was dead. A buddy used his power pack to charge it and it has been working fine since. This may explain it though.

Let me know what you think.

 

[t-tony]

I would also suspect the inlet cam sensor, when it failed on my Z3 2.0 it didn't throw a fault code or put the light on but the symptoms were the same.

Tony.