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This is my first post here. I have been lurking for sometime though. Here is the scoop...

My girlfriend has a 1988 535is we are turbocharging. We are nearing completion and I had a few questions on how to put it back together .

We took this apart last summer and changed the head gasket, there were a few plugs I am having trouble placing. I have some terrible pictures from my cellphone, I used my advanced MS paint techniques to better show what I need help with.

First is 3 plugs, 2 black and 1 blue by the intake manifold, I cant for the life of me find where these go.


And this 2nd photo is a vacuum line coming from the under the intake, I tried to trace its path as its not well pictured.







I'll get some more pictures up of the car and of some of our progress if anybody is interested. Any help on the questions would be appriciated though. Thanks

The blue plug goes to the cold start valve, which is under the intake manifold and unnecessary generally.

The other two plugs are for the flywheel reference sensors, which are necessary if you're running motronic 1.0. One is speed and one is the reference sensor, so they have to be plugged in properly. There should be a grey and black plug hanging around somewhere on the harness. If they're plugged in backwards, the car won't start.

I can't see the line you're talking about, but I'm assuming it goes inside the car to the climate control sensor on the bottom of the driver's knee panel.

wkohler hit the nail on the head.

Do you have anymore pics of the turbo setup? What turbo/manifold are you running? And what are you doing about engine management?

wkohler wrote:The blue plug goes to the cold start valve, which is under the intake manifold and unnecessary generally.

The other two plugs are for the flywheel reference sensors, which are necessary if you're running motronic 1.0. One is speed and one is the reference sensor, so they have to be plugged in properly. There should be a grey and black plug hanging around somewhere on the harness. If they're plugged in backwards, the car won't start.

I can't see the line you're talking about, but I'm assuming it goes inside the car to the climate control sensor on the bottom of the driver's knee panel.

The black and grey plugs I am holding are coming out of the harness. Is there a lower harness on the transmission they connect to then?

I'll check for a vacuum line through the firewall when I get home from work.

Thanks a lot.

clongo wrote:wkohler hit the nail on the head.

Do you have anymore pics of the turbo setup? What turbo/manifold are you running? And what are you doing about engine management?

There was an ebay vender selling a setup from a 745i. We used the manifold, a new k27 turbo and 60lb injectors that were included. We are making a wastegate adapter for a tial 38mm, downpipe and intercooler piping.

As far as engine managment: The seller included a chip for the ECU. We are going to give it a shot ( I am not sure at this time who programmed the chip), but if we have any problems I will be contacting TCD for one of theirs.

We haven't started on the intercooler piping or downpipe yet, but I'll get some pictures as it comes about. It'll be a week or two yet.

Here's a better picture of the car though, this was when we took it out of storage last year before tearing it apart. She's looking to order coilovers and lower it more once it's running. Right now its on cut eibachs.

There are two sensors in the left side of the bellhousing. They have wires attached that run up the left side to those plugs. There are two braces for the intake manifold and they reside in the rear one. Diagnostic connector in the front one.

Mr._Vales wrote:We are making a wastegate adapter for tial 38mm]

Care to share a pic of this? Willing to make another?

Those 60lb injectors are way too big for the stock motronic. You won't be able to lean them out. Try to find a used set of 24lb or 30lb injectors. The chip is only for timing. You will also need a RRFPR for adding fuel pressure while in boost.

I had the same issues with my recent turbo build.

In terms of the two black plugs for the speed and reference sensors, one of my two black plugs had a grey zip tie on it, not sure if that was from the factory, or from a wise mechanic along the way. The one with the grey zip tie went to the....grey connector! Seems kind of foolish to use two identical connectors for non-interchangeable wiring.

I'm willing to bet the vacuum line simply plugs into a small hose barb sticking out of the bottom of the manifold. You should be able to run your hand down and feel a vacuum barb at the bottom of the manifold.

I have been doing a home made water to air intercooler, check out the post in case you havn't seen it yet.

The original sensors have a grey and black connector. Replacement sensors were all black because...they're the same sensor.

Ok, well my disdain for Germans has once again dissipated

Thanks for the clarification!

Cupholder Nazi wrote:I had the same issues with my recent turbo build.

In terms of the two black plugs for the speed and reference sensors, one of my two black plugs had a grey zip tie on it, not sure if that was from the factory, or from a wise mechanic along the way. The one with the grey zip tie went to the....grey connector! Seems kind of foolish to use two identical connectors for non-interchangeable wiring.

I'm willing to bet the vacuum line simply plugs into a small hose barb sticking out of the bottom of the manifold. You should be able to run your hand down and feel a vacuum barb at the bottom of the manifold.

I have been doing a home made water to air intercooler, check out the post in case you havn't seen it yet.

It is that vacuume line! . It's hooked up to the intake, but I do not know where it leads to from the manifold

ldsbeaker wrote:

Mr._Vales wrote:We are making a wastegate adapter for tial 38mm]

Care to share a pic of this? Willing to make another?

It hasn't been made yet, but I will post pictures. My friends doing most of the fabrication for me, but I'm sure he'd make another if you were interested.

clongo wrote:Those 60lb injectors are way too big for the stock motronic. You won't be able to lean them out. Try to find a used set of 24lb or 30lb injectors. The chip is only for timing. You will also need a RRFPR for adding fuel pressure while in boost.

I didn't even consider a fuel pressure regulator, thanks.

I'll look into smaller injectors, 60lb's may be incorrect too. It was a year ago when we bought them, so I may be mistaken on the flow rate.

Mr._Vales wrote:

ldsbeaker wrote:

Mr._Vales wrote:We are making a wastegate adapter for tial 38mm]

Care to share a pic of this? Willing to make another?

It hasn't been made yet, but I will post pictures. My friends doing most of the fabrication for me, but I'm sure he'd make another if you were interested.

I'd gladly pay for this adapter as well. Let me know if your friend wouldn't mind. Thanks!

That vacuum line should lead to the stock fuel pressure regulator, and perhaps the temp sender on top of the thermostat housing.

You definitely need to get an FMU (RRFPR) to add on. Basically what it does is restricts the return flow to the tank, creating a higher pressure in the fuel rail, causing more fuel to flow out of the injectors. The higher the boost, the more it restricts the return line, the higher the fuel pressure in the rail, the more fuel flows through the injectors. Todd supplies the BEGI 2025 unit with his turbo kit, and its worked very well for me. You can see it mounted on top of my intake manifold in the picture of my engine bay, its the shiny round thing between the stock FPR and the throttle body.

Mr._Vales, where are you located? (looks like IA tags) YOu may want to add this to your profile. If anywhere near some of us locals us, you may want to check this out. Last year when had a small meet-n-greet that went over very well.

Hope to see your car running soon! We could use more fresh turbo blood around these parts.