Intake connectors; plastic is very hard, should it be? wiring harness?

[BMSman]

The intake connectors between the MAF and the DK's on my car are very hard. I was expecting them to be pliable to some extent. Is this the effect of age and heat or are they supposed to be hard plastic? They are surprisingly inexpensive to replace (~ $8 ea).

850iintake.jpg

Any words of wisdom with regards to the Engine wiring harness; As you can see in the pic below, mine touches the valve cover and the outer jacket is broken. I can tape it up that but what concerns me is the wire bundle feels very hard and inflexible. I suppose a bit of heat may soften it up but I'm afraid of damaging it when I move the wiring conduit on top of engine. What sort of tape should I use, will cheap pvc tape quickly turn to goo?
850ivac.jpg

You may also notice that the vacuum line to one of the fuel pressure regulators is not connected. How would this affect engine performance?

[danieldd]

I can speak to the boots between the MAF & the DK. Yes, they are hard and most of it is due to age and heat. I replaced mine, since they're not too expensive. The new ones are a bit more pliable and somewhat easier to work with. Suggest you buy new ones since they are are relatively inexpensive.

With regard to the wiring harness, you may consider stripping off the outer jacket and using self vulcanizing tape. This is just a suggestion. I am sure others here will chime in an offer some better solutions.

[Ahmed303]

I'd recommend you take the whole harness out and rebuild it. But it will be a pretty tough and time consuming job. If you want a temporary solution to tape up the harness, you could use these:

Fire Tape

Quick Fix Tape

[wokke]

definitely replace these boots. First they become very hard and then they crack - preferably underneath where you don't see it.
Unmeasured air will enter the engine, your CEL will come on and you start searching

[toomanyparts]

I'd recommend you take the whole harness out and rebuild it. But it will be a pretty tough and time consuming job. If you want a temporary solution to tape up the harness, you could use these:

Fire Tape

Quick Fix Tape

Thanks for the links! I will pick some of this up.

[Bluesman]

Thanks for the links! I will pick some of this up.

Mike, If you need some I have a roll of clothe tape BMW used in the e24/28s to wrap their engine bay wires that your welcome to use. It doesn't "melt" when hot and stays in place. LMK. see you soon possibly this weekend.

[Neuance]

It looks like your fuel pressure regulaters are hooked up wrong, the driver side regulator vacume line is supposed to be hooked to the passenger side DK and vice vesa, remember the intake runners are crossed over ( the left one feeds the right side and the right one feeds the left side)

[toomanyparts]

Mike, If you need some I have a roll of clothe tape BMW used in the e24/28s to wrap their engine bay wires that your welcome to use. It doesn't "melt" when hot and stays in place. LMK. see you soon possibly this weekend.

Steve,

Thanks. I might just take you up on that offer!

Mike

[BMSman]

It looks like your fuel pressure regulaters are hooked up wrong, the driver side regulator vacume line is supposed to be hooked to the passenger side DK and vice vesa, remember the intake runners are crossed over ( the left one feeds the right side and the right one feeds the left side)

Thanks for pointing this out...

Can you explain what these vacuum lines do? My understanding is the FPR bleeds off fuel pressure back to the fuel tank to maintain the desired fuel pressure in the fuel rail. What does the vacuum line do - modify fuel pressure based on engine needs? Does it really matter if these are crossed?

[Ahmed303]

The Vacuum lines carries any fuel vapor/excess mist back to the DKs to be mixed with airflow and burn off. If they are crossed, it is hard to troubleshoot any FPR or emissions (excess HC, etc.) related issues.

PICT0633.jpgPICT0940.jpgPICT0951.jpg

[BMSman]

The Vacuum lines carries any fuel vapor/excess mist back to the DKs to be mixed with airflow and burn off. If they are crossed, it is hard to troubleshoot any FPR or emissions (excess HC, etc.) related issues.

PICT0633.jpgPICT0940.jpgPICT0951.jpg

I read elsewhere that if there is any fuel in these lines it is an indication the FPR is bad (diaphragm deteriorating).

- - - Updated - - -

I should have searched the web... the vacuum line lowers the fuel rail pressure at idle.

[Ahmed303]

I read elsewhere that if there is any fuel in these lines it is an indication the FPR is bad (diaphragm deteriorating).

That is correct for wet fuel traces.

I should have searched the web... the vacuum line lowers the fuel rail pressure at idle.

Yes.

[cartoonz]

The Vacuum lines carries any fuel vapor/excess mist back to the DKs to be mixed with airflow and burn off....

Uhh... no. No, they definitely do not perform that function.
Well, ok they might if the regulators are broken and perforated... but that is most certainly not the design.

[Ahmed303]

I stand corrected.

[Neuance]

the vacuum lines control the fuel pressure based on the amount of vacuum produced by the intake. The lower the vacuum the more fuel is allowed to return to the tank, and of course the higher vacuum is going to let less fuel go back to the tank as the demand from the injectors is going to be greater. That is why the vacuum lines need to be hooked up to the correct DKs.