Urgent Please help with suspected vacuum leak question

[rcorujo]

Hello People:

Need help troubleshooting engine rough idling and when press the pedal driving power loss and back firing sound in my 1985 Carrera euro. The car was running fine and suddenly start misfiring while driving. Sounds like working on 5 cylinders.

I suspected that the spark plugs need replacement and I just replace all 6 but the condition continues the same as before.

Reading misfiring issues here in the forum I think the car has a vacuum leak or maybe a bad injector. So What to look from the removed spark plugs to discard the bad injector possibility?

Another thing I did was the removal of the big elbow boot between Throttle body and air flow meter for inspection of possible vacuum leak cracks and I found that the rubber part of this Air/Hose vacuum Pipe P/N - 93011032803 is cracked; Please see the photo:


So the big question is if this cracked hose can make my car engine rough idle and when press the pedal driving power loss and back firing sound ???

Thanks for your time and help!

[cabmandone]

Your problem doesn't sound vacuum related to me. I had cracks like that on several hoses and my car didn't run as you're describing. The only time my car did what you are describing is when I accidentally bumped the connector for my CHT and it wasn't making contact. The car would start hard, and have no power under throttle and would backfire. There's nothing wrong with starting at the vacuum lines and getting things sorted out there. I'd also want to verify your fuel pressure at the fuel rail.

[Bob Kontak]

That crack wont do this.

DId anyone move the distributor timing?

Take one plug wire off at a time and start the car and blip the throttle. If you find one that when pulled off makes no change, you are getting close to the problem. Could you have wires on backwards?

[ischmitz]

Maybe you are running rich and that's why the engine sounds rough? An open CHT can cause that. It's the white connector (top one) on the left side of the engine. Unplug it and see if it makes a difference. Then with an Ohm meter check the plug on the engine. It needs to read 1k - 3k when the engine is cold and 90 Ohm when engine is hot.

[rcorujo]

I was driving normally and suddenly begin the roghness, if I pressed the accelerator pedal continue rough and with some strong noises from the muffler.

No one touch the distributor.

I suspect about the crack hose from the vacuum pipe or a clogged injector. Also Im thinking to replace the elbow rubber boot that has a small crack where the brake pipe goes.

May be is the CHT, what are the bad CHT symptoms ?

[GregT2000]

2nd the suggestion to inspect the plugs and wires again.

I have had similar symptoms, once with a loose terminal nut on a spark plug on a 89 carrera and once on an 91 Benz with a worn plug wire.

[Bob Kontak]

Originally Posted by rcorujo

May be is the CHT, what are the bad CHT symptoms ?

What you described.

Pull the part out of the engine and see if it gets worse or stays the same.

[T77911S]

check the rubber \boot from the AFM to the throttle for cracks

[rcorujo]

Hello Guys:

My friend Sadly find out that the miss fire is produced by Broken engine Stud
Maybe its the end of my Porsche experience, Only God knows...

I may have to sell this beautiful 1985 Carrera Euro as is. I'm feeling terrible, but trust God will.