JBrown

If a CIS 930 saw 1.8 bar boost i would think you would blow the motor? Am i wrong. I no i just put a tial waste gate on my car with a 1 bar spring. I was no told that with a GHL exhaust you will see 1.2 bars and bang went my motor.

strudel

It looks like there are a few things to check. I'll send the boost gauge to Palo Alto Speedo to get checked, and get the waste gate checked to make sure it's operating correctly.

PorschePhD

Pull a plug and you will know for sure. See if it has what looks like little ***** on it. If it does you have problems.

1.2 will not blow the motor first time it hits, or even the second time unless the motor is weak to begin with. 1.8, yes it would crack a ring in a hurry.

pete77930

with the older GHL headers you'll have a bad case of boost creep if your running a good turbo. I had a .7 spring in my tial and was consistantly getting 1.2 bar in 2nd thru 4th, and my kill switch always cut in in 3rd and 4th. I had a larger diameter, shorter wastegate pipe grafted onto my headers in the stock location... now I have no more boost creep.

PorschePhD

You need to watch the new ones as well. They too will still creep as tested so if running GHLs and a HF you will need to run a lower spring rate than desired if you want to hit target. It will overshoot. We have switched to B&Bs and havbe not had any issues due to the design change.

sand_man

Stephen, explain this please. When I pulled and changed my spark plugs I noticed that the ones I removed (Bosch W3PDO) sort of looked like the electrodes (combustion chamber end) had these "little *****". I've been traveling quite a bit and still haven't had a chance to tear my engine apart. I've been setting up my garage for the rebuild. I'm curious to see what other suprises awaite me. I'm deffinately going with a new waste gate. What about replacing my injectors too?

PorschePhD

If you weld it almost looks like welding slag all over the electrode. I will see if I can snap a picture of a plug here. Not sure my camera will get in well enough.

The injectors should be checked for pattern and flow. I have a special injector tester (550.00) to check opening pressure, flow, and pattern. FWIW any diesel repair shop should be able to test them as well.

sand_man

In the faithful words of SNL (Saturday Night Live) character Rosana Danna Anna (Gilda Radner):"...There's ALWAYS somethin'..."!!!!!!!!!!!!! The welding slag that you describe is right on the money! Is this caused by overboost? I have B&B headers (about 7 months old) and the original waste gate. To my knowlege the OEM spring is still in it. To my knowledge the overboost switch has not been grounded out.

PorschePhD

It is not always overboost that creates denotation. Don't misread that. Overboost will cause it, but other things get overlooked as in your case that overboost does not exist. Timing is a factor, CO is a factor, and octane which relates back to CO or AFRs. Cars will detonate even with the smallest amounts of boost if an improper condition exist.

strudel

I checked a plug and it looks fine. I guess the next thing is to test the wastegate.

strudel

The line from the intercooler runs to the boost ****. Then from the other side of the boost **** to the lower inlet on the waste gate, (the turbo manual refers to this as the control line). I connected an air hose to the line from the intercooler and can control the air flow back to the inlet hose by the boost ****, so the **** is working.
According to the manual, with the engine running, there should be noticealbe vacuum in the control line. I don't feel anything. Is this connected up right?

nathanUK '81 930 G50

No, it's not right.

Do what I said earlier in the post and see what happens.

strudel

Bear with me, I appreciate the help.
Do I leave the top connection (a line that runs from the front center of the waste gate to the bowls of the motor) connected or should I disconnect it?
I ran air through the control line of the waste gate (21 psi) and can hear the wastegate opening & closing.


It sounds like the wastegate never opens to me.
Try connecting the tube from the intercooler to the lower connection on the wastegate. Let the top connection on the wastegate vent to the atmosphere.
See what boost you get after this.

strudel

Try connecting the tube from the intercooler to the lower connection on the wastegate. Let the top connection on the wastegate vent to the atmosphere.
See what boost you get after this.

No boost.
So, should I assume that the line coming down from the manifold (?) is the control line and goes to the back of the wastegate. And the line from the intercooler is the vent line and goes to the front of the wastegate? Meaning who ever connected it up had it backwards? The boost **** goes between the control line and the back of the wastegate?

Kevin

The line from the intercooler cannot be a vent.. It is your supply pressure used force the diaphram open. For just a minute please leave your boost controller out of the picture.. Do you have a factory Wastegate?

If you have done this, then someone might have installed a smaller wastegate spring so that the manual controller could bleed off the control pressure. Regardless you are flying blind and need to find out what you have installed.. Finding this out now will keep your engine from going back to the shop. You can install a stock wastegate spring for starters..