whalenlg

Month 3 of my 944 Turbo endeavor...finally have everything updated/replaced to where I have no worries to drive normally.

Non Stock upgrades:
-Lindsey Dual Port Wastegate from 2002 + Lindsey MBC
-Huntley Stage 1 turbo from 2002
-Replaced OEM cat with a universal Cat + O2 sensor - passes smog with near 0 emissions

MBC is turned all the way down (counterclockwise)

Under WOT in 2nd gear, my stock boost gauge edges up towards 2 bar.

I put in a cheap Bosch boost gauge in line with the boost controller (after the T that goes to the wastegate & before the boost controller).

At idle, the Bosch reads 0 - seems like I should be measuring <0 to show the vacuum pressure since it can go to -30 psi
Stock boost gauge shows <0 at idle and I verified correct vacuum pressure under the hood with a real vacuum gauge

Under WOT in 2nd, the Bosch goes past 20 psi and I don't feel any overboost back off

Neither one of these readings seem correct, so is there a simple way to test the Wastegate on the car? I was thinking to clamp the output of the MBC and check the boost again.

Any ideas?

Thanks in advance
Mike

red44T

Contrary to what one would do naturally. CCW increases boost. CW decreases.

https://www.lindseyracing.com/LR/Parts/TECHMBC.html

At the bottom

whalenlg

Hi - that's for the single port setup - mine is a dual port which the same page says "When adjusting the controller on this set-up, you adjust the **** "clockwise" to raise the boost level, and "counter-clockwise" to lower it."

Mike Goebel

Did you try a different setting on the MBC?

Mike G.

Tom M'Guinn

I'd start by hooking up the boost gauge to a good manifold port. You can T into the line going to the KLR in the passenger footwell without running a new line into the cabin, or T into the line on the side of the intake where it goes to the fuel pressure regulator. The factory boost gauge would be pegged to the right at 20psi, and if your Bosch gauge reads vacuum, you should be seeing that. So I agree that something doesn't seem right with the gauge readings.

Do you know if you have aftermarket chips? Most of them eliminate "overboost" protection. I'd tread carefully until you get it sorted. When you shoot in the dark with these cars, the bullets always tend to hit the head gasket.

whalenlg

Not yet - I was looking for general procedures to isolate the components.

whalenlg

Thanks Tom - I haven't opened up the DME to see about the chip, so that's a concern. Most of the major service history was provided and there was no evidence of a chip upgrade (but of course I wouldn't count on it until I open up the DME). But of course I'm more concerned about either the boost gauge, MBC or DP Wastegate at this point.
I'll move the Bosch gauge to where I connected my vacuum gauge to see if I get vacuum in the engine bay. There are already lines coming into the glove box for the MBC so that's what I hooked the Bosch gauge into. I don't really like the thin plastic tubing it came with, so I probably won't touch the KLR line for now.

Mike Goebel

When I first wanted to check my boost I also bought one of those cheap BOSCH gauges from Pet Boys. What a POS! It bounced all over the place and never stabilized. Got a VDO and it is rock solid. I have to admit I'm always surprised at all the issues that come up with first time install of a MBC. Seems like it should be plug and play. I guess I'll find out first hand this weekend.

Mike G.

whalenlg

I put my vacuum tester gauge under the hood and connected to the vacuum line that connects to the fuel damper. Got negative pressure at idle (great).

Moved the vacuum tester to the MBC input - reads 0 at idle (same as the Bosch).

Connected to the Bosch to the vacuum line that connects to the fuel damper. Got negative pressure at idle (great).

Ok so both gauges are working and it seems that connecting the Bosch to the hard pipe between the turbo and intercooler is the wrong spot as it is always positive pressure.

Looks like I need to connect to either the KLR or the manifold to get a good reading.

Tom M'Guinn

Not entirely sure where you hooked up the controller and gauge, but maybe snap some pics. Sounds like whatever line it is, it's open to atmosphere somewhere...? I think it's worth confirming here you have the MBC and wastegate hooked up right.

whalenlg

This Lindsey diagram shows how I am set up before adding in the boost gauge - I put the gauge between the T and the MBC.

Mike Goebel

100% agree, unless I'm wrong then its your fault.

Mike G.

whalenlg

Hmm How does that explain the 20+ psi pressure reading at WOT?
Should the intercooler pipe be seeing negative pressure at idle? Anyone actually measure this point?

Mike Goebel

DUH! I'm wrong. It makes perfect sense that the IC feed pipe is at 0 psig at idle. The entry to the turbo is at atmospheric pressure and since the compressor isn't adding any boost because there is no exhaust mass flow (no power to run compressor) at idle the exit side of the compressor is also at 0 psig. Why you getting 20 psig I have no idea other than you are getting 20 psig.

Mike G.

whalenlg

Meandering along on this mystery, I took apart the manual boost controller to clean it out and bench tested to make sure it was working ok.

Put it back in the car with a boost gauge on the output side of the boost controller and verified only 2-4 libs of pressure when I set it at minimum (that goes to the secondary port on the dp wastegate).

Even still, I was still getting too much boost in 2nd gear, so I opened up the DME. There was a handwritten note on the mylar sheet "DME 944T.M89 8.25.95" and a business card for "Club Sport Autowerks Engineering." The chip had what looks like an original sticker (# 1267355235) on it, but after I cleaned the DME metal case, there was a handwritten note like "Stage (unclear) Chip 8/95".

So of course I google "Club Sport Autowerks" and get this article about the guy whose card I found in the DME - 1 month after the date on the DME mylar this happens:
https://www.nytimes.com/1995/09/26/n...olice-say.html

Let me know what this sounds like or if anyone has ever heard of "Club Sport Autowerks".
I assume that the EPROM was reprogrammed but not re-marked.
It would be great to borrow an original chip to see if the boost gets scaled back to reasonable levels.
Next step is to do an isolated pressure test of the wastegate primary port.