3B swapped US model 90 running issues

[UrS4boy]

Question like that, what is the stock vaccuum the diverger valve needs to open ? 1.3 bar

You need to do some review of what vaccum means in Bars.

A strong throttle off vacuum on an AAN (for example) is around 22 inches of mercury (Hg). This is only about 0.745 Bar. The diverter valve should be open way way before that, like 5 inches of Hg or about 0.16 Bar (don't quote me on that but it will be a very small amount of vacuum).

[Racerguy381]

Now it's on to sorting the last little bit of wiring. My cooling system isn't operating correctly yet and a few gauges aren't reading properly either. Should be easy from here on out though!

[etsola]

Question like that, what is the stock vaccuum the diverger valve needs to open ? 1.3 bar ?

I have a dahlback racing diverter but unknown spring strenght in it. I want to test it before putting it in.

Glad you found your issue ! I have 1990 CQ swapped with a 3b

Thanks

[UrS4boy]

By-pass Valve Info

Exactly but if the spring is light enough it won't need any help to open under vacuum. The Vortech valve has an adjustable spring tension on the top.

Here is how a By-pass Valve is supposed to work on a 3B/AAN/ABY/ADU:

Read this: By-pass Valve Info:
http://forums.quattroworld.com/s4s6/msgs/20994.phtml

[Racerguy381]

Exactly but if the spring is light enough it won't need any help to open under vacuum. The Vortech valve has an adjustable spring tension on the top.

[andy10v]

The vac line provides boost pressure to keep it shut, and vacuum to open it.

[Racerguy381]

Thanks for the info Andy! I was thinking of possibly running some kind of one way check valve in the vacuum line to keep it from opening under vacuum but still pressurize the BOV under boost.

[andy10v]

Motronic is not designed to run an atmospheric blow off valve, it should recirculate. At idle engine vacuum pulls the diverter valve open and then the MAF is not metering the airflow into the engine and will not fuel correctly.

You can fit a stiffer spring to prevent idle pulling it open, but soft enough when you lift off boost it will open, you will still get incorrect afr when you do that as air that has been measured into the system is now lost.

I would just set it up as per OEM.

Or pressure mount the maf and live map, or switch to speed density if you really want it to go whoosh.

[Racerguy381]

Good news I figured out the source of the problem! It was the damn Vortech BOV and the vacuum line running to it. Soon as they undid the vacuum line the car runs perfectly fine! Anyone know why this would be or do I just need to not run the vacuum line to the top of the BOV considering it just vents to atmosphere and not back into the intake.

[Racerguy381]

Done all that Newsh... The ECU I have is a stage 1 chipset. But I have a stock ECU I tested and the car runs the same.

[newsh]

Is there any chance your ECU has been modified?

[newsh]

Clean the maf connector terminals, both male and female contacts, with 1000 grit wet and dry and coat them with silicon dielectric grease.
Check or replace the white temp sensor on the back of the head.

[Racerguy381]

The car is still in the middle of the engine swap. I have it in the garage on blocks so I can't test drive it. And I was able to check the 02 with the multimeter and the FPR with a gauge. I know it's Rich from all the gas fumes in the garage when it's running with the MAF plugged in and and the amount of voltage then it's reading when terminals 1 and three are jumped with a multimeter

[andy10v]

Any fault codes?

How did you check the FPR and lambda?

How rich? How do you know its rich?

Is this cold start, when driving, when hot?

[UrS4boy]

G70 Mass Air Flow (MAF) sensor info including cleaning, testing, etc

G70 Mass Air Flow (MAF) sensor info including cleaning, testing, pins out of their sockets, etc:

http://forums.quattroworld.com/s4s6/msgs/20442.phtml