Dropping boost with ecu install. Long!

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Dropping boost with ecu install. Long!

Postby audiisbest » Fri May 19, 2017 4:37 pm

I'm struggling with boost drop after a couple of hard pulls. This ECU in previous 20v pulled to 21 lbs. Now in this 20v pulls to 21 first couple of hits, then drops to 15lbs . Shut car off, restart, back to 21lbs for a couple of hits again?

Decided to look through my stash of N75's and see exactly what i have before pulling current valve out.

Valve i pulled from my last DD, now parts car turns out to be a h model (AAN). And, like the other two valves i have out, all three have 300ish ohms vs the 28-30 they;re supposed to have. (one in the now DD, glacier blue is 28 ohms and clicks on the output test)

The "last" pearl white DD seemed to have much better boost down low, and now know why! Seems that the wastegate hose was on the long nipple and not supplying pressure to wastegate.

Plan is to pull the N75 and physically test on bench. (passed ohms and output test/clicking solenoid)

Did like the quicker boost with N75 plumbed incorrectly! Thinking i could could plumb in a MBC once i get this sorted?

Below is other post from elsewhere detailing everything done to resolve

So, finally installed my chipped ECU in the glacier blue. Old ECU was putting out 11 lbs – 1.7ish which was about right for stock.

Initial road test with new ECU had 21 lbs on first hit. Then shortly thereafter would only go to apx 15 lbs.

Then discovered that if I shut the vehicle off and restarted I’d get 21 lbs again?

No codes, although I did get a 1111 once (typical for chipped ECU’s)

Car runs smooth and well, will pull to apx 7k with no problems

History, all work in last month or so, purchased in Feb and worked on till recently

Full tune-up to include narrow tip rotor
Timing belt etc.
New bosch correct oxygen sensor
Gutted cats
Replaced all vacuum lines
Replaced FPR with know good as original crapped out
Cleaned ground points
Ben swan chip, wastegate spring, 2.5pt (consistent 21 lbs)
New throttle body hose
Samco hoses
Forge bypass valve
Fuel injectors sent out for cleaning/testing
Installed new knock sensors (Bosch)
Pressure checked to 25lbs.


IAT sensor, ohmed out okay
TPS, checked out good
Altitude sensor, checked, seems okay, pulled sensor from car that had chipped ECU and put in
ECU ground to body, good!
Disconnected MFTS to see if any difference (reducing boost)
Checked waste gate control, ohms correct and clicks with output test. Believe it’s good? Was going to swap parts car solenoid in, but that one does not ohm out correctly! Now determined glacier white had a "H" N75 which was also plumbed incorrectly!


Posts: 6
Joined: Mar 27, 2017
Location: Catskills NY

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