Too much boost after mods removed?
#1
Nordschleife Master
Thread Starter
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I've pulled out all the engine mods in the car until I can afford to do em right...They were't much, a jetted banjo bolt and autoth chips.
With that setup, the car was boosting too high anyway...18psi in 3rd gear with a #145 jet.
However..the car is still boosting to 1 bar boost on the stock gauge...I haven't checked the aftermarket cause its just hanging there right now...I have to ghetto install it to the steering wheel colum for the next test session.
SO, what's causing my excessive boost? Vac leak? bad/drilled cycling valve?
If it is an issue with the cycling valve, how much does is it approximetely? Can I use an MBC without a dual port WG (and without modifying my stock WG)? In installing the MBC, I would assume the cycling valve is removed? If not, can the cycling valve be removed when installing an MBC?
Is 1 bar safe on my stock chips? No matter what I'm turning it down to stock...but I just wanna know if its safe to test further.
thanks,
Adrial
With that setup, the car was boosting too high anyway...18psi in 3rd gear with a #145 jet.
However..the car is still boosting to 1 bar boost on the stock gauge...I haven't checked the aftermarket cause its just hanging there right now...I have to ghetto install it to the steering wheel colum for the next test session.
SO, what's causing my excessive boost? Vac leak? bad/drilled cycling valve?
If it is an issue with the cycling valve, how much does is it approximetely? Can I use an MBC without a dual port WG (and without modifying my stock WG)? In installing the MBC, I would assume the cycling valve is removed? If not, can the cycling valve be removed when installing an MBC?
Is 1 bar safe on my stock chips? No matter what I'm turning it down to stock...but I just wanna know if its safe to test further.
![Big Grin](https://rennlist.com/forums/images/smilies/biggrin.gif)
![Big Grin](https://rennlist.com/forums/images/smilies/biggrin.gif)
thanks,
Adrial
#3
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just a suggestion, maybe you should advertise your autothority chips on ebay as 1 bar chips, which is what they should be, 18-20 psi may not garner much bidding.
Jason
Jason
#5
Burning Brakes
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Adrial, I have seen this before on 89 951s and 88TS. Your car is screwed beyond repair, you must now sell it to me for salvage price. (you are getting VeRy sLeEpY)
No, really though. I dont have much of a clue about what is happening ot your car. Hopefully it isnt something very bad. Now the fun part, what are you gonna get with the money your chips yield? Since youre going factory specs (assuming only factory MECH. specs) why not get a killer amp and some nice 10s or 12s to bump your favorite tunes?
No, really though. I dont have much of a clue about what is happening ot your car. Hopefully it isnt something very bad. Now the fun part, what are you gonna get with the money your chips yield? Since youre going factory specs (assuming only factory MECH. specs) why not get a killer amp and some nice 10s or 12s to bump your favorite tunes?
#6
Race Director
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Wierd, maybe your car had both the banjo-bolt mod and shimmed wastegate for inscreased boost?
Also check for any leaks or clogs from the banjo-bolt all the way to the wastegate. Could be the cycling-valve is broken and not letting any of the boost-control signal get to the wastegate at all?
Also check for any leaks or clogs from the banjo-bolt all the way to the wastegate. Could be the cycling-valve is broken and not letting any of the boost-control signal get to the wastegate at all?
#7
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with fully stock chips, shouldn't the boost limit circuit cut the fuel or spark or something if the boost gets too high?
and when you say one bar of boost on the stock gauge, you mean the needle is pointing to 2, right? i think the 'A' in bar stands for 'absolute', so 1 is ambient pressure at sea level. to see how much boost you are getting over ambient, turn the key on and see what the gauge reads with the engine not started, then subtract that. mine must not be calibrated right because i live at less than 1,000 feet and mine only goes to 0.8 or so with the engine off.. it goes up to the 1.8 range before the boost limiter jars my teeth, although it's hard to read, so i might be getting a full 'bar' of pressure (there i go using an absolute scale as relative... grrr). that's, what, like 14.7 psi or something?
and when you say one bar of boost on the stock gauge, you mean the needle is pointing to 2, right? i think the 'A' in bar stands for 'absolute', so 1 is ambient pressure at sea level. to see how much boost you are getting over ambient, turn the key on and see what the gauge reads with the engine not started, then subtract that. mine must not be calibrated right because i live at less than 1,000 feet and mine only goes to 0.8 or so with the engine off.. it goes up to the 1.8 range before the boost limiter jars my teeth, although it's hard to read, so i might be getting a full 'bar' of pressure (there i go using an absolute scale as relative... grrr). that's, what, like 14.7 psi or something?
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#9
Nordschleife Master
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Ambient for me (just turn the ignition to the run position, pos II i guess) is a tiny tiny bit under 1 bar...like .95 bar...
Anybody have any tips for checking if the cycling valve was drilled? Which openind would be drilled? The one to the wastegate, the intercooler pipe (banjo bolt) or intake? I would think the one to the WG?
thanks,
Adrial
Anybody have any tips for checking if the cycling valve was drilled? Which openind would be drilled? The one to the wastegate, the intercooler pipe (banjo bolt) or intake? I would think the one to the WG?
thanks,
Adrial
#12
Nordschleife Master
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Yes, I am still selling it, but I have a few people I need to get back to.
I ghetto rigged the aftermarket gauge temporarily to the top of the steering column (tape!
)...the car is in fact making stock boost, further proof that the factory gauge is useless. I didn't get a great look at the gauge because this was at night and the light in the gauge wasn't hooked up (only the interior light on), but it looked like it was @ about 12psi.
The cycling valve doesn't appear to be drilled.
On a related note...I drove my destination, stayed there for an hour and then drove away. Maybe 4 minutes after leaving, this doofus was on my *** (couldn't see his headlights...nope wasn't a camaro cop car)....so I got on it. I was in 3rd off boost (2500rpm?) when I got on it...once under way I looked in the rear view and I saw smoke..once I shifted to 4th it appeared to go away. It has been a few days since I got on it...and the car did do a short trip (1.5 miles) this morning...Is it safe to assume that what I saw was just water burning off? I did check the oil cap while the car was resting at home and it did have condensation on it. Typically I'll go the long way to school (oil doesn't get fully warmed up...but better than a 1.5 mile drive, not sure how far the long way is...5 miles maybe) and then off to work (10-15 miles). I just wanna make sure that its normal behavior.
I checked the exhaust tip when i got home, it was black and sooty...but not wet.
thanks for any peace of mind,
Adrial
I ghetto rigged the aftermarket gauge temporarily to the top of the steering column (tape!
![Big Grin](https://rennlist.com/forums/images/smilies/biggrin.gif)
The cycling valve doesn't appear to be drilled.
On a related note...I drove my destination, stayed there for an hour and then drove away. Maybe 4 minutes after leaving, this doofus was on my *** (couldn't see his headlights...nope wasn't a camaro cop car)....so I got on it. I was in 3rd off boost (2500rpm?) when I got on it...once under way I looked in the rear view and I saw smoke..once I shifted to 4th it appeared to go away. It has been a few days since I got on it...and the car did do a short trip (1.5 miles) this morning...Is it safe to assume that what I saw was just water burning off? I did check the oil cap while the car was resting at home and it did have condensation on it. Typically I'll go the long way to school (oil doesn't get fully warmed up...but better than a 1.5 mile drive, not sure how far the long way is...5 miles maybe) and then off to work (10-15 miles). I just wanna make sure that its normal behavior.
![Big Grin](https://rennlist.com/forums/images/smilies/biggrin.gif)
thanks for any peace of mind,
Adrial