Help Boost jumping
18 February 2003, 05:43 PM
#1
Scooby Regular
Thread Starter
Join Date: Jul 2002
Posts: 258
Likes: 0
Received 0 Likes
on
0 Posts
I have replaced now my original BOV, instead of a Forge one.
Other mods are : Unichip, Samco hoses, Scorpion exhaust.
When driving the boost went to 1.4bar, so I retuned it with a bleedvalve to 1.25bar.
Probably the Forge was broken because the piston inside was not going in a straight way, but more sideways, that could explain the higher boost when using the original BOV.
But when I floor it now from 40mph in 4th gear, the boost goes to 1.25 then back to 1.1 and then back to 1.25 (sometimes 1, then 2 times...) and then going down to 1 (on 5000rpm)
What could explain this behaviour, I cleaned all the hoses and solenoid, and have a new MAF also.
Help me out here
Wally
Other mods are : Unichip, Samco hoses, Scorpion exhaust.
When driving the boost went to 1.4bar, so I retuned it with a bleedvalve to 1.25bar.
Probably the Forge was broken because the piston inside was not going in a straight way, but more sideways, that could explain the higher boost when using the original BOV.
But when I floor it now from 40mph in 4th gear, the boost goes to 1.25 then back to 1.1 and then back to 1.25 (sometimes 1, then 2 times...) and then going down to 1 (on 5000rpm)
What could explain this behaviour, I cleaned all the hoses and solenoid, and have a new MAF also.
Help me out here
Wally
18 February 2003, 11:25 PM
#5
Scooby Regular
Join Date: Oct 1999
Posts: 3,491
Likes: 0
Received 0 Likes
on
0 Posts
Last attempt ever...
A BOV will never ever raise your boost, worst case, it will lower it when there is a leak somewhere.
Using a bleedvalve to help control boost with a Unichip is a bandaid, a full remapping of at least the solenoid duty cycles is in order there.
A Forge may help during lift off/gearchanges, but at the cost of being less protective of your turbo.
The haunting boost typically suggests that either a wire in the Unichip came loose (this is the ECU trying to control overboost), typical overshoot/undershoot scenario, or your MAP pressure is actually way higher than your boost gauge pressure suggests (i.e. leak somewhere). Or the Unichip boost controller is fried.
MAF sensors have got zilch to do with all this, as do blue hoses.
Check all hoses, and make sure there is no leak anywhere. Borrow a standard working OEM dumpvalve to see yours is not leaking. Ask your dealer (the great one who lets you play with DeltaDash) for a replacement to check this out.
Again, try listening up & be a bit less frantic... a dumpvalve will not, I repeat, NOT, increase boost. At best, boost stays the same no matter which one you use, at worst, it will lower it because of leaks. Your story suggests both the programmed Unichip duty cycles are off the scale and your OEM dumpvalve is buggered.
Don't push your car until you sorted this out. Don't want to read your next post "turbo had gone bust because of overspeed".
Theo
A BOV will never ever raise your boost, worst case, it will lower it when there is a leak somewhere.
Using a bleedvalve to help control boost with a Unichip is a bandaid, a full remapping of at least the solenoid duty cycles is in order there.
A Forge may help during lift off/gearchanges, but at the cost of being less protective of your turbo.
The haunting boost typically suggests that either a wire in the Unichip came loose (this is the ECU trying to control overboost), typical overshoot/undershoot scenario, or your MAP pressure is actually way higher than your boost gauge pressure suggests (i.e. leak somewhere). Or the Unichip boost controller is fried.
MAF sensors have got zilch to do with all this, as do blue hoses.
Check all hoses, and make sure there is no leak anywhere. Borrow a standard working OEM dumpvalve to see yours is not leaking. Ask your dealer (the great one who lets you play with DeltaDash) for a replacement to check this out.
Again, try listening up & be a bit less frantic... a dumpvalve will not, I repeat, NOT, increase boost. At best, boost stays the same no matter which one you use, at worst, it will lower it because of leaks. Your story suggests both the programmed Unichip duty cycles are off the scale and your OEM dumpvalve is buggered.
Don't push your car until you sorted this out. Don't want to read your next post "turbo had gone bust because of overspeed".
Theo
18 February 2003, 11:31 PM
#6
Scooby Regular
Join Date: May 2001
Posts: 403
Likes: 0
Received 0 Likes
on
0 Posts
you care more than most Theo, it does you credit 
It could be an intermittent contact problem in a connector somewhere, which will mean examining every single connector in the engine management system, if you fancy it.
It could be an intermittent contact problem in a connector somewhere, which will mean examining every single connector in the engine management system, if you fancy it.
18 February 2003, 11:49 PM
#7
Scooby Regular
Join Date: Dec 2001
Posts: 238
Likes: 0
Received 0 Likes
on
0 Posts
I still reckon it's his cleaning fluid: Independant tests have shown that some cleaning fluids can actually clog the pipes to such an extent that they will cause lower diameter thresholds within pressure-regulated intakes, causing the abnormal Boost spikes you're seeing Wally.
My advice would be to soak these pipes in a de-congestion mixture (typically 30% toluene, 30% brake fluid and 40% Night Nurse) an then put it all back together and measure the results.
My advice would be to soak these pipes in a de-congestion mixture (typically 30% toluene, 30% brake fluid and 40% Night Nurse) an then put it all back together and measure the results.
Trending Topics
19 February 2003, 07:10 PM
#8
Scooby Regular
Thread Starter
Join Date: Jul 2002
Posts: 258
Likes: 0
Received 0 Likes
on
0 Posts
to THEO...
Spend the whole afternoon with my dealer (Haestincks in BOOM)
The Forge was bleeding due to a broken rubber seal.
I contacted Mark from EMS an he recommended the following :
Now using back my original BOV, the jumping is cured also...
First we did a run with the bleedvalve but without the solenoid connected, result way to lean mixture in the low revs !!!!
Then we connected back the solenoid and I adjusted the bleedvalve till 1.25bar, that would be safe together with the Unichip.
Then I had the idea of checking the Unichip wires. Result of that : a wire that holds itself together with just one copper string, and thats no good. I checked everyting out and found three wires that were very badly connected. I joined them back together and problem was solved.
Now running with 1.25-1.3 peak pressure and around 1bar on 6000rpm.
That should be fine I think till I go for a ECUTEK. Soon...
Spend the whole afternoon with my dealer (Haestincks in BOOM)
The Forge was bleeding due to a broken rubber seal.
I contacted Mark from EMS an he recommended the following :
Now using back my original BOV, the jumping is cured also...
First we did a run with the bleedvalve but without the solenoid connected, result way to lean mixture in the low revs !!!!
Then we connected back the solenoid and I adjusted the bleedvalve till 1.25bar, that would be safe together with the Unichip.
Then I had the idea of checking the Unichip wires. Result of that : a wire that holds itself together with just one copper string, and thats no good. I checked everyting out and found three wires that were very badly connected. I joined them back together and problem was solved.
Now running with 1.25-1.3 peak pressure and around 1bar on 6000rpm.
That should be fine I think till I go for a ECUTEK. Soon...
Thread
Thread Starter
Forum
Replies
Last Post