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Hi all. Got boost problem. Cant figure out why the boost is always 0.8 bar 1500-7000rpm.
The car has following mods:
77mm clutch pulley
82mm tb
Longtubes
Cooling
Ecu
Custom cai with no filters through high beams.
On 81mm pulley i was seeing 13.5 psi with these mods.
At one point i saw 14.5 psi @ 4000rpm falling to 12psi @ 7000rpm, but the belt was slipping. It had completely eaten away the pk.
Not long after that boost is always 0.7-0.8 bar in any gear, at any rpm.
Here is what we tried:
Stock tune
Changed bypass
Checked for boost leak
Chamged clutch on the pulley
Went back to 81mm
Went for 77
Went for 76
Changed blower oil
Took blower appart, wings did apear scratched but i doubt to the level that blower can loose its capacity to blow.
Changed map sensor
Changed gas pedal
Few other tunes.
Today, i officially declared dead end. Please help...
Ps. The funny thing is the car pulls good. Real good. Considering its stock boost...
I check both with a boost gauge as well as obd. They slways same.
Got 1 psi. But i m still far from desired boost level.
Also. Just dynoed the car.
3rd gear 450 whp 680 wnm
4 th gear 470 whp 480 wnm @5200rpm.
My torque is horrible. Mustang dyno.
1 psi is a lot so that means that the cai was not working as well as you thought. Remember that cold air going in the tb can add another .5psi so you would be at 13psi
Is your belt slipping? If you still have the engine cover on, check underneath to see if there is some rubber "dust" building up. One member here claims to have picked up 2 psi by adding the belt wrap kit.
He said that he had the boost before, so elevation is not the issue. I doubt it's belt slip because it would show spikes which he is not claiming. Do a leak down test demetak
He said that he had the boost before, so elevation is not the issue. I doubt it's belt slip because it would show spikes which he is not claiming. Do a leak down test demetak
Also. I m being told that it can be torque converter. To prevent slipping ecu pulls boost via bypass. On the dyno graph it can be seen be a spike in torque and hp curve and then a suden drop followed by a gradual rise
Suction is clean.
What do u think of the torqu converter. Could explain me making 600nm at stock boost while it should be 700. And boost being limited from ecu to protect tranny
No not tq converter, very very unlikely since you take off the intake and you gain over 1 psi
Do a leak down test, it will show if everything is sealed because air has to be going some where..
Tomorrow i will put back stock tcu.
The torque limiter is removed on my weistec tcu tune and i showed 700 wnm in 4th with 81mm pulley.
If no change. I ll do the leak down test.
The reason tc sounds logical to me is that coz of the dyno graph. This is in one geat, it wont downshift when on wot at 2k rpm and still this happens.
At the beginning of the run, the car literally tries to jump off the dyno, but then for some time the rpm gets stuck at the same point and power starts to gradually increase.
09-19-2015, 01:18 PM
