Over boosting

[babajangas]

Hi y'all was towing the van over Christmas and car threw a code (over boost) so installed a boost gauge and car sometimes gets up to 20 psi on the boost gauge.From what I've read on here 20 seems pretty high. I'm running a three inch exaust with no cat when the car is over boosting you can really here the turbo spool and seems to lack a bit of power. I have read plenty of posts on over boosting with no real answers and wondering if anyone else has been experienceing the same symptoms and what they did to find the cause. I don't want to go replacing expensive parts to find out it was something minor.also I replaced map filter cleaned maf and restricted egr to a 7 mm hole any help would be much appreciated
Cheers matt

[dano85]

Hi mate
Mine does this, has never thrown the code tho it does regularly spike to around 20psi on the high way if I slowly feed the throttle on when I am cursing at around 100kms to overtake someone or go up an incline it will go from the normal 15psi very quickly to 20psi and instantly drop back to around 10psi, like it cuts it instantly.
Mine has the standard exhaust with no muffler.

[Talktheroo]

So, P1251 fault code, Matt?
These vehicles do need a bit of back pressure, as in the exhaust system.
See how you go, but you should fit a high flow cat converter for legal reasons, or a restrictor washer in the dump pipe.
Otherwise, you will have to do it through software and the ECM.
The Roo.

[Jacko9]

whacking a cat converter in there isn't a bad idea i don't think anyways.

[babajangas]

Cheers roo yeah p1251 code it was might get a cat and put it on I'm getting the ecu tune done and want to iron out a few little problems first what kind of cat should I be looking for?thanks for the help
Cheers matt

[babajangas]

Hey dano mine is same symptoms as your when holding a gear it seems to spike worse if I stomp it a bit seems to boost normally maby my granny driving style is the problem

[dano85]

yea not sure if its normal or not, we need other members to chime in that have boost gauges.

[babajangas]

I've got a cat going in next week I'll let you know if it makes a differance

[babajangas]

Does any one know if I should go for the 100 cell or 200 ?
Cheers

[Talktheroo]

One of the high flow ones. I like the Taipan XP gear.
Yes, expensive taste, especially in stainless steel.
200 cell.

[ugli-1]

Taipan xp is the way to go specially in stainless and I know for a fact Kerry at taipan stands behind his 10 year warranty on stainless system

[ugli-1]

Taipan xp is the way to go specially in stainless and I know for a fact Kerry at taipan stands behind his 10 year warranty on stainless system

[babajangas]

I had a 200cel hi flow cat installed today car is still over boosting mainly in second when holding a gear didn't have a chance to open it up in third and forth. I'm going to go over all Vacume lines and hoses tomorrow and check for leaks any things in particular I should be looking for or anyone has any ideas what I should be checking next would be much appreciated
Cheers matt

[Earlyninja]

A blocked/blanked EGR (even with hole) will let more exhaust flow through the turbo, in turn letting more air into intake manifold. Having almost eliminated exhaust backpressure (eg, bigger exhaust with flow through) allows the turbo to spool even quicker resulting in overboost.
Not sure if the wastegate is adjustable, but if possible give that a go.

[johnwood]

A blocked/blanked EGR (even with hole) will let more exhaust flow through the turbo, in turn letting more air into intake manifold. Having almost eliminated exhaust backpressure allows the turbo to spool even quicker resulting in overboost.
Not sure if the wastegate is adjustable, but if possible give that a go.

Don't think there is a 'wastegate' - you need to program the nozzles to open slower or something similar its a VNT turbo, I have no idea if it is possible, or at what cost.. probably cheaper to put a cat converter in for some backpressure, if the lack of backpressure is what the problem is.

[babajangas]

Don't think its a lack of back pressure as the 200 cel cat has not sorted it out double checked all Vacume hoses today and the all looked good .......

[Earlyninja]

Don't think there is a 'wastegate' - you need to program the nozzles to open slower or something similar its a VNT turbo

Sorry mate, what I should have said in place of 'wastegate' is the small vacuum chamber that adjusts the vanes of the VNT (VNT actuator) usually has an adjustable rod to change the preload on the chamber. Some turbos are push-rod VNT, others are vacuum-solenoid VNT.
I used to experiment with Garrett turbos years back. Am feeling a bit behind the times now...

[johnwood]

Don't think there is a 'wastegate' - you need to program the nozzles to open slower or something similar its a VNT turbo

Sorry mate, what I should have said in place of 'wastegate' is the small vacuum chamber that adjusts the vanes of the VNT (VNT actuator) usually has an adjustable rod to change the preload on the chamber. Some turbos are push-rod VNT, others are vacuum-solenoid VNT.
I used to experiment with Garrett turbos years back. Am feeling a bit behind the times now...

I see - think the Hilux is a rod, electrically driven by a computer, changing the signal inputs into this would require getting into the stepper motor control / ECU which Toyota do everything they can to stop!

WE had a orignal KUN26, fitted a 3" got boost related codes. FItted a 3" with a cat, got boost related codes, Fitted new turbo, got boost related codes, put it back to factory, no codes. The ECU isn't a princess, but when it see's values outside of parameters it throws codes. Wonder how the new one will go

[babajangas]

Just an update I reseted the ecu last night and car seems to be running a lot better max boost around 16 psi maby needed a reset after cat being installed ? All good thanks for all the help
Cheers matt

[Gipsy]

guys, the dump pipe is where the backpressure is generated, not in the cat, too far downstream to make a difference. there is a thread here somewhere about a 'collar' in the dump pipe to keep the pressure up there. roo knows a bit more about this. my 3" xforce so far has no codes, but the idle-1600rpm grunt is lower than oem and then it gets motoring fine right to redline.

16psi should be within specs as some are running 20+

cheers, G