SwedeSpeed - Volvo Performance Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
71 Posts
Discussion Starter · #1 ·
Hi there,

I've been making researches about this "strange" boost spike i am experiencing since the day i bought back in 2012 but never really found the solution.

The problem is big boost spike, but only comes problematic when i ease of the throttle ar high rpm's easyly when boost spikes so much that i get cutout.

If i floor it and keep it floor to shift it wont spike as much between gears ( it's an auto box ), but when i step of of a throttle in high range rpm's i'd get a cutout ( immediatelly after throttle release ).

ECU is chipped from previous owner and have boost gauge installed - when floored and let it shift boost spikes between shifts for small amount max 0,1 bar but when i release throttle at high rpm's boost spikes for 0,2 if not 0,3 bar - it is most noticable in 3rd gear (cca 150 km/h ) as from 4th to 5th in high range it is allready to fast to watch this and really drive that fast in rare occasions :)

Any hints what to look after? C70 t-5 2001 me7, aw 55-51sn gearbox, chipped, car goes insane fast, boost maxed @1.1bar.

I have "blinded" the original blowof with plate, and mounted forge BOV immediatelly when i bought it....everything else on the car is stock - turbo's, boost controler everything.

Thanx!
 

·
Registered
Joined
·
24 Posts
hey,

I am nearly 100% sure the BOV is fcking it up. The Volvo engine management is not based on boost pressure control like the Reza etc. but it is based on mass airflow calculations.
Dumping measured air from the inlet might not look like a big deal, but this air will be missed by the system. Might trigger diagnostic funcs.

Another thing with these BOVs with air mass controlled system is that if you dump the measured air, it can increase the response time, as there´s no pressure built up in the inlet, once the throttle is open again.
You´d have to use a BOV where the air is recirculated back in the system. It sounds sh*t when compared to typical BOV that dumps the air in the atmosphere. It would be a HKS Super Sequential BOV.

Still, BOV is really a sh*t upgrade for ME7 cars. The downsides by far outweight any possible performance addition.

regards
Kriss
 

·
Registered
Joined
·
7,614 Posts
Also, you say it's "chipped" - whose tune is in it? ARD tunes are notorious for overboosting like that on ME7 cars. But they usually throw a code and go into limp mode.
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #4 · (Edited)
Thanx to both for input!
@KrissPappas - Will make a switch back to original state and report any improved results, been thinking myself that BOV was totally useless from the begging and it might be the fault for this....this weekend on to do list.
@LloydDoble - It's not any volvo familiar tune - here in Slovenia where i come from there are no official Volvo tuners available, it is a custom map from, to me uknown tuning provider as it was already mapped when i bought it. I do not get any fault codes.

But on the other hand, i just remembered one thing which could be in connection with this.

Few times - max 5 since i own it i noticed i got a limited boost pressure, wont go past 0,4 bar from unknown reason - once the engine is restarted again, everything goes back to normal.
The other day i noticed what triggers this problem - if i, let's say, prepare to pass a vehicle and i flor it down, kickdown to 3rd and full boost and at last moment i cancel to pass ( due to not seen vehicle on the other side or whatever ) i release the throttle, BOV makes a ussual "hiss" sound and from that moment, boost pressure is limited to max 0,4 bar - no error codes, been pluged to VIDA - nothing.

As soon as engine is restarted, all is OK.

Cheers
 

·
Registered
Joined
·
24 Posts
Thanx to both for input!

Few times - max 5 since i own it i noticed i got a limited boost pressure, wont go past 0,4 bar from unknown reason - once the engine is restarted again, everything goes back to normal.
The other day i noticed what triggers this problem - if i, let's say, prepare to pass a vehicle and i flor it down, kickdown to 3rd and full boost and at last moment i cancel to pass ( due to not seen vehicle on the other side or whatever ) i release the throttle, BOV makes a ussual "hiss" sound and from that moment, boost pressure is limited to max 0,4 bar - no error codes, been pluged to VIDA - nothing.

As soon as engine is restarted, all is OK.

Cheers
I think this is exactly what I was talking about in the first post. There was not enough pressure after you let off the throttle and stepped on it again (the BOV let this pressure out and there was nothing built up to give you standard boost level) does it make any sense ?
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #6 ·
I do hope so, i am not very well educated about how turbo's and all the stuff around Works, i only know when it Works as should and when it doesen't and that's it :)

Will change during this weekend and report the results.

If anybody else can confirm or have different theories about this, feel free to drop a line :)

Cheers
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #7 ·
Just a quick update, on friday afternoon i removed forge bov and installed back old original part on it....and voila, no more aggressive boost spike, yestrday went to highway just to play with it in all possible ways and couldnt make it happen to get any cut out, so the problem was obvious with forge bv as suggested in the first place by you.

Cheers for help!
 
1 - 8 of 8 Posts
Top