98 volvo s70 t5 wont boost beyond stock psi with ecu tune

RobTarD · Post by **RobTarD** » 06 Apr 2012, 23:02

I adjusted the wastegate actuator and now I'm boosting to just about 1 bar, and it holds steady. I've been driving pretty conservatively so I haven't noticed any spiking yet, but if the old numbers are anything to go by it should only spike to about 18 psi.

I sheared a bolt when I was removing the heat shield and now it won't fit properly without that bolt (one side hangs down and actually touches the turbo). Am I putting any components at risk? My old 760 Turbo didn't have a heat shield and seemed to do just fine.

volvohighway · Post by **volvohighway** » 07 Apr 2012, 09:56

It's funny what you said, because I actually have cel light and it's the front o2 sensor but I bielive its a vac leak. But umm right know I have a new wg the whole piece just so I can adjust it, mines was totally rusted, and also ordered a mbc too just for the heck of it. Right know am at the point trying to find a way to test the boost leak. But no I coudlnt get past 12 with the wg line disconnected, and I do have the front o2 sensore cel light.

volvohighway · Post by **volvohighway** » 07 Apr 2012, 09:58

I haven't installed the new wg. Or the mbc should be at my place in a few days.

Post by **matthew1** » 07 Apr 2012, 10:20

Just so we're all on the same page, let us know you're talking about boost spikes during shifts, or boost spikes between shifts. Big difference.

Also, a CEL can very easily cause half boost. Even no CEL can cause half boost(!). Always clear codes before testing boost. See this for explanation: https://www.matthewsvolvosite.com/volvo-pre-code

Eliminating these variables will further this troubleshooting process quite a bit.

Post by **matthew1** » 07 Apr 2012, 10:24

For the record, my 850 T5 engine/transmission is Stage 0, and it boosts to 10psi at 4k or so RPMs+, and spikes to 12-13psi between shifts.

mrbrightside2009 · Post by **mrbrightside2009** » 07 Apr 2012, 11:57

volvohighway wrote:It's funny what you said, because I actually have cel light and it's the front o2 sensor but I bielive its a vac leak. But umm right know I have a new wg the whole piece just so I can adjust it, mines was totally rusted, and also ordered a mbc too just for the heck of it. Right know am at the point trying to find a way to test the boost leak. But no I coudlnt get past 12 with the wg line disconnected, and I do have the front o2 sensore cel light.

i have cleared my codes just in case it was in limp mode, my front o2 im pretty sure is original at 166k, so i'm just gonna replace it and to finish my stage 0. i'm gonna say you may have a weak wg actuator if you cannot boost past 12 psi with line disconnected, like i said i boosted up to 15 and def. could do more. I'm actually going to make some wg adjustments today and see what happens.

volvohighway · Post by **volvohighway** » 07 Apr 2012, 19:23

Yeah thanks for tip but I have reset my cel light queit a few times. I will be installing the new wg, and mbc and let you guys know. Also for sure check for boost leaks.

volvohighway · Post by **volvohighway** » 07 Apr 2012, 19:31

To answer your question about spikes, I only get the spike when am wott,it hits 12 really quick and goes right back to ten. Also my boost doesn't hold at a certain Rpm at all, it only holds when am at wott that's it. When I got my HD tcv and tried to follow the instructions for calibration to system, and told me to a certain boost level for wv seconds it was imposiible for me to do, which confused me. Because the only time I can get the boost to hold is when am at wott shifting threw all the gears. Does that sound fishy or is it normal, does that mean I have a huge leak??

mrbrightside2009 · Post by **mrbrightside2009** » 07 Apr 2012, 21:15

just kinda sounds like boost fade, i think its the crappy stock tcv, i kind of have the same issue, cannot hold boost very well with it, but with my mbc boost comes in quicker, no spikes and holds steady no problem half throttle, wot, w.e throttle i'm at, i def. just like the mbc controlling boost, feels so much better, just want to figure this crap out.

RobTarD · Post by **RobTarD** » 08 Apr 2012, 22:54

My car chokes when it hits 1 bar, then fades to about 13 psi. Is that the stock overboost protection? I thought that would have been disabled with a tuned ECU.

It's really an issue only when I'm accelerating from a stop, floored. It doesn't happen so much at speed, but I'll need to do some more testing. My car seems like it's all over the place right now.

98 volvo s70 t5 wont boost beyond stock psi with ecu tune

Re: 98 volvo s70 t5 wont boost beyond stock psi with ecu tun