95 850T full throttle, no boost

Sean-E-Boy · Post by **Sean-E-Boy** » 18 Apr 2012, 11:37

Ok, so the title is a bit misleading, full throttle from a stop or gradually increase throttle to full, no problem. However, imagine following a slow vehicle while going down a hill and coasting while waiting to pass, traffic clears, floor it, tranny downshifts and nothing happens, in fact I SLOW DOWN.

As this takes place, the boost gauge goes way negative and the only way to regain power is to let off the throttle and once the tranny settles gradually roll into the throttle until there is some boost and then punch it.

This happens at highway speeds and also as slow as about 35, or anywhere when the boost goes far negative while coasting.

This started happening just recently while troubleshooting missfire and long term idle too rich (or lean, don't remember) codes. Replaced pcv stuff a while back and source of those codes was the vacuum line running into the intake manifold not being connected.

So, I have double checked all the vacuum lines associated with pcv and tcv and all are connected correctly as far as I can determine.

On a side note, what does the vacuum line running into the compressor housing itself do?

Another problem showing it's head after reconnecting that vacuum line to the intake manifold is that the engine will occasionally die. Happens most often after driving, turn car off to run into store for a few minutes, turn car on, drive away for 30-60 seconds, then dies, mostly while accelerating slowly or slowing to a stop from 20-30mph, never happens while giving it more than 50% throttle.

Any ideas?

Sean

Post by **rspi** » 18 Apr 2012, 15:01

Open the hood and play with the throttle while watching the motor. Many have found/seen their intake hose collapse. Check that out first.

Sean-E-Boy · Post by **Sean-E-Boy** » 18 Apr 2012, 15:05

I'll check it out, thanks. But wouldn't the boost spike at least momentarily?

Post by **matthew1** » 18 Apr 2012, 15:40

Sounds like a collapsing hose to me too.

Sean-E-Boy · Post by **Sean-E-Boy** » 18 Apr 2012, 17:41

Yup, between throttle body and the intercooler.

Thanks, as usual you guys nail it.

Now how about the dying issue?

Post by **rspi** » 18 Apr 2012, 21:45

That's why I never put two problems in one thread.

Post by **MoVolvos** » 19 Apr 2012, 03:02

Sean-E-Boy wrote:Yup, between throttle body and the intercooler.

Thanks, as usual you guys nail it.

Now how about the dying issue?

Is this the one? I saw a video sometime ago of a hose collapsing but forget where and which hose? Thanks.
http://www.eeuroparts.com/Main/PartDeta ... id=9161093

Blessings,
BKM
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Post by **jblackburn** » 19 Apr 2012, 08:11

After replacing vacuum hoses and that intercooler hose, reset the computer...yank the negative battery cable, step on the brake pedal, and then reconnect it. See if it stops cutting out on you after that.

FYI, it will idle a little funky for the first 2-3 trips after doing this, but it will then smooth itself out.

Sean-E-Boy · Post by **Sean-E-Boy** » 19 Apr 2012, 18:00

Yes, that one collapses, but it's caused by the one between that hose and the intercooler collapsing first.

Post by **MoVolvos** » 19 Apr 2012, 18:30

Sean-E-Boy wrote:Yes, that one collapses, but it's caused by the one between that hose and the intercooler collapsing first.

Thanks Sean-E-Boy. In normal driving does your car seem sluggish at times but other times has normal power especially from a stop? Mine sometimes feels like it can really move, which feels normal though I never drive it hard while other times slow but never running rough. Idles higher in Park but as soon as the shifter is moved RPM goes down but steadies at 850-900 RPM. When put back in Park will spike to 1,100 and then settle back down. Combined MPG is around 22-24 MPG high and Combined Low is around 19 MPG and Highway 26+ MPG but I drive conservatively.

Blessings,
BKM
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