99 T5 - Runs terribly, lost brake booster

Post by **j-dawg** » 20 Oct 2015, 05:49

This morning, I was driving to work when everything 'sploded. At about 60mph on the highway, the car suddenly started running like garbage - something it's done intermittently for a few months, but never at speed - and this time the ETS and CHECK ENGINE lights came on immediately.

I'd assume something simple but I can't find any (more) vacuum leaks and this time I also lost the brake booster. I was able to nurse the car home at like 15mph (it was 5am, so the roads were clear) and grab my other car to drive into work.

Other notes: the car has been operating with a steady "pulse" in power lately: power drops every three or four seconds and comes back up, more or less independent of where I have the gas pedal. Makes it very hard to drive slowly.

Any hints on what this could be? I'd been assuming it was just an ETM on the way out, but the brake booster is throwing me. Could a failing brake booster have been causing a giant vacuum leak that I couldn't find earlier? Why would that throw an ETS light? And if that could be it, would a junkyard part from an 850 fit? Not many S70s in my local yard.

All this on the week I was planning to change the timing belt and water pump on Miata. Good thing I didn't start taking it apart.

Post by **FLXC90** » 20 Oct 2015, 07:46

Yes, if the diaphragm or check valve went out it could lead to massive vacuum leaks, disconnect the hose that goes to the booster and cap it, see if it runs properly.

Post by **abscate** » 20 Oct 2015, 12:46

When induction on a turbo ETB car goes bad, its ugly. I almost got rid of my T5 for scrap when I found this cool place called MVS that helped me figure it out.

A vacuum leak big enough to take out a booster will affect engine operation for sure.

Post by **FLXC90** » 20 Oct 2015, 18:18

gotta go to work, don't have time to link it, but there's a post in the database of reference photos-vacuum routing that talks about the line to the booster, more likely than the booster itself

Post by **j-dawg** » 20 Oct 2015, 19:23

FLXC90 wrote:Yes, if the diaphragm or check valve went out it could lead to massive vacuum leaks, disconnect the hose that goes to the booster and cap it, see if it runs properly.

that is SMART! I pondered over this at work today, but it never occurred to me to just isolate the brake booster. I'll give it a go tomorrow.

FLXC90 wrote:gotta go to work, don't have time to link it, but there's a post in the database of reference photos-vacuum routing that talks about the line to the booster, more likely than the booster itself

I won't say it's not possible - I did recently find a giant leak in the hose from under the manifold (ugh, come on Volvo) to the brake booster hose. But I replaced it, and I didn't find any tears in the booster hose itself this morning.

abscate wrote:When induction on a turbo ETB car goes bad, its ugly.

Yeah no joke. The only thing that gives me comfort is the thought that it's probably all part of the same problem, given that the car has only been giving me issues over the last few months, and they all seem related.

Post by **FLXC90** » 21 Oct 2015, 06:00

Thought about it last night...How were your brakes? good but needed legs of steel? or did the pedal drop to the floor with little effect?

The former would be a loss of boost or booster, latter would be failed master cylinder. Could be more than one problem.

Post by **j-dawg** » 21 Oct 2015, 21:38

Good but needed legs of steel. The pedal was very firm, like after the engine has been switched off and you pump the pedal a few times.

Haven't had a chance to try blocking off the booster hose yet.

Post by **scot850** » 22 Oct 2015, 16:15

The check valves to fail and give you the 'holy crap' moment and you lose your brake booster.

Neil.

Post by **j-dawg** » 25 Oct 2015, 00:39

Isolated the brake booster, no difference.

I also read P0121. After months of being in denial, I'm pretty certain it's an ETM, based on that code and the symptoms listed in George's thread at Swedespeed.

I still can't puzzle out why I lost the brakes.

As far as ETM replacement options - Xemodex versus buying the Sacer kit and DIYing it? For some reason I can't find any start-to-finish writeups on this, just a bunch of disjoint conversations that seem to start and end in the middle. I'm kind of sick of dumping money into this car and I'm not afraid of a bit of soldering, I just have no idea what the whole picture looks like, and all the sellers on eBay etc are super-cagey about instructions. Is there a good link I'm missing?

Post by **FLXC90** » 25 Oct 2015, 14:06

Where did you isolate the booster? At the manifold, or at the connector down low, Or at the booster?

The common denominator is vacuum. sounds like you lost a hose or connector.
If you didn't already, plug the vacuum line art the manifold/tree and see how it runs. My cars are both 98s so I can't just go look. Is there access to the line AT the booster? If so, you can try to pull vacuum with a mityvac and check the brakes...once, or with a straight run of hose, to test integrity of the booster.