Ridin Dirty

Sunday drive with kids....cracked her down into third boost came on hard as always but then full stall/shut down.

Re-start, then lumpy limp home... boost only to .2 bar then stall again. So then a still rolling re-start and managed to make it home by not engaging boost anymore. Ran sort of okay IF I didn't engage turbos...but then back at home very erratic idle....almost stall, then levels off.

Checked all hoses...all appear okay; even icv just fine. No other symptoms prior. Pulled strong earlier in same ride.

any ideas?

OverBoosted28

Check both boost blow off valves. If not on the valves, at the base of the intake where they attach. I had the pass. side blow off at the track and thought the worst until I chased it down (via brail) and found it had blown off. There is not a whole lot of purchase at the base of the intake. Maybe an inch and a half at the most. Check one of my preveious post regarding finding heater/radiator hoses to use as replacements. Much stronger (thicker) than oem and I am sure they will hold any pressure created by boost. Hope this helps.

Basal Skull

sounds like a big boost leak to me too. The most common problem is just the boost hoses, even if they look like they are on, might be frayed and partially off, esp on the turbo end. Blow off valves are more of a pain since they are harder to see/get to.

Ridin Dirty

hhhhhhmmmmmm....all the hoses look/feel tight. Now to find location of blow off valves??? and if i find them how do i know if they are bad?.... via tactile/brail interpretation?

and a hose/or blow off valve failure would effect idle a bit too?... and make it erratic? (just so I'm chasing the right demon)

EntropyChaser993

Do you have the original boost hoses or the updated ones (orange ends)? This definitely sounds like an air intake problem. To answer your question, yes, issues with the hoses and valves can cause an idle problem. In fact if the air leaks are bad enough the car will not run at all. I suspect the issue is a partial tear. Check all the way around the hoses and clamps on the turbocharger side of the hoses.

Ridin Dirty

I have orange. Okay so at least intercooler must come off to properly diagnose..when i get home i will remove. But these are big hoses and some of the only items one can see easily on 993's...they do look good...but until i get intercooler off i won't really know....they could be off at the turbo and that's very hard to reach.... i think...

Hope there is an actual appreciable tear b/c i have no clue how to diagnose blow off off valve failure.

EntropyChaser993

No need to take off the intercooler to check the hoses and clamps on the turbo ends. These can be inspected from the underside of the car. Best of luck.

OverBoosted28

Directly below the IAC valve is 3 bronze/brass nipples. They are at the base of the plenum. The IAC and both diverter valves attach there. You can reach behind the engine and feel for the diverter valves. Chase the hoses towards the base of the plenum and you'll feel where they terminate. This would only be if both of your boost hoses from turbos are in good shape and still connected. The boost will take the easiest route and rarely (if ever) would 2 seperate hoses blow off at same time. I found my diverter hoses were fatigued and needed replacement after I finally got the passenger side intercooler hose to stay on. Now with the S-Car-Go intercooler hoses I don't think they'll ever get blown off. Good luck

OverBoosted28

I had finally got both my intercooler hoses secured to the point of not blowing off at the track. Well the next weak link reared it's ugly head (boost blow off valve hose/pass. side). After that fix, it was the idle air control valve. Found that 16 yr old rubber will not tighten anymore. Solution: I took all three formed hoses to the auto parts store and tried to match them up with similar hoses. Found three that were extremely close. They are all much thicker than the factory hoses. Without being perfect fitting hoses, I had to do some work to get them on securely. The hoses were not exact length. I was able to replace the hoses which the blow off valves are mounted with, their connections to the intake and the IAC hose. I am happy to say that they have all stayed and I am sure they will not need replacing in my lifetime. Cost under $40.00 bucks including new clamps all around. Cheapest factory hose is about $65.00


Attached Images

OverBoosted28

OverBoosted28

Sorry, I couldn't figure out how to get my previous thread posted here from the ipad. But these are the hoses I would suspect if both intercooler hoses are good and secured.

John@Fabspeed

Hook up a smoke machine to your vacuum/boost system and look for smoke leaking from one of the hoses. its by far the easiest way to check for and or find a boost leak. We use it in dealerships all the time.

Ridin Dirty

I am familiar with everything boost and entropy are stating as to what to chase. I've fiddled with a stuck icv before and removed it so no worries doing that.

...But... what is at the bottom of the abyss?...meaning the intercooler hoses of course; they are right in your face at the intercooler and easy to see but i assume they attach to the top of the turbo down that "abyss"...but how does one "check" and/or repair that area?...from below?

Bradford

Circled in yellow is a breeze (hose) clamp holding the hose onto the top of the turbo. This picture was taken with the muffler removed. It is common for the hoses to pop off here especially if your hose clamps have not been upgraded.

OverBoosted28

That pic also has the muffler bracket removed so yours will be behind/inside of the bracket