puzzling problem. Loss of power, rough idle

850TurboTurtle · Post by **850TurboTurtle** » 28 Jan 2013, 13:27

I was driving on the freeway when there was a 'pop' like a backfire, and suddenly lost a lot of power. I was low on gas and thought maybe it was running dry, but got gas at the next exit and the problem persisted. This is our only car, and money's tight, so any wisdom on what to look for is greatly appreciated.

Current state:
idles rough and dies sometimes when first started
hesitates up to 1 second when pressing the accelerator from a stop
on one start only, the engine raced at 2000rpm for a minute before dropping to a rough idle
when cool the engine behaves fairly well, but once it begins to warm up it idles rough and hesitates when accelerating from low speed or a stop.
Hesitations when driving about 30mph. Feels the same as a clogged fuel filter on my old ford - power rises and falls without moving pedal.
My wife says the engine sounds different to her, a little 'hiss-ier'. (Technical term there.)
milky crud in the oil. Yes, the dreaded head gasket leak. (And no, it wasn't doing that before.)
No moisture/mist in exhaust (except normal, when cold starting)
It does behave better with the turbo in sport mode, but not quite up to the normal performance of economy mode. It feels more like my old 740, gutless acceleration that gets to 60 eventually in economy mode. Like it is running on only 4 of the 5 cylinders.
No smoke or anything unusual in exhaust: starting, accelerating, idling all look fine.
slight whirring noise around 2500rpm, not there in past. Like a loose wheel on an idler at a resonate frequency?
hole blown in the rubber hose leading from fan shroud to air filter. Must have been that backfire!
Sluggish, boggy, wimpy performance.
Mileage dropped to about half. Now getting about 10mph city.
Check engine light is on, of course. Haven't read the codes yet. Will add to post once I get to that.

Previous conditions:
smells like the catalytic is dying - some rotten egg smell after hills
I suspect the oil condenser is plugged, because it wants to vent oily mist from the oil check tube, and I can smell a lot of exhaust when idling at a stop. This has been going on for about 1000 miles now.
Front struts need replacing, not that I can see a connection...
I replaced the water pump, timing belt, idler pulley last spring. It was running great after that.
check engine light came on occasionally in past month+, but intermittent.

Suspicions:
Timing belt jumped a cog??
head gasket failure blowing coolant into piston when warmed up and pressurized, leading to poor performance on one cylinder?
Emissions computer freaked out by sensor going bad, or broken vacuum hose, and setting mix to wrong levels??

Thanks for any suggestions,

Rick and the 850TurboTurtle

850TurboTurtle · Post by **850TurboTurtle** » 28 Jan 2013, 13:29

10mpg, not mph! I've had it up to 70mph in sport mode since then. It runs smoother at that speed than at 30mph. Also, it pulls away from a stop better with a little gas than a lot. More pedal bogs it down, chokes it for a few seconds.

Post by **jreed** » 29 Jan 2013, 04:44

You mentioned that there was a "hole blown in the rubber hose leading from fan shroud to air filter. Must have been that backfire!"
I haven't encountered that before and I'm having trouble envisioning the hose and location you're referring to... can you take a photo of it and post it up?

Did you get a chance to read the Check Engine light codes?

Post by **jblackburn** » 29 Jan 2013, 06:57

I believe you blew up/off an intercooler air hose. The sensors will no longer measure correct air amounts and the engine will run like crap.

Check every hose from the turbo down to the intercooler and then back up to the throttle body.

850TurboTurtle · Post by **850TurboTurtle** » 01 Feb 2013, 15:10

Thanks for the replies. Just getting over a flu bug, so I haven't gotten those codes yet. But I can walk again today so I'll have them tomorrow.

Here's a shot of the blown hose above the radiator. Taken from above looking downward. Front of car at top of photo.

I will check all the other hose connections with the turbo. Thanks for those leads! I can hardly say how grateful I am to you guys for sharing your knowledge!

Rick

Post by **erikv11** » 01 Feb 2013, 18:24

You can check the other hoses but they aren't likely a problem - fix the intercooler hose and you should be back in business, most of the symptoms should go away.

The milky crud in the oil is probably just condensation. Does the car go on a lot of short-distance trips? A head gasket leak is only the very remotest of possibilities at this point.

Sounds like the PCV system may need changing/cleaning too.

850TurboTurtle · Post by **850TurboTurtle** » 02 Feb 2013, 17:10

I can't get a replacement part in town today, so I found a large cooling hose at OReilly's, and cut it to size for a fix until my FCP order can arrive. That way we can at least get to church tomorrow.

The bend in the cooling hose was not sharp enough, so I had to manually make it fit the 90° corner from the intercooler to the hard plastic pipe to the throttle intake. The replacement hose is crimped at the bend - probably cutting the inner diameter to 1/3 the normal airflow.

It accelerates like a dream up to 30mph - very punchy, just like normal again. But above that it gets balky if I use more than just a touch of pedal. It cruises great at 60-65mph, smooth as ever, and it says it's getting 25mpg on the trip computer. But it has no passing power. The way it cruises I suspect it would slowly accelerate to 80 or 90 and be fine there too as long as I didn't try to accelerate hard.

My guess is that the jerry rigged hose just won't let enough airflow through to burn more fuel than a sip at a time. Not sure why it runs fine up to 30mph though. Any ideas? Do I need to reset the computer so it adjusts the fuel flow?

I'll post another update after the real part arrives and it installed.

850TurboTurtle · Post by **850TurboTurtle** » 02 Feb 2013, 17:45

Definitely need the PCV replacement. That will be my first job when the rains stop here (Tacoma.) And yes, Erik, lots of 10 mile trips for the last 3 months - almost nothing longer than a 20 minute drive. Thanks for the tip/encouraging word.

C30quin · Post by **C30quin** » 09 Jun 2024, 00:27

Rough Idle after Timing Belt change and Solution
I just did my timing belt change on a Volvo C30 P1 2.4i exactly following the videos on fcpeuro and mtl carguy.
I got my timing belt perfectly lined up with all timing marks lined up even after 2 sets of turning the crankshaft manually.
I also used the camshaft locking tool which I bought online form IPDUSA.
After everything was done I started the car and it was idling very rough at idle speed. Once the revs went up there was no problem and it went easily to max revs.
From all the online comments and forums I was panicking about what I did wrong and thought it skipped a tooth or 2.
Following my wife’s advice to start with easiest fault finding, the next morning I took off the manifold cover. Then I realized there was a small hose right underneath the manifold cover that I forgot to plug back in when I put back the manifold. It looks like a small breathing hose that plugs just behind the throttle body but directly underneath the manifold, so very easy to miss. Plugged it back in and bolted down the manifold and everything was fixed. Car running normal with idling now perfect. So there was never any timing belt tooth skip as my timing marks still line up.
Fix time 3-4 minutes
Thought it important to post this as no one seems to comment on this.