I got my Miata started today for the first time since before Christmas. It isn't ready to drive yet, mostly because the clutch line is leaking and the new one hasn't arrived yet. Naturally, my Volvo (92 740 turbo) got jealous and wanted some attention.
While delivering pizza it started to bog down and die when I came to a stop. No problem, I just kept my foot on the gas to keep it alive. Next delivery it does the opposite, when in park it idles at 1500 rpm instead of the normal 800 or so. Then after it was started it would bog down and have no power for about 5-10 seconds then it took off fine.
I got back to the store and popped the hood to see if anything obvious was wrong, then the coolant tank decided that was a good moment to spring a leak at the bottom fitting and spray coolant all over the hot turbo. After awhile it calmed down but there was still coolant in the tank (although not pressurized enough to come out).
It is now very down on power but has sudden spurts of energy. Maybe it was just sensing that I was starting to like it too much. I even cleaned out the PCV system a bit the other day and ordered an new oil separator and it was running better than ever.
So, any thoughts from the Volvo people? I am wondering if the coolant tank crack is related to the other problems or just brittle from 232k miles of holding hot liquids. I am going to dig into it tomorrow morning but wondered if anyone has had a problem with similar symptoms and knows what to look for.
TL:DR: Volvo runs like crap, pissing coolant at turbo, I have to deliver pizza tomorrow.
Air in system now, and pissing off coolant temp sensor?
That's all I've got.
Check for ruptures in your air intake hoses, from the afm back. Beware especially the underside of all the greasy goey hose sections.
High idle and uneven power delivery sounds kinda like vacuum leak - possibly one that closes under boost. These symptoms can also point to a bad AMM - try unplugging the AMM (with engine and power OFF), then run it gently and see if it drives w/out drama. If behavior is stable with the AMM disconnected, but wonky with it plugged in, you've found your culprit.
I was going to say vacuum leak too
had a similiar problem, I was told by my mechanic that there was some crap on the air flow sensor, just needed to be cleaned, runs fine now
Hmm, maybe this has something to do with it.

It's amazing what you can miss at night, even with a flashlight.
I also found that the coolant tank has been patched before, right next to where it cracked this time. Hopefully I can patch it enough to hold on a bit longer.
Can you put vise-grips on the hose to the coolant tank?
True story...
For about a year i was missing by best set of visegrips..could not find them to save my life, cleaned the garage etc. no luck. Then the car i was working on / and off over the year lost it's tail pipe clamp so i crawled under in to wire tie it up to get home and i found my visegrips....where you ask? On the rear brake hose...one of the rear lines had popped one night while doing burn outs and i had just clamped it off and fogoteen...


I just finished epoxying the crack on the coolant tank, it was on the outlet where the hose connects, it was already sleeved with a copper pipe so the epoxy should do it.