'98 S70 T5 Won't idle, big delay in throttle response

rudsaki · Post by **rudsaki** » 10 Apr 2025, 17:46

Rear exhaust seal completely blown out, so performed that fix, PCV service(including cleaning gunk when I saw it) and new vacuum lines to turbo.
Post start it went to ~1500 rpm then dies. Try again same thing. Try to keep it alive with throttle, but barely responds to input. Noticed I did not put the fresh air intake snorkel on. Fixed that and gave the MAF some shots of throttle body cleaner. It did make a better try at idling, now giving me 5 seconds of chugging. Throttle the same. I doubled checked my turbo routing. I did not completely un-hook my intake manifold, just flopping it over and back many times.
New to me car that ran very well, except for dumping out a quart of oil!

daninater · Post by **daninater** » 10 Apr 2025, 19:55

Check for vacuum leaks below the manifold, on the manifold and turbo, on the pcv connections to the box.

Post by **abscate** » 11 Apr 2025, 03:14

You need to check the entire induction path for splits, cracks, loose clamps

On a turbo car, that’s 10 clamps and hoses, not counting PCV!

rudsaki · Post by **rudsaki** » 11 Apr 2025, 07:23

Yah try to be methodical in re-assembly, but it's a lot and connectors also. Hopefully did not break any wires digging and flopping stuff around

rudsaki · Post by **rudsaki** » 11 Apr 2025, 08:58

was able to use a free OBD scanner software and got
P0102: Mass or Volume Air Flow Sensor "A" Circuit Low

Because of oetiker clamp the air box lid was still attached and I moved it a lot doing the job. Maybe damaged it or is this still a sign of air leak?

rudsaki · Post by **rudsaki** » 12 Apr 2025, 21:16

Tried junkyard MAF, same result. Pulled MAF connection so it would barely idle then sprayed carb cleaner looking for vacuum leak. Two fuel injectors gave the biggest response. Replaced all o-rings and it ran 10% better. Spraying top edge of intake manifold also got a response, but all bolts tight.
This short video you can hear one of the backfires in the intake.

rudsaki · Post by **rudsaki** » 18 Apr 2025, 09:04

To complete the loop, my main problem was putting the PCV clip on the inside out the intake manifold like this guy in the UK.
https://www.volvoforums.org.uk/forum/te ... -after-pcv

Putting it back on the outside did the trick confirmed by carb cleaner spray test, perfect idle and throttle response. Other smaller leaks were the trashing 2 injector O-rings and loose oetiker clamps on vacuum tree big hose.

Now I can move on to making it pretty!

Thanks for the suggestions,
Rod

Post by **abscate** » 18 Apr 2025, 10:58

Ah yes, putting the holder on before the manifold.

A very good friend of mine did that once , years ago.