porsche engine power loss that so far foxes the experts
Discussion
ok here is the challenge, a beer or 12 for the person who solves this one:
Porsche boxster s 2000 yr. 30% approx (very noticeable anyway) down on power. maf and O2 sensors changed, genuine parts, diagnostics show no fault codes, all values correct, engine breathing tested ok. problem started with intermittent power loss, eventually engine check light on, codes suggested O2 and maf sensors. changed O2 all perfect for 2 starts/stops with 18 miles then same problem. changed maf but perm down on power but started better, changed last O2, and no difference (only 2 02's on this model. car has been to porsche and bosch experts. much scratching of heads. no vacuum leaks, air filter checked. coil packs recent, spark plugs new, in fact everything obvious has been checked as you would expect with the guys that have looked at it. any clues anyone no matter how remote or silly sounding welcome, before I double tap to the brain. lol. thanks.
Porsche boxster s 2000 yr. 30% approx (very noticeable anyway) down on power. maf and O2 sensors changed, genuine parts, diagnostics show no fault codes, all values correct, engine breathing tested ok. problem started with intermittent power loss, eventually engine check light on, codes suggested O2 and maf sensors. changed O2 all perfect for 2 starts/stops with 18 miles then same problem. changed maf but perm down on power but started better, changed last O2, and no difference (only 2 02's on this model. car has been to porsche and bosch experts. much scratching of heads. no vacuum leaks, air filter checked. coil packs recent, spark plugs new, in fact everything obvious has been checked as you would expect with the guys that have looked at it. any clues anyone no matter how remote or silly sounding welcome, before I double tap to the brain. lol. thanks.
+1 for cats
You need to log a drive will as many relevant parameters as you can.
MAF airflow, g/cyl, rpm, TPS, ECT, IAT, Spark, KRet, injector pulsewidth, commanded afr, O2 MV etc, etc.
Power loss = reduction in airflow assuming all other air/fuel/spark is ok
Cats is a common issue. Time to go catless and gain more power too
You need to log a drive will as many relevant parameters as you can.
MAF airflow, g/cyl, rpm, TPS, ECT, IAT, Spark, KRet, injector pulsewidth, commanded afr, O2 MV etc, etc.
Power loss = reduction in airflow assuming all other air/fuel/spark is ok
Cats is a common issue. Time to go catless and gain more power too
Strictly speaking you'd want to see zero pressure in there. Chances of that are unlikely though.
But if the cat is blocked so badly that performance really is suffering, then I'd expect well into double figures psi when you try and drive it under load.
if it is less than say 10psi at max engine laod, it still isnt ideal, but unlikely it's the cause of such a huge performance loss
But every case will be different depending how good or bad the original exhaust was in the first place
But if the cat is blocked so badly that performance really is suffering, then I'd expect well into double figures psi when you try and drive it under load.
if it is less than say 10psi at max engine laod, it still isnt ideal, but unlikely it's the cause of such a huge performance loss
But every case will be different depending how good or bad the original exhaust was in the first place
after more research, I don't think it's cats because before maf/o2 was replaced the problem was intermittent and vacuum test was normal and the most puzzling thing was that it ran perfectly for those 18 miles after O2 sensor change. it's like a low power switch has been activated,. Anyway back at Bosche on Monday will update thereafter.
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