Replaced Check Valves and now having problems

[dbgmpd]

I had a CE light; and replaced the check valves. Now the CE light is gone; but when the car is started up while cold the car for the first 2-3 minutes is hesitating to the point where it feels like the engine is going to stall out. The CE light is not coming on. Everything replaced has been rechecked and nothing found amiss; any help??

[Loren]

It would be really helpful if you would tell us:

- the model and year of your car

- US/Canada or RoW car

- the faults codes that led to the valve replacements

Thanks.

[dbgmpd]

sorry.

97 boxster w/manual trans. i had the codes p0411; i can't remember the other one (both secondary air induction system). I replaced trhe check valves, cleaned the throttle body and maf sensor. before this the car ran ok; but had a cel light on. now, no cel but the car will feel like it will stall in the first couple minutes of driving (bad enough that i have to pull over and hope the car does not stall. also the car has no power; thus i can't rev out of the rough running).

i've gone through all of the posts; maybe a bad maf sensor??; maybe i need to unplug the battery to reset the computer,something i did or didn't do when replaceing check valves, i also replaced the air filter.

[Loren]

MAF has nothing to do with your idle - just unplug it and I doubt you will see any change.

Perhaps you had:

P0410 Secondary Air Injection System - Signal Implausible (Cylinders 1 - 3)

P1411 Secondary Air Injection Sy.stem - Signal Implausible (Cylinders 4 - 6)

Possible faults:

Secondary air injection pump is not triggered.

Secondary air injection pump does not work.

Air supply lines restricted.

Electric change-over valve does not work.

Air change-over valve does not work.

Vacuum system leaks.

- Wiring harness or fuse

- Relay

- DME control module

- Air supply lines

- Secondary air injection pump

Does your air pump run at startup?

[dbgmpd]

yes, those were the codes that were present. my issue is that the car was running fine when those codes were present. i then changed the changeover valves and am now having this issue. at least the CEL is not coming on!!

everything is normal except for the intermittent hesitation. took the vacuum hoses, throttle body, and intake manifold again and reassembled. i thought i had it fixed, but tonight around 2-4000 rpm's the problem came back. not as bad as it was, but still there.

also, the temp guage is normal, but the engine seems to be throwing off alot of heat and associated odor around the right rear tire.

also, this has always happened while the car was in motion; not at idle.

Edited July 21, 2008 by Loren

[dbgmpd]

now cel is back on with codes 1123 and 1125.