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-   -   ZX5 engine stumble when stopped, help! (http://www.focusfanatics.com/forum/showthread.php?t=269453)

pumafeet10 09-27-2011 06:30 PM

ZX5 engine stumble when stopped, help!
 
Recently installed an AEM SRI on our 03 ZX5 zetec auto, shortly thereafter i noticed the car would idle rough and somewhat stumble when I was stopped at a light.

Not sure what it might be, but plugs and coil look fine and there are no problems other wise

Also other then the intake the car is stock

I had also be recommended to replace the DPFE sensor, as i might have hit it and damaged it while installing the intake? not sure but it is in the general area

Not sure if there might be a problem with the EGR, do they seem to have problems getting clogged and not flowing enough?

Thanks for the help

three_X_Z 09-27-2011 06:59 PM

There are two places that have caused this on my car. One is the classic PCV tube that comes out of the back of the intake manifold. Its the biggest of all the vacuum lines coming out of the manifold. It often fails right at the spot where it connects. Kinda collapses on itself and causes a vacuum leak. The other one that I've had is a small leak in one of the plugs on the back of the intake manifold. Basically feel around down there with the engine running and see if your finger gets sucked into something.

pumafeet10 09-27-2011 07:05 PM

thanks for the idea, anything i can check is a good lead, but wasn't thinking that would be it

thanks

BC_ZX3 09-27-2011 07:59 PM

When you fit any type of SRI you must clear the previous "learned" adaptive fuel strategy settings from the ECU. Did you disconnect the battery after installing the intake for 5 minutes or more? Most SRI instructions tell you to do this.

Once the new intake is fitted, let the car simply idle for a few minutes. If you are still having idling problems after a reasonable amount of driving time has elapsed, you have likely unintentionally introduced a vacuum leak into your intake system. Check the intake tube to throttle body connection clamp in particular and also where the MAF screws into the intake tube. Both areas must be air tight as they are behind/near the MAF sensor. Airflow after the MAF isn't compensated for by the ECU.

If the car ran fine before your modifications, don't go chasing other possible causes until you've rechecked your work.

sailor 09-27-2011 10:26 PM

X2 - Couldn't have said it better!

pumafeet10 09-30-2011 12:47 PM

Everything has been checked over, and the battery was disconnected form the entire install time, so plenty of time to reset the ecu.

I checked for leaks using some soapy water to watch for air bubbles but nothing,

I'm not just randomly searching, as there is an abundance of sensors that are in the area and could have been disrupted during install, that were fine before, like the dpfe sensor.

If it was the Maf it would be causing a problem all the time, no?

It only happens when we are stopped, which is why I was leading to the dpfe as it is vacuum operated with the erg, possibly not getting enough flow at idle

pumafeet10 10-19-2011 12:04 PM

replaced and rechecked clamps, checked maf and all is good.

still cant figure it out

alz focus 10-19-2011 12:44 PM

Use brake or parts cleaner to check for vacuum leaks. Soapy water is not going to do anything but get sucked in in there is a leak.
Spray while car is idling, if revs jump, focus on that area for the vac leak.

pumafeet10 11-15-2011 07:38 PM

So the problem persists...

My wife was driving to work this morning and in stop and go traffic, the car stalled. The cel and brake light came on..

No code was there to be read, so still unclear as to what is wrong, really need to get this figured out

pumafeet10 11-15-2011 09:56 PM

Checked for leaks with brake clean and soapy water to see if there are any air bubbles, and nothing.

Sprayed a bunch of Maf cleaner into the intake, enough that the car stalled but ran fine after I started it again.

Plugs, wires and coil are fine and uncorroded so not sure what it could be.

There does seem to be a very tiny stumble at idle, but am really unsure

Took the car for a drive and could not get it to stumble when the brake was applied


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