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Discussion Starter #1
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
 

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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.
 

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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.
 

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X2 - Couldn't have said it better!
 

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Discussion Starter #6
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
 

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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.
 

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Discussion Starter #9
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
 

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Discussion Starter #10
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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2006 ZX5 2.0, 2004 ZX3 SVT EE. 2004 ZX3 SVT
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Any high mileage Focus owner should clean around the butterfly in the throttle body.Oil from the crankcase vent and the pcv system causes a sticky residue to form which causes the low idle, hard starting problem
 

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Discussion Starter #12
The car only has 80k, so not what would be considered high mileage at all, but throttle butterfly was cleaned when the AEM intake was installed and again yesterday, along with everything around the intake manifold area
 

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Hmmmm. Car ran fine until you put an intake on it. Now it runs like crap....... I dunno......maybe reinstall the factory airbox (after disconnecting the batt again) and see if your problem still persists.

If the car uses an airflow sensor to calculate fuel delivery and load, it would be important that the airflow through that sensor is capable of being properly sampled.
 

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Have to say sounds like an intake leak.You should always check whatever work you just performed before suspecting anything else. You can spray a little wd-40 where the intake and head meet and if the idle goes up you found it. Disconnect battery for at least 15 minutes to reset and it should relearn within five minutes of driving.
 

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Discussion Starter #15
as stated a few times, i have checked over all rubber hoses, tb connections, maf connections, pcv and anything else that is located on the head on the engine, and nothing made any difference.

The only thing that i keep thinking it may be is the maf, as i stated before, i sprayed maf cleaner into the intake and it stalled after a second or two of spraying.

I sprayed with brake clean all over the outside of the intake with everything hooked up and nothing happened at all

Does the zetec engine have a iacv? i know on my honda civic that is a very common problem

Sadly i will need to but a new or used oem intake as i sold mine, but no big deal if i have to do that, but would like to get this working correctly first
 

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Discussion Starter #16
Still have a problem, actually was driving today, less then a quarter tank of fuel and the car stalled at lights twice! Which makes me think fuel system, maybe fuel pump?
 

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Did you (or previous owner) in the distant past replace your fuel pump with an older one from a junkyard?

The reason I ask is that a classic symptom of the recalled fuel pump in the early model Focii was just that - stalling at stoplights with quarter tank or less of fuel. It probably happened to me a half dozen times before the problem was correctly diagnosed.

The recall only affected vehicles mfg'd through the end of 2001 (mfg date, not model year), so your '03 wouldn't have wound up with a defective pump unless it received one from a junkyard or old inventory.
 

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Discussion Starter #18
We are the only owners of the car since new, but that still doesn't mean that it's not the fuel pump. I don't want to just waste money on replacing perfectly good parts but sometimes stuff just needs replaced
 

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during a normal start, a healthy pump will make a "whirring" sound for a few seconds. It is very obvious in a quiet garage if you turn the ignition key to its final detent without turning it all the way to starting.

Do you hear that sound when trying to re-start the car in its stalled condition?
 

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Discussion Starter #20
I know the sound, and it is very faint, and actually was listening for it on my drive today after it stalled once, when my civic pump primes, it's very noticeable, but on the focus it has always been very quiet
 
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