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Discussion Starter · #1 ·
I recently bought a 2003 svt with 110,00 miles on it. Check engine light is on and was on when i bought the car. Previous owner said it needed a MAF. So far i have replaced the MAF and upstream 02 sensor and new spark plugs. Any ideas what i should check next? We have also checked for leaks by the MAF by spraying Carb cleaner around the area with car idling. The car also shuts off/stalls when im at a light sometimes and the rpms drop below a 1,000 right before it happens. The car seems to have a rattle too it as well dont know if that is related to the rich bank one or not.
 

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check your PCV valve directly to the right of your headers. the hose can crack and cause a vacuum leak which will set off your light and cause a rough idle. spray carb cleaner on it and see if there are any effects.
 

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I remember the idle problem. If I remember right, it lead to a faulty PCV that was only able to be replace as a whole piece with the manifold at the dealer. (I was under warranty in that period.) I guess they sold it as a one piece unit back then. (2004?)
 

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tps is another cheap sensor to replace that helped with my idle issue....try cleaning the throttle body really good and maybe cleaning your iacv...you replaced the o2 sensor with a motorcraft o2?
 

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Discussion Starter · #5 ·
We hooked up to one of the vacuum lines to a gauge and the pressure was normal. So could it really be a bad PCV? Also I replaced the front one(which is the one giving me the code) but i replaced it with bosch. I can pick one a motorcraft 02 from Ford dealership for $60 so i try that too? Tps is throttle position sensor right? What would be signs of that being bad?
 

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SVT's are known to hate o2 sensors that are not motorcraft but I have seen people getting away with Bosch....it could be the o2 sensor im not sure and yes tps is throttle position most people will say that the tps wont cause those problems tho...but I would hate to tell you its the Bosch o2 and then you go spend 60 buck on the motorcraft one and that not be your problem
 

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and the rattle....it could be anything! is it a suspension rattle? engine rattle? if your cat still has the factory heatshields those are known to come lose and rattle and the rear heat shields sometimes vibrate and make funny sounds.
 

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Chances are it is a vacuum leak. I'd take the car to a shop with a smoke machine, it is the best and quickest method for diagnosis.

The Motorcraft O2 for the front is a DY1040 and can be had for as little as $25 online.

You also need to be using the correct plugs. The originals are Motorcraft SP487's which has been superseded by SP524's.

When you replaced the MAF sensor did you use a Motorcraft remanufactured AFLS183RM or an original 1L5F12B579AB?
 

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Discussion Starter · #9 ·
We hooked up a gauge to a vacuum line and tried it at different throttle levels and the vacuum pressure seemed find. The MAF and front 02 are both from Autozone. What part number should i get from ford for both of these(realizing i probably shouldve gone with these instead of what i got at autozone)?
 

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Moved to "General Technical Chat" as this is a maintenance discussion and not a performance upgrade discussion. Also want to note that you only need to make one thread on this subject. I am going to delete your other one and leave this one.
 

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Is it a 2 wire or 4 wire o2?

If it's a 3 wire PM me.

NTK made o2 sensors for Motorcraft
 

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The dtc for rich if true means that nothing listed in thread to do with vacuum leak is the issue, rich is the opposite of that................sorry buckos.
 

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Discussion Starter · #13 ·
Latest update on my car is the CEL still on. The car uses lots of gas while im traveling getting around 20 mpg on the freeway which doesn't seem right to me.....tonight or tomorrow will probably record a video and post on youtube and give you guys a link to hear the rattle i hear. Going to check spark plugs and have a tuner on the car I dont know if I will be given the datalog but ill make sure to get the fuel trims.
 

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Discussion Starter · #14 ·
I have replaced the upstream 02 sensor with the ford motorcraft dy850. I reset the CEL with my scanner then i drove to work today and the light is back with the P0172 rich code again. We pulled spark plugs to look at them and spark plugs for cylinder 1 and 2 showed signs of being rich where three and four did not. So now I'm thinking most likely a bad coil pack bank that powers the 1 and 2 cylinder or Fuel injectors for those two cylinders are bad. Any other suggestions? Car seems to be idling much better with motorcraft 02 sensor and the spark plugs i have it are NGK platinums by the way. Also keep in mind that the coil pack and spark plugs wire are stock so it could maybe just be wires too, but I find it odd that two cylinders next to each other go out at the same time.
 

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Check the fuel pressure sensor.

A. it can go bad leading to fuel getting into the intake manifold through it's reference vacuum hose - extra fuel is an obvious rich situation & it can easily affect a couple cylinders closest to where the line enters the manifold.

B. If that looks OK, checking fuel pressure with a scan tool could help let you know if that seems to be reporting reasonable numbers. (if it's off, report back for folks to help with that)
 

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Pull the vacuum hose to pressure sensor and check for fuel in it, they can rupture the diaphragm inside to leak fuel into intake and your rich. Or leaking injector can do it as well.
 

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Yeaaaa don't use ngk plugs in your car no, no. They don't work well in foci. Change those to motor craft double platinum's when you can. Iirc that's what rolled off the lot.



Ask me how I know. To not use ngks. Car ran like dog shit when I was having your issue.



I also had your exact same issue by the look of things. I'm willing to bet its your fps.
 

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Discussion Starter · #20 ·
I'll probably swap the plugs out after christmas. So is there anyway with a scanner to test the fuel pressure regulator? i'm looking for the part and found one from ford but it's $145. So do i need to drive the car for a little bit then when i come home pull the vac line off the sensor? or can i just turn the key so the fuel pump goes then pull the vacuum line?
 
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