Rough Idle, Stalling Out, Etc.

[Ferocious]

So recently i got a new PI intake manifold put in and ever since the car has been idling rough.
The shop who swapped the intake told me i just needed new plugs since my old ones had been drenched in coolant and oil from the previous faulty manifold.

Well i replaced the plugs with OEM motorcraft ones and got new FRPP high performance wires. I cleaned out all the plug holes and the coil packs as well.
However, the car still idles very weird. Driveability is great, but at a stop light, the idle goes up and down from 200-1000. While acceleration at lower RPMs i hear what is a ticking sound.
A few times, it has stalled when put in reverse due to the rpms falling too low.

The idle whether in park, neutral, or drive is rough. The car vibrates and it sounds like its completely cammed, when its not.
Any ideas what this could be? I've been told it could be a vacuum leak but i'm not sure where to look first.

And by the way, last week i cleaned out my cold air intake, the MAF sensor, my throtlle body, and the IAC.

 

[chris91]

Sounds like a vacuum leak. Get a can of carb cleaner and start spraying around the manifold. If it idles up or down you have found your leak.

 

[MustangChris]

any word on this, brotha?

 

[g36 monkey]

Chris91 gave you the best advice. Spray carb cleaner all around, typically it will make the motor race up for a second if there is a leak

 

[ChemicalGuys]

$20 says you need new Upstream o2 Sensors.

 

[Ferocious]

I did the carb cleaner and honestly cant notice a change. The problem is it's constantly going up and down at idle, so i dont really know if its a vacuum link cause i constantly hear a change in rpms.
I'm taking the car to my brothers shop monday to pull some codes and hopefully diagnose the issue more.

And as far as the 02 sensors go, i don't have any plugged into the exhaust. Not the fronts, nor the rears lol.
But i've had that for like 8 months and never had a problem.

 

[Ferocious]

I'll try to get a video tomorrow before i go fill her up.

 

[chris91]

No o2 sensors at all?? Were they turned off in a tune? If not then thats your problem right there.

 

[D3VST8R96GT]

Any codes?
Clean maf and hold the throttle slightly above idle just so it stays constant and then re try the spray test. Have you tried making a custom iac gasket? There's a write up on here

The D3V

 

[g36 monkey]

Yea, I bet the O2 sensors decided they were going to give you trouble now. Any welding done on the car by chance. That reset my computer one time and got rid of my tune and made my O2 sensors freak haha

 

[joekd]

My money is on vacuum leak. When I did the 1st manifold on my car it was doing exactly what you describe. Chased it for a week with no luck, finally took it to my local mechanic, they put it on the smoker and found a small hole on the back of the manifold that caused it. So hidden I didn't even see it when I painted the manifold.

Contacted the seller who swapped it out for a brand new FRPP one, swapped and trouble free since

 

[Ferocious]

Okay, so basically one of my fuel injectors was bad so I had that replaced today. Its not missing anymore and acceleration is pretty much as smooth as can be.
The idle still is a bit rough, but it doesnt bounce up and down as much. It stays between 500-900 as lights, but doesnt seem like its gonna stall anymore.

My mechanic said i definitely need to put the 02 sensors back in, and even my cats (not sure if im gonna do the cats though).
Another thing is that my fan's computer module isnt working properly, which i'm gonna have to look into cause i didnt have this problem until i installed my new radiator and i dont really know how to fix it.

I'll be ordering some sweet exhaust tips today and the tailpipes + 02 sensors should be back on the exhaust in no time.

 

[MustangChris]

do cats. they are like $60.00 each... .. . . .. . why not? . .. .. pfft.

 

[framda]

Yea, I bet the O2 sensors decided they were going to give you trouble now. Any welding done on the car by chance. That reset my computer one time and got rid of my tune and made my O2 sensors freak haha

Getting ready to put on my subframes as soon as I finish the bike and was wondering about this myself. I thought about unhooking it or taking it out completly before I start welding.

 

[Musturd]

Catts are gay