I need of a Car nut.

[Silver 10+ year member]

Who's good with the 4.6L SOHC?

Ok so I have been having a rough idle and surging below 3k rpm untill vehicle warms up, since my CEL is blown (bulb) I got my car scanned at Auto-tards.

I don't recall the name but it has something to do with the air to fuel mixture causing the rough idle. I also have EGR excessive flow, but I've had that for years now. I've cleaned the channels also.

Recently I did a harsh (thru shrader valve on fuel rail) fuel injection clean.

The car idles rough and it feels like there is a dead cylinder when first cold. Intermittently I get a backfire or hear a LOUD pop from my Intake tube. It goes away within one minute.

When I first start the car it idles fine around 1k rpm. Soon as the IAC adjusts and dips rpm it starts shaking and misfiring away. Then at 1/2 throttle it sounds like a dirty maf would, ect. At WOT the misfire goes away and comes BACK when i let off throttle.

One thing I do notice. The motor makes a "click" noise and the car runs fine after that like almost something is being stuck shut @ 3/4 or below throttle.

I have NO IDEA what to do. Could I have killed an injector? If so, what would diagnosis mechanically for a fuel injector be?

So far I've cleaned my maf, replaced plugs wires, tried another fuel injection clean, checked torque converter (before code was thrown), checked valves (bad guides, burns oil), compression test. Everything check out OK. A long time ago the car had a rough idle and my pops messed with the set screw on the throttle body (this was 3-4 years ago). I dunno if the ATF mixture is incorrect now.

This problem is bugging me pretty bad now, because I was leaning towards fuel injectors untill that code was thrown.

Please help!!!

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[LoudCrownVic 5,000+ posts]

Wow, sucks to hear the probs you are having wit your tbird.

I'd say that given the problems I had with my Crown Vic, it's quite possibly an electronic issue.

You might have to replace the Mass Airflow Sensor.

The only problem i remember I had in my Crown Vic when the MAFS went out was strange throttle response, mind you.

I have no idea how you would check it but I assume that there is changing impendance or voltage that moves through the wires from the sensor as the airflow changes, stable at idle. Whle the car sits at idle and your voltmeter/ohmeter is bouncing or eratic, you could have your problem right there. Of course I will stress again that have no idea how you are really supposed to check the MAFS, you will want to look that up. The readings from OTHER sensors might affect this one. And MAFS are not cheap. It was like 400 bucks with diagnostics to fix mine. If you do replace it you might as well look into one of those Granitelli motorsports ones that give you a performance boost.

If the code read as a problematic air fuel mixture, I wouldn't be suprised if this is to blame.

Another thing that can cause engine bay electronic mayhem in general is bad grounds. Like all those little grounding staps here and there to the body or the block can go bad and cause all kinds of erattic readings. I doubt this is your problem though.

 

[mapolley07 10+ year member]

check your exhaust system too. my dad's grand marquis idles rough with a busted catalytic converter. one of your cats could be busted or blocked. if you have no emissions testing in your area, remove the cat and replace it with flexpipe or straight pipe.

 

[Ferendon 10+ year member]

IAC/IAB valve. Very common issue on alot of Fords. That wouldn't be the problem if it continues when you touch the gas, but it might be contributing to the idle problem. MAF sensor is a good place to check, and I'd recommend checking for a fouled plug or 2. The FI cleaning may have been nice and cold, which may have damaged a spark plug, or possibly even an injector.

 

[Silver 10+ year member]

Update, for the first time it didn't do it at start up. Only difference is it was raining out and very humid. Which is very odd.

I already looked at the IAC, I don't have a tool reader so I couldn't diagnose if its working properly.

I think I am going to clean it first. I also am going to replace the EGR valve and the DPFE sensor to clean that code up. I'll report back.

 

[LoudCrownVic 5,000+ posts]

Good I'm curious to see what happens!

 

[Silver 10+ year member]

Cleaned the IAC, everthing is working good.

 

[azbass 5,000+ posts]

I car nut need of a?

 

[Silver 10+ year member]

I car nut need of a?

It was suppoed to say. "In need of a car nut."

***.

 

[Beat_Dominator 5,000+ posts]

First thing that came to my mind was MAF or Oxygen sensor..... but it sounds like you're getting it figured out //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[oglejust 10+ year member]

egr valve will make it run rough

 

[blimblam 10+ year member]

i got the same problem! people kept telling me thats the problem, IAC valve. what did you use to clean it?

 

[Silver 10+ year member]

egr valve will make it run rough

Correct, espically if the valve is stuck open. Will cause a lean condition.

I'm replacing it soon, I cleaned the channels 3 times due to carbon cloging.

 

[LoudCrownVic 5,000+ posts]

I demand T-Bird pics.

 

[Silver 10+ year member]

Nothin special man, trust me. Here ya go though.

SuperCoupe Rear Bumper on its way.

***** I put in it. (4r70w) Stang *****.