Running Bad Around 3000 RPM's

We're thinking it's the processor!

SKEDDIE said:

We're thinking it's the processor!

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Why?

BruceH said:

Why?

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It's not giving any codes for anything. The only one code it gave was a random misfire code. (1 time) The Ford IDS shows all parts in working order. I've already changed a bunch of stuff. Eric @ PCM went through a big list of stuff that he's already tested. We're just going to shoot from the hip on the processor and hope it works.

How did you make out with the processor? I'm having a similar issue.

Hmm, mine has a light, very light, what feels like a mis-fire at 3,000 to 3,500 RPM at partial throttle. sigh

I am thinking, hoping its tune related...

Let us know whats going on.

Thought it was the motion plates...???

I have an air leak where the actuator connects to the cmcv (cylinder 8 side). I'll be taking my shot with the cmdp's hoping this is my issue but I'll definitely be following this thread as well.

Ended up just buying another stock intake (used). No luck. It did stop the air leak and the car is now running smoother but I'm still getting the misfires when holding in 3rd or 4th at 3000rpms.

Have you talked to your tuner? Once all the mechanical issues have been resolved, its only tune related after that.

I have a similar issue where my tuner changed the strategy and I know have a 3,000 to 3,500 misfire or something.

I'm running the stock tune still with no mods to effect A/F ratio. It literally only happens in 3rd or 4th gear when coasting at or gradually passing 3000rpm-3500rpm. I've had to change my shifting patterns just to get around all of this. That's the worst part about it is that The car runs great everywhere else: WOT in any gear or coasting in any gear at any rpm outside of the range I mentioned above above.

We'll I replaced the processor two times!!! Finally the tuner was able to change it somewhat. But now runs like shit when it's cold. He was able to get it to run okay when at tempature. Because of the changes made and the way it runs hot cold etc I know it's all in the tune. It definitely needs some more work! Good luck guys!

Thanks. Glad to hear you're getting yours ironed out too. I wasn't able to do the compression test because I couldn't find any settings that fit (went to all of stores). I did check on my plugs again since I had them out and #3 had burnt oil on the electrode on up to about 3 threads. No bueno. I'm ordering the correct size of fittings for the compression test but I'm thinking I might just want to go ahead and get a leak down done at this point.

Defiantly not the tune. I took the car to another shop. He said they're may be a sticking tappet. Because when the oil is cold it runs like shit. As it warms it gets better. He said it was a valve train issue. Time to tear it down I guess. Damn it!

A mechanical problem is a mechanical problem all the time. If anything, thicker oil and higher pressure hide some mechanical issues under the hood. I would get your datalogs together and talk to Lito before you dump more money chasing the white rabbit.

fuel rail pressure sensor not giving proper reading to ecu?

Had a similar problem a while back. Have a look at this thread.I've fixed a few just by pulling the fuel pump and cleaning the pre-filterhttp://www.moddedmustangs.com/forums/2005-2010/438570-hesitation-mid-range-rpm.html

It's amazing! When you think you've checked everything. Thanks guys. I'll look at those things next.

whats with all these problems with NC cars lately ?

SidneyGT said:

Had a similar problem a while back. Have a look at this thread.I've fixed a few just by pulling the fuel pump and cleaning the pre-filterhttp://www.moddedmustangs.com/forums/2005-2010/438570-hesitation-mid-range-rpm.html

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Agreed. That pre-filter aka 'strainer' causes no end of grief. My FPDC was 96-98%. FPDC remained at 98% even AFTER the 10 ga wire upgrade kit installed.
I could bring it up to 6 krpm..as long as it wasn't into boost. With my foot into it, it would gag..at any rpm, in any gear. FPDC shot up to 99%..and fuel rail pressure would drop from it's usual 40 psi...down to just 2-4 psi.

The fuel pump strainer / pre-filter was completely clogged. Fuel pump removed, then pre-filter removed and placed over a pail. Filled it with brake clean, then hit it with the air compressor. Did this at least 20 times to clean all the crap out. You could easily use plane water + compressed air to clean it out. You need the tapered rubber thing on the air compressor fitting..so it seals tight on the strainer filter. Then use the compressed air to ensure it's bone dry.

Once re-installed, pump had to be primed 3-5 times, b4 eng started. Put key to 'on' position, and you can hear the pump making werid noises. Shut it off, then repeat several times more, till pump makes zero noise..then fire up the eng.

Problem solved ! FPDC dropped from 98%...down to 82% (gas pedal mashed to floor, blower on, max boost, 6.2 krpm in 2nd gear, going uphill ) Fuel rail pressure rock solid @ 40.3 psi

This is about the 7th case of known pre-filter /strainer being clogged. The normal fuel filter ( aprx below the drivers side rail) was changed out abt a month later..on spec. Zero improvement after the oem ford fuel filter replaced.

Interesting to note the amount of crap and crud floating at the bottom of the tank. The pre-filter has 3 x small feet that sit directly on the bottom of the tank. No wonder it got clogged. To really do it right, the tank needs to be down to 1/8....then suck out the remaining fuel + crud.

I don't believe you can buy the pre-filter from anywhere. A few fellow's were billed stupid amounts by their local ford dealer.....to replace the oem pump. New pumps come with a new strainer..which is what fixes the problem. Dealer of course will tell you the... 'pump is no good'.

So a last ditch thought of mine was that hopefully cylinder 3 had a lot of gunk built up in it, which would allow some oil to get through and foul up the plug that I've replaced so many times. Since my last post, I added some Marvel's Mystery Oil to the oil and ran it for about 750 miles and then changed the oil (didn't notice much difference during this period). I went with some high mileage oil, but this time also added Seafoam. I ran this for about 1200 miles assuming that I was going to get a leak down test. But during this period, my misfire at 3-3.5K rpm's in 3rd and 4th was gradually cut down to only getting misfires when the engine is cold (as mentioned by SKEDDIE above). I'm now on my 3rd oil change and 2nd treatment of Seafoam (still using high mileage oil and just used the remainder of Seafoam from what I had before) and I haven't had a misfire in a good 500 miles, hot or cold. I haven't been losing as much oil and I can also see those results in the soot level on the cat back tips. I must add that each time I've changed the oil, I've also changed the spark plug in cylinder 3 and the "foul" level has gone down each time too. I will continue to do this at 1000-1200 mile intervals for a few more cycles before reassessing the next step.

My tuner says its back washing the air meter between 2700-3200 after that the graph smoothed out. Even at WOT it was doing it, it just wasn't noticeable driving it.