HELP!! Need expert in 5.0 engine workings...IDLE ISSUE

[Fred Z]

Gentlemen, I am needing a top notch professional on 5.0 Ford motors. My car runs excellent with exception of the idle. At correct idle its at 975 to 1k. But for no reason it suddenly goes into drop mode to 850 and flutters. We have tried everything......everything! It's a 427 W, 550 hp and same tq. Massflo injection and we cleane the entire throttle body , adjustED the TPS, NEW TFI , new plugs, and now ...... We just ordered a new IDLE CONTROL VALVE.
My wrencher is extremely solid and we are asking for your help. Either PM or here. It's this last issue. Oh, BTW..... The BBs are running better than ever so to those still considering......go get em!
Fred z

[PSB]

Have you talked to Mass-Flo? I had a similar problem until I had a custom chip burned for my EFI computer, but I'm running Mustang EFI.

Pete

[Fred Z]

Ok, I just got through installing a new Idle Control Valve.....hoping it would solve the problem.....it didn't! I am about out of ideas. I was hoping I might get some ideas here or better yet...a confident solution. We have done everything possible to remedy the issue with the exception of ordering a new chip! I am not sure that would be the issue as it runs perfect otherwise. I will order one as the last effort.
As explained in the above lead post.......it idles nice, then goes very low, then sometimes back again. But the 1k idle we are trying to keep just wont stay and it sometimes starts in the AM and after a 20 sec run, shuts off.
It just seems to be struggling to get air or fuel. Even took out the fuel filter but it was spotless.
Can't be a huge thing, but we cannot find it.

[vector1]

you can try speedtalk.com and post there, there are some pretty knowledgeable efi guys.

[olddog]

What is the fuel pressure doing and how much do you have? You should have 39 psi with the vacuum disconnected and it should drop 1 psi for every 2 "Hg of vacuum.

Try disconnecting the PCV valve and plugging the line. See if that makes a difference. The PCV is sucking air in and it is not measured by the mass flow meter as the system comes. That can cause it to run lean at idle.

Does your ECU have a chip in it? The mass meter, engine displacement, and fuel injector size either have to be correctly entered into the chip or the mass meter must be scaled in the correct ratio to injector size verses the original Mustangs 19 lb/hr injector size. As stated give Chris Richards a call. He is fairly knowledgeable.

[PSB]

Sorry, but there's no shortcut here. You're expecting a computer that thinks it's controlling a stock 225hp 302 with 19lb/hr injectors to control an engine with twice as much power.

If you REALLY want to fix the problem, don't ORDER a chip! Find a good dyno tune shop and get a chip custom burned for your car while being tested on a dyno. I honestly don't get why people will spend $15-$20k on an engine but won't spend $300 to get it turned properly.

I took my lowly 351W to a local tuner and got a custome chip burned. For $300, he fixed my idle and drivability issues AND got me 50hp to boot.

Pete

[Fred Z]

Pete, no offense meant here....
But it was running perfect for 5 years! I called Chris...and its NOT the tune...its the idle. Runs great on the move....just hiccups on idle. For the record....I totally agree that when spending X amount for a top flight motor there is no reason to 'cheap out' when wanting it in top shape.
I get it. But thanks, I appreciate your words.
fred

[Jerry Clayton]

5 years?????????/ what were you running for fuel and what now------------when we are chasing other peoples tunes, we find lots of basic stuff that needs attention---exhaust header leaks that then effect O2 sensors, vacume leaks that effect mass air flow, heat build up that effects inlet air temp,rpm changes because of alternator loads from electric fans,etc,etc

Why are you trying to get it to idle at 1000??????????an efi engine should idle fine at 750-850

Does your distributor have a locked curve or is the advance still active?????????

[Fred Z]

Jerry, running the same fuel as always. I don't veer off successful situations since ...if they work great....I leave them alone! Keep in mind...this all began right after a TFI module went dark......replaced with another and since then....never has been right.
Chris Richards said.......only POSSIBLE to be one of 3 things:
Air into engine, Timing advance, Voltage. that's it!
As for 1,000.....that is the sweet spot for this car. anything lower than 9ish and its a bit too much loping...
So, if I can figure out which one of the above 3 it is.....I will be ecstatic!!

fred z

[olddog]

Originally Posted by Fred Z

...this all began right after a TFI module went dark......replaced with another and since then....never has been right.

Are you sure you put the right type TFI module on it?

There are different types. Mine was black from MassFlow, but the Ford TFI of the same type is grey. A black Ford module is the wrong one. I would have to re-read some stuff to explain it any better.

[Jerry Clayton]

Can you post a pic of your module? showing the numbers on it?

Corey has equip to burn chips for the Ford stuff and I remember that there is an area of concern where something has to be scraped off for good contact------

And the comment about air, timing advance, voltage ---thats the reason there are over 100 wires on most of these ECMs------

[ffr 1137]

You may have a fault stored in the ECM, causing it to default to
"limp home mode". You've probably done this already but do a reboot
by disconnecting batt for a min. Or, if you've got access to a known
good ECM try a swap-out. Just a thought.

Mike

[Fred Z]

STILL NO SOLVE ON THE ISSUE!!
I have tried everything with my man.......but it still intermittently stumbles down to 850 ish.....then back to the preferred 1k. I know some have said the 850 is fine....we all have our cars in different comfort zones....mine is 1k idle. But the damn thing won't hold it there. It runs perfect so no issue there, but the idle just bugs the crap out of me.
We are stumped!