Update on Mustang

gwstang

Well-known Member
For your entertainment purposes only.
'66 mustang with 5.0 HO engine with EFI Speed Density wiring/computer.

Update on stumble when taking off, then runs like a scalded cat.

I changed the plugs/wires.
Adjusted the tps to .90 (book says anything from .65 to 1.0 is okay) Had to elongate the holes a little to achieve this.
Got some of the stumble out but not all.
It acts like a small intake leak somewhere but I have sprayed starter fluid all around and no leak or change in idle.
The idle does fluctuate a little up/down when it is warmed up. Acts like it going to die when I shift into gear (auto transmission) unless I feather the gas a little.
I will check the trouble codes (if any) tomorrow and maybe that will point in another direction.
This efi stuff is way more complicated than the old school carb stuff ever was. Also, changing the spark plugs on a '66 with the very close shock towers (they went wider in '67 and up) is a major teetotal absolutely complete cluster #@*^ with headers involved. I skipped the compression testing because of this. Ceramic headers do get scratched up btw. :evil:

Other than the hiccup, it runs great.
 
On a related topic, my B-I-L rebiult the 5.0 in his '92 F-150 and added headers cause the exhaust manifold were cracked and the exhaust wan't much better, including the crossover and the cat.

It runs worse than your 'Stang on the OEM speed density system. We have most of what we need to convert it to MAF, and will then try to tune it with TWEECER. Should be interesting!
TWEECER
 
http://www.carcraft.com/techarticles/electronic_fuel_injection/

Either my puter is crap'n out are YT has a issue... I am not a Ford man but one thing they do is make you get down and dirty checking out the EEC system... Your diagnosis is not dependent on scan tool data you have to install a break out box are fiscally back probe the sensors... (Don't tell anybody but its not that hard to do)...

FIRST TEST I also want to see if theirs any voltage drop on the main GROUND wire at the battery for the ECM.. (They tie that MF'er rite to the negative battery post) It will throw you a curve ball if the grounds are not good... It must be tied to the negative battery cable WINK WINK

Ford ask you to do a KOEO test it will self test its self key on engine off you fix any codes that show up their FIRST,,, if you have a issue fix it its a issue and the engine is not even run'n so how do you expect it to run with a issue that shows up before to start it...... Then you do a KOER test (key on engine run)...

Ford diagnostics trouble shoot'n SHUcK... They have nuttin to do with what the sensors are reporting to the ECM...

I will not go any farther ( and I am not try'n to be a smart arse) unless you tell me KOEO test, KOER test results, fuel pressure, what the vacuum reading is with a vacuum gauge Tee'ed into the vacuum line at the MAP sensor at idle and what the vacuum reaction is when you goose the throttle and let off of it...
I am sure Bob ( I highly respect his ability) will back me up its not that hard to do You skip nuttin there is no silver bullet if someone shoots one at ya dodge it they are not of much help...

What grips my arse is Some folks think because they can build it they know it all and will tell the world how smart they are when you question them... If I dunno I will tell ya I am stupid and need answers to the questions... It always turns into how smart I am i dare you to question my degree..

Millions of folks see a apple fall from a tree but Newton was the one who questioned it...
 

FIRST TEST I also want to see if theirs any voltage drop on the main GROUND wire at the battery for the ECM.. (They tie that MF'er rite to the negative battery post) It will throw you a curve ball if the grounds are not good... It must be tied to the negative battery cable WINK WINK

I did tie it directly to the battery for sure. I will do the koeo stuff tomorrow to see what that reveals (besides what I don't know what the he** I am doing most of the time...lol).
 
BTW the BOO test (brake on off) press the brake pedal and let off)... Don't get in a hurry... I had to ask someone what the ell is a BOO test :lol: :oops:
 
Is this hesitation the same as when the carb was on it? or just similar ('cause there's some hesitation)? I got to thinking over the weekend that if it's identical to when it was carburated then it's got to be something still in the system and that got me thinking it might be transmission/torque convertor issues where the TC is putting too high of a load on the motor before it's ready.... hence higher stall convertor availability.

Anyhow, just one more thing to consider. I'm curious to find out what the problem is/was.
 

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