[WDfrmTN]

A little long but bear with me, okay?

First off, the car is my son's - he bought someone else's headache, and I'm trying to sort it out. '91 5.0?
Me? Not much of a Mustang man at all (mostly SB Chevy man), but I am a mechanic - diesel certified, licensed A&P, and have previously owned and kept running two EEC-IV Tempo's.

Here's what's in it so far:
'97 Mountaineer short block from salvage (8.8:1 comp, best I can find out)
Windsor Jr. heads
Ford Racing E303 cam shaft
JEG's rockers (not sure of ratio)
Trick Flow upper (75mm), spacer, and lower intake.
BBK/Edelbrock throttle body (65mm)
BBK CAK (75mm?)
EGR blocked
EVP locked to "full closed signal"
24lb/hr injectors
Fuel Pressure 40psi
Ford Racing shorty headers, HEGO's operational
Crappy H-pipe exhaust w/out CAT/CON's
T5? Trans (no VSS)

Okay, by now, you've probably started guessing some of the problems
Crappy idle, dies on decel, running rich, backfring through exhausts, "Bad" TFI/SPOUT symptoms.

(Don't ask me why the boy wasted $5,500 on this...I'm just wanting my Sonoma back!)

Anyway, what we've done so far:
1. Set valve lash correctly.
2. Removed, stripped, repaired, continuity ck'd, Ohm'd out, shot for shorts/grounds the ENTIRE EEC and injector harness (had them laid out in the living room floor).
3. Repaired any/all possible vacuum leaks to be found.
4. Replaced pos/neg battery cables, eng/body ground, battery/body ground, EEC/body ground (grounds replaced with aircraft grade bondings).
5. Removed, disassembled & cleaned IAC valve, EGR body, & throttle body (Lord were they cruddy).
6. Cleaned MAF sensor.
7. Reassembled/reinstalled all, cleared all stored codes, test ran, setting idle regulated fuel pressure to 40psi w/vacuum reconnected to regulator, and base spark advance to 14*BTDC.

Pulled new codes:
31 - EVP Ckt Below Min Volts
84 - EGR Valve Reg Ckt Failure
85 - Canister Purge Ckt Failure
(Yep, have a few things to pin out, now).

For his rough idle, I've found he's using 93 octane, so I told him to go back to 89 octane, due to the low compression ratio. Also found out he's running a 150* t-stat, and told him to put a 185* or 190* t-stat in.
I'm strongly recommending him to match all his air components to the same mm bore, (frankly, I think 65 mm is sufficient for a daily driver, 75mm a bit too much and too quick for 19-year-old) and to add a VSS to prevent any problems with decel lean-out/dying.

Suggestions? (No "hot-rod-racer" stuff, please).

[WDfrmTN]

Uh, yeah...found the EEC was for an automatic.
Have an A9L (what the VIN calls for) on the way!

[C MY 4D]

Which Maf is on the car?
What is the TPS set at for idle?

[WDfrmTN]

Originally Posted by C MY 4D Which Maf is on the car? What is the TPS set at for idle?

I'm positive it's the 75mm listed on this page: RJM Injection Tech » Fuel Injection Parts compatible with 89-93 Mustang 5.0L Mass Air EFI engines

Haven't been able to set the base idle or TPS yet. I can get it smoothed out at about 1200+rpm, but then the TPS would be too high, if I'm thinking correctly. Shooting for the T-stat (stable idle temp & closed loop achieved), 89 octane fuel, and try again.

[C MY 4D]

Well the IAC has a problem providing enough air to the motor during idle on a modified 5.0. Usually what I'll do is try to get the TB to open as far as I can get it while the TPS is reading .9-.95. If it still has an issue idling I'll drill a small hole in the throttle plate and move up in size as needed.
Is the MAF calibrated to the injectors?

[93hatch]

the auto computer works fine with a 5 speed fyi

[WDfrmTN]

Ah...okay, set the TPS at WOT voltage! Don't know why that didn't cross my mind. Thanks!
What about the Ford P/N IAC plate? I've seen them recommended for the E303's quite a bit.

MAF calibration? Not sure, the data plate/tag isn't marked (which struck me as being pretty odd). Any pin-checks to determine this?
All I can tell you about the injectors is that they are "blue, 24lbs/hr".

BTW, does anyone make a good realtime data reader for the EEC-IV? (My last EEC-IV was gone about 10-12 years ago )

[C MY 4D]

No, no set it at idle.... it should be .9-.95 at idle.
You could waste your money on that plate but drilling the throttle plate does the same thing.
Truly the only way to tell is by what they wrote on that data plate.
I recently borrowed a friends about a year ago that worked nice but I can't remember the name of it.

[WDfrmTN]

Originally Posted by C MY 4D No, no set it at idle.... it should be .9-.95 at idle. You could waste your money on that plate but drilling the throttle plate does the same thing. Truly the only way to tell is by what they wrote on that data plate. I recently borrowed a friends about a year ago that worked nice but I can't remember the name of it.

Okay, got it, now.
I was thinking I had to set the base idle first, then check that the TPS was correct at that throttle-plate-angle. I'll get to the checks, Thurs, probably.
Thanks for the tip on drilling the throttle plate - I've done that on flat-slide carbs on bikes, but didn't think about it for this.

[93hatch]

you shouldnt have to do it though, thats just a way of working around a problem

[Iwannagofast]

Originally Posted by C MY 4D No, no set it at idle.... it should be .9-.95 at idle. You could waste your money on that plate but drilling the throttle plate does the same thing. Truly the only way to tell is by what they wrote on that data plate. I recently borrowed a friends about a year ago that worked nice but I can't remember the name of it.

Damnit man i cant get any reading done with your avatar going

[WDfrmTN]

Originally Posted by 93hatch you shouldnt have to do it though, thats just a way of working around a problem

Shouldn't have to do what?

[sniperd]

Originally Posted by WDfrmTN Shouldn't have to do what?

He mean's you shouldn't have to drill the throttle plate...

[93hatch]

[WDfrmTN]

Originally Posted by sniperd He mean's you shouldn't have to drill the throttle plate...

Ah...okay.
If it works though....
I'm just wanting to get it dependable and driveable right now - he's set up wrong, for sure (comp ratio, cam, mixed air components, injectors, etc.) but he's gonna hafta make some more $$$ to get things right.

Shoot, the thing runs on the stomp-down like a raped-ape now, so I'm just shooting for basic driveablity and idle performance. He picked up the t-stat last night so we can swap that today, and then start from there.

Frankly, I'm looking at the C&L MAF body, so we won't be dealing with something that's essentially "tricking" the computer and messing with the fuel tables. Then it'll be to getting the computer programmed to the iron. I never did like fixes that "trick" the computer, since you can't get the full benefit of the computer's algorithms.

Funny, I'm beginning to have more fun than my son is with this....may wind up getting me a little Fox!

[WDfrmTN]

TPS out of range. Slotted the holes and had to go "full travel" to barely get .98.
New TPS in, still had to slot the holes and rotate some, but have good readings now: 2-3ohms return (KeyOff), 4.98-5.0V (KOEO), and .99-1.00V signal (KOEO)

Installed 180* t-stat, EEC now reads ECT and drops idle correctly after warmup.

Regapped plugs to .054 (they were at .045).

Ran tank almost empty, put 5 gals of 89 octane in due to 8.8:1 compression.
Seems to have helped some with cold start/idle.

Idle is still surging, even after warmup, but is better than before.

Q1: With the 8.8:1 comp ratio, is that E303 "too much" cam?
Q2: With the 65mm TB, is that E303 "too much" cam?

I still have to address those 31, 84, & 85 codes, too.

[93hatch]

its not too much cam, have you gone through this?

Mustang idle surge and base idle reset

[WDfrmTN]

Originally Posted by 93hatch its not too much cam, have you gone through this? Mustang idle surge and base idle reset

Yup, but gonna' redo Monday (should have the new EEC in by then).
Idle just doesn't want to run very good below 1,000RPM -about the lowest I can get it, much lower and it acts like it's starved out and then dies.

Also, I'm a tad confused as to why guys here are recommending .9-.95V on the TPS, when 1.0V+/-.1V (nominal) is recommended here:
http://www.youtube.com/badshoeproduc.../0/lJEGigONelc
I know they agree in range, just wondering about the tendency toward the lower setting?

[93hatch]

apparently perfect is .98

[WDfrmTN]

Okay....
Installed the new EEC (A9L), and cleared it.
Reset fuel pressure.
We've done the IAC/IAB checks,
TPS checks, fixed the 31, 84, & 85 codes*
did the base idle & TPS setting procedures,
double-checked timing settings.

Idle is MUCH better, though not perfect.

Problem NOW is no power worth a crap when driving.
Before, I could peel the tires dang near off, grab rubber in second, etc..