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About to drown this thing in the Bayou - EFI issues

rustbucket

Bronco Guru
Joined
Mar 22, 2004
Messages
1,579
Well, the old Rust Bucket is about to become the Old Boat Anchor, or Old Gator Trap after I roll it into the bayou!

Some of y'all (yes, we say y'all in the South) may have read some of my other threads over the past few months while I have been trying to get this thing back on the road.

I installed the 5.8 in '94 or '96 using a Motorsports harness, GT-40 upper and lower, 65mm Motorsports throttle body, Pro Flow (Pro-M) 70mm Mass Air Flow meter, and Ford OEM sensors. Ran fine.

After sitting, I have had a hard time getting the thing to idle properly. I replaced the IAC and fuel pressure regulator. Both made incremental improvements, but it still doesn't idle well, and hesitates under load at lower RPM's. I can rev it up in neutral or park, but once in gear, it misses and sputters. Smells a bit rich, too. Exhaust pops. When I try to start it, it takes several attempts, and it idles real low at around 500-600 RPM's for a few seconds, and gradually dies. I adjusted the idle to just above 1000 RPM's as a test, and it will stay idling, but it misses quite a bit. Still misses severely under load at low RPM's. Once in mid-range, it seems to pull much cleaner. It's as if it suddenly has power!

It's not the dizzy or TFI. Both replaced (yeah, I'm starting to throw parts at it%) )

I have check and rechecked for vacuum leaks. Used carb cleaner and propane.

Cleaned the injectors per instructions from fordfuelinjection.com, and replaced o-rings, screens and pintle caps (This could still be the problem).

Fuel pressure is fine. Replaced regulator anyway, as I was cleaning injectors (Why the H did the engineers decide putting the screws on the bottom of the fuel rail was a good idea?)

Checked codes, and got a 12 during KOER, indicating problems hitting upper rev limit during test, hence, I changed the IAC.

Gas tank was almost empty when I parked it. I have since filled about 8 gallons of fresh gas in the tank.

Replaced fuel filter.

Tested TPS. 1.08V at idle position, 4.50 at WOT. Nice linear sweep.

Unplugged MAF. No change.

Tested alternator output. Puts out 14+V.

Checked ground. ECU is grounded directly to negative battery terminal with a 10g wire. Resistance between negative battery terminal and block is zero.

I have not yet checked the O2 sensors, as I'm not getting any codes for them. Seems unlikely to be the culprit, but you never know with these things.

Also thinking the ECU may just be bad. Maybe the humidity down here, combined with no use for 4 years just killed it?

Am I missing something? Any suggestions?
 
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67EB_in_619

Bronco Guru
Joined
Mar 6, 2003
Messages
1,868
Loc.
San Diego
no change on the MAF is interesting.. do you see voltage there? Also, your TPS voltage is high @ idle.. should be like .98 or something.

If you introduce a vac leak, does it get better? same? worse?
Is it pinging at all?
Stock injectors?
what is the timing set at with the SPOUT pulled at operating temp?
 

HGM

Sr. Member
Joined
May 24, 2010
Messages
973
Loc.
Senoia, Ga.
Sorry if I missed it in your description somewhere. But, what are you using for a scan tool? Do you have datalogger capabilities? Seems like your desctiption is screaming for a look at the o2's and fuel trims for a clue.. It may seem like a dumb question, but is your IAC installed in the right orientation? If installed backwards, it could cause idle issues.
 
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rustbucket

Bronco Guru
Joined
Mar 22, 2004
Messages
1,579
Timing is at 10 degrees BTDC with SPOUT disconnected. Injectors are stock 19 lb units. 1.08 on TPS is still within specs, so I don't think it can cause this much of a problem. It's not pinging.

my scan tool is a Auto X-Ray EZ-Scan. It's an older model, but I think it has data logging. I have never tried it, but will check it out this weekend. I'll check for voltage to the MAF, as well.

I have not ruled out O2 sensors. I am using BCB shorties (headers) and stock 5.0 O2 sensors. Is there a good way to test them?

I am suspicious that the injectors are just "bad". I hate just throwing more parts at it, though.
 

dbevans2249

Sr. Member
Joined
Sep 21, 2003
Messages
610
Loc.
Buena Park, Ca.
First let me say that 4 months ago I could not spell EFI. Almost all I have learned is from reading here and Ford Fuel Injection dot com. So I hope this is a fairly good sudgestion.
You may want to try resetting the base idle. Here is what I coppied from a Mustang Forum. I hope it helps and at least it is not throwing parts at it.

How to do it
1. Disconnect the battery's negative terminal to reset/clear the computer's memory. Leave it disconnected for 30 minutes. WARNING: Whenever removing your battery cables ALWAYS disconnect the negative battery cable first and reconnect it last. Otherwise you could destroy your computer or cause a battery explosion.
2. Disconnect the plug going to your idle motor which is located on the front of your throttle body.
3. Reconnect your battery's negative terminal.
4. Start the engine, and set the idle to the rpm you want with the stop screw on the bottom of the throttle body.
5. Turn off the engine.
6. Reconnect the plug on the idle motor
7. Make sure all accessories (radio, blower motor, a/c, lights, etc) are off and start the engine.
8. Let engine run for two minutes.
9. Turn engine off and wait two minutes then restart engine and let idle for two minutes with all accessories on.
 

HGM

Sr. Member
Joined
May 24, 2010
Messages
973
Loc.
Senoia, Ga.
Your TP is probably fine since you mentioned adjusting the idle up..

Your o2's are probably fine. They dont go bad in pairs, typically, regardless of what the parts house tells you. The o2 is a voltage generator. When hot, they should switch between .1-.9v fairly quickly. You may have SFT or LFT that will tell you what corrections your PCM is making to keep the o2 switching. A +number means adding fuel, a -number means subtracting fuel.. This will help indicate whether you are running righ or lean. That should give you a starting point.

Your scan tool should give you a MAF output voltage. If you have voltage out, you have voltage in. By unplugging the MAF, you take it out of the loop and put the fuel system in default, guessing on airflow. If you have no change, it's probably not the MAF..

I'd still double check the IAC.
 

70_Steve

Old Guy
Joined
Dec 13, 2002
Messages
8,317
Have you run the KOER test? Smelling rich at idle doesn't mean it's running rich. Could be a lean idle misfire. Ask me how I know...:mad:

As was stated, disconnecting the MAF with no change is more than interesting. Your symptoms sound very similar to what I had when I first started my EFI, including the rich idle smell so strong it would burn your eyes. Ultimately for me, it came down to a "modified" MAF housing, which was bored out to a larger inside diameter. That F'd up the air flow indications resulting in a lean condition. Changed the housing (same sensor) and all was OK.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
With the engine cold and freshly started spray around the intake at the heads and where the manifold halfs connect together and check for a vacuum leak. Hook up a vacuum guage and see if you have a steady vacuum reading. With all the failed intake gaskits I have heard about lately I worry about an issue there.
 
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rustbucket

Bronco Guru
Joined
Mar 22, 2004
Messages
1,579
70_Steve, It was a KOER test I performed. I fixed it in my original post. Actually, I have done both. Just mis-typed. 12 is the only code I get that isn't expected. i.e., emissions stuff I don't have.

Rustytruck, I have done that countless times now. I'll try again. A vacuum leak does seem plausible.

I may go ahead and do a compression check just to make sure everything else is healthy, but I don't think I will find anything there. Like I said, once I get the revs up, it smoothes out.

What are the symptoms of a bad BP sensor? Wouldn't think it would be that severe, but I'm grasping at anything I can.

I'm keep coming back to the ECU.

Unfortunately I won't be able to do anything until I get back in town from business.

Anyone know any good parts/accessories shops in Houston to check out?
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
You can always have a vacuum leak on the inside of the manifold thats causing the issue and will be undectable. Try retorquing the intake bolts.
 
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rustbucket

Bronco Guru
Joined
Mar 22, 2004
Messages
1,579
I did re-torque the lower intake and snugged down the valve covers when I had the upper off.

No, I don't have vacuum going to the BP.
 
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rustbucket

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Joined
Mar 22, 2004
Messages
1,579
Well, I thought I had a bad ECU, so I changed it out. Still not running right!

KOER codes 12, 33, 44 and 94. Of these only 12 has me concerned. I changed out the IAB with no change.

KOEO code 85

Memory code 11

I checked vacuum, and I have about 20" steady.

Base timing at 10* BTDC

Fuel pressure at 30psi idle. Goes up with throttle.

It seems to idle better, and I can rev it in park okay, but it does "pop" out the exhaust sometimes. It when it's under load that it really starts missing bad. Guess I'll go do a compression test and see what I get. Should have done that a long time ago!
 
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rustbucket

Bronco Guru
Joined
Mar 22, 2004
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1,579
I'm sorry, that was with the vacuum line connected. It's 39 with vacuum line disconnected.
 

73azbronco

Contributor
Bronco Guru
Joined
Nov 11, 2007
Messages
7,796
fuel injection diagnosing steps:

First, get the codes and clear the memory, then see if the codes come back after trying to start.

Proper battery/electrical voltage
Proper compression
Proper routing of intake vacuum hoses.
proper routing of spark plug wires.
No vacuum leaks (to do this right you need to "smoke" the intake)
Base timing set.
Spark at plugs when cranked.

You have now removed mechanical, vacuum, electrical issues from the checklist.

Next, fuel:

Correct Fuel pressure at rail at right time. I don't have the book handy, whats it say you need at idle with vacuum disconnected and with connected at idle? How long does it take to bleed the pressure back to zero? No set parameter but the faster it bleeds down, the more issues you have with pump or regulator.
Fuel flow volume at rail, need to remove regulator and use a bucket.

You now have fuel, ignition, compression, rotation.

it should fire. If it doesn't, you have a computer issue, what are the codes?

Since our problem is we build this thing, you might need to verify every wire to every component.

hints: O2 sensors aren't used during start, only after warm up, so those can be discounted if it doesn't start, in my experience.

If you have mixed and matched injectors, MAF sensors from different sources than the ECU, I recommend you go back and baseline your components to one model year that matched the ECU.

you noted "fixing' your injectors. This is going to suck but for $100 I strongly recommend you send those out to be cleaned and flow tested at an injector shop. Bad idle/stumble can be defective pintles/injectors, especially saince it sat for a year with no fuel, lots of critters can make their way in there and become injector cloggers.
 

70_Steve

Old Guy
Joined
Dec 13, 2002
Messages
8,317
I'm sorry, that was with the vacuum line connected. It's 39 with vacuum line disconnected.
I know you said you put a new one on, but does the idle speed change if you unplug the IAB?

Also, what do the plugs look like?
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Is your motor warming up to 195 Degrees. A steady vacuum reading would indicate proper mechanical function so I would conclude its not in the mechanical function of the motor but in its controls.
 
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