Hesitation @ mid-throttle and backfire @ WOT

[stangman16]

Hello,

Trying to work all the bugs out of this '92 mustang EFI conversion in my '66 stang, it runs - now it's just a matter of getting it to run just right. It seems to idle fine, I'm unsure of what cam is in there but it seems mild because i have 14.5hg of vacuum and a lumpy sound to it. (8.9:1 compression, ECM is programmed for the non-HO firing order which this cam is)

When I give it mid throttle it feels real hesitant and then if I give it WOT it backfires.

I don't have money to be throwing at this thing in parts, and I'm more than interested to learn how to diagnose and fix such a problem with an EEC tuner like my quarterhorse. I just don't know how to interpret the data to find the cause.

I'm leaning on fuel injectors being old and gummed up. But I'd like to ensure this is it since they are costly to replace. However I am curious if the $25 injector service kit on fordfuelinjection.com would do the trick if my injectors are truly the cause of the hesitation and backfire.

I've checked plug firing order = okay. Timing is at 11º, at 14º it was throwing codes 41 & 91, so I backed it down to 11º, reset ECM and drove around for a minute and those two codes did not return.

NO EGR, thermactor, CANP = all disabled via the quarterhorse using Binary Editor from Clint Garrity. (very impressive program might I add!)

499.1697115_____204__196__33.58__17.79__13.9______13.9____3.53__3.57__0.0025__0.0025__1052__16.8___0.89
499.233742______204__196__33.58__17.79__13.9______13.9____3.53__3.57__0.0025__0.0025__1052__16.8___0.89
499.2840207_____204__196__33.58__17.79__13.9______13.9____3.53__3.57__0.0025__0.0025__1052__16.8___0.89
499.3739799_____204__196__33.27__17.91__13.9______13.9____3.58__3.58__0.0025__0.0025__1032__20.5___0.89
ET_____________ACT__ECT__MAF___LOAD__LAMBSE1_LAMBSE2_PW1__PW2__HEGO1__HEGO2__RPM__SPARK__TP


This is at idle of 1000 rpms. I did a KOEO code check and I'm getting 15 and 95, then a 10. I did some research here and on the web and I cannot find a code 10.

Code 15: I am going to check the PIN1 for power...checking tomorrow.
Code 95: I have to get a connector for the VSS sensor... in process.
Code 10: ??

Can you help me diagnose this hesitation issue?

 

[rbonella]

I had the same problem with my old high mileaged highway patrol mustang back in the day. Idled fine, but once on the street with 1/2 throttle to full throttle it would hesitate, pop, bog etc... I replaced coils, ingnition modules, caps, rotors, wires, plus, injectors ...you name it. It was a months worth of nightmares. I had a hidden suspicion I had a MSD 6AL that was going bad, so I removed the ignition box and replaced the fuel pump with an aftermarket 190/hr unit. From that day on I never had a problem again.

 

[7upstang91]

I think the fuel pump may be going bad. When my fuel gets low it does the same thing. So i try to fill my tank up with 4 gallons left or 1/4 tank. Annoying I know but i have been doing it for two years the and the stock fuel pump is still going.

 

[stangman16]

I had the same problem with my old high mileaged highway patrol mustang back in the day. Idled fine, but once on the street with 1/2 throttle to full throttle it would hesitate, pop, bog etc... I replaced coils, ingnition modules, caps, rotors, wires, plus, injectors ...you name it. It was a months worth of nightmares. I had a hidden suspicion I had a MSD 6AL that was going bad, so I removed the ignition box and replaced the fuel pump with an aftermarket 190/hr unit. From that day on I never had a problem again.

Hmm.. I may need to check the ignition system then, but I don't have any aftermarket system like MSD attached. The fuel pump I have is a Holley fuel pump with less than 100 miles on it, I sure hope it isn't burned out already.

 

[stangman16]

I think the fuel pump may be going bad. When my fuel gets low it does the same thing. So i try to fill my tank up with 4 gallons left or 1/4 tank. Annoying I know but i have been doing it for two years the and the stock fuel pump is still going.

I think I have less than 1/4 tank currently, worth a shot - I'll fill it up. I'll change fuel filter also and see what that does.


Any more suggestions to try after work?


EDIT: btw, my fuel pump is an external Holley, no baffles in my tank so I need to keep it above 1/4 until I can afford a fuel cell

 

[jrichker]

There is no code 10. Sometimes you get a phantom flash, or the second flash that would give you code 11 is so faint you can't see it.

 

[stangman16]

There is no code 10. Sometimes you get a phantom flash, or the second flash that would give you code 11 is so faint you can't see it.

I'm using a hand-held scanner, it said 10 and even so after I clear the computer codes, drive around and recheck them it displays 10 again... should I be worried since there is no 10?

 

[stangman16]

..bumped up to mid-grade gas which is 89 around here, it hasn't backfired yet - of coarse I filled up the tank too. Still feels a little hesitant, how can I find information to fine-tune this engine? I have the hardware, I just need to know where to get/find the knowledge..

 

[stangman16]

UPDATE.. still need some help please.

I found the orange ground wire NOT connected which is from the injector harness. Connected and now I get KOER of 42.

Did a search and I just have a few questions,

“Code 42 & 92 (engine running) System rich - Fuel control or (memory) System was
rich for 15 seconds or more (no HO2S switching) - Fuel control. Look for leaking injectors,
fuel pressure too high, cylinder(s) not firing due to bad ignition.”

Questions…
1) How do you check for leaking injectors? Did a cyl. Balance test, came back 90 = ok //today I've done about 5-6 of these
2) No schrader valve on FR, how do you test? FPR is new, FP has less than 100 miles but it is 3-4 years old
3) Bad ignition such as spark plugs, plug wires, or coil? TFI tested good



This is right after a cylinder balance test is done and looks to me like HEGO1 is running good and HEGO2 is running lean. During the test HEGO1 was running rich and HEGO2 was in the green:

 

[jrichker]

There should be a schrader valve on the pressure feed line right behind the alternator.

 

[stangman16]

There should be a schrader valve on the pressure feed line right behind the alternator.

There's not one there, I think this is an older style fuel rail.. What about questions 1 & 3? Does the cylinder balance test indicate there is no leak in the fuel injectors?

 

[stangman16]

Anyone?

Everytime I run a cylinder balance test it passes. Does this rule out leaking injectors? Or maybe they are clogged or not flowing same rate?

I checked my datalog and the Hego readings bounce from high to low when the engine is fully warmed and during part throttle. System code 42 is given during a KOER test. The engine runs well when it's cold, but rough/hesitant/bogging when it is warmed up. I assume this is from the 42 running rich.

 

[jrichker]

1.) Check the O2 sensor ground. It is the orange wire in the engine injector harness that comes out near the TPS wiring. Ground it ot the cylinder head or intake manifold.

2.) The 42 code can be due to a misfire condition, which means you get to chase the spark plugs, plug wires, PIP, TFI and ignition coil as being possible causes. If you do not see or feel evidence of a miss as the engine runs, this may not be a productive path to take.

3.) There is a sneaky way to add a schrader valve to the fuel line. You use an A/C service port adapter with a self piercing valve. Since the fuel lines are steel, you may need to drill a small hole in the tubing before clamping the adapter in place.

See Stride Tool Inc. - Imperial® Accessories & Tools for Refrigeration and A/C Service for more information
Cost is $7.25 plus shipping
Or
ROB 40472 - Straight Line Tap Fits 1/4in , 5/16in , 3/8in
Cost is $6.12 plus shipping

 

[stangman16]

1.) Check the O2 sensor ground. It is the orange wire in the engine injector harness that comes out near the TPS wiring. Ground it ot the cylinder head or intake manifold.

2.) The 42 code can be due to a misfire condition, which means you get to chase the spark plugs, plug wires, PIP, TFI and ignition coil as being possible causes. If you do not see or feel evidence of a miss as the engine runs, this may not be a productive path to take.

3.) There is a sneaky way to add a schrader valve to the fuel line. You use an A/C service port adapter with a self piercing valve. Since the fuel lines are steel, you may need to drill a small hole in the tubing before clamping the adapter in place.

See Stride Tool Inc. - Imperial® Accessories & Tools for Refrigeration and A/C Service for more information
Cost is $7.25 plus shipping
Or
ROB 40472 - Straight Line Tap Fits 1/4in , 5/16in , 3/8in
Cost is $6.12 plus shipping

Guess that's my next step, thanks for the info! So, I just need one of those, no adapter and the fuel gauge will mount right up?


Here's exactly what my fuel rail looks like:

Been doing searches on fuel rails and I see alot of these without the schrader valve. Makes me wish I did more research when I started this project so I'd have one currently and not be in this predicament. Oh well, live and learn.


Question: I have a stock fuel regulator, and my fuel pump is an after market Holley pump, high performance. I don't have the specifics as of right now, but would that cause fuel pressure to be high?

 

[jrichker]

The regulator is supposed to take care of any excess pressure that the pump puts out.

On my 89 Mustang, the Schrader valve is on the body part of the metal tubing that feeds the engine mounted fuel injector rails. The fuel rails don't have the Schrader valve fitting on them.

The A/C service port adapter has a 1/4", 45 degree automotive flare fitting on it. Any gauge or line that mates to a 1/4". 45 degree automotive flare will work fine.

 

[stangman16]

On my 89 Mustang, the Schrader valve is on the body part of the metal tubing that feeds the engine mounted fuel injector rails. The fuel rails don't have the Schrader valve fitting on them.

So your fuel rail looks the same? I can't quite picture what you're describing. But the AC adapter tool will work just fine for me. When I drill into the fuel line, need I be worried about it catching on fire?


Hey I'm going through your surging idle checklist and checking my datalog with Livelink 5.1.0 (awesome that you can take the CSV and see things visually), and I notice my VBAT is less than 13 @ 1000rpms, no higher than 13 either, and MAF Volts are 1.154 ; and I will be testing the MAF as described in your instructions.

My questions are:

1) Could the MAF high voltage cause a rich condition? (I try and understand how things work...)
2) Does the low battery voltage cause incorrect sensor readings? I have a 60amp alternator, just need to research hooking up the 3G that I have.

 

[jrichker]

So your fuel rail looks the same? I can't quite picture what you're describing. But the AC adapter tool will work just fine for me. When I drill into the fuel line, need I be worried about it catching on fire?


Hey I'm going through your surging idle checklist and checking my datalog with Livelink 5.1.0 (awesome that you can take the CSV and see things visually), and I notice my VBAT is less than 13 @ 1000rpms, no higher than 13 either, and MAF Volts are 1.154 ; and I will be testing the MAF as described in your instructions.

My questions are:

1) Could the MAF high voltage cause a rich condition? (I try and understand how things work...)
2) Does the low battery voltage cause incorrect sensor readings? I have a 60amp alternator, just need to research hooking up the 3G that I have.

Normal location for the Schrader valve is on the fuel pressure line behind the alternator. That's why you don't see it on the fuel rail.

Remove whichever fuel line you install the AC tap adapter. That will eliminate the fire danger and keep the metal shavings out of the fuel system.

MAF operational theory:
Changes in RPM causes the airflow to increase or decease, changing the voltage output.
The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Generally speaking, higher MAF output voltage means more fuel delivered.
Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer. Be sure to measure the sensor output by measuring across the pins and not between the pins and ground.

You need 13.8-14.2 volts to keep the battery charged and the electrical system working smoothly.

All the computer sensors run on the 5 volts from the computer's internal power regulator. As long as you have 9 volts or more, the computer sensors will not be affected by variations in the car's electrical system.