Project Boomerang

Do you have an adjustable fuel pressure regulator.  Odd, pressure seems 10 psi high but the plugs look lean.  Unless you think you are making much over 350 horse the stock 19lb injectors should be almost good enough.  325-350 is about max, you should be right there or a bit over depending on the head and cam relationship.  

Does it loose power over 3000 at WOT or partial throttle?   If under part throttle quick floor it for a second when it starts to go flat and see what happens.

Check your TPS for closed voltage and voltage range across full travel.

In reply to akylekoz :

It's an adjustable regulator, so I can easily dial it back. 
Supposedly the hci set up is good for 360 hp so it might be too much fuel at that pressure and injector size but want to verify before I change. 

 

the power loss is at WOT. It'll pull ok to 3000 then stop accelerating. When I let off it then pops in the exhaust 

TPS was supposedly reset but if I've learned anything so far it's that I should verify 

Update

So Tim got the injection pipes welded back up and I was able to bolt the new h pipe back in place. 

There are a few long term fitment adjustments needed for the tail pipes but it’s not leaking and good enough to test drive to collect AF readings

Start up and it’s bouncing around 16:1 at idle

Take it out for a drive and within a minute or so the gauge (AEM brand) is reading “- - -“ and the dial shows full lean. 

Limp it back home thinking my Amazon sensor failed, but noticed it briefly blinked a number pulling in the drive. Shut the car off and cycle the key and it gets back to the base number 14.7 with the car off. 

Not a full confirmation but it seems like the sensor is still functioning. 

Let it cool over lunch and check the manual. It looks like the sensor will show the “- - - “ if it reads above 18. So I could be very very lean. 

After it cools I start it up (to put it away) and it’s reading 14-16 again. I quickly give it some gas to back down the drive way and the AF dips to 11-12 with the throttle inputs. Test it a few more times and it's adjusting rich with the throttle. After a min or so, it goes back to reading the “- - -“

So that leaves me with: 

-Gauge seems to indicate it’s very lean

-It doesn’t start out lean right away, assuming the idle readings are directionally accurate

-The fuel pump likely is not the issue as the idle pressure is good and while it was reading it seemed to get richer with throttle input

-It’s going lean as it heats up

Brainstorming possible issues:

-it could be a leak getting worse as it warms letting in unmetered air

-It could be the ECU adjusting based on something going wrong (gonna check the eec book on this)

-something else? 

Going to borrow Wae’s smoke tester this week and check for intake leaks and go from there. 

Went and picked up Wae's smoke tester and borrowed a vacuum gauge. 
 

Cold start and tested vacuum

holds steady at 12 until it idled down and then it holds at 10

Unofficial sources (mustang forum posts) seem to indicate the TFS stage 1 cam is usually 12-14 at idle. So I'm possibly a little low but that could also be due to being lean.  The wideband confirmed again what I saw yesterday; 14-16:1 cold start idle and a shift to full lean on gauge after idle shifts. 
 

I didn't have a great way to seal the intake tube for the smoke test so I am going to try again with a better cap and a second set of eyes, but I did run smoke through It for a while with a small leak at the source connection. No obvious leaks anywhere on the intake manifold, throttle body or EGR spacer. The only leak found was completely unexpected:

behind the emblem on the cold air kit. 
 

Next up:

- a re-run of the smoke test with extra set of eyes

- taping/ sealing the emblem and checking A/F and vacuum ahain

-plan of attack sorted on testing sensors 

Progress! 
 

Decided to mess with the MAF sensor tonight. 
I pulled the BBK one that was on the car and installed the NIB spare pro M 75mm that came with the car. 

Immediately the idle fattened up to ~ 14.2-15:1

Hooked up a vacuum gauge and vacuum is up to 12-13. 
 

Take it for a spin and notice the throttle response is much improved. 
Do a 3rd gear pull and it's still losing power and stopping accelerating at ~ 3100rpm. A/F is reading 10:1 at WOT, so it's running a bit rich.

You might recall from earlier posts that rail pressure was at 55ish. I adjusted this down to ~40 which is the stock pressure. 
Vacuum dipped to 10-11".

Checked AF at idle and it's still looking healthy 

I take it around the block again and it seems happier, throttle is much smoother. Try another 3rd gear pull and it's accelerating harder, but still hitting a wall around 3100rpm. 
 

I ran out of time for the day but making progress. 
 

I think next I'm going to recheck the plugs and install a fresh set

Im then going to drop timing down a little to 14 and see if it's better, worse or no change

So if there’s been a theme for this so far, it’s trust but verify. 

Since pick up, my brother stressed to me that I should change the advance springs on the distributor as the default springs are slow advance. He said LMR advised him on it and a package of springs had been included with the spares. 

In thinking through my current symptoms I thought maybe my advance was too slow, as the auto ECU I have (car was a factory auto) has this advance curve which is pretty aggressive 

 which with the base setting of 10 puts it at 36.75 at 3000

With the slow advance springs and my base of 16 I would only have 31 degrees so 6 below

Before throwing fresh plugs in, I decided I would install the faster advance springs and see if maybe that is impacting as well. 

Only - it’s not a mechanical advance distributor. It’s ECU controlled. The MSD packaging and LMR site state mechanical, but its definition ecu controlled

Which creates a different possible issue

The 26.75 advance at 3000 ontop of my base of 16, puts my total timing at 42.75, which seems a bit higher than I’d like 

Adjusted my base down to 12 to test that theory. Also added a few gallons of fresh gas and a new set of plugs. 

Problem still persists. I made sure to test the 3000rpm zone at part and low throttle and noticed that around 2400 you can feel it start to stumble and miss. 

Will pull plugs later today and see if I can sort out an unhappy cylinder that may have been hidden by the overall lean issue. 

Beyond that I’m out of simple ideas, will likely start swapping parts to ID if there’s a tfi module or coil or plug wires. 
 

If anyone following along has ideas, I'm open to suggestions 

Update. 

After the last  round of trouble shooting i decided to take a step back and take a different angle. 

I pulled the new plugs but they still looked new

I checked the temperature on the primaries and all seemed balanced. 

I bought an OBD-1 code reader and decided to check if there were any codes or signs a sensor could be bad

Checking the Key On, Engine Off method found no codes active or in memory

I checked the Key On, Engine Running and found codes 98, 44 and 33. All are related to systems currently bypassed, so unlikely to be causing the issue. 

One kind of crude but cool bit of EEC-IV diagnostics is that it can do a cylinder balance test where it plays with timing/fuel pressure and checks the impact on rpm to pin point if a particular cylinder is weak. If you run multiple iterations it can directionally tell you if it’s an ignition problem. The car passed with no issues. 

Whatever is going on is universal. 

So it could be: 

• Fuel (not likely based on AFR readings) 
• Ignition - easy to verify 
• ECU- harder to verify

I went the easy path and tried ignition.

I have never trusted MSD boxes, so I bypassed the 6AL-2 box. Test drove again and found it made no difference. 

I have a spare, older coil and decided to swap on. test drove and no difference.

A barely used Accel distributor was included with the spares (was pulled for the MSD kit) so I decided to swap. 

Jackpot. 

Set the timing to 14 and took it for a spin. Car fires right up and now rips fully to redline. Took it around the block and I didn’t get to watch the AFR gauge fully at WOT as it was getting a little loose, but it hit 10:1 a few times, so she’s a tad rich. 

Ran out of time messing with it but it’s running great

Next steps: 

• Button everything back up from the diagnosing 
• Drop fuel pressure a little to lean it out some at wot
• Fix tail pipe alignment
• diagnose and fix the front brake clicking sound when driving
• ​​​​Check all front suspension bolts 
• Professional alignment 
• Get subframe connectors welded in
• Start driving it 

Congrats!

Took advantage of the last few evenings to check off a few items on the list. 
 

I fully removed the MSD 6AL2, reinstalled the newer coil and found the brake noise was loose lug nuts (oops). 
 

With a little loosening and adjusting I was able to get the tail pipes positioned to clear the floors and bumper. 
 

I did an oil changed and did a quick wipe down to prep for a maiden cars and coffe voyage in the morning. 
 

It's about a 12 mile drive to the event so this would be my longest shake down run today. 
 

The car was flawless; pulled strong, tracked straight and cruised smoothly - for about 9 miles. 
The ignition started intermittently cutting out (car nearly shutting off the kicking back on with a jerk) every few mins at cruising speeds for the last few miles to the event. 

I hung out for a bit and paid close attention to it on the way home. 
The cut outs increased in frequency as I went and the car is down on power while accelerating (but still smooth) 

The car ended up fully dying about 3 miles from my house and wouldn't restart  until it coasted for a bit. After the restart I was able to get it all the way home under its own power. 
 

The cut out seems ignition related to me as AF goes rich when it cuts. 
Google indicates these are common symptoms of a failing TFI module or PIP sensor. Both of which are attached to the distributor.  The one I just put in was used (maybe 1000miles) so I guess it's possible it failed from sitting or poor quality. 
I'll do a little poking around but it's sounding like distributor #3 is imminent. 
 

Anyone have experience with distributors dying frequently? 

So to answer my last question; people do frequently kill ignitions on these (foxbodies)

Doing a bit of research indicates that TFI module failures are pretty common on Fords:

When I brought the car home, I did notice the distributor and TFI module were very hot to the touch. Some research seems to support that complete loss of ignition and hot ignition issues are common to TFI module failure.

Given the probability and the fact that the distributor / TFI module I installed were used, I decided that I would start fresh; rebuilt stock distributor (new seem to be NLA) and a new motorcraft TFI module. 

In doing my research I found that on some models (and for the 94-95 Mustangs) Ford remote mounted the TFI module on a heat sink. 

I liked this option but there wasn’t a full plug and play OE solution. Many of the options required splicing into the harness and that’s not something I want to do. 

Thankfully I found a really slick, novel, plug and play solution from the monster Miata world. 

McCully racing makes a full plug and play TFI heat sink kit that uses a dummy TFI module mounted on the distributor to run connections to a remote, heat sink mounted TFI module you can install in a location of your choice.

I bought the kit and about 2 weeks later it delivered. Set out to installing and it was as straightforward as described. 

Here's the kit unpacked 

dummy TFI next to the rebuilt distributor

dummy TFI installed 

New motorcraft TFI mounted on the heatsink with Arctic silver heat paste (included with kit)

Laying out for the heat sink mounting 

With all mounted I fired it up, and reset timing. Ran out of time before getting a road test, but that will happen soon. 

Post install clean up I noticed a coolant smell. A quick check found a small puddle that appears to be originating somewhere around the water pump.

More digging in will happen when time permits, but it sounds like there are several common areas to check. 

Nice work tracking down the problems, high fuel pressure, TFI, etc.  The whole time I owned mine it had a small coolant leak at the timing cover, left a small puddle just below the distributor.  

In reply to akylekoz :

Thanks! 
 I suspect this small leak has been there a while as I've often caught a faint coolant smell after driving. 
 

Going to check a few things but keep cautiously driving it. It needs to log some miles 

 Back on GRM so figured I'd give a small update to both of you who are reading along. 

Summer vacation and kid sports have kept me from much fox time. I've now logged about 170 miles or so, which I'm happy about.  It even survived running  EastsideTim around the block on one of the drives. 

The new TFI and relocation kit are working flawlessly. I've found a few small things I want to fix for the winter, the biggest being lock actuators and a new PS headlight adjuster. 

The idle and driveability seem to be improving and it's pretty docile when not going WOT. I don't hate the 4.10s as much as I expected. Still a little rich but I think the timing is fine. It keeps temp, stops and cruises without much fanfare.

As part of the 170 miles logged, it completed one of the big milestones I had: driving it to and from work. My work commute is a ~ 45 mile trip with some rush hour traffic. It had no issues and cruised at 3000rpm at 70. 

Hope to install some subframe connectors when Wae's lift opens up. Will update with more progress once that happens.