Injector Swap - now low load stumble

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
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I guess I'm going to have to buy and play with one of these just to get to vocabulary words. :p


Your transistor though, is a fairly common one. I use MPS2222A transistors in Single Board Computer projects. Any measurable feedback to those transistor will effectively take them out.
 
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a91what

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This is true, there is however a flyback designed into the circuit.
I also use a diypnp although mine is far from spec at this point.

I believe you are on to something, can you do a high speed log for me? It's an ignition datalog.
 

a91what

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What do you mean by a "high speed log ". Last time, I almost didn't get it back to the garage.
Can I just rev it up in the garage to see if the timing changes?
Yes you can, running a high speed or composition log will show the input and output of the ignition system even if the car is not running. I use this to troubleshoot ignition i/o
 

Blown88GT

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Started doing it before you replied. See previous post.
What's a composition log? How can it show anything if the engine isn't running? Or do you mean the car not moving?

Idle Advance is ON.
Idle Advance.jpg


Sets the timing vs engine load or RPM or Adaptive when Idle-Advance is active.
Load: Typically the curve will ramp from low advance at low load to more advance at higher loads to stablise idle.
RPM: Typically the curve will ramp from higher advance at lower RPMs to less advance at higher RPMs to stablise idle.
Adaptive: Typically the curve will ramp from higher advance at negative RPM deltas (below target) to lower advance at positive RPM deltas (above target) to help stablise idle.
Idle Adaptive Advance Timing.jpg
 
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Blown88GT

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I'm now pretty sure it's the drive shaft front u-joint going bad.
I see a grease stain along the side. Rubber seals not looking too good.
They're 30 years old. Never had the drive shaft out.

This pretty much describes it.
U-joint failure will cause vibration when both accelerating and decelerating. Additionally, when your vehicle is not moving, the vibration will stop, even if you gun the engine.
 

a91what

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Started doing it before you replied. See previous post.
What's a composition log? How can it show anything if the engine isn't running? Or do you mean the car not moving?

Idle Advance is ON.
Idle Advance.jpg


Sets the timing vs engine load or RPM or Adaptive when Idle-Advance is active.
Load: Typically the curve will ramp from low advance at low load to more advance at higher loads to stablise idle.
RPM: Typically the curve will ramp from higher advance at lower RPMs to less advance at higher RPMs to stablise idle.
Adaptive: Typically the curve will ramp from higher advance at negative RPM deltas (below target) to lower advance at positive RPM deltas (above target) to help stablise idle.
Idle Adaptive Advance Timing.jpg
This makes sense now, this is wrong.
Apply as: adder = this is what you need

Setting this as 'set value' forces the timing to that amount at idle. Sorry I didnt catch this sooner.
 

Blown88GT

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That will probably help the idle, but in the mean time I can't break the flange bolts free even after soaking in PB Blaster. Not a lot of clearance for the 12mm 12-point 3/8" socket. Need to adapt the 1/2" electric impact. Out of time for today. Got the rear end jacked up high in the garage. Best price for HD Moog U-joints (#270) is Rock Auto, $31.41 for the pair shipped. If I have to take it somewhere, at least I can hand them the correct parts.
 

Blown88GT

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Bolts wouldn't break free & no noticeable play in the drive shaft.
Started it up today, pulled it out in the driveway to warm up.
There is a noticeable vibration in the steering wheel at 1500 rpm.
I think the drive shaft (harmonic) balancer elastomer (rubber) has hardened & not doing it's job.
 

a91what

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Its possible that the harmonic balancer ring has slipped this needs to be checked very soon. If the rubber on the balancer is bulging out then it likely needs a replacement.
 

90sickfox

I didn't really have an issue with the stink...
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On the driveshaft bolts.... I usually use a 12mm wrench with the box end on the bolt. Then I hit the wrench with a hammer.... works like a charm. Helps to have a decent brand wrench and not an el cheapo. ( meaning use craftsman, kobolt, snap on, matco...but not the pot metal cheap ones )
 

Blown88GT

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The electric impact wrench wouldn't break them loose.
The Craftsman 12mm wrench with the box end with a pipe slipped over the open end wouldn't break them loose.
No room to swing a 3ft pipe, even with the rear end up as far as the jack stands would go even when put them on the LCA rear end instead of the axle. Probably needs some heat on the bolts to break them free after 31 years.

The harmonic balancer elastomer has probably hardened after 31 years, so it's not dampening anymore.
 

Blown88GT

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Its possible that the harmonic balancer ring has slipped this needs to be checked very soon. If the rubber on the balancer is bulging out then it likely needs a replacement.
Balancer is out. Backside rubber displays all the classic signs of needing replacement (bulging & cracking), front looks fine.
New one on the way.
IMG_1012.JPG
 
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Blown88GT

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Put the breaker bar on the bolt. Put a jack under the breaker bar.

Yes... Heat definitely helps. Keep yo face outtah da way. :)
It took a torch & air impact to free all 4 bolts.
When I had the clutch replaced about 25 years ago, they probably used an air impact to tighten them.
Torque spec is 70-95 ft-lbs

Car back on the road today for a road test.
1. Larger injectors (Ford Racing LU-47)
2. New harmonic balancer (DAYCO PB1084ST)
3. New SVE aluminum radiator.
4. Ford Racing aluminum drive shaft.

Had to reconfigure radiator & Mark VIII e-fan & DCC controller mounting.
Moog #270 u-joints would not fit original driveshaft.

Took 4 weeks, same as the road in front of my house.

Looks like the old balancer might have slipped 5 deg, base timing with new balancer was 5deg BTDC when it's been set at 10 forever.
Since MS table in the lower left is 16, in reality it was 11 which may have been the root cause of the low load stumble. Steering wheel still has some shake at 850 rpm. Didn't have time to analyze the tune further.
 
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