Missing under load

[Makdaddymac]

just like title, car is missing from 3k to 5k under load, inly does in under real load like a 2nd or 3rd gear stomp, in 4th or 5th crusing it does not, but when you want to punch it in 2nd it will miss/jerk/heistate and the tach whips all over the place like its busted....

it has new wires,plugs,cap,rotor.....no loose dis bolt, but im thinking it is the distributor? and or a injector??? or could this be a fuel pump/pressure thing.....
obviously its spark or fuel but any of you guys/gals got had or have similiar porblems to help me diagnose?

 

[Beasty306GT]

my car is doing the same thing i just put a new 306 motor in it with 30 lb injectors and the trick flw fuel rails and regulator and ss braided lines...today was the first day i really drove it since it being built...my question is where should the timing be and the fuel pressure be at for a pretty moddified motor.. it felt fine when i got on the highway goin from 4th to 5th...but just getting on it it hesitated on me also here is a pic of my setup

and here is where the distributor is my buddy set it advanced if it right?

 

[Makdaddymac]

sorry to hear that, sucks to have put all that together to have these bugs that could be anything. im in the same boat although ihave the gt40 mods for a i just recently strated using the car and enjoying it, but everytime i go for a ride i get hit with something else...as for your timing i would still think 12*to 16* even with your mods....

.are your injectors new or used???

 

[Beasty306GT]

the injectors are basically brand new...i also forgot to mention it takes a few minutes to idle on its own i have to let it warm up..but mine is doing the same as yours hesitates when i give it some gas

 

[Makdaddymac]

DIGGIN THIS BACK UP, I am bit by the stang bug, car is sitting with no tag again due to money issues but i have some extra cash to fix my bug:
in attempt to fix my problem i am goin to inspect my injectors. while i have the intake off i was thinking of just putting in some 24lbs, and doing a mas air flow swap...i know my setup is fine with the 19's but wil it really hurt to upgrade to 24's with a proper MAF??? will the stock fuel pump handle the 24's? should i just replace them with some 19's and fut an AFPR.???

also i was thinking to replace the distributor, mainly cause i cant think of anything else causing this issue...

 

[Makdaddymac]

?

 

[jrichker]

The TFI module mounted on the distributor is usually the culprit for a high speed miss on a warm engine. If the problem does not occur when the engine is cold, the TFI module is definitely suspect. You may need a special socket to remove the TFI module, but most auto parts stores will have one for $5-$7.

Be sure to use plenty of the heat sink grease on the new TFI and clean the old grease off the distributor.

View attachment 214470

See Automotive Tools Specialty | Auto Mechanic & Technician Diagnostic, Testing Equipment | Thexton

 

[Makdaddymac]

thx this is a start... would a injector act up after the engine gets too warm/ operating temp...??

 

[jrichker]

thx this is a start... would a injector act up after the engine gets too warm/ operating temp...??

Not likely. The TFI is more likely to cause the problem.

 

[Strype]

Like jrichker said, usually it's the TFI or the PIP. I've also had that happen when I was running too much fuel pressure.

 

[SLO_5-OH]

Two suggestions:

Check the basic ignition parts also (plugs, wires, cap, rotor). Those items can be the problem under heavy load but allow the car to be ok during idle and light load.

Don't rule out the 10-pin connectors either.

Did you have any codes in the computer to give you a starting point?

 

[5.0kroh]

missing issue

just wondering if you have mass air for one?
what is your fuel pressure set at?
does it buck at all under a low load like 5th gear lugging it?
what is your timing set at?
what octane fuel?
does your check engine light flash and if so did you check codes?
could be a number of things i agree with every one so far
tfi module
some thing also to look at is the injector harness sometimes the connections at the back of the intake have problems pulling pin connectors and could cause your same issue
also you say tack jumps all over the place do any other guages jump when this happens if so you could have a bad ground; check ecm ground, next to battery, check rf ground from battery little wire from ground post to ecm ground next to battery. block ground strap.
if the car is speed density yet, check vacuum lines especially to map
just some suggestions

 

[Makdaddymac]

new cap,rotor,wires,plugs..
speed density
timing at 12 degrees
does miss under 5th gear luggin but also in3 3rd gear stomps.
tach just jumps no other gauges,
93 octane
fuel pressure is idk that is something i need to check and or install afpr....also vacuum to map is original hose so that could be the a problem but from what i remember it was is okay shape.........

 

[jrichker]

Did I miss the post where you replaced the TFI?

 

[Makdaddymac]

lol sorry, i will get on this asap i was waiting for payday....(today)