Popping and stuttering after Efi install and rebuid

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luke6262

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318 small block 302 heads, stock internals, 4bbl intake, Aces tbi and distributor.

I'm having bad stuttering and some times poping out of the exhaust while accelerating almost like the engine is just cutting in and out until 3,500 rpm then it gets better, also engine doesn'twanna pull past 4,300ish could jusy be the old springs tho. Afr is always in rang but some times a bit rich dipping into the low 10s. I've checked timing multiple times and even made multiple map tunes trying to get the timing right as I feel like that is the problem.
static timing is set to 15 btdc and advace at 32-36 when system is first set up which runs okay but it advances as soon as you start accelerating which I thought was odd so I made the map tune to have a timg curve and that made it even worse.

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Also my 727 trans I'm running without the wiring harness just manually shifting gears which should be fine bdut not sure if that could play a role in anything as it does feel like the engine is under unnecessary load especially at lower rpm
 
How does it idle? Popping out exhaust is the spark firng or explosion happebning when exhaust valve is open timing chain is set right? 15 BTDC sounds advanced by about 5 degrees and I think by static you mean initial timing as in timing at idle with no advance? static timing is the timing chain setup.
 
Idle is totally fine but it does pop every 45 seconds or so out of the exhaust while warming up. While idling in gear the truck does jerk sometimes when I start to let off the brake which could be my low idle around 750.
Yes by static I mean initial advance and it idles about the same at 10btdc.
When assembling the engine i must've checked 10 times that the 2 dots where aligned crank dot facing up and cam dot facing down.
 
And I don’t see throttle pressure linkage. If you’re running the 727 without the linkage, STOP, and hook it up. You’ll destroy the trans in a short amount of time.
 
have you verified that the TPS is correctly calibrated (the arm works right and the action is correct)?
 
Yes tps was calibrated before start up and re calibrated ot just to eliminate that problem. Why would I need kickdown linkage of I'm deciding when to shift gears?
yes the killshot intuctions say to set at 15 degrees btdc with timing locked and then check with timing light at multiple rpm which checked out. Then it says to unlock timing and then it will be "controlled by ecu" which is just 15 degrees at idle then advance almost immediately after acceleration. It says to then check advance timing with timing light. Also checked out.

Could this cause cross fire?> the left side header gasket has a pice of gasket in-between the two center cylinder and the opposing side does not. I'll link a picture

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Also I did have a exhaught leak but I've had one before and it has never effected drivablity this drastically I'm open to the idea tho it could throw off afr. But as of right now I don't have a noticeable one if I do
 
The exhaust leak will affect the o2 sensor, which the ecu uses to adjust fueling. So yea it matters. The linkage for the trans is THROTTLE PRESSURE, it adjusts the pressure to the clutches depending on throttle opening. Even if you shift manually, with no linkage you’ll destroy the trans. At least zip tie the lever on the trans all the way forward. But you should put the linkage on it.
 
luke6262 said:
318 small block 302 heads, stock internals, 4bbl intake, Aces tbi and distributor.

I'm having bad stuttering and some times poping out of the exhaust while accelerating almost like the engine is just cutting in and out until 3,500 rpm then it gets better, also engine doesn'twanna pull past 4,300ish could jusy be the old springs tho. Afr is always in rang but some times a bit rich dipping into the low 10s. I've checked timing multiple times and even made multiple map tunes trying to get the timing right as I feel like that is the problem.
static timing is set to 15 btdc and advace at 32-36 when system is first set up which runs okay but it advances as soon as you start accelerating which I thought was odd so I made the map tune to have a timg curve and that made it even worse.

View attachment 1716203868

View attachment 1716203869
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I would be tempted to throw a known good carb and distributor on it and see how it does.
 
Like I said I know a leak can throw off afr I'm just saying I've worked on many cars with exhaust leaks and it's never effected drivablity to the extent I am having. I have no exhaust leak anyway so that's out of the question.

It's a 1989 dodge d150 and it has no original wiring and the transmission has the harness cut out. Original Transmission works fine shifts great I'm swapping to a manual asap anyway.

If I had a spare 4bbl carb and distributor definitely would
 
15* BTDC static [ initial ] timing will not cause problems.
Thoroughly check the ign system,: cap/rotor for cracks, bad plug leads, sooty spark plugs, etc. Swap the ign coil/box if you have another. Check that you are getting the correct voltage to the coil.

If ok, I would look at the valve train: lifter adjustment/pre-load, burned valves, weak broken v/springs, wiped cam lobes.
 
I had a minor exhaust leak and it did cause exactly what you're experiencing. Fitech efi with timing control.

Also, a bad o2 sensor can do it. I've had them go bad over that winter. They can be bad and still read too, but they get slow and confuse the ecu.
 
Phreakish said:
I had a minor exhaust leak and it did cause exactly what you're experiencing. Fitech efi with timing control.

Also, a bad o2 sensor can do it. I've had them go bad over that winter. They can be bad and still read too, but they get slow and confuse the ecu.
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I'm thinking this may be the problem now otw to work today I didn't get any reading to my dash for the afr. It did do this before but only for 5 min maybe thought it could be just a lag in the dash software for a minute, but no ready for 25 minutes has me thinking they sent me a faulty o2 sensor
 
Spark plug wires are also on correct I checked multiple times because u had done this once before its not backfiring as hard as it was when I had accidentally swapped plugs. When plugs were swapped it actually sounded like guns shots not just a little pop lol
 
You could disconnect one plug wire at a time to see if it's a particular cylinder while not shocking your balls on the fender. My buddy looked like a zombie because he did that
Got the timing adjusted though
Swapped plugs my idle didn't even drop, just a soft backfire like yours
 
65TerrorCuda said:
Similar prob here, turns out I had swapped 1&3 plug wires. AFR read way lean
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Ah yes, but it wasn’t lean.
There was just lots of unburned oxygen.

I got tricked by that once.
Motor started hiccuping and showed really high numbers on the AFR gauge so I thought it was the fuel pump dying.
Turns out it was a failing ignition module and not a lack of fuel.

Unburned 02 was actually the cause of the lean numbers, and not a lack of fuel.
 
TT5.9mag said:
If you’re running the 727 without the linkage, STOP, and hook it up. You’ll destroy the trans in a short amount of time.
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This comment gets repeated quite often and it mostly comes from people with no direct experience from it, they just say what they have heard.
While it is not good for the transmission to be operated without the linkage attached and functioning properly, it is not always a death sentence. Several factors come into play.
I've bought cars that were driven for awhile with the linkage missing or broken. I've had it fall off while driving and fixed it later. What really kills automatic transmissions is excessive heat and heavy loads when the linkage is disconnected. If one were to drive easy in a light car, you could put a LOT of miles on it before you'd see damage.
I wouldn't temp fate though. I'm not dismissing the warning entirely, just stating that those that claim destroy in short order are often exaggerating and not being sccurate.
 
Kern Dog said:
This comment gets repeated quite often and it mostly comes from people with no direct experience from it, they just say what they have heard.
While it is not good for the transmission to be operated without the linkage attached and functioning properly, it is not always a death sentence. Several factors come into play.
I've bought cars that were driven for awhile with the linkage missing or broken. I've had it fall off while driving and fixed it later. What really kills automatic transmissions is excessive heat and heavy loads when the linkage is disconnected. If one were to drive easy in a light car, you could put a LOT of miles on it before you'd see damage.
I wouldn't temp fate though. I'm not dismissing the warning entirely, just stating that those that claim destroy in short order are often exaggerating and not being sccurate.
Click to expand...
I was speaking from experience, I destroyed a 904 in a 72 dart in about 30 miles of normal driving because the linkage had fallen off. The clutches have no chance of holding if they have no line pressure and a bare minimum of line pressure is what you’ll have with the linkage absent.
 
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