Fuel injection install not so smooth

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Fuel injection install not so smooth

December 01, 2011, 05:13:17 PM

So I bought a Mass-Flo EFI and got it all installed and on the final steps where I'm supposed to bring it up to operating temp and set base idle. And it flat out doesn't want to idle. My car has always been a bit touchy on timing and now it seems like there is no sweet spot for it to fire up with the fuel injection.

Its setting at 14* and will start if I crank it awhile and push the gas pedal down. Then it will idle around 1100-1200 ish fine for a bit then start to cough and miss a bit. With the spout unplugged it runs much better, but still bad. Its like it is "searching", up and down and then smooth for a bit and it will start to stumble again. It does rev smooth though so I'm at a loss. Is it my O2 sensor placement in the headers? They are summit brand longtube headers, the 02 sensor is in the last cylinder primary instead of collector so its closer to the cylinder.

FYI mass flo is pretty much any mustang efi setup except has a diff intake and throttlebody.

Any ideas why it won't idle and why it is idling rough?

Side note: I live pretty far from my car and when I do get near it I only have about 5 hours usually. I took me 2 months to get this stupid setup together as timing cover was leaking from having the bolts out of it for a week, and then waiting on parts etc etc, pretty much your common hang ups. Really wanting to move back to home town to be closer to family and car

Fuel injection install not so smooth

Reply #1 – December 01, 2011, 05:50:17 PM

Can you pull codes?

Fuel injection install not so smooth

Reply #2 – December 02, 2011, 01:44:14 AM

As mentioned, codes?
Vacuum leaks?

What intake and TB?

Fuel injection install not so smooth

Reply #3 – December 02, 2011, 01:54:44 AM

http://www.massfloefi.com/mass-flo-efi-systems/ford/289-302-5-0-mass-flo-efi-system-for-small-block-fords.html

Should be a gm style mass air meter with tps and iac built into the 4brl style throttle body.

I would call them up and have them tell you its not working correctly and see what they say.

What is your fuel pressure, and is the maf clean? New or used?

Fuel injection install not so smooth

Reply #4 – December 02, 2011, 10:17:13 AM

Its all new, fuel pressure is 40lbs no vac line. It does have capability to pull codes but didn't have scanner handy at time. I'll pull them next time I'm down there (may be a week or so)

Just wondering why with spout out it runs so much better. Hoping i don't have a clogged injector either.

Fuel injection install not so smooth

Reply #5 – December 02, 2011, 01:18:54 PM

Double check your timing perhaps...?

Fuel injection install not so smooth

Reply #6 – December 02, 2011, 03:47:51 PM

Check your timing, then pull codes. You should be at 10* with the spout out. Also, I am not sure if you can check the tps like a mustang, but generally a cruddy idle is either tps, or iac. I would pull codes and see what it says.

Fuel injection install not so smooth

Reply #7 – December 02, 2011, 04:01:25 PM

Timing is at 14* check 2x. TPS and IAC are new but ya that doesn't mean anything. IAS was unhooked at one point to rule it out and still made it stumble.

Appreciate the feedback, just want to make sure no stone unturned kinda thing. I'm betting pulling codes will be the most enlightning.

Fuel injection install not so smooth

Reply #8 – December 02, 2011, 07:40:45 PM

Did you have to replace the dizzy? A vacuum leak on the intake manifold will also let it idle high, the the computer will try to compensate by cutting ignition or gas.

Fuel injection install not so smooth

Reply #9 – December 05, 2011, 10:12:28 AM

Ya it has a mustang style distributer. I don't think I have a vac leak but I could be wrong. Only vac line on my car is to the fuel reg. Brakes and heater are electric.