added ignition box, runs good but has a miss/pop at cruising speeds

[Foxfan88]

i ordered a Summit street/strip ignition box, and a summit coil.

installed the box and coil and the COIL DIDNT WORK, wtf anyways i am running my stock coil.

the car starts and runs ALOT smoother with the box and the car drives fine.

but under regular acceleration and while cruising down the road the engine misses or something, it pop and stuff and you and feel it. nothing HORRIBLE. Once you give it gas to accelerate some it clears up and WOT it acts just fine and runs as strong as ever.. just while cruising with a very light load on the car it pops and misses..

i tinkered with fuel pressure some and clocked the MAF some, noticed no real changes.

should i try opening or reducing the plug gap, or step down to a colder plug?

right now i am running regular motorcraft plug ( not platinum)with a .038 gap.

i was fighting the same missing and popping issue when installed my boost pipe and such. it wasnt this bad, and i had it cleared up completely pretty much then i add the multispark box and it starts acting up

would ignition timing cause this?
and is there a way i can tell if my brake booster is causing a vacuum leak or not, the car doesnt seem to make much vacuum at all

any help is appreciated.

 

[LtDavis]

How old are your O2 sensors? My car was doing the same thing and it turned out the O2 sensors were so old they were literally falling apart and only made the connection at WOT. Hope that helps

 

[Foxfan88]

they arent too old maybe a year i duno but it hasnt been long

 

[Ranchero5.0]

It's hard to quess on, are you running a A/F meter? I use mine a lot more for troubleshooting driveability problems vs WOT A/F stuff. I put a switch under the dash to select between the two O2's so I can see if one is whacked. It's helped diagnose two bad O2's and a wiring failure in the O2 harness. With a meter you could see if it's a lean pop or just ignition related. If the motor is running good under boost then the gap and high voltage ckt should be ok. Clocking the MAF has worked for me too. Also try unhooking the PCV fresh air line from the oil fill to the blower inlet to see how it changes things (leans the idle ckt a little). There's a ton of things that screw with driveability.

Jamie

 

[Foxfan88]

its not the o2s it will do it upon start up, i noticed that it DOES do it at idle.

upon start up the EEC is operating in open loop where it doesnt even look at the o2 readings unitl closed loop when the engine is up to temp and all the parameters are good. the engine will miss all the time with the box on the car

i am pretty sure its related to the box or something. earlier i bypassed the box and ran of the factory setup and it runs perfect now. the box is hooked up right and the wiring is good i am pretty sure.

so i took the box out and am going to call summit and ask for some help there or something