'88 350 TPI, on cold start runs OMFG rich. Stumbles. Bogs, dies. Once it hits closed loop, runs great and no real issues.

About a month ago it through code 43 MAF, so we swapped in a new one. It was throwing the CEL and surging occasionally at cruise. The cold start problem got progressively worse even after the new sensor. The car has always been a bit nasty about starting but never super rich and blowing smoke like this.

Things we've checked:

MAF, new plugs and wires, new fuel filter, fuel pressure, fuel pump, distributor, cold temperature sensor, grounds are all clean, plugs are clean, MAF burn relay...

Wtf are we missing here? The plugs were fouled out. New plugs and wires, much stronger spark and fires off quicker but still running rich as **** (until closed loop, when magically, everything starts working great).

'88 w/cold start injector delete. LT4 hotcam, ZZ4 bottom end, Vortec heads, EGR delete. 30# Ford SVO injectors. 180* thermostat.

Any and all help would be fantastic. About the only thing untouched at this point is the computer...

 

You mean stock tune?
If so I can see a major problem with those injectors given the ECM is programmed for 22's .
In OL, the ECM is supplying fuel from a fixed program (thinking it has stock injectors ) with no feedback from the O2 to adjust the fueling

Have you ever datalogged your car after the mods?

With those mods I can see it calling for some serious tuning changes regardless of how well you "think" it runs in CL
You would be surpised how well a SOTP feeling you can get until you datalog and find everything is up sh*t creek

 

Sorry should've clarified. Sent a series of dyno pulls to Fast Chip about six years ago for the current tune. It is programmed for the Ford injectors, the 9-th injector delete, and the EGR delete.

 

And when I say it runs great, no idle hunting, strong power, no stuttering, etc. If I walk away from the car for an hour or two after its hit operating temp, it'll crank right up with no drama and I'm on my way.

As it stands now, I have to idle it with my foot for five to ten minutes until it warms up--then it idles fine and stops running poorly.

 

Have you checked your IAC? Maybe needs cleaning or possibly re-adjustment

 

I went through a similar issue a few months back. I'm not saying the cause is the same but at least this will give you some direction.

In my case it was a lack of gas when cold. Why the black smoke? (that otherwise would indicate a rich mix) 'cause the misfires caused by the lean condition resulted in un-burnt fuel going raw through the exhaust.

My tune was so tight that a small drop in fuel psi resulted in cold start up/warmup with severe misfiring. Once it reached operating temps it corrected (ECM removes fuel).

I suggest you check this App for iPhone/iPad or for Android

Is a calculator for quickly calculate required injector or pump flow among other cool stuff like E85/Boost injectors and pump, exhaust, etc.

Check it out may work for you. Hope this helps.

 

i'm glad i read through that MAF relay thread... happy to report that new burn off and power relays have completely solved my issues. thanks for the suggestions guys.