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Hey guys, new member here. So I bought a 93 svt Lightning for cheap. Got it home and staring tearing into it and well, one thing led to another. When first purchased it ran rough... had to turn up idle to keep it running. Trans didn’t slip but only shifted from 1-2 and really hard shift into 2. I started tearing into it and broke a lower intake manifold bolt. Ended up pulling the heads. I lapped the valves, did new valve seals. Pulled the tranny and did a new rear main and oil pan gasket along with new motor mounts. Got everything put back together and did first test fire today. Little back story it had an egr delete. So I got it starter to find that the granny now is slipping (really bad) after fluid and filter change. And the engine is running really rough. After messing with it it will idle up for a minute and run fine and then continue to choke out and run rough. I tried rotating the ignition coil and there was really no consistency. Currently I have it running on open headers with the o2 sensor hanging down. I noticed there is three wire pigtails that seemingly go to nothing all coming from the fuel injector wire harness right under the throttle body. Frustratingly enough the new rear main is leaking (I used rtv and loctite retaining compound) seeking advice as I’m new to the 351w. Would like advice on the trans slipping only after fluid change, the trans only shifting from 1-2 and not past 2, and the rough idle. The trans fluid was really burnt, truck had been sitting for 2 years. I lapped the valves, did new valve seals, new gaskets from the heads up, put in fresh tranny fluid and filter along with engine oil and filter. Had to replace pcv grommet and a few sensors. Also had to rebuild the upper part of the steering column. Any help is appreciated as I fell defeated after spending the last month trying to go through this damn truck and seemingly getting nowhere.
 

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First confirm the firing order is correct. Its 13726548 as opposed to the 302 (regular F150 non HO) 15426378. Can you post pictures? The fuel injector harness I think also has the tps, iac, iat and ect sensors on it. Is it mass air or speed density?


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51965

Thanks for the reply! I believe it is air density. My spark plugs are 13726548 the kid who previously owned it was a fool and abused the truck, or so I’m learning.
 

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I don’t recognize those plugs. You said it is speed density, ok so the map sensor could be bad. When it does run is there black smoke? Does the map sensor have a dedicated vacuum line?


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Yes the map sensor has a vacuum line. When I bought the truck there was black soot where the exhaust exits.
 

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It sounds like either the vacuum line to the map sensor is low, the ect is acting up or the map sensor is bad. When I had issues with the map sensor in my 87 grand marquis it would start and run but the idle was high and the ecu thought the engine was revving, due to low vacuum, so it compensated by dumping fuel into the engine.

This shows how to test the map sensor


And a cylinder balance test


Heres how to pull codes without a scanner


If you are going to pull codes remember that you could get erroneous codes if the engine is not up to operating temperature.


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Not sure what the connectors might be intended for, but I have a pinout that should be very close to what you have. It's actually for a 92 Mustang GT (the engine in my truck). Are there any stored codes?
 

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well I’ve gone through and replaced the map sensor, fuel pressure regulator, and a few other things. Only getting backwards. Today it looked like I had no spark until the sun set and I captured this. Looks like the ground electrode is bridging to the engine ground (if that makes sense) not sure what would cause this, I have attached a pic.
 

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There is a ground ring terminal on the fuel injector harness that should be bolted down to one of the rear upper to lower intake manifold bolts. Make sure that is in place. Also, I’m not sure if your truck has salt and pepper shakers (black and white 10 pin connectors) like the mustangs and passenger cars did but if it does I recommend reseating the connectors and checking for continuity.


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There is a ground ring terminal on the fuel injector harness that should be bolted down to one of the rear upper to lower intake manifold bolts. Make sure that is in place. Also, I’m not sure if your truck has salt and pepper shakers (black and white 10 pin connectors) like the mustangs and passenger cars did but if it does I recommend reseating the connectors and checking for continuity.


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Didn’t see any sort of ground ring. I will look again.
 
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