tfnaaf

I've done some searching and a LOT of reading and would appreciate any advice/help that any of you may be able to offer. Friend of mine purchased a 87 mustang 5.0 minus an engine. He installed a 5.0 with a SD system with a e303 cam. He has since been called up to active duty in the militaryand needs to sell the car to pay some bills. I offered to help him out while hes deployed by trying to get the car to run proeprly and sell it for him.

Now i do understand that the E303 will surge/hunt for idle and thats not a concern. Problem is, when cold car runs amazing no problems at all. Soon as it gets wamred up it surges at cruse, and under acceleration coughs and bucks and pops thru the intake and basically a turd. Funny part is you can pull over shut it down for 5 mins? Start it up and its fine again for a short while then back to its problems. It feels like its being choked. Base timing @ around 10-15 degrees (tried different settings didnt help). Now he did install a new fuel pump that seems loud to me for i think being a stock pump(distinct humm). And i was thinking it may be fuel issue but the cold verse warm running has thrown me for a loop. With my limited 5.0 experince it seems like a timing issue the way it runs.

Any suggestions advice is appreciated in advance.

ih8chevy

the e303 cam was not ment to work witha speed density setup, so either get another cam or convert to maf

90Lxstanger

yeah ur on ther right track, its too big ofa cam, not enough vaccum,check this out https://mustangforums.com/m_1645702/tm.htm,
hope it helps some

shaners90lxhatch

This would not be affected by engine temperature. He likely has a vacuum leak as things get hot and expand. Otherwise if were a management thing, it would do this nonsense as soon as the PCM went into closed loop. It should do this before the engine reaches full temperature. I don't think the cam is your problem. Disconnect the MAP (or both oxygen sensors) and retest. Bump the management system back into open loop and if it runs the same, you know its not the cam messing with the MAP sensor. Hell, get a vacuum pump on the MAP and pump it up a bit. If it runs better, it may be the cam.Only if the richness of a cold motor covers up the lean condition created by this whole DS thing should your issue be temp related.

tfnaaf

i understand how theE303 was not designed for a SD system because of the lobe overlapbut the only symptoms that ive read about is the hunting for idle. I've read of others that ha ran the E303 on a SD system with ONLY idle problems and not driveability issues. So im concerned that if i change the cam or change to MAF i'll still have the same issue. If someone could confirm the symptoms im having then great. I dont have a problem spending a few $$$ if it fixes the problem.

Thanks again for your responses

tfnaaf

So just unplugging the MAP will throw it in to OL?

shaners90lxhatch

Yes.
No MAP signal to PCMwill force you into open loop.

tfnaaf

Thanks, i'll try that next!

tfnaaf

Well i uplugged the map sensor and it seemed to make it run better after fully warmed up. Hard to say 100% that its because its SD system because it did make it run VERY sluggish with the map unplugged. Tomorrow im going to see what i can get for prices on used computer/MAF sensor/ bracket and such then firgure out if i would be better off changing cams or converting to MAF. Thanx for all your help!!!