Couple questions

[mustangibew]

I am new here and have a couple of trouble shooting questions i need help with.
First off, In the morning when i start my car and start to drive down the road before it is all the way warmed up if i give it too much gas it will sound like it is backfiring. This also happens after i have been to the car wash. I wash it with the hood down so there shouldnt be any water getting in the dist cap. I have changed the cap and plugs and wires to all new. i cant figure this out.

I also have a weird rythmatic vibration i can feel that seems to be coming from the trans or driveshaft at diff rpms. Most noticably at 2,000 in 5th gear.
Here is a list of mods to my car. 1993 LX 5.0 with Griffin 2 row alum radiator,balck magic electric fan,undrive pulleys for crank and water pump,BBK castor camber plates,MSD,Crane coil,1 1/2" unequal length shorty headers,off-road X-pipe,flowmaster american thunder cat back,adjustable fuel pressure regulator,cobra intake,C & L 76mm mas with inlet tube,moroso cold air system,motorsport 65mm T.B.,air cond eliminator pulley kit,180 degree therm,1982 mustang heads with 3 angle valve job ported and shaved with hight life springs and rooler rockers,trick flow alum valve covers,manual adjustable clutch quadrant, motorsport king cobra clutch,sub frame connectors, pro 5.0 shifter,ford motorsport alum driveshaft,lakewood driveshaft safety loop,mega-bite jr lower conrol arms,urethane trans mount and cross member bushings,rear end girdle,stainless steel brake lines, cross drilled rotors. The cam is stock and so is the rest of the block.

Now it used to run great and smooth till after the head install. This is when the back firing started. once the car is warmed up it is fine. If i wash it I must drive it till the back firimg stops also.

Any suggestions would be greatly apprciated and helpful. Thanks.

[83GTMUSTANG]

Do You Have Solid Motor Mounts Or Trans Mounts,,,,, Check Your Timing Let The Car Run And Turn It 1 R 2 Degrees Tighten The Nut Down An Test An See If It Stops
Did You Remove The Dist. When You Did The Head Change If So Timing Might Be Off,,,,,,,,,,and Check Your Uni.joints On Your Drive Shaft

[mustangibew]

I have factory motor mounts and urethane trans and trans cross member mount bushings. I have checked the timing and it isnt off. Universal joints are fine. I did notice that the shaft that slides into the back of the tranny can be moved around a bit. Maybe worn trans rear bearing? Once the car is warmed up or driven for a bit after washing the back fire stops.

[Capri306]

83GTMUSTANG: Might wanna turn off the caps lock key, dude. Punctuation would also make your posts easier to read.

As for the hard running when cold, there are a couple of things to check. First on my list (because I'm a geek) would be the coolant temperature sensor. That's the one in the steel lines going to and coming from the heater core, up on top of the engine. My reasoning is that it's possible that the sensor isn't sending the correct information about the actual temperature of the engine, thus it's not adjusting the a/f ratio for the operating conditions. Also, after a certain amount of time has elapsed, the EEC will look at the oxygen sensors for feedback to know where the a/f ratio is (within certain limits). Is the engine full of coolant, even when cold? Was the sensor wiring damaged (done this one before!)? How about the last time it was replaced? If you could take a measurement of the resistance across the terminals of the sensor when cold, and then when at operating temperature, it might reveal something.

The other more-likely problem I would check is for possible vacuum leaks. Anywhere from the throttle body down to the intake valve is a candidate...but since it appears that the heads you are running are shaved, I would be led to believe there could be some gap between the intake manifold and cylinder head. It's entirely possible that the gap is there when the engine is cold, and is eliminated when warm. Thermal expansion is a b!tch. Read your spark plugs if it's being a bastard to find....even if not it could be another clue.

Only other things I could think of are air being drawn into the exhaust stream, or a lean condition until the engine is in closed loop (cause to be determined).

Regarding the vibration, your driveshaft shouldn't move at all from the axis of the tailshaft, only along it (in statics, I would say only translation along and rotation about the z-axis, if the tailshaft is the z-axis). Replace that bushing and seal!

Good luck.

[mustangibew]

Why would it do this after going to the car wash? It only does this after trying to drive it cold or after a car washing. That is what's tripping me up on this. What would a car washing do that starting it cold and trying to drive it have in common? How could a car wash cause it to backfire or misfire? New plugs,distributor cap, and plug wires eliminate those possiblities. Help me with more info please.

[mustangibew]

I replaced the Coolant temp sensor and went to the car wash and it still sputters and backfires until driven for awhile. I think something is getting wet that shouldnt be. It was washed with the hood down. It just doesnt make sense to me why washing the car would do this. I will find out either later tonight or tomorrow morning after the engine has completely cooled to see if the new sensor helps the cold start up and drive.

[mustangibew]

Ok, I re-tightened my Lower and upper intake, checked my header bolts and it seems to be alot better. Still get a little backfire upon start up first thing in the A.M. but not what it was. Better acceleration,alot smoother where before it seemed sluggish until reaching higher rpm's. Hmmmmm. maybe heads are milled too much?

[smokedchevy]

Not sure on your engine, but my tranny did the same thing. The tail shaft shouldn't wobble at all. It should be solid. Tranny probably needs a rebuild. Does it leak from the rear of the tranny where the Dshaft yoke goes in?

[mustangibew]

No, the tranny doesnt leak at all. I found on 50resto a piece that looks like the culprit for the tranny prob. It is called a tailshaft bushing, it is supposed to keep what is happening to mine not happen,lol. I prolly need a new one. Looks like the tranny rebuild I had done needed one more piece. Actually, it has been done twice,once by a local shop and one by a friend of mine. My friend found a cracked shift fork after the shop did a chitty job. The vibration has caused my rear main seal to leak a bit though. I wonder if this tailshaft bushing can be removed and put back w/o having to tear apart the T-5?