Replaced 302 w/ 351, Noticed a couple drivability issues
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
first off why did you remove the pcv system? what are you gaining by doing that. Same goes for the EGR. that should be hooked up, the smog pump and lines from that setup are not necessary which i am sure you know.
what year 351w did you get? did you make sure that the injector wiring matched the firing order of that motor?
what year 351w did you get? did you make sure that the injector wiring matched the firing order of that motor?
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Posting Guru
Joined: Jul 2004
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From: Cottage Grove, WI
I removed the pcv system because I dont like all the oil and carbon buildup that develops in the intake and on the valves and all over. I didnt plug the holes in the valve covers, just ran the pass side down a hose to the ground, and got a breather cap for the dr side.
For the EGR, i will be hooking that back up, but i need to buy the correct pipe to connect it to the exhaust. my 302s wouldnt work
The 351 is from 84. AFAIK the 351HO shared the same firing order as the 5.8 EFI.
So, time for more problems. when hot, the engine doesnt like to start right away, unless I crack the throttle slightly. almost like its flooded out and needs the extra air...
I backed out of my driveway, put it in drive, and right when i touched the throttle, it died, and would not start. I had to unplug the spout connector to get it to start again, then it started right up... It starts every time w/ spout unplugged, but ocassionally it does not when its plugged in. This is the first time its died on me though....
For the EGR, i will be hooking that back up, but i need to buy the correct pipe to connect it to the exhaust. my 302s wouldnt work
The 351 is from 84. AFAIK the 351HO shared the same firing order as the 5.8 EFI.
So, time for more problems. when hot, the engine doesnt like to start right away, unless I crack the throttle slightly. almost like its flooded out and needs the extra air...
I backed out of my driveway, put it in drive, and right when i touched the throttle, it died, and would not start. I had to unplug the spout connector to get it to start again, then it started right up... It starts every time w/ spout unplugged, but ocassionally it does not when its plugged in. This is the first time its died on me though....
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
a properly working pcv system wont do what you said but what ever. i dont agree with that end result.
are you 100% about that firing order? you may need to take it down to a shop and have the computer tuned. just because you have mass air doesnt mean its going to run correctly.
1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 should be the firing order and injector wiring order
are you 100% about that firing order? you may need to take it down to a shop and have the computer tuned. just because you have mass air doesnt mean its going to run correctly.
1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 should be the firing order and injector wiring order
Lead Driver
Joined: Sep 2003
Posts: 7,015
Likes: 208
From: SoCal
The firing order of the 5.0 HO engine is the same as the 351W. Was the 302 from your F150 an HO engine? I don't believe so, so the two will have different firing orders.
PCV messing up the intake will happen if your engine is producing a lot of blow-by, as in from worn rings. Was this the reason you replaced the old engine? What's the condition of the 351W replacement? If it's not blowing smoke every time you accelerate, it should not have severe PCV fouling. Of course, you won't know for sure until you can get it running smoothly.
PCV messing up the intake will happen if your engine is producing a lot of blow-by, as in from worn rings. Was this the reason you replaced the old engine? What's the condition of the 351W replacement? If it's not blowing smoke every time you accelerate, it should not have severe PCV fouling. Of course, you won't know for sure until you can get it running smoothly.
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
I've had both 5.0HO and 5.8 motors running on a 5.0 computer without making any wiring changes whatsoever so I'm thinking your problem doesn't lie there.. unless you accidentally miswired a couple injectors.. the wires are long enough to get switch around if you're not paying attention. I'd also suggest you get to the bottom of that TPS code, the pump circuit code is a red herring.. it shows up on all dual tank trucks, and the OD swich is one of those thing you have to perform during the test, so you can ignore those two.
Postmaster
Joined: Jan 2009
Posts: 4,558
Likes: 2
The firing order of the 5.0 HO engine is the same as the 351W. Was the 302 from your F150 an HO engine? I don't believe so, so the two will have different firing orders.
PCV messing up the intake will happen if your engine is producing a lot of blow-by, as in from worn rings. Was this the reason you replaced the old engine? What's the condition of the 351W replacement? If it's not blowing smoke every time you accelerate, it should not have severe PCV fouling. Of course, you won't know for sure until you can get it running smoothly.
PCV messing up the intake will happen if your engine is producing a lot of blow-by, as in from worn rings. Was this the reason you replaced the old engine? What's the condition of the 351W replacement? If it's not blowing smoke every time you accelerate, it should not have severe PCV fouling. Of course, you won't know for sure until you can get it running smoothly.
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Posting Guru
Joined: Jul 2004
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From: Cottage Grove, WI
Ill double check the injectors tomorrow, I didnt rewire anything, but i also didnt think to install the wiring harness until after i put the upper intake on... and then i thought "oh it will be easier to just snake it around..." So if the wires are long enough its a definite possibility that I may have fudged that up.
Ill look up how to test the TPS tomorrow its always worked fine, only thing i can think of is maybe it got damaged in the swap somehow... but i dont think i did anything out of the ordinary handling the throttle body....
You pointed out a few threads back that the dist. was the only ignition componant replaced, and you were right. Id like to test that also, but im having a hard time finding the procedure. Probably just havnt looked hard enough lol.
Ill look up how to test the TPS tomorrow its always worked fine, only thing i can think of is maybe it got damaged in the swap somehow... but i dont think i did anything out of the ordinary handling the throttle body....
You pointed out a few threads back that the dist. was the only ignition componant replaced, and you were right. Id like to test that also, but im having a hard time finding the procedure. Probably just havnt looked hard enough lol.
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Posting Guru
Joined: Jul 2004
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From: Cottage Grove, WI
Picked up the new EGR pipe this morning, and im going to replace the pip sensor with the one off my 302, just for chits and giggles, see what happens. ill do this after work tonite, so wish me luck!!
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From: Cottage Grove, WI
Well its official... I am an R-tard. Replaced the pip sensor in the distributor, it ran better, and would run w/ the spout plugged in, but still not great, had a miss going down the road. Started pulling wires to locate the dead cylinder, found #8 not firing. Pulled the plug, and this is what I found:
No damage to the plug, looks like i did this before I put it in. I have no idea when, I checked the gap on all of them before I put them in. Fixed the gap, reinstalled, and she RUNS LIKE A DREAM!!!!!! 302 MAF ignition system, down to the pip in the distributor, runs a 351W!!!! I am so happy right now. Im going to put some miles on it now, and ill get back to you guys in a few days with anything I do notice.
No damage to the plug, looks like i did this before I put it in. I have no idea when, I checked the gap on all of them before I put them in. Fixed the gap, reinstalled, and she RUNS LIKE A DREAM!!!!!! 302 MAF ignition system, down to the pip in the distributor, runs a 351W!!!! I am so happy right now. Im going to put some miles on it now, and ill get back to you guys in a few days with anything I do notice.
Senior User
Joined: May 2011
Posts: 422
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From: Charm City
Good job, at least it was an easy fix! What exactly is the 'pip' in the dizzy? I tried to start mine today, it cranked but wouldn't fire. I ran out of day light so hopefully I'll be able to get it tomorrow.
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Posting Guru
Joined: Jul 2004
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From: Cottage Grove, WI
The pip is also called the ignition pickup, or coil pickup, some old timers also called it the stator, but thats not exactly right. Its the electrical part of your distributor.
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Posting Guru
Joined: Jul 2004
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From: Cottage Grove, WI
Ok, ive already come across a couple issues, I hope you guys can help me out.
1) Truck starts hard. spits and sputters a little takes about 10 full seconds of cranking to get it to start. Unless i crack the throttle open a little, then it starts much easier, but revs up instantly, as it should. I dont like doing that on a cold engine, i know its not good. Any ideas what could cause this? Im going to try and clean the IAC, possibly replace it if theyre not too pricy.
2) A couple times now, coming up to a stop sign, then planning on rolling through, its like the trans isnt downshifting as it should. I slow down, slow down, slow down, to about 15mph, then give it gas, and it spits and sputters and bogs way down. doesnt downshift, and it just grunts along until its back up to speed. If i come to a complete stop it downshifts all the way, just doesnt seem to know when to downshift on the fly. No idea what would be causing this, the trans worked fine w/ the 302
For anyone new to the topic, I replaced the MAF 302 in my 95 with a 351. I used the same 302 computer and controls, creating a MAF 351. currently engine has no EGR or PCV. Smog pumps still hooked up though lol
1) Truck starts hard. spits and sputters a little takes about 10 full seconds of cranking to get it to start. Unless i crack the throttle open a little, then it starts much easier, but revs up instantly, as it should. I dont like doing that on a cold engine, i know its not good. Any ideas what could cause this? Im going to try and clean the IAC, possibly replace it if theyre not too pricy.
2) A couple times now, coming up to a stop sign, then planning on rolling through, its like the trans isnt downshifting as it should. I slow down, slow down, slow down, to about 15mph, then give it gas, and it spits and sputters and bogs way down. doesnt downshift, and it just grunts along until its back up to speed. If i come to a complete stop it downshifts all the way, just doesnt seem to know when to downshift on the fly. No idea what would be causing this, the trans worked fine w/ the 302
For anyone new to the topic, I replaced the MAF 302 in my 95 with a 351. I used the same 302 computer and controls, creating a MAF 351. currently engine has no EGR or PCV. Smog pumps still hooked up though lol
Lead Driver
Joined: Sep 2003
Posts: 7,015
Likes: 208
From: SoCal
This is just a guess on the transmission. Does it use a vacuum modulator? Maybe you need to get one that's properly calibrated for the bigger engine. Its load, as measured by manifold pressure, will be less than the smaller engine, so that could be messing up the shift points.
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