MAP sensor troubles ... but no map sensor
Thread Starter
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Senior User
Joined: Oct 2013
Posts: 181
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From: wentzville MO
MAP sensor troubles ... but no map sensor
So the troubles I am having are exactly as described by this article.
You'll also experience:
Part 1 -Manifold Absolute Pressure MAP Sensor Test (Ford 4.9L, 5.0L, 5.8L)
You'll also experience:
- Engine cranks for a long time before it starts.
- When the Engine starts, you get a lot of black smoke coming out of the tail-pipe.
- Engine stalls as soon as it starts.
- If the Engine stays running, it idles very rough.
Part 1 -Manifold Absolute Pressure MAP Sensor Test (Ford 4.9L, 5.0L, 5.8L)
Thread Starter
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Senior User
Joined: Oct 2013
Posts: 181
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From: wentzville MO
its a 351w with an RV cam. i dont know the exact specs as i lost the piece of paper. however I did reach back out to the engine builder so hopefully I get info back on that.
95 f150 was a 5.0 but swapped in a 351w. 19lb injectors (good to 300 hp which i am probably at 260 if i am lucky)
95 f150 was a 5.0 but swapped in a 351w. 19lb injectors (good to 300 hp which i am probably at 260 if i am lucky)
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
Maf is dirty
Buy maf cleaner and read directions.
Do you have an oiled air filter in it, that could be the cause of dirty maf.
Fuel pressure regulator could be bad and putting fuel through the vacuum fitting. Take off line and cycle key to see if fuel comes out.
Being a 95, does the 5liter share firing order of the 351.
When you put the 351 in the truck, did you change the computer, or leave stock 5liter one in it.
Buy maf cleaner and read directions.
Do you have an oiled air filter in it, that could be the cause of dirty maf.
Fuel pressure regulator could be bad and putting fuel through the vacuum fitting. Take off line and cycle key to see if fuel comes out.
Being a 95, does the 5liter share firing order of the 351.
When you put the 351 in the truck, did you change the computer, or leave stock 5liter one in it.
Thread Starter
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Senior User
Joined: Oct 2013
Posts: 181
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From: wentzville MO
Its the 5.0 computer. Same firing order. Last night i got a new IAC valve and a new MAF. Still the same problem. Starts up and then dies right away. I can catch it with the throttel and get it to rev up a few times but its still supper rich.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
I saw in your last thread the fuel psi was 35 psi. Did it hold 35 psi after fuel pump quit or did it leak down?
After priming fuel system several times with key, I would pull plugs and see if any are wet with fuel. You may have an injector leaking.
Unfortunately, you have many posts and all have different info on your build. Even if you got new injectors or rebuilt or reused the old ones, it would be good to see if any of the plugs are soaked with fuel.
Also, did you put new spark plugs in?
You also stated that the IAC had water in it. Did you powerwash or wash the engine bay? If so, then it might be a good idea to start checking wiring connections to the PCM or pull the PCM and open it up to see if everything looks ok.
After priming fuel system several times with key, I would pull plugs and see if any are wet with fuel. You may have an injector leaking.
Unfortunately, you have many posts and all have different info on your build. Even if you got new injectors or rebuilt or reused the old ones, it would be good to see if any of the plugs are soaked with fuel.
Also, did you put new spark plugs in?
You also stated that the IAC had water in it. Did you powerwash or wash the engine bay? If so, then it might be a good idea to start checking wiring connections to the PCM or pull the PCM and open it up to see if everything looks ok.
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Senior User
Joined: Oct 2013
Posts: 181
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From: wentzville MO
I saw in your last thread the fuel psi was 35 psi. Did it hold 35 psi after fuel pump quit or did it leak down?
After priming fuel system several times with key, I would pull plugs and see if any are wet with fuel. You may have an injector leaking.
Unfortunately, you have many posts and all have different info on your build. Even if you got new injectors or rebuilt or reused the old ones, it would be good to see if any of the plugs are soaked with fuel.
Also, did you put new spark plugs in?
You also stated that the IAC had water in it. Did you powerwash or wash the engine bay? If so, then it might be a good idea to start checking wiring connections to the PCM or pull the PCM and open it up to see if everything looks ok.
After priming fuel system several times with key, I would pull plugs and see if any are wet with fuel. You may have an injector leaking.
Unfortunately, you have many posts and all have different info on your build. Even if you got new injectors or rebuilt or reused the old ones, it would be good to see if any of the plugs are soaked with fuel.
Also, did you put new spark plugs in?
You also stated that the IAC had water in it. Did you powerwash or wash the engine bay? If so, then it might be a good idea to start checking wiring connections to the PCM or pull the PCM and open it up to see if everything looks ok.
sorry about the multiple threads. i didnt want to keep stacking issues onto the one because i thought it would be a pain for others to search through a big one.
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Lead Driver
Joined: Aug 2006
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From: Sand Lake, MI
fuel pressure stayed up between 35 and 40lb the entire time. I rebuilt the injectors, new spark plugs, no power wash and the IAC was wet but it was black and oily.
sorry about the multiple threads. i didnt want to keep stacking issues onto the one because i thought it would be a pain for others to search through a big one.
sorry about the multiple threads. i didnt want to keep stacking issues onto the one because i thought it would be a pain for others to search through a big one.
Thread Starter
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Senior User
Joined: Oct 2013
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From: wentzville MO
Ok i finally got the cam details. Its got 270/276 duration with 452/465 lift. Is that my problem? Next step for me is just going to be purchasing a custom chip. Thanks yall for the help.
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
Lobe separation is what's typically looked at to predict efi compatability.
112 is ok if you have a custom tune but 114 is what's desired.
Type out what the cam card says.
Adv duration
Lift
Lobe separation
Duration at .050
Part number
Thread Starter
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Senior User
Joined: Oct 2013
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From: wentzville MO
270/276 duration
452/465 lift
112 lobe separation
230 at .050
do those make sense??? it was very hard to understand the guy on the phone. thank,
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
112 lobe separation is at the limits of the stock efi. A custom chip or tuning software will make it run much better. If it were 114 then the efi would probably have compensated for it by itself.
Still, it should run decent. But it will have a few weird traits like cold start or on/off/on throttle hesitation.
Probably part of your hard starting issue as well.
Maybe crack the throttle open a hair more with the throttle stop to give it more air when starting. It's either not starting because of too little or too much air. Try it both ways.
Keep at it. You'll get it figured out.
Still, it should run decent. But it will have a few weird traits like cold start or on/off/on throttle hesitation.
Probably part of your hard starting issue as well.
Maybe crack the throttle open a hair more with the throttle stop to give it more air when starting. It's either not starting because of too little or too much air. Try it both ways.
Keep at it. You'll get it figured out.
Thread Starter
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Senior User
Joined: Oct 2013
Posts: 181
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From: wentzville MO
UPDATE: I purchased a custom chip for my truck and plugged it in. this should solve all the issues we had with the cam, larger displacement, and unused sensors (egr and knock). I was able to get the truck to run long enough to make some heat in the headers and noticed something. NONE of the cylinders on the passenger side are firing. before i rip off the intake and swap the injectors, is there any thought on why this is happening? Thanks,