Rough running 2.9l

[franklin2]

I’ll buy a new distributor and see if I can set the timing correctly

I would not buy a new distributor unless I had to. You have no codes from it. All the distributors I know of that you can buy are rebuilt by Cardone and you may end up with more problems than you have now. Check the timing, it's easy once you clean the damper off so you can read the numbers. The bolt is a little hard to get to that loosens the dist. Only loosen it enough that you can force the distributor to move by hand. Then you can move it with the engine running.

 

[NM_Broncoii]

I would not buy a new distributor unless I had to. You have no codes from it. All the distributors I know of that you can buy are rebuilt by Cardone and you may end up with more problems than you have now. Check the timing, it's easy once you clean the damper off so you can read the numbers. The bolt is a little hard to get to that loosens the dist. Only loosen it enough that you can force the distributor to move by hand. Then you can move it with the engine running.

Okay thank you I’ll redo the timing today I wouldn’t think I’d be a distributor since it runs fine with map disconnected but has absolutely no throttle response. You push the throttle down and just sucks air and doesn’t increase the rpm’s till about maybe 10 seconds later. If I bump the throttle by the time my foots off the gas then it revs up so weird

 

[NM_Broncoii]

Sounds like timing to me. Check where it is now. With spout unplugged like mentioned.

Ran truck with the spout unplugged and ran the same but didn’t check timing since I didn’t have a timing light. I’ll pick one up today for sure

 

[NM_Broncoii]

Try pulling the codes...see what you come up with.

All I get is code 11,10,11 in that order

 

[NM_Broncoii]

So my question is would the map sensor have anything to do with the timing under load when reved? I would think if timings wrong the car would always run like crap and not only if the map is plugged in unless the map tell the truck what timing it should be under load

 

[rusty ol ranger]

All I get is code 11,10,11 in that order

Well thats good cause it passed that test

So my question is would the map sensor have anything to do with the timing under load when reved? I would think if timings wrong the car would always run like crap and not only if the map is plugged in unless the map tell the truck what timing it should be under load

The MAP basically reads the vaccum inside the intake and tells the ECM what it is so the ECM can use that input (along with input from varjous other sensors) where to put the timing, A/F mix, etc etc.

@RonD any input here?
.

 

[NM_Broncoii]

Well thats good cause it passed that test


The MAP basically reads the vaccum inside the intake and tells the ECM what it is so the ECM can use that input (along with input from varjous other sensors) where to put the timing, A/F mix, etc etc.

@RonD any input here?
.

Hmm maybe I have a massive air leak or something I do have a fully gasket set for the truck so I might pull off the intake and clean injectors and intake then regasket everything and maybe that will help. Also redo the timing Might even see if I can find another computer for it today at the salvage yard aswell.

 

[ford4wd08]

Ran truck with the spout unplugged and ran the same but didn’t check timing since I didn’t have a timing light. I’ll pick one up today for sure

Get a timing light that can read RPMs at the same time and can do dial back.

It is a tool that greatly under valued.

I won't tune one by ear anymore.

 

[rusty ol ranger]

Hmm maybe I have a massive air leak or something I do have a fully gasket set for the truck so I might pull off the intake and clean injectors and intake then regasket everything and maybe that will help. Also redo the timing Might even see if I can find another computer for it today at the salvage yard aswell.

Get it to run with the return line pinched and spray starting fluid around the gasket mating surfaces, listen close for any changes in rpm. Thatll tell you if you are sucking air. But a vacuum leak massive enough to make it run like you describe should be very obvious.

Long shot but have you tested the TPS?

 

[NM_Broncoii]

Get it to run with the return line pinched and spray starting fluid around the gasket mating surfaces, listen close for any changes in rpm. Thatll tell you if you are sucking air. But a vacuum leak massive enough to make it run like you describe should be very obvious.

Long shot but have you tested the TPS?

Haven’t tested tps yet since it was a new one but I will check. I went out to check the fuel pressure from sitting overnight had the gauge connected all night and it has no psi at all now. Shouldnt it be able to hold it overnight?

 

[RonD]

Should hold pressure for a few months, but 0psi engine off is just a cold start issue, as long as engine running pressure is 30-40psi fuel flow isn't the issue
Check the vacuum hose on the Fuel Pressure Regulator(FPR), if FPR leaks that vacuum hose sucks raw fuel into the intake causing rough running

Air/fuel is a WEIGHT ratio, gasoline uses 14.7 to 1 ratio, So:
14.7 pounds of air to 1 pound of gasoline
14.7 grams of air to 1 gram of gasoline
This is why fuel injectors are rated in pounds per hour
(also why 200mpg carbs and pre-vaporizers are hooey, lol)

Yes, MAP sensor helps computer see engine load but also elevation, like a barometer, with key on MAP data is outside air pressure, that's a reference point set and used after engine start up, because engine vacuum is effected by outside air pressure
At sea level outside pressure is 30"
At 5,000ft its 25"

An engine idling at 700rpm might have vacuum level at sea level of 19"
At 5,000ft 16", because air pressure difference and lighter(thinner) air

If MAP data was strictly based on vacuum level in intake that would be an issue
Lower vacuum in intake means higher load on engine so more fuel would be added, but if that was done at higher elevation where the air is lighter engine would flood out
So it is not a simple vacuum level reading = fuel injector open time formula

In mountain driving people with MAP systems would often report rough running as they got higher OR lower in elevation, but after shutting off the key and then restarting, the engine would run much better
Because MAP was reset to current elevation(outside pressure)

MAF systems don't have that issue since they WEIGH the air directly, they don't have to "assume" air weight by pressure

Spark timing
Air/fuel mix of 14.7 to 1 has a static(fixed) burn time
This means when a spark plug fires to ignite the air/fuel mix the FULL ignition of that mix happens in a fixed amount of time, it is NOT instant
Lets say its 100 time

You want FULL ignition to happen AFTER TDC so the explosive pressure pushes the piston DOWN adding power to the crank shaft, if it happen before TDC then engine would stop, or break something, lol
For best power you want full ignition just after 7deg ATDC, so the explosion has good leverage to push piston down but still a SMALL space to expand in for best power

The piston is moving, of course, and that is also a time factor
At 700rpms it takes a fixed amount of time for the crank/piston to move from 10deg BTDC to 10deg ATDC
At 1,400rpms it take 1/2 that time
This is where RPM spark advance comes in, you need the spark plug to fire sooner, 20deg BTDC, as RPMs increase to get full explosion at say 10deg ATDC
And all of that is just math and fairly straight forward
Fix burn time for fuel mix and rotational speed

The monkey in the wrench is the fuel mix ratio, a richer mix, say 13 to 1, burns FASTER than the 14.7 to 1 mix
So when you want to accelerate quickly the fuel mix must change and spark timing must change with it
And this is what Load spark advance is for, and why you need it

There is way more to this, and some good stuff to read on it, to give you a better understanding of what and why you need to set a good base timing for spark, to get good performance from a gasoline engine

 

[rusty ol ranger]

Should hold pressure for a few months, but 0psi engine off is just a cold start issue, as long as engine running pressure is 30-40psi fuel flow isn't the issue
Check the vacuum hose on the Fuel Pressure Regulator(FPR), if FPR leaks that vacuum hose sucks raw fuel into the intake causing rough running

Air/fuel is a WEIGHT ratio, gasoline uses 14.7 to 1 ratio, So:
14.7 pounds of air to 1 pound of gasoline
14.7 grams of air to 1 gram of gasoline
This is why fuel injectors are rated in pounds per hour
(also why 200mpg carbs and pre-vaporizers are hooey, lol)

Yes, MAP sensor helps computer see engine load but also elevation, like a barometer, with key on MAP data is outside air pressure, that's a reference point set and used after engine start up, because engine vacuum is effected by outside air pressure
At sea level outside pressure is 30"
At 5,000ft its 25"

An engine idling at 700rpm might have vacuum level at sea level of 19"
At 5,000ft 16", because air pressure difference and lighter(thinner) air

If MAP data was strictly based on vacuum level in intake that would be an issue
Lower vacuum in intake means higher load on engine so more fuel would be added, but if that was done at higher elevation where the air is lighter engine would flood out
So it is not a simple vacuum level reading = fuel injector open time formula

In mountain driving people with MAP systems would often report rough running as they got higher OR lower in elevation, but after shutting off the key and then restarting, the engine would run much better
Because MAP was reset to current elevation(outside pressure)

MAF systems don't have that issue since they WEIGH the air directly, they don't have to "assume" air weight by pressure

Spark timing
Air/fuel mix of 14.7 to 1 has a static(fixed) burn time
This means when a spark plug fires to ignites the air/fuel mix the FULL ignition of that mix happens in a fixed amount of time, it is NOT instant
Lets say its 100 time

You want FULL ignition to happen AFTER TDC so the explosive pressure pushes the piston DOWN adding power to the crank shaft, if it happen before TDC then engine would stop, or break something, lol
For best power you want full ignition just after 7deg ATDC, so the explosion has good leverage to push piston down but still a SMALL space to expand in for best power

The piston is moving, of course, and that is also a time factor
At 700rpms it takes a fixed amount of time for the crank/piston to move from 10deg BTDC to 10deg ATDC
At 1,400rpms it take 1/2 that time
This is where RPM spark advance comes in, you need the spark plug to fire sooner, 20deg BTDC, as RPMs increase to get full explosion at say 10deg ATDC
And all of that is just math and fairly straight forward
Fix burn time for fuel mix and rotational speed

The monkey in the wrench is the fuel mix ratio, a richer mix, say 13 to 1, burns FASTER than the 14.7 to 1 mix
So when you want to accelerate quickly the fuel mix must change and spark timing must change with it
And this is what Load spark advance is for, and why you need it

There is why more to this, and some good stuff to read on it, to give you a better understanding of what and why you need to set a good base timing for spark, to get good performance from a gasoline engine

This is why i called ron

 

[NM_Broncoii]

Should hold pressure for a few months, but 0psi engine off is just a cold start issue, as long as engine running pressure is 30-40psi fuel flow isn't the issue
Check the vacuum hose on the Fuel Pressure Regulator(FPR), if FPR leaks that vacuum hose sucks raw fuel into the intake causing rough running

Air/fuel is a WEIGHT ratio, gasoline uses 14.7 to 1 ratio, So:
14.7 pounds of air to 1 pound of gasoline
14.7 grams of air to 1 gram of gasoline
This is why fuel injectors are rated in pounds per hour
(also why 200mpg carbs and pre-vaporizers are hooey, lol)

Yes, MAP sensor helps computer see engine load but also elevation, like a barometer, with key on MAP data is outside air pressure, that's a reference point set and used after engine start up, because engine vacuum is effected by outside air pressure
At sea level outside pressure is 30"
At 5,000ft its 25"

An engine idling at 700rpm might have vacuum level at sea level of 19"
At 5,000ft 16", because air pressure difference and lighter(thinner) air

If MAP data was strictly based on vacuum level in intake that would be an issue
Lower vacuum in intake means higher load on engine so more fuel would be added, but if that was done at higher elevation where the air is lighter engine would flood out
So it is not a simple vacuum level reading = fuel injector open time formula

In mountain driving people with MAP systems would often report rough running as they got higher OR lower in elevation, but after shutting off the key and then restarting, the engine would run much better
Because MAP was reset to current elevation(outside pressure)

MAF systems don't have that issue since they WEIGH the air directly, they don't have to "assume" air weight by pressure

Spark timing
Air/fuel mix of 14.7 to 1 has a static(fixed) burn time
This means when a spark plug fires to ignite the air/fuel mix the FULL ignition of that mix happens in a fixed amount of time, it is NOT instant
Lets say its 100 time

You want FULL ignition to happen AFTER TDC so the explosive pressure pushes the piston DOWN adding power to the crank shaft, if it happen before TDC then engine would stop, or break something, lol
For best power you want full ignition just after 7deg ATDC, so the explosion has good leverage to push piston down but still a SMALL space to expand in for best power

The piston is moving, of course, and that is also a time factor
At 700rpms it takes a fixed amount of time for the crank/piston to move from 10deg BTDC to 10deg ATDC
At 1,400rpms it take 1/2 that time
This is where RPM spark advance comes in, you need the spark plug to fire sooner, 20deg BTDC, as RPMs increase to get full explosion at say 10deg ATDC
And all of that is just math and fairly straight forward
Fix burn time for fuel mix and rotational speed

The monkey in the wrench is the fuel mix ratio, a richer mix, say 13 to 1, burns FASTER than the 14.7 to 1 mix
So when you want to accelerate quickly the fuel mix must change and spark timing must change with it
And this is what Load spark advance is for, and why you need it

There is way more to this, and some good stuff to read on it, to give you a better understanding of what and why you need to set a good base timing for spark, to get good performance from a gasoline engine

.
So much to take in thank you so much for all the knowledge definitely helpful. Update I used my timing light I bought and with spout disconnected it says timing is at 0

 

[RonD]

That would explain low power and rough running
10 to 12deg Before TDC was usual timing with vacuum advance or SPOUT(computer load advance) disconnected

At 0 deg the air/fuel mix is "exploding" well after 20deg ATDC, so engine runs just no power
With SPOUT connected it would change it to 10deg BTDC so it would run better, but driving wouldn't have any power

 

[NM_Broncoii]

That would explain low power and rough running
10 to 12deg Before TDC was usual timing with vacuum advance or SPOUT(computer load advance) disconnected

At 0 deg the air/fuel mix is "exploding" well after 20deg ATDC, so engine runs just no power
With SPOUT connected it would change it to 10deg BTDC so it would run better, but driving wouldn't have any power

So I redid the 10 degrees mark with new white paint marker got it to 10 and still would die ran a lot better tho not really a misfire. Only when I plug that map sensor in it does it 3rd one I’ve tried. Runs good for a lil bit with map plugged in then low idle n dies plus no throttle response once at all. What’s the best way to make sure the engine is at tdc at the right stroke?