Motor not running right, air fuel problem please help

[deftsound]

Ok this mustang I bought has a 91 motor conversion. Obviously the original 86 motor didn't have mass air flow and this one does.

The problem is when you get over about 2500 rpms the motor sounds like a 'bumble bee' or like its underwater, its like a bbbwbwbwbwbw sound, it just does NOT sound right. It also feels like there is a real lack of power. I had new mufflers put on today so I know the sound is not because of the exhaust. It is running very rich also.

I think this has to do with the mass air flow conversion. Now, if I'm not mistaken didn't the mass air flow cars come without MAP's sensors? My car has a map's sensor still hooked up...I worked on it today with a mechanic at a local shop and we were trying to figure out whats wrong and thats what he told me.

Another clue, when we unplug the TPS sensor and start it up, then try to plug in the tps sensor the car immediately dies. Also we read 5volts at the black ground wire on the tps sensor, my mechanic said that is not right.

When we try to adjust the idle to around 750 or 800 the car wants to die.

Any ideas what would be causing my motor to sound like this and run like this? Sorry if this is confusing I am just trying to think of everything that we looked at today.

 

[deftsound]

Also, the vacuum lines coming off the throttle body are just hooked into one another. And there is no PCV valve, just a plug in the valve cover...

 

[jrichker]

Disconnect the MAP sensor from the vacuum source when you do a Mass Air Converstion. The MAP sensor vents to the open air. Be sure to plug the vacuum line that used to connect to the MAP sensor.

If you already have the MAP sensor disconnected from the vacuum line, Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

See http://www.troublecodes.net/Ford/

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/pc-7208-90-equus-digital-ford-code-reader-3145.aspx – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

 

[deftsound]

Ok this is a noob question but where exactly is the map sensor and what does it look like?

Also, i found out cylinders 1 and 2 on the passenger side arent firing. I am going outside right now to troubleshoot more. I dont think they are even getting spark, i found some water in the boot...

 

[deftsound]

Ok im really starting to piece the puzzle together here.

Turns out #1 and #2 are not firing. I am assuming the spark plugs are fouled which in turn was caused by the person who converted the car to MAF not plugging the MAP vacuum line. Correct me if i am wrong but wouldn't not plugging that vacuum line cause all sorts of havoc on the air fuel ratio and what not?

Anyway i'll see if new spark plugs fix the misfire, hopefully by tomorrow afternoon i'll have this thing running like new!

Edit: I have a feeling this is not the only thing this guy messed up converting the car to MAF. He said he installed a 91 GT motor in it and I asked him if had to put a new ECC in or anything and he said no.....

 

[5.0Droptop]

wow....

 

[88mouse]

First off you need to check and make sure that it does have an MAF computer in it.

An open vac line on a SD car doesn't tend to make them run bad.

 

[deftsound]

First off you need to check and make sure that it does have an MAF computer in it.

An open vac line on a SD car doesn't tend to make them run bad.

Well i do know this much

When i unplug the MAF sensor and try to start it, it will NOT start until i plug the MAF sensor back in.

It only starts when the MAF sensor is plugged in

 

[deftsound]

bump

 

[jrichker]

The MAP sensor is mounted on the firewall just behind the upper intake manifold.

Make sure that you disconnect the vaccum line and let the sensor vent to the open air. There shouild not be anything obstructing the enrty of air into the MAP sensor.

Then plug the the vacuum line or remove it from the intake manifold and cap the manifold port.

 

[deftsound]

The MAP sensor is mounted on the firewall just behind the upper intake manifold.

Make sure that you disconnect the vaccum line and let the sensor vent to the open air. There shouild not be anything obstructing the enrty of air into the MAP sensor.

Then plug the the vacuum line or remove it from the intake manifold and cap the manifold port.

ok just got done doing that, could that have been causing it to run rich thus causing my plugs to foul?

 

[jrichker]

ok just got done doing that, could that have been causing it to run rich thus causing my plugs to foul?

Yes. However, it would cause all cylinders to run rich, not just one or two.

Dump the codes and do a cylinder balance test to look for more possible problem causes.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a
jumper wire or paper clip to put the computer into test mode. Start
the engine and let it go through the normal diagnostic tests, then
quickly press the throttle to the floor. The engine RPM should exceed
2500 RPM's for a brief second. The engine RPM's will increase to about
1450-1600 RPM and hold steady. The engine will shut off power to each
injector, one at a time. When it has sequenced through all 8 injectors,
it will flash 9 for everything OK, or the number of the failing cylinder
such as 2 for cylinder #2. Quickly pressing the throttle again up to
2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is
weak and isn’t putting out power like it should. See the Chilton’s Shop
manual for the complete test procedure

Here's the link to dump the computer codes with only a jumper wire
or paper clip and the check engine light, or test light or voltmeter.
I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

89 through 95 cars have a working Check Engine light. Watch it instead of a test lamp.

For those who are intimidated by all the wires & connections,
see http://www.actron.com/product_detail.php?pid=16153 for what a
typical hand scanner looks like. Normal retail price is about $30 or so
at Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes
or beeps.. Cost is $33.

Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder
balance test. Low compression on one of these cylinders rules out the
injectors as being the most likely cause of the problem. Look at cylinders
that fail the cylinder balance test but have good compression. These
cylinders either have a bad injector, bad spark plug or spark plug wire.
Move the wire and then the spark plug to another cylinder and run the
cylinder balance test again. If it follows the moved wire or spark plug,
you have found the problem. If the same cylinder fails the test again,
the injector is bad. If different cylinders fail the cylinder balance test,
you have ignition problems or wiring problems in the 10 pin black &
white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark
plug hole. The other type leaks too much to get an accurate reading.
Your local auto parts store may have a compression tester to rent.
If you do mechanic work on your own car on a regular basis, it would
be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the
throttle wide open, crank the engine until it the gage reading stops
increasing. On a cold engine, it will be hard to tell what's good &
what's not. Some of the recent posts have numbers ranging from
140-170 psi. If the compression is low, squirt some oil in the cylinder
and do it again – if it comes up, the rings are worn. There should be
no more than 10% difference between cylinders. Use a blow down
leak test (puts compressed air inside cylinders) on cylinders that
have more than 10% difference.

See the link to my site for details on how to build your own blow
down type compression tester.

 

[whtnotch]

My map wasn't hooked up eather...?would that cause the car to run poorly?you said to cap it up altogether?

 

[deftsound]

well new spark plugs and wires didn't help...i found some oil on the 2 spark plugs...

sigh.....

i dont have the tools to do this test right now, guess its gonna have to wait till I get back home...

edit: i jumped to conclusions there really wasent a significant amount of anything on the spark plugs i p ulled they looked brand new, i don't know whats going on and frankly I dont even know if the right eec is in the car...im lost

 

[jrichker]

My map wasn't hooked up eather...?would that cause the car to run poorly?you said to cap it up altogether?

Go back and read the post.

The MAP or Baro sensor is critical to getting the correct air/fuel ratio.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $25-$30 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.

 

[cenok is family]

My map wasn't hooked up eather...?would that cause the car to run poorly?you said to cap it up altogether?

the harness plug on the MAP/BARO sensor stays plugged in. on speed density cars, there is a vacuum line that runs from the underside of the upper intake to the vacuum port on the MAP/BARO sensor. when converting to mass air, you remove that line, plug the port on the underside of the intake and leave the port on the MAP/BARO sensor unplugged to vent to the atmosphere.