Starting blues

8

86bluecobra

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Dec 20, 2004

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Aug 24, 2007

#1

• Aug 24, 2007

• #1

This is not a mass air flow 302 but it has a maps sensor so its speed density. Lately it has been running horrible. Very rich. Black smoke out the tail pipes. I don't get any codes with my scanner. The issue is it won't start unless you put your foot to the floor with the gas pedal. It runs rough on initial start up but then smooths out. If you shut it off then go to fire you have to put the gas pedal to the floor again and black smoke out the pipes. I realize it has to be running rich but how and where do I start to correct this issue. It was running fine until the last month were it started doing this all the time. Previuosly it might do this once and a while but it was rare. Please help thx in advance.

 

91 HATCH

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May 17, 2007

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Aug 25, 2007

#2

• Aug 25, 2007

• #2

It sounds like you have to much fuel pressure at the carb.Check to see if your timing is ok.Also might be sticking floats.

 

8

86bluecobra

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Aug 25, 2007

#3

• Aug 25, 2007

• #3

Fuel pressure was what I was thinking. This is on a EFI 302 however. I am getting black smoke and black liquid comming out of my tail pipes. I just don't have a fuel pressure gauge to check on the shrader valve. I changed the o2 sensor the old one was completely carboned up, coated completely. It has to be running way rich but not getting codes.

 

green

New Member

Apr 26, 2003

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Aug 25, 2007

#4

• Aug 25, 2007

• #4

maybe a map sensor?

 

8

86bluecobra

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Dec 20, 2004

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Aug 25, 2007

#5

• Aug 25, 2007

• #5

green said:

maybe a map sensor?

Click to expand...

I wondered about that but I had one fail on a v-6 tarus and the thing just quit. I don't know if they work poorly or if they just give up the ghost. I always kinda thought they worked or they didn't.

 

91 HATCH

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May 17, 2007

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Aug 25, 2007

#6

• Aug 25, 2007

• #6

Try testing your injectors

 

8

86bluecobra

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Dec 20, 2004

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Aug 25, 2007

#7

• Aug 25, 2007

• #7

91 HATCH said:

Try testing your injectors

Click to expand...

how exactly do I do that? I am guessing I have to remove them?

 

HISSIN50

"How long does it take to get help in here?

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Aug 25, 2007

#8

• Aug 25, 2007

• #8

I agree with checking the MAP out further. Ensure the vac line to it is good and that it doesn't have holes, etc in it.

I have experience with a sensor failing. It ran a bit like your car is.

Just something I'd really go over.

Good luck.

 

jrichker

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Aug 25, 2007

#9

• Aug 25, 2007

• #9

Hot start problems characterized by black smoke and rich running after startup are usually a ECT that is borderline.

Dumping the codes will normally show a faulty sensor. The ACT & ECT may be on the outer limits and not set a code but cause problems. Use a DVM or multimeter to check them.

Pin 25 ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Pin 7 ECT signal in. at 176 degrees F it should be .80 volts

The ACT & ECT have the same thermistor, so the table values are the same.

Here's the table: The values are +/- 15%, so don't get worried if your readings vary a little bit.

Voltages are measured across the two connector pins of the sensor with the sensor connected. Some safety pins used to probe the connector from the rear will be helpful

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

 

8

86bluecobra

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Aug 26, 2007

#10

• Aug 26, 2007

• #10

I replaced the ECT about a year ago because I broke the sensor when I was playing with the heater hose. I guess i could look at it. I might have my old map sensor from my 86 mustang I should try plugging in that sensor.

 

8

86bluecobra

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Aug 26, 2007

#11

• Aug 26, 2007

• #11

I did not have any sensor codes when I put my code scanner on.

 

HISSIN50

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Aug 26, 2007

#12

• Aug 26, 2007

• #12

It doesnt matter with the codes - if either the ECT or MAP are out of calibration, it can cause issues. However, they are often still within absolute parameters, ergo no code.

 

8

86bluecobra

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Aug 26, 2007

#13

• Aug 26, 2007

• #13

thanks Hissin I'll check out the maps and vacuum line going to it.

 

8

86bluecobra

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Sep 3, 2007

#14

• Sep 3, 2007

• #14

I am getting code 116 which is a coolant temp either higher or lower then expected code. The truck was at normal operating temp. Would this be enough to indicate the ect has gone bad? It was replaced 1 and a hlaf years back because I accidently broke the old one.

 

HISSIN50

"How long does it take to get help in here?

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Sep 3, 2007

#15

• Sep 3, 2007

• #15

I'd check the ECT signal output. If it looks good at the sensor, check it at the puter.
If it doesnt look good at the sensor, check the incoming voltage and then disconnect the sensor and check resistance.

 

8

86bluecobra

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Sep 3, 2007

#16

• Sep 3, 2007

• #16

Looks like I am getting infinet ohms at the sensor. I would say the sensor failed. I have not checked the voltage however.

 

8

86bluecobra

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Sep 3, 2007

#17

• Sep 3, 2007

• #17

Yep changed the ECT sensor and truck running like a top again. Stupid plastic sensor that I bought. Should have just bought a good Ford one off the bat.

 

8

86bluecobra

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Sep 4, 2007

#18

• Sep 4, 2007

• #18

bump for our friend with the 306 running rich.