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1993 Mazda Truck Runs cold, pops and farts when warm

Tiny
JTHFI58
  • MEMBER
  • 1993 MAZDA TRUCK
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 168,000 MILES
The trucks runs and accelerates when cold, once warm the truck pops and farts under acceleration. Fuel pump pressure checked good, O2 sensor, engine coolant sensor, fuel filter and ignition module replaced.

Ok cold, bad when warmed up
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Saturday, April 11th, 2009 AT 4:01 PM

7 Replies

Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
The popn' and fartn' is idicitive of a lean condition. When it's doing this, if you really stick your foot into it does it take off, or is it the same thing? Please advise.
Is the truck carbed or PHI?
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Saturday, April 11th, 2009 AT 10:36 PM
Tiny
JTHFI58
  • MEMBER
  • 4 POSTS
The truck is fuel injected. When it is in the closed loop it runs and accerates fine, when the temperature rises to closed loop operation it pops and farts in closed loop and is worse upon revving the motor. I have changed out the o2 sensor and checked the wiring and signal voltages. I have changed out the engine coolant sensor due to an error in the resistance in the Chiltons manual. The ignition system is fine, plugs, rotor, cap and ignition module are all new. I have tested the throttle position sensor and the resistance appears linear and changing as expected. I looked at the PCM and cannot see any burned components.

This is kicking my butt and the Chiltons manual is lame and full of errors. The self check connector pin in's and pin outs are not defined or shown in the manual so I cannot run the self check. I do not have any check engine light warnings other than the lamp test upon turning the key on. Which works. HELP!

John
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Sunday, April 12th, 2009 AT 10:34 AM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
Not knowing whether your truck is a 2.2 or a 2.6, the attached diagrams are for either. I had to cut the diagram into sections in order for you to read this. If I try to post it in entirety, they would just be a blurr 'cause of space limitations. I would test the intake air sensor, then the Mass Air. When the engine goes into closed loop, it relies on the IAT and mass air mostly to run the engine.
Not knowing where you reside, what is your average air temp outside?


https://www.2carpros.com/forum/automotive_pictures/248092_93_mazda_ECM_1_1.jpg



https://www.2carpros.com/forum/automotive_pictures/248092_93_mazda_ECM_2_1.jpg



https://www.2carpros.com/forum/automotive_pictures/248092_93_mazda_ECM_pins_1.jpg



https://www.2carpros.com/forum/automotive_pictures/248092_93_mazda_ECM_pins_2_1.jpg



https://www.2carpros.com/forum/automotive_pictures/248092_93_mazda_ECM_pins_3_1.jpg



https://www.2carpros.com/forum/automotive_pictures/248092_93_mazda_ECM_pins_3_2.jpg

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Sunday, April 12th, 2009 AT 4:27 PM
Tiny
JTHFI58
  • MEMBER
  • 4 POSTS
Thank you James, for the diagrams, I feel more at home with them then what the chilton's book has. I would appreciate telling me the manual ISBN number the diagrams came from and name so I can purchase it.

The truck is a B2600I, 2.6 liter, 170,000 miles on it and very pampered.

I am unable to get back to work on it until after the 16th, the self diagnostic connector "Pin 1" is alluding me, I think I found it and there are 3 wires on it, but I am nervous to ground one of them to figure out the correct one to ground. I will gladly renumerate you much better than the 20 bucks I sent to check out the site with

Can I purchase "breakout cables" to insert between the connectors and plugs anywere? I am noy comfortable piercing the insulation with a pin to read the voltages. Happy Easter James

John
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Sunday, April 12th, 2009 AT 10:10 PM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
John, we have access to the Mitchell library here. I had my own shop for 14 years and Mitchell (which we sell at this site) and Motors are the only manuals I would buy. They're not cheap, but when it comes to manuals, you get what you pay for. Chilton will tell you just enough to get you in trouble.
I have no way of telling which manual your information came from, but I'm sure if you ordered one for your model/year it would have the same info.
Keep me posted.


https://www.2carpros.com/forum/automotive_pictures/248092_B2600_test_con_1.jpg



https://www.2carpros.com/forum/automotive_pictures/248092_B2600_test_con_2_1.jpg

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Sunday, April 12th, 2009 AT 11:25 PM
Tiny
JTHFI58
  • MEMBER
  • 4 POSTS
I am going to fix this damn thing tomorrow.

I have the B2600i and if you could try to get me a clearer document of the connector, schematic, and the troubleshooting chart for a 93 Mazda B2600i, 2 wd, auto tranny with OD I would be very greateful.

The chiltons manuel says the IAT should be 30K ohms to 36 K ohms at 25 deg C and 2K ohms at 100 deg C.

Is this what you think also?

Grateful. I will order the mitchell manual through your site right now

John
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Friday, April 17th, 2009 AT 9:04 PM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
John, a lot of the older diagrams don't come through very well 'cause of space constrictions. If you will send me your email address and a list of what you would like to see, I can ship you the info in PDF files. They will be much clearer.
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Sunday, April 19th, 2009 AT 1:20 PM

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