Mechanics

DIES OFF WHEN I GIVE IT GAS, EVEN IN NEUTR

1991 Mazda b2600

Engine Performance problem
1991 Mazda b2600 4 cyl Four Wheel Drive Manual 110000 miles

With my truck running in neutral and idleing fine, I press the accelaerator and the engine sputters and drop down to like 200 rpm and dies if I don't release the pedal. The problem just happened. I have spark and good fuel pressure (40 psi inline while running, 79 psi from pump), I checked the throttle position sensor it tests good. Has new air filter, dist cap and rotor. Check engine light comes on and goes off upon engine starting. Any ideas please help this Alaskan fella out. Thanx.
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Chadliness
February 20, 2010.




Hi chadliness, Welcome to 2carpros and TY for the donation.

Okay last frontier man-clean out the EGR valve and make sure the vacuum solenoid is operating also the PCV valve- recheck the fuel pressure with vacuum and w/o vacuum and record readings and comeback with the readings.

Further check ignition timing-

With vacuum-28-37psi and W/O 38-46psi

Get back with some results

Rasmataz
Feb 20, 2010.
Hey Raz, I rechecked the fuel pressure about 39 psi with vac 44 without. Solenoid seems to work if the engine is at temp, I used mitchell test procedure. PCV valve rattles. There is no EGR to clean, unless it is called something else. Havent checked timing but going there next.

Tiny
Chadliness
Feb 25, 2010.
You CEL is coming On and Off scan the computer for code/s and get back. Boy! Don't I miss the land of the midnite sun-Houston/Wasilla/Palmer areas-

Also test the airflow meter

Rasmataz
Feb 25, 2010.
Hey raz, I meant the CEL comes on when the key is turned on and goes out when it starts like normal. More info, the ignition timing is right on at 5 btdc. I have found that sometimes the truck will run good, (engine will accelerate normally) for a period of time, maybe 5 or 15 minutes, and then go back to dying when the throttle is applied. This doesn't always happen. Will check that sensor next and try to pull codes. I don' have a code reader but I will see if I can pull with the CEL or MIL lamp. Good to hear you like the mat-su valley area. I live down in Girdwood. Thx 4 all.

Tiny
Chadliness
Feb 25, 2010.
Lets try to check for code/s-Do below


http://www.2carpros.com/forum/automotive_pictures/12900_b26001_1.jpg



http://www.2carpros.com/forum/automotive_pictures/12900_b26002_1.jpg



http://www.2carpros.com/forum/automotive_pictures/12900_b26003_1.jpg


Rasmataz
Feb 25, 2010.
Its a long list follow it like snagging the big one out of Russian river or at Seward

Inspect and test all the following listed below: Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard.

Rasmataz
Feb 25, 2010.
Hey Raz, its been a while but Ive been diligently troubleshooting this intermittent problem. I loose the 5 volt reference for the tps sensor, sometimes. Ive checked it mant times but it was intermittent and I couldnt get it. I have made sure that the wiring to the ecu is good, 1 ohm sensor to ecu, and no shorts to ground or any where else. I also made sure that the ground has continuity to ecu and batt -. The other wire has continuity to ecu as well 1 ohm. I made sure that I can read the coorect sensor resistance all thru the range at ecu. I also get a 14 code for atmospheric sensor. Mitchell says thats a bad ECU also. Is my best set replace ecu. Send it off to be tested? Is there any manufacturer you suggest or would avoid. My 1st thought is Napa for about $500 for a new one. Thanx for all help so far, I had 2 throw ya more cash cause you rock.

Tiny
Chadliness
Mar 18, 2010.
Thank you for the extra $$$$ appreciate it-Okay DTC 14 is Atmospheric Pressure Sensor the repair/fix is to replace the computer as stated in Mit1. Maybe go to Anchorage and get with TKD auto-dunno if they're still in Old Seward Hwy near Diamond Blvd check phone book check with them maybe they know a local place that does it. My opinion best shot with NAPA. Once again TY and Good Luck
AD

Rasmataz
Mar 18, 2010.

AD