Surging

Tiny
LESERZ
  • MEMBER
  • 1992 GMC C1500
  • 2WD
  • AUTOMATIC
  • 307,000 MILES
1 st timer here. I have a 1992 c1500 4.3 V6 TBI fuel injection. 3000.000+ miles on it. This thing is driving me nuts. For the last 18 months after I have been driving it and at 190 - 200 * temp. St times it will start surging or act like the ignition is shutting off for 1/4 to 1/2 second. As long as it is at a steady speed it will surge. Give it a tad of gas it`s will stop surging or and up grade in a road it`s fine try to drive at 55 mph surges like mad some times after 20 minutes some times after 1/2 hour. I replaced the fuel pump and gas filter no change put in a used EGR valve no change put in a new EGR valve selinoid no change. Put in a ner dist modgel (sp) no change stuck in a used dist. Same thing. New TBI base gasketthe large ring just under the rotor is not easy to turn like old dist. No idea what that part is called. New vacuum lines new PVC valve. I have sprayed around the intake manifold no change in rpm once it did by the EGR valve but not again. Every once in a while the service engine soon light will come on. Checked codes with jumper wire shows only code 13. The truck will restart after normal temps but like the ignition is advanced to much or a low battery no matter where the timing is it`s the same thing. I do know I need a new radiator for it it is pretty rusted up in side. Not losing any fluid in radiator. Don`t know what to do. Can not afford to buy another used truck. Any one have any ideas? This needs to last me a year or two longer
Thursday, January 6th, 2011 AT 9:47 PM

3 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
A faulty O2 sensor can cause the symptoms described. Here are the procedures for diagnosing the peoblem

Code 13 = Open Oxygen Sensor Circuit.

When exhaust temperature is less than 600°F (316°C), the O2 sensor is open and produces no voltage. An open sensor circuit or cold sensor will not all system to entire closed loop.

NOTE: Test numbers refer to test numbers on diagnostic chart.

1. Code 13 will set at normal operating temperature if at least 2 minutes have passed since engine start, Code 21 or 22 is not present, O2 signal voltage is steady at.35-.55 volt and throttle position sensor signal is greater than idle. All conditions must be met for at least 1 minute.

2. This determines if fault is in O2 sensor, ECM or wiring.

3. Use only a high-impedance Digital Volt-Ohmmeter (DVOM) while checking for continuity in signal and ground circuits. If ground circuit is open, voltage on signal circuit will be greater than.6 volt.
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Friday, January 7th, 2011 AT 3:53 PM
Tiny
LESERZ
  • MEMBER
  • 3 POSTS
Sorry that should have been code 12 not 13 there is no 02 sensor on my truck any place not on the left or right manifolds on on the wxhaust any place. At one time before I changed distributers if the service engine soon light came on it would stop surging and run great thats what has me stumped
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Friday, January 7th, 2011 AT 6:24 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Code 12 does not indicate anything significant as it would appear if ALDL is grounded with key on and engine off.

You should try to get the code when the CEL indicates by grounding the ALDL without turning off the engine.

When CEL turns on, the component that is faulty would be overridden by the PCM which usues a preset value and that is the reason the engine would run smoother.

Have you tried using a scan toll to retrieve for trouble codes?
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Saturday, January 8th, 2011 AT 3:23 PM

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