1992 Chevy Truck loss of power

Tiny
CWWJR88
  • MEMBER
  • 1992 CHEVROLET TRUCK
  • V8
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
Truck acted like it had no power. Rough idle and would die at times. During power braking, it would back fire sometimes. Replaced distributor cap, rotor, spark plugs, fuel filter. No better.
Took to shop they replaced fuel pump. Ran truck for hour over different driving conditions. Ran fine. Daughter borrowed truck. Ran fine. She filled truck up(20 gal of 32 gal tank). Ran for 20 minutes, then lost power.

Exwife went to drive truck home. Ran fine. Put in new battery and had altenator checked.

I went to look at, replaced coil and spark plug wires. Started truck, idled fine. Went for test drive. Ran fine. After waiting for light, took off, truck lost power. It also sounded like engine was pinging. Pulled over into parking lot, turck died. After waiting a minute, started truck, ran fine.

After driving for a minute, same symptoms. If I put truck in 1st gear, it would buck and ping then clear up and drive fine for another minute or so.

After getting back to their house, opened hood. Motor smelt hot, but showed fine on temperature gauge.
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Tuesday, February 3rd, 2009 AT 11:11 PM

7 Replies

Tiny
RACEFAN966
  • EXPERT
Ok are you will to do some tests? I will need to know if you have a digital multi meter. I would like to test the distributor module and the timing spark control module. Let me know what you are up to doing and we will take it from there.
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Wednesday, February 4th, 2009 AT 10:53 AM
Tiny
CWWJR88
  • MEMBER
I work in maintenance at a large plant, so I do know my way around a VOM!

If I am given some direction, I can follow!

The truck is currently 100 miles from me, so it will be this weekend before I can do any actual testing
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Wednesday, February 4th, 2009 AT 8:19 PM
Tiny
RACEFAN966
  • EXPERT
Ok first I would like to test he knock sensor it is on the engine block below the right side (passanger) exhaust manifold and what you need to do is unplug it and set your meter to ohms and check the resistance between the sensor terminal and the engine block it should read 3300-4500 ohms. If not then replace it.
Is the check engine light on? If so then we need to get a paper clip and jump the ALDL connector and turn the key on engine off and count the engine light as it blinks. It will blink 1 then pause and 2 =(12) then pause longer and do the next code in the same manner. Here is a diagram of the diagnostic port and what two terminals to jump with the paper clip which are term. A and B.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic_31.jpg


Let me know what you find and we will go from there.
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Wednesday, February 4th, 2009 AT 9:10 PM
Tiny
CWWJR88
  • MEMBER
Any other things to check? Going to work on this weekend.
Thanks
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Friday, February 6th, 2009 AT 4:40 PM
Tiny
RACEFAN966
  • EXPERT
Check the cap and rotor and ohm the wires no more then 1000 ohms an inch. I know you replaced them but check them just to be. I would also like you to check the TPS sensor.
With the throttle position sensor you will need to find the green wire and back probe it and hook up your multi meter and then turn the key on engine off and you should read .8 to 1 volt with the throttle closed now slowly raise the throttle and it should gradually and steadily increase to 4.5 to 5 volts. If it drops or glitches as you raise the throttle then it is no good. now also ohm the coolant temp sensor unplug it and ohm the term on the sensor to ground and give me the ohms and temp of the sensor at the time of the test. Let me know what this brings.
I also would like you test the ignition module in the distributor and the electronic spark contol module I will include pic of both ok.
The ignition module test the ground path circuit number 423 it should be less the 500 ohms. With the ohm meter hooked up still take a test light and touch circuit number 424 and the ohms should over range the 100-200 ohm scale to around 5000 if this tests good then all it ok if not bad module replace it. This test is done with the key on engine off. Here is a pic of the module and circuits.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic_37.jpg



Now the Electronic spark control unit. With your volt meter check term C and if when the truck is running the (may need to be in gear) there is 12 volts pressent the the ESC needs to be replaced. If there isn't 12 volts then take a small hammer to ratched and tap on the block near the Knock sensor and 12 volts should show. Check the ohms at term D to ensure a good ground and check Term B with the key on engine off to ensure battery voltage this way you know that there are no bad wires ok.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic2_6.jpg



Let me know what you find. Thanks.
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Saturday, February 7th, 2009 AT 8:56 AM
Tiny
CWWJR88
  • MEMBER
Knock sensor was bad. Replaced. Check engine light is not on and I checked the codes couple of weeks ago. No codes stored.

Checked wires. OK. Checked TPS sensor. Tested fine.

Did not get the chance to check anything else.

Couple of other things I noticed/forget to tell you. When it is messing up, it will not idle. RPMs drop, then it shakes and sputters, knocks, then levels out and is fine. Sometimes after it dies, starter really has to work to turn over motor. Could the idle air control valve be flaky? Can you test it?

Also heard a popping sound coming from the muffler/cat area after truck had been running 10-15 minutes. May have just been warming up?

Problems always happen after truck has ran for 10-15 minutes. Fine before that point.

Going back up to work on the truck on Tuesday. Any suggestions besides the spark control and ignition module which I plan on testing at that time?

Thanks for all your help. Learning as I go!
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Sunday, February 8th, 2009 AT 9:53 PM
Tiny
RACEFAN966
  • EXPERT
No not at this point as with what you are discribing I am thinking timing issue. So test the ESC first then test the module. The ESC with the knock sensor control the timing. If the ESC thinks it is pinging then it will retard the timing or advance it if it sees the signal incorrectly and make it ping and then it would be very hard to start as the timing is advanced beyond what the engine should be. Does this make sense? If not let me know I will try to explain it better.
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Monday, February 9th, 2009 AT 9:56 AM

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