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Stuck in safe mode/limp mode and ABS light and service engine

Tiny
TURBO3052002
  • MEMBER
  • 1997 CHEVROLET S-10
  • AUTOMATIC
  • 200,000 MILES
We have the truck listed above long bed, regular cab, 4.3L (i think it is 4.3 the filter says V6 Vortex). The service engine light has come on and off in the past from our honest guessing it is due to a loose wire. Well that was not a problem just annoying. Well in the past two months its has either stalled while driving and never/did kick back to normal while driving. Or we had to pull over to turn off and then turn back on to get it to back to normal. Well the past two weeks it went from bad to horrible. One day while I was working it was running then it would not turn over. It fires but not start. Well had a horrible back yard mechanic/tow guy put only one fuel filter (not two that cost us $320.00 for him to put it on and we were in a hurry since its our only ride and one of us only works) and fuel pump. But back to subject at hand. After he messed it up and it only ran that one day we got it from him, it would not even run. And if it did run it would stutter or even stall when driving. Well now we have a great neighbor who is putting his blood and sweat in the truck to help us keep going and for me to keep working. The ABS light came on in the past two weeks and when I saw it, I got scared. I called the neighbor and he told me to drop it to his place and he will do his best. Well after talking to people one guy said its in safe mode and the throttle position sensor is half of what is going on. My neighbor hooked up his blue tooth code reader to the truck and it is saying the water is over three hundred degrees/running hot. Now my guess is that it need a new computer and that might at most fix it or at least help get things close to normal. Neighbor believes it is a connector somewhere.

I know I am rambling. Please help! We need this truck to get back to at least running so I can go back to work. Or find a job where I will not use it for work only to get to work.

update: 3-21-18/ we replaced the TPS and still no luck again.
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Wednesday, March 21st, 2018 AT 4:24 PM

27 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,293 POSTS
A coolant temperature reading that high would likely be from a bad ECT (engine coolant temperature) sensor. This sensor sends a signal to the computer so the computer can use the information to adjust fuel/air mixture, idle speed, ignition timing, and other things. According to Prodemand, an out of range ECT sensor reading will not necessarily set a trouble code. Replace the sensor. Its location is attached in the images. When you get the sensor, make sure you are getting the sensor that sends the signal to the computer, and not the one for the gauge. Yes, they are different sensors.

If that does not do it, then I would suspect failing spider injectors or possibly a failing fuel pump. A fuel pressure test and bleed down test would be the diagnostic procedure for that. I will lay it out for you if needed. Do the ECT sensor and let us know how that goes.
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Wednesday, March 21st, 2018 AT 6:45 PM
Tiny
TURBO3052002
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  • 18 POSTS
Thank you and will give update.
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Thursday, March 22nd, 2018 AT 1:07 PM
Tiny
TURBO3052002
  • MEMBER
  • 18 POSTS
HEYMAN1104 update: installed sensors: MAP, MAF, ECT, TPS. Stalling has decreased but backfire has increased. The codes we have been having and are still having are soft codes not hard code. The codes are P0102 and P0117. Also engine has become warm and not cold anymore.
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Friday, March 23rd, 2018 AT 6:29 PM
Tiny
HARRY P
  • MECHANIC
  • 2,293 POSTS
Wait, now the coolant temperature gauge is working? If so, while you fixed a problem (the gauge not working), you replaced the wrong coolant temperature sensor. You have to do the other one in order to get the right data sent to the computer. Live data while the engine is idling will probably still show it at 300 degrees.

It is possible that the ECT sensor harness is shorted. I am including GM's information on the mater.
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Friday, March 23rd, 2018 AT 7:13 PM
Tiny
TURBO3052002
  • MEMBER
  • 18 POSTS
Okay thanks again and I will let my neighbor know about the other coolant temperature sensor. I forgot to add this 1997 s10 is an old utility truck. Hope this helps you helping me.
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Friday, March 23rd, 2018 AT 9:55 PM
Tiny
TURBO3052002
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  • 18 POSTS
We do not know where the other coolant temperature sensor is. Runs rough after warm up, and once foot is on throttle it dies/chokes out. We put the second fuel filter on today. Below is a video of it in park. Sorry no video of it starting and stalling. Will post more when we have updates.
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Saturday, March 24th, 2018 AT 9:34 AM
Tiny
HARRY P
  • MECHANIC
  • 2,293 POSTS
Okay, let's take a step back here. Since your scanner has a live data mode, read the coolant temperature when the engine is off, key on. Do it again right after starting the engine. And again after the engine idles long enough to warm up. Then we will see what readings are getting to the computer. If there is a 300 degree reading again, I would think that it indicates a short circuit, and we need to be looking at the wiring to the sensor, and the sensor itself. If the readings are normal, then we need to be looking somewhere else. So go ahead and get those readings and we will go from there. While you are at it, re-scan for codes and see if anything new pops up.

Oh and where was the sensor located that you replaced?
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Saturday, March 24th, 2018 AT 6:14 PM
Tiny
TURBO3052002
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Can you tell me what this is? I have my finger on it.
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Sunday, March 25th, 2018 AT 3:43 PM
Tiny
TURBO3052002
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Engine coolant sensor.
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Sunday, March 25th, 2018 AT 4:39 PM
Tiny
TURBO3052002
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  • 18 POSTS
Map sensor.
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Sunday, March 25th, 2018 AT 4:40 PM
Tiny
TURBO3052002
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  • 18 POSTS
Maf sensor.
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Sunday, March 25th, 2018 AT 4:41 PM
Tiny
TURBO3052002
  • MEMBER
  • 18 POSTS
This sensor does not have any voltage coming from the computer. We suspect is the intake temperature sensor.
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Sunday, March 25th, 2018 AT 4:42 PM
Tiny
TURBO3052002
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TPS is new and under where my finger is on.
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Sunday, March 25th, 2018 AT 4:44 PM
Tiny
TURBO3052002
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This is the computer. Also, most of our diagnostics are being done with an Android app. The app is called torque.
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Sunday, March 25th, 2018 AT 4:48 PM
Tiny
HARRY P
  • MECHANIC
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The thing in the first image is your EGR valve. Not likely your issue, but it is never a bad idea to take it off and clean the pintle/valve part with some carburetor cleaner, making sure it can move in and out freely and smoothly. I am familiar with Torque. It is a pretty decent app. Since it does have live data, get those temperature readings and we will go from there.

As far as the IAT sensor, how did you test it exactly? Did you ground your multi-meter to the negative battery cable and then look for the reference voltage with the key on, engine running (KOER)? I am attaching ProDemand's information on the IAT in the images below.
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Sunday, March 25th, 2018 AT 7:02 PM
Tiny
TURBO3052002
  • MEMBER
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On the intake air temperature sensor we had zero reference when he tried to crank it it might have come up 2.3 batteries low though.
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Monday, March 26th, 2018 AT 4:12 PM
Tiny
HARRY P
  • MECHANIC
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If you are absolutely sure that there is 0 reference voltage to the IAT, then start inspecting the wiring to it for burns and cracking and such things. The wire or the connector is likely the culprit.
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Monday, March 26th, 2018 AT 6:54 PM
Tiny
TURBO3052002
  • MEMBER
  • 18 POSTS
We checked the fuel pressure it was key on at 65lbs. Dropped to 57lbs while idling. Both six and four cylinder trucks, neighbor is s10 4 cylinder, both MAF read 0. Torque said fuel Flow of.3 gallons a hour. 15.8cc per minute, we do not know why it is that. Our two codes are still there P0102 P0117. We are debating on whether it is the computer and looking for either a new or junkyard one.
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Tuesday, March 27th, 2018 AT 5:25 PM
Tiny
HARRY P
  • MECHANIC
  • 2,293 POSTS
With the key on, and engine off, you should get at least 60psi, so you are good there. Running pressure is always lower than not running. If you are not seeing an signal voltage from the MAF using torque, you can back that up with manually checking voltage output with a multi-meter. If you get a reading there, and no reading at the PCM, you will need to inspect wiring for shorts, loose connections, etc.
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Tuesday, March 27th, 2018 AT 6:42 PM
Tiny
HARRY P
  • MECHANIC
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Since you have a fuel pressure tester, run a bleed down test. Basically, you will check the pressure like you did, then turn the key off and see how it drops. If it drops more than *I think* 10psi in five minutes, then you likely have a bad spider injector or fuel injectors (not sure which you have in your truck), which would cause the truck to run bad and not necessarily throw codes.
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Tuesday, March 27th, 2018 AT 6:47 PM

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