LT4 Service engine soon question
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 871
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From: Union KY
LT4 Service engine soon question
Last night about five miles after filling up, I noticed some very minor engine roughness. Just then the Check Engine Soon light came on (in the non flashing mode). Withing a few minutes, the roughness went away, but the light stayed on. This morning it's stil burning. Here's the question, will the light go out if the trouble that made it come on initially clears up ... Or does the fact that it continues to burn mean that there is a continuing emissions problem? Thanks.
Cire96 :confused:
Cire96 :confused:
Le Mans Master
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From: Moving forward, in reverse.
Re: LT4 Service engine soon question (cire96)
Since the light has stayed on it set a "hard code" in the system. The problem may have resolved itself, but you need to pull codes to see what malfunctioned & reset basic settings. If it happens again you need to replace the culprit part. Hope this helps.
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 871
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From: Union KY
Re: LT4 Service engine soon question (96 LTRex-4)
Rex:
After i pull the code, can the clearing function be accomplished by disconnecting the negative battery cable, or is there a direct method to clear the code?
Cire 96
After i pull the code, can the clearing function be accomplished by disconnecting the negative battery cable, or is there a direct method to clear the code?
Cire 96
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Re: LT4 Service engine soon question (cire96)
yeah you have to disconnect the negative terminal for about a minute, and the code will clear
just make sure you get the code out
just make sure you get the code out
Le Mans Master
Joined: Jun 2002
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From: Moving forward, in reverse.
Re: LT4 Service engine soon question (cire96)
That is correct about the negative terminal. Disconnect it for 2-5 minutes. If the light stays on the next way to reset settings is with a GM type scan tool. Otherwise the component probably needs to be replaced. What code did you pull?
Safety Car
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From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Re: LT4 Service engine soon question (96 LTRex-4)
You do not need to disconnect the battery to extinquish the SES light. My suggestion is to do nothing for a few days and see if it goes out by itself. I had a similar event last year and the light went away after 2-3 days. It had a misfire at WOT and the SES light came on. I changed the plug wires as I determined they were bad.
If the SES light is flashing, it means the code is currently being thrown by the problem. But if the light is constant, then the problem is not currently active but happened recently and is stored in the ECM history. If the problem does not happen again, the SES light will go out by itself within a few days. It actual depends on the number of cycle, which I don't have the details here at work.
If you disconnect the battery, you will loose all the history codes stored in the computer making it impossible for a technician to examine history trying to resolve the problem if it does not go away.
The SES generally means something is out of spec in the emission control system, so if the engine is running fine, the situations may have only been a single event, and probably it will go out in a few days.
If the SES light is flashing, it means the code is currently being thrown by the problem. But if the light is constant, then the problem is not currently active but happened recently and is stored in the ECM history. If the problem does not happen again, the SES light will go out by itself within a few days. It actual depends on the number of cycle, which I don't have the details here at work.
If you disconnect the battery, you will loose all the history codes stored in the computer making it impossible for a technician to examine history trying to resolve the problem if it does not go away.
The SES generally means something is out of spec in the emission control system, so if the engine is running fine, the situations may have only been a single event, and probably it will go out in a few days.
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 871
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From: Union KY
Re: LT4 Service engine soon question (96 LTRex-4)
Rex:
I haven't pulled them yet. It was late when I got home and this morning all there was time to do was fire it up to see if was still there.
Cire96
I haven't pulled them yet. It was late when I got home and this morning all there was time to do was fire it up to see if was still there.
Cire96
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Melting Slicks
Joined: May 2001
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From: San Diego CA
Re: LT4 Service engine soon question (cire96)
I keep a big fat paperclip in the console for just this purpose. It takes about 2 minutes to pull the codes. It takes longer to find the codes in the manual.
Melting Slicks
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From: NW Chicago Suburbs
Re: LT4 Service engine soon question (John Row)
I keep a big fat paperclip in the console for just this purpose....
Eric
Thread Starter
Burning Brakes
Joined: Feb 2002
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From: Union KY
Re: LT4 Service engine soon question (cire96)
Thanks to all for your usual great assistance. The codes were 101 and 108. Both relate to the MAF sensor. We cleared the computer and after fifteen miles and three restarts, all is okay.
After determining the codes, I think I may know the cause... Last weekend I pulled the K&N filter and cleaned it. When I reinstaled it, I disconnected the drain line that comes off the drivers side of the "snorkel" that reduces the air cleaner frame down to the diameter of the MAF collar. I had neglected to reconnect it and did notice it last night (and reconnected it). I suspect that opening allowed some unfiltered particles to enter, where it might have boogered the MAF's sensor wires. Anyone have thoughts on that theory?
Cire96 :confused:
After determining the codes, I think I may know the cause... Last weekend I pulled the K&N filter and cleaned it. When I reinstaled it, I disconnected the drain line that comes off the drivers side of the "snorkel" that reduces the air cleaner frame down to the diameter of the MAF collar. I had neglected to reconnect it and did notice it last night (and reconnected it). I suspect that opening allowed some unfiltered particles to enter, where it might have boogered the MAF's sensor wires. Anyone have thoughts on that theory?
Cire96 :confused:
Team Owner
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Re: LT4 Service engine soon question (cire96)
Have you had any rough driving problems since you got the codes out?
MAF is serious if there is anything really wrong with it.
Also if you over oiled the K&N, that would screw up the MAF.
MAF is serious if there is anything really wrong with it.
Also if you over oiled the K&N, that would screw up the MAF.
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 871
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From: Union KY
Re: LT4 Service engine soon question (vader86)
vader:
Seting aside the paranoia one has whenever your car hiccups, I think it's run fine since the few miles of very minor rough running I experienced last night. That having been said, I worry that if I got some particle of yuck lodged in the MAF sensors wires, it might not self correct. What do you think?
Cire96
Seting aside the paranoia one has whenever your car hiccups, I think it's run fine since the few miles of very minor rough running I experienced last night. That having been said, I worry that if I got some particle of yuck lodged in the MAF sensors wires, it might not self correct. What do you think?
Cire96
Burning Brakes
Joined: Jun 2001
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From: Out by the bridge again, TampaBay
Re: LT4 Service engine soon question (fullboogie)
If you've overoiled the filter, take the MAF out of the car and spray the sensor wires with brake cleaner.
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 871
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From: Union KY
Re: LT4 Service engine soon question (Half Fast)
After I arrived home last might, the SES light was back on! I disconnected the battery to clear the codes and then pulled the MAF sensor. I took good look at the sensor wires. They looked very clean with no visible debris to be found anywhere inside the MAF's body.
On the outside of the MAF's screen however, there were several particles of loose debris. I used an air hose to blow them out (backwards) and reinstalled the MAF. So far so good. The light stayed out on the ten mile run to work and the car was smooth as ever. Unfortunately the brake cleaner idea reached me after this process. If the problem reoccurs, I'll take that route next. Thanks to all (again),Cire96 :cheers:
On the outside of the MAF's screen however, there were several particles of loose debris. I used an air hose to blow them out (backwards) and reinstalled the MAF. So far so good. The light stayed out on the ten mile run to work and the car was smooth as ever. Unfortunately the brake cleaner idea reached me after this process. If the problem reoccurs, I'll take that route next. Thanks to all (again),Cire96 :cheers:
Le Mans Master
Joined: Jun 2002
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From: Moving forward, in reverse.
Re: LT4 Service engine soon question (cire96)
I agree with the crew here. Sounds like oil in the MAF. Try the brake clener & let us know. Those MAF units are very sensitive.
