Trying to understand a SES Code and why?
Thread Starter
Instructor
Joined: Apr 2009
Posts: 213
Likes: 0
From: Tulsa Oklahoma Area
Trying to understand a SES Code and why?
Ok, i am throwing codes 15,22,32 in a 89 stock L98. Here is my question? FYI i have just put new fich injectors, plug wires, plugs, dizzy bug/cap etc...
What i don't understand and would like someone to explain is why would these 3 codes being thrown allow the vehicle to run perfect untill it appear to have warmed up. When it warms up it acts like it fattens up and runs like crap below about 1800 rpm. I don't understand how these 3 codes affect anything at a warm idle and not a cold idle, but yet allows the car to run fine at WOT from a stop up through the rpm range but when parked and idling once warmed up is barely able to keep itself running.
I am just trying to gain understanding on how these codes can cause this it doesn't make sense that a (tps /coolant /egr code) could create this kind of issue. i am just trying to further understand the relationship which will help me understand (open / closed loop) in the computer better i hope.
I just like to understand what and why i am fixing something, i am from old school rods and this vette just boggles my mind at times.....
I am thanking you in advance and i know someone can explain the relationship between these 3 codes....
What i don't understand and would like someone to explain is why would these 3 codes being thrown allow the vehicle to run perfect untill it appear to have warmed up. When it warms up it acts like it fattens up and runs like crap below about 1800 rpm. I don't understand how these 3 codes affect anything at a warm idle and not a cold idle, but yet allows the car to run fine at WOT from a stop up through the rpm range but when parked and idling once warmed up is barely able to keep itself running.
I am just trying to gain understanding on how these codes can cause this it doesn't make sense that a (tps /coolant /egr code) could create this kind of issue. i am just trying to further understand the relationship which will help me understand (open / closed loop) in the computer better i hope.
I just like to understand what and why i am fixing something, i am from old school rods and this vette just boggles my mind at times.....
I am thanking you in advance and i know someone can explain the relationship between these 3 codes....
Last edited by dry; Jun 5, 2009 at 01:05 PM. Reason: spell
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
CTS (15) and TPS (22) share a ground with the MAT. I'd guess that it's open - maybe you damaged the harness when you swapped injectors? The 32 means that the EGR Temp Switch didn't ground when EGR was commanded (cruise only) or it was grounded at startup. With it running like crap, I'd suspect a vacuum leak or broken vacuum line at the EGR solenoid, again, damaged or broken when you did your injector swap.
Thread Starter
Instructor
Joined: Apr 2009
Posts: 213
Likes: 0
From: Tulsa Oklahoma Area
Thanks!
Ok, but wouldn't a vacuum leak cause it to run bad from cold thru warm cycle not just when the motor warms up? What did you mean by the shared MAF ground? do any of these codes create a richening condition when warmed up or in a closed loop mode when warm?
Ok, but wouldn't a vacuum leak cause it to run bad from cold thru warm cycle not just when the motor warms up? What did you mean by the shared MAF ground? do any of these codes create a richening condition when warmed up or in a closed loop mode when warm?
Team Owner
Joined: Sep 2001
Posts: 62,137
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
The ECM really only reads the CTS and TPS in open loop, and some preprogrammed tables, and in closed loop it pays attention to everything. At WOT you are in open loop mode, not closed. So if it runs fine after startup and at full throttle, but doesn't idle well or run well at part throttle when warm, theres something thats being read differently in closed loop.
The CTS and TPS ground in the same place the MAT sensor does, he is not talking about the MAF sensor.
Vac leaks would affect total operation, but the symptom may not show until it drops into closed loop and programs air/fuel based on the O2 and MAF sensor readings in addition.
Rule of thumb is to fix the code from the front of the motor first. I would go for the CTS, then clear codes and see what comes back, then the TPS. With luck the EGR may just be a glitch based off those two codes, and it may not come back.
The CTS and TPS ground in the same place the MAT sensor does, he is not talking about the MAF sensor.
Vac leaks would affect total operation, but the symptom may not show until it drops into closed loop and programs air/fuel based on the O2 and MAF sensor readings in addition.
Rule of thumb is to fix the code from the front of the motor first. I would go for the CTS, then clear codes and see what comes back, then the TPS. With luck the EGR may just be a glitch based off those two codes, and it may not come back.
Thread Starter
Instructor
Joined: Apr 2009
Posts: 213
Likes: 0
From: Tulsa Oklahoma Area
Thanks make a little more sense now, I think i will check out the TPS and CTS and make sure they are both correct or repaired.
One more thing once the injectors were replaced upon start up the car idled at 1400 rpm and and wouldn't back down even once warmed up or relearned so i adjusted the throttle stop torx screw down to 750 rpm should i put it back to 1400 rpm where it was running once injectors were replaced? before injectors replaced it was at 750 rpm but they were leaking badly.....
One more thing once the injectors were replaced upon start up the car idled at 1400 rpm and and wouldn't back down even once warmed up or relearned so i adjusted the throttle stop torx screw down to 750 rpm should i put it back to 1400 rpm where it was running once injectors were replaced? before injectors replaced it was at 750 rpm but they were leaking badly.....
Team Owner
Joined: Sep 2001
Posts: 62,137
Likes: 1,727
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Correct idle is about 750. Fix the codes and see if it changes itself somehow, maybe the TPS is just bad.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
The screw is only used to set Minimum Idle so you're going to have to reset it. Ground the diagnostic link and turn on the key. When the IAC motor stops running, disconnect it. Start the car. If it won't start or idle, turn the screw to open the butterfly. Adjust it until it idles at 450 rpms. Turn it off, unground the link and reconnect the harness. Adjust TPS voltage to .54 volts +/- .8 volts. Restart with the accelerator slightly depressed. Let it run for 10 seconds. Off for 5 seconds. Restart should be +/- 100 rpms from Targeted in Park/Neutral; 50 +/- Targeted in Drive. If you don't have a scanner, you'll have to guess.
Above may/should clear the 22 as turning the screw the way you did could have easily whacked out the idle signal from the TPS.
Fix the 15 and then troubleshoot the 32.
Above may/should clear the 22 as turning the screw the way you did could have easily whacked out the idle signal from the TPS.
Fix the 15 and then troubleshoot the 32.
Team Owner
Joined: Jan 2003
Posts: 20,297
Likes: 240
From: Summerland B.C. Canada
If you mess with the minimum idle screw, you mess with the TPS setting. I'll assume that's why you got the TPS code.
Reset the TPS to .54v +/- .075v, then follow the procedure to set minimum idle, then reset the TPS again.
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Reset the TPS to .54v +/- .075v, then follow the procedure to set minimum idle, then reset the TPS again.
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
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