soulless_mudvayne Posted December 26, 2007 Report Share Posted December 26, 2007 Hey guys. I'm new here and found the info on here pretty helpful but i havent found anything with my specific problem... i hope you can help. I have a 93 Cadillac deVille with the 4.9 v8...Friday as i was coming home from work, the car started acting like it had a bad set of plugs and my SES light came on, error code E26 "shorted throttle switch signal". I'm not exactly car literate, but i can piddle and paddle around a bit with them. I've talked to a few different people about it, and i've heard everything from trying to replace the throttle position sensor to buying a new ECM I did replace the TPS and the problem has eased up slightly i.e. i can make it down my driveway without starting the car 10 times but it's still acting like it has a bad set of plugs...Checked the distributor cap and everything, no track marks or anything out of the ordinary, all 8 cylinders are firing properly. I cleared the codes Saturday night and drove it Tuesday, no codes yet but still acting the same. Any help before i get out my 12-gauge? Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 26, 2007 Report Share Posted December 26, 2007 Using an ohm meter, check each ignition wire's resistence and record it, post the results here. Did you pull the plugs and have a look at condition (carbon tracking, cracking, electrode wear, bridging) and gap? CLEARLY explain what you mean by, "the car started acting like it had a bad set of plugs" How did you determine that all 8 cylinders are firing properly?, an engine oscilliscope? When you replaced the TPS, did you adjust it according to the manual? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Ranger Posted December 26, 2007 Report Share Posted December 26, 2007 Also try rodding out the two EGR tubes down in the TB. How about the ISC (Idle Speed Control) motor? Do you hear it ratchet when you shut down and does the gas pedal also ratchet (click). Link to comment Share on other sites More sharing options...
soulless_mudvayne Posted December 28, 2007 Author Report Share Posted December 28, 2007 Adjusting the tps... maybe that's what i didnt do. My Chilton's manual says to do that, but its not exactly clear on how you go about doing it. It says to enter the diagnostics and select pcm override ps103, but i have no idea how to do that. Is this something i can access through the climate control panel, like how you view the PCM codes? and i guess i shouldnt say it's acting like it has a bad set of plugs... I have high idle when the car first starts and then it calms down, but when im driving down the road i pretty much have to stomp my accelerator to get any decent power out of it. the plugs are fine, i just replaced them about two months ago, and each one looks brand new. Gaps are .050 as they should be,no tracks, cracks, etc. and i checked to see if the cylinders were firing by putting my hand down where the spark plugs go into each individual one good way to cook yourself, i know, but i have no specialty tools. I guess my first option is to access the pcm override since i didnt do that... how do i go about getting to it? And I'll have to get my roommate's multimeter when he gets back from vacation tomorrow, ill post the ohm readings as soon as i can. Thanks for being patient with me, guys Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 29, 2007 Report Share Posted December 29, 2007 Adjusting the tps... maybe that's what i didnt do. My Chilton's manual says to do that, but its not exactly clear on how you go about doing it. It says to enter the diagnostics and select pcm override ps103, but i have no idea how to do that. Is this something i can access through the climate control panel, like how you view the PCM codes? and i guess i shouldnt say it's acting like it has a bad set of plugs... I have high idle when the car first starts and then it calms down, but when im driving down the road i pretty much have to stomp my accelerator to get any decent power out of it. the plugs are fine, i just replaced them about two months ago, and each one looks brand new. Gaps are .050 as they should be,no tracks, cracks, etc. and i checked to see if the cylinders were firing by putting my hand down where the spark plugs go into each individual one good way to cook yourself, i know, but i have no specialty tools. I guess my first option is to access the pcm override since i didnt do that... how do i go about getting to it? And I'll have to get my roommate's multimeter when he gets back from vacation tomorrow, ill post the ohm readings as soon as i can. Thanks for being patient with me, guys Yes, I have the procedure in my desktop computer and its sitting in the corner unplugged. But the procedure involves the minimum air adjustment, a 500 rpm idle and adjusting the tps via the DIC readout. <<<that is NOT the procedure, just my recollection and I could be confusing the TPS adjustment with the ISC adjustment, but the TPS is adjusted with the help of a value in the DIC. If someone does not post it, I will hook up my scanner to my laptop and scan the relevent pages for you. Have you used the DIC overrides and monitored values? Do you have the DIC chart for you car?, showing how to navigate the screens? We have that chart to navigate the DIC also, if you need it, maybe someone can post that... I can't wait to get my network back up, I am missing my desktop and the resources in it. PLEASE PLEASE PLEASE, DO NOT check the spark that way again, you can purchase an inexpensive device, these coils are putting out 40,000 volts (I can't be patient with that diagnostic "technique" ). And besides that, I doubt you can tell the difference between 10,000 volts and 30,000 volts by the shock value . Don't ever disconnect the ignition wire from either end and let it spray high voltage to ground you will kill electronics. You would be amazed how incredibly powerful and loud the spark is, if you saw it jumping around looking for a ground, the arcs are 4 to 5 inches long (don't ask me how I know this it involves my x wifes car). The 4.9 has a single coil HEI ignition but it still packs a punch. Cool, post the ignition wire resistence. See the spark tester here, please spend $5.00 <a href="http://www.thetoolwarehouse.net/shop/LIS-50850.html" target="_blank">http://www.thetoolwarehouse.net/shop/LIS-50850.html</a> Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
soulless_mudvayne Posted December 29, 2007 Author Report Share Posted December 29, 2007 No, no no no no no no hahaha I didnt mean i touched the spark plugs with the engine running with bare hands, or i wouldnt be sitting here writing this. I just let the engine run for about three minutes with the spark plugs installed and felt the cylinder to see if it was hot or cold. Anyone with half a brain knows not to touch spark plugs with them hooked up sorry about the confusion. But yeah, this is no huge rush, im driving my girlfriend's Volkswagen to work right now. Kinda miss the ride and all the neat gadgets, but i can wait if it means i dont have to take a trip anywhere in the car itself... i dont know if the problem will get worse or not, but i dont wanna risk it. Thanks --edit no, i dont have any info on how to navigate the DIC interface. my chilton's manual just tells me how to get into it to read codes, i have no idea how to do anything else Link to comment Share on other sites More sharing options...
Ranger Posted December 29, 2007 Report Share Posted December 29, 2007 error code E26 "shorted throttle switch signal". I think that switch is in the ISC motor. Adjusting the tps... maybe that's what i didnt do. I didn't think there was an adjustment to the TPS. I was talking about adjusting the ISC motor. when im driving down the road i pretty much have to stomp my accelerator to get any decent power out of it. Someone correct me if I am wrong, but I seem to recall our old Guru saying that a bad TPS acts much like a bad accelerator pump on a carb, similar to the above quote. Have you checked and/or rodded out the EGR tubes? Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 29, 2007 Report Share Posted December 29, 2007 No, no no no no no no hahaha I didnt mean i touched the spark plugs with the engine running with bare hands, or i wouldnt be sitting here writing this. I just let the engine run for about three minutes with the spark plugs installed and felt the cylinder to see if it was hot or cold. Anyone with half a brain knows not to touch spark plugs with them hooked up sorry about the confusion. But yeah, this is no huge rush, im driving my girlfriend's Volkswagen to work right now. Kinda miss the ride and all the neat gadgets, but i can wait if it means i dont have to take a trip anywhere in the car itself... i dont know if the problem will get worse or not, but i dont wanna risk it. Thanks Hey I take nothing for granted.... keep in mind that you DID say this > "i checked to see if the cylinders were firing by putting my hand down where the spark plugs go into each individual one good way to cook yourself, i know" That did not sound like you were feeling for heat to me I am thinking cook yourself with sparks, Let us know what you find, my guess is its a bad ignition wire. Your DIC has some VERY cool diagnotic overrides, you can test the injectors with it doing a powerbalance test. I will post lots of good stuff tomorrow morning while I am having coffee.. Mike Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
soulless_mudvayne Posted December 29, 2007 Author Report Share Posted December 29, 2007 My bad, i meant the ISC not TPS. I didnt think about checking out the EGR, i'll do that tomorrow. I only changed my TPS because of advice from a friend of mine... as i said, i can do small things with cars, but other than changing fluids im at a complete loss. My father did not see fit to bestow his extensive knowledge of cars upon me so im learning as i go id take it to a mechanic, but im short on cash and besides, id rather fool with my car and learn than take it somewhere and have some unknown being tinkering with it and learn squat. Thanks guys, ya'll are awesome, i love this forum Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 29, 2007 Report Share Posted December 29, 2007 error code E26 "shorted throttle switch signal". I think that switch is in the ISC motor. Adjusting the tps... maybe that's what i didnt do. I didn't think there was an adjustment to the TPS. I was talking about adjusting the ISC motor. when im driving down the road i pretty much have to stomp my accelerator to get any decent power out of it. Someone correct me if I am wrong, but I seem to recall our old Guru saying that a bad TPS acts much like a bad accelerator pump on a carb, similar to the above quote. Have you checked and/or rodded out the EGR tubes? I think he said he replaced the TPS, he said this "I did replace the TPS and the problem has eased up slightly", but he didnt adjust it, if it were not adjusted properly it might give him a lag. I had to adjust my TPS when I replaced mine. The TPS was the first thing I had go bad, I was dazzled by the DIC and what it could do. I also think the PCM utilizes the TPS signal to shift the tranny, if downshifting were not occuring he would bog also. But yes, the ISC can be adjusted also Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
adallak Posted December 29, 2007 Report Share Posted December 29, 2007 My bad, i meant the ISC not TPS. I didnt think about checking out the EGR, i'll do that tomorrow. I only changed my TPS because of advice from a friend of mine... as i said, i can do small things with cars, but other than changing fluids im at a complete loss. My father did not see fit to bestow his extensive knowledge of cars upon me so im learning as i go id take it to a mechanic, but im short on cash and besides, id rather fool with my car and learn than take it somewhere and have some unknown being tinkering with it and learn squat. Thanks guys, ya'll are awesome, i love this forum You are moving in right direction. If you want to keep the car and learn fxing small stuff indepenedently, get a factory service manual FSM (not Chilton) on eBay. They are very cheap and I see them on eBay all the time. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
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