| CEL | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: CEL Tue Jul 20, 2010 9:40 am | |
| I'm posting this up for guesses My new 95 is trying to alert me to a problem When I'm driving with my foot in the throttle the CEL comes on. This is not EVERY time but pretty consistent. When I drive normally it turns on randomly but usually pretty consistent 70% of the time When I get off it & drive normally the CEL turns off 90% of the time When I throttle down & / or idle it turns off 100% of the time. I know the PCM's been tuned & it wasnt by Alex because it isnt set up like he does. I havent gone through the tuneup items yet because it runs pretty good. I know I'm giving you nothing to work with here, but I'd like to hear some guesses. Last time I had a quiz like this Bill M got it right on the 1st guess & in record time 38 minutes so I decided to make it tougher | |
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Pooge
Posts : 1700 Join date : 2009-03-24
| Subject: Re: CEL Tue Jul 20, 2010 10:00 am | |
| My first guess would be Throttle Position sensor since it seems to be directly related to how much throttle you give it.
That being said, I suck at troubleshooting
Doug | |
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bammax
Posts : 2301 Join date : 2009-02-22 Age : 42 Location : Mansfield, Ma
| Subject: Re: CEL Tue Jul 20, 2010 2:36 pm | |
| Of course you'll check it for codes before you start throwing money at it so it's ok to guess Since it's tied into the throttle yet the car still runs well I'd suspect it's a bad sensor that relates to reading the cars current peramiters. I'd rule out o2's since those wouldn't be as specific to throttle. Some sensors would trigger a limp mode response which rules out a few. I'd think a bad tps would cause poor running characteristics which rules that out. My guess is the iat or maf is lazy and not keeping up with the actual airflow characteristics. That would create an odd lean curve everytime the throttle gets going since the fuel isn't being applied based on the actual airflow numbers. That would cause a cel at the o2 since the air/fuel would be off, and it would also fix itself when the throttle is released as the air flow would be reduced to bring the mixture back to a level point. Of course my first test would be all the vaccuum lines since those are cheap and easy and can cause all kinds of problems when they come loose or crack | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Tue Jul 20, 2010 2:47 pm | |
| Next clue. It'll only do this under load. I can hold the pedal at 2k-3k rpm & no CEL | |
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bammax
Posts : 2301 Join date : 2009-02-22 Age : 42 Location : Mansfield, Ma
| Subject: Re: CEL Tue Jul 20, 2010 3:06 pm | |
| It's either based on throttle position which is air/fuel related, or it's based on rpm which would lead to suspecting other sensors or possibly the opti. Maybe a loose cel bulb socket that grounds out whenever the car leans back on a hard launch | |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Tue Jul 20, 2010 4:30 pm | |
| why don't you just scan for the code ?
my guess code 44 O2's lean | |
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jvette65
Posts : 111 Join date : 2010-02-16
| Subject: Re: CEL Tue Jul 20, 2010 4:39 pm | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Tue Jul 20, 2010 5:37 pm | |
| No scanner Usually just run by my friends shop I've only had 2 or 3 CELS in my B-Body history Next clue: I can almost turn the CEL on & off with my A/C as soon as I put it on 5 seconds on comes the CEL This is not the ONLY time, it does it with my foot in the throttle etc as described before | |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Tue Jul 20, 2010 5:54 pm | |
| change the fuel filter & check fuel pressure | |
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Guest Guest
| Subject: Re: CEL Tue Jul 20, 2010 5:54 pm | |
| First off if you take it to auto zone, they will scan the codes for free. In the mean time, I would chech your secondary fan (drivers side) to make sure it is working. It should automaticly come on when the a/c is on at stop or lower speeds. Or to confirm it's operation, you can disconnect the temp sensor on the water pump. Disconnecting it will cause the pcm to default to both fans on, and will throw a code, but it will comfirm operation of both fans. Just remember to plug it back in. Also could be a gross evap leak that is not seen by the pcm until load is put on the engine. Get the codes pulled and we can put you in the right direction. |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Tue Jul 20, 2010 6:24 pm | |
| Started it up Both fans on. Driverside turned off. A/C on fan running. Didnt pull temp sensor Pushed EGR diaphram stalled quick. Restart, push egr bog & release Unplu TPS CEL on no change at idle Unplug IAC no CEL no change in idle PVC looks like its been living there a long time Plugs & wires (although no indication of problems) may be old as well OPTI no clue. This isnt a firing thing, this is an under load..sensor says problem thing Under no load A/C doesnt set CEL. A/C works great. CEL doesnt come on period. I'll get the codes read. Do they have a plug in reader at AZ? I've heard of then poking around with paperclips & frying PCM's AZ is in my backyard at work. My friends garage couple of towns over. | |
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GasTT
Posts : 2675 Join date : 2009-01-19 Age : 36 Location : Treasure Coast, FL
| Subject: Re: CEL Tue Jul 20, 2010 6:28 pm | |
| AZ will only scan a '96+ car (obd2) and they will not clear it for you either. | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Tue Jul 20, 2010 7:16 pm | |
| So what are the options for a 95 Are there any scanners that are worth buying? I'm not paniced here, the car is running fine I'm thinking Bobby is right with the O2's or lean bank (although I cant here any exhaust leaks) OK googleing readers
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Guest Guest
| Subject: Re: CEL Tue Jul 20, 2010 7:33 pm | |
| I would just have your friend scan for codes and take it from there. Could be a lean condition under load. |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Tue Jul 20, 2010 7:34 pm | |
| Datamaster and a cable FTW
http://www.ttspowersystems.com/DataMaster_downloads2.html | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Tue Jul 20, 2010 8:02 pm | |
| Guess I shoulda bought a cable before TTS stopped making them Who sells them now? any idea Whats with that paperclip trick & flashing codes? Wish that would work | |
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Guest Guest
| Subject: Re: CEL Tue Jul 20, 2010 8:11 pm | |
| - sdstick wrote:
- Guess I shoulda bought a cable before TTS stopped making them
Who sells them now? any idea Whats with that paperclip trick & flashing codes? Wish that would work http://pcmperformance.com/ http://pcmperformance.com/cables.html |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Tue Jul 20, 2010 8:12 pm | |
| paperclip trick will not work on are cars. if you have a hypertech programmer I have a cable that uses half of the hypertech cable that I don't use
http://www.pcmperformance.com/cables.html
http://www.akmcables.com/ic.htm | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Tue Jul 20, 2010 8:26 pm | |
| I have the hypertech for obd2 sitting brand new in a box (came with the car) Think I'll have my buddy scan it THEN I'll look into the cables when I'm not in impulse buy mode. Thanks all for your help, I need to do some site work tomorrow so I'll try to get answers Thursday. | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Wed Jul 21, 2010 2:56 pm | |
| Exhaust is Frankenstien, for 2-1/4 (from cats ) to 2-1/2 (muffler in & out) 2-1/4 (over axle) to 2-1/2 (tailpipes) back & forth. Matt loved the sound but I'm too old for that note (unless its at WOT) This was my 1st tankful of 87 octane. Car didnt seem to mind. Not that I could hear it...lol The car has always shifted hard making me to wonder if it had a shift kit. Tranny has had attention I can see it & feel it I installed my old 95 pcm & it shifted nicely (but new 95 has air delete) so I had a CEL & then re-installed the original All of the above made me wonder if the kid had a buddy that programs. Maybe this program is sketchy. Runs good. Thats it, on my way to get it scanned.
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Wed Jul 21, 2010 4:28 pm | |
| you do not need air pump delete in the pcm with 94-95 leave relay and fuse in and just unplug air pump | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Wed Jul 21, 2010 6:19 pm | |
| - mean ss wrote:
- you do not need air pump delete in the pcm with 94-95 leave relay and fuse in and just unplug air pump
The new 95 has all that gone. If I plug a relay & fuse back in I wont get CEL? If that will work I can use my old 95 pcm to trouble shoot this. Thats great info thanks. Scan said tps & knock sensor TPS was replaced when it died a few weeks ago but I never reset the code. I'm assuming this code was left over from the bad tps incident I did unplug the battery for the pcm swap I did but I dont know how long it needs to be unplugged to reset. Reset both & I stomped on it going out of the shop. CEL almost instantly Back in to the scanner only code was knock. Reset & went to get 93 octane gas. Came on before I got there & after. Turning on the A/C still results in a CEL. Thats the one that makes me think its not knocking. Stepping on the throttle aggressively still results in CEL Back to his shop tomorrow. I'll throw it on a lift & see if anything jumps out at me. He may also have some scanner tricks that might help In the meantime please guess away if you have any ideas. | |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Wed Jul 21, 2010 6:42 pm | |
| no CEL with relay and fuse in. I had a new A/C delco TPS bad out of the box but you should check the connector | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Thu Jul 22, 2010 1:56 pm | |
| So this AM I jump in the car & it quickly greets me with the CEL (I'm ignoring it now) 1 quick stop at a convenience store, car idles for 1 minute & off I go Efin thing NEVER CAME ON AGAIN Only things that changed 1) 93 octane last night (drove 20 miles & the CEL was still off & on) So I have a full tank versus empty 2) Cooler this morning then recent days so no A/C but did hit the defog briefly Because it was off I didnt want to flip on the A/C. I know this is wierd but somehow its related. I'm really kicking myself for not checking fuel pressure when Bobby told me to I'll travel with the gauge now to catch it if it happens. I'll also pop in a new filter just because This is my little CEL diary here Lets see what happens this afternoon on the way home. | |
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bammax
Posts : 2301 Join date : 2009-02-22 Age : 42 Location : Mansfield, Ma
| Subject: Re: CEL Thu Jul 22, 2010 7:26 pm | |
| It may have been programmed to run higher octane. If it's set to run 91 and you run 87 then you'll get detonation under heavy throttle which the knock sensor will pick up. That's the reason for the knock code. | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Thu Jul 22, 2010 8:19 pm | |
| Ride home = FAIL CEL came back on. I've got to hook up my fuel pressure gauge & run with it but I dont think thats it Car runs good. I cant explain why the A/C is tied into this, I want to make it heat related but the gauge is not budging from it's under 1/2 position Tomorrow its going on a lift I guess | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Fri Jul 23, 2010 10:16 am | |
| Dear Diary: Today started like yesterday, no CEL. This morning I checked the fuel pressure. 38 prime, 45 run (removed vacuum from regulator) I ran the A/C all the way in no problem I'm leaning toward heat related issues here, even if its the fuel pump not performing as well. If the CEL comes on again I'll check the fuel pressure again. I'll run over my friends place & see what his diagnostic method is. At least I'll pop in a fuel filter & check sensors & wiring | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Fri Jul 23, 2010 3:10 pm | |
| Dear Diary: Put this thread to bed CEL came on at lunch, checked my pressure no change it's fine On my way to my friends shop I threw in some octane boost to rule out gas Light never came on again. Guess it was knocking after all. Why the 93 didnt satisfy it I dont know Reset DTC43 & tried to run diagnostics from his $5K scanner, couldnt retrieve data. I really dont care but WTF? I'm changing the plugs, wires & fuel filter just so I know theyre ok Putting my stock pcm in & sending this one to Alex for a REAL program Funny how I couldnt feel any timing being pulled. Maybe because the light was so intermittent? Dont know? This is the end of my internet diagnostics thread save the applause Thanks for the replies | |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Fri Jul 23, 2010 3:29 pm | |
| FYI Datamaster is free for the first 20 data logs | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Fri Jul 23, 2010 3:32 pm | |
| I'll be all over that now Thanks for helping me out | |
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mean ss
Posts : 648 Join date : 2009-02-25 Age : 66 Location : Nashua NH.
| Subject: Re: CEL Fri Jul 23, 2010 3:38 pm | |
| once you have a cable you can load your tunes yourself no need to send the PCM anywhere | |
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sdstick
Posts : 4292 Join date : 2009-03-20 Location : Revere, MA
| Subject: Re: CEL Fri Jul 23, 2010 9:38 pm | |
| Problem NOT solved. I'm done posting on this until I fix it I thought it was to easy | |
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bammax
Posts : 2301 Join date : 2009-02-22 Age : 42 Location : Mansfield, Ma
| Subject: Re: CEL Fri Jul 23, 2010 11:04 pm | |
| Just throw another pcm in it with a standard program and see what happens. If there's never another problem then you know the issue. | |
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