SES Light
Printed From: West Coast Fieros
Category: Technical Topics Forum
Forum Name: Technical Questions and Discussions
Forum Description: Got a technical question about your fiero? ask it here.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=2498
Printed Date: 25 April 2025 at 7:28am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: SES Light
Posted By: orange
Subject: SES Light
Date Posted: 07 June 2011 at 10:03pm
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So my 4.9 swapped 86 gt is giving me some weird annoyances. When i
start the car, no matter what situation, after the idle starts going down so maybe 20-30 seconds after start, i get an ses light and exactly when it comes on the idle raises about 75 or 100 rpms... its strange. When i try checking codes the ses light turns off the very second i plug in the aldl connector to the computer... so i cant read the code. Also it seems to run better on open loop, and when it is in closed loop it feels like someone retarded the timing a couple degrees, just a very slight loss of power, hardly noticeable though. Also when its cold...ish (half or less operating temp) there is a dramatic loos of power when in top gear and WOT, while in 4th you can floor it and then start letting off a big and you feel it accelerating more and more the less your in the throttle, it seems like half throttle is quickest, clutch slippage? non heated o2 fail? ive got nothing. Help would be nice.  ------------- Orange 4.9 |
Replies:
Posted By: Romeo
Date Posted: 08 June 2011 at 10:00pm
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Could also be a fuel issue (If the fuel can't keep up with the air, it'll make more power at mid-throttle than at full) or a MAF fault (If it gets covered in oil, it wont read the air rushing past, and more air will only over-richen the mixture). This could be a fun one to figure out. ------------- Never shift into reverse without a back-up plan. |
Posted By: orange
Date Posted: 10 June 2011 at 12:29am
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I though it was fuel too, but i have above 40psi at any rpm under any load.
And i dont have a MAF i have a MAP, if that changes your thoughts. and remember it only does it when coldish ------------- Orange 4.9 |
Posted By: Romeo
Date Posted: 10 June 2011 at 10:14pm
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Well, cold air is more dense, and will cool a MAF quicker, but obvious that whole theory goes to hell if you don't have one. Back on topic though, I think it's safe to say the fault is a sensor related one, not a mechanical one (So I doubt it's clutch slippage), due to the fact the fault "resolves" itself when in open-loop. Forgive me, it's been a while since I've used a ALDL scan-tool, but can you look at sensor voltages with it? If so, keep them open, and check your readings at various loads. ------------- Never shift into reverse without a back-up plan. |
Posted By: Bassman
Date Posted: 11 June 2011 at 8:22am
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I am concsidering this polisher (kit) until my trans blew up...may take a trip South and pick it up. http://www.griotsgarage.com/product/car+care/car+polishing/orbitals+and+car+polishing+tools/griot%27s+garage+random+orbital.do - http://www.griotsgarage.com/product/car+care/car+polishing/o rbitals+and+car+polishing+tools/griot%27s+garage+random+orbi tal.do ------------- Brian (Bassman) 86 GT Fastback 3.2L 2013 Mazda3 Sport GS SkyActive [IMG]http://i170.photobucket.com/albums/u243/Bassman68/BassmanSignature.png"> |
Posted By: orange
Date Posted: 11 June 2011 at 11:33pm
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Yes i can read almost all sensors, i just dont know what to look for. ------------- Orange 4.9 |
Posted By: Romeo
Date Posted: 12 June 2011 at 12:00am
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Anything that doesn't make sense under the condition. As throttle gets opened more, MAP should increase, injector pulse should increase, oxygen sensor should go up and stay up (At WOT). Easiest bet to start with would be to check the O2 readings and see what's going on when you step on it (Is it leaning out? Puking fuel?) ------------- Never shift into reverse without a back-up plan. |
Posted By: orange
Date Posted: 12 June 2011 at 12:29pm
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Ok ill do some tests, i though it might be a funny o2 but its brand new and
acdelco, when i blip the throttle sometime it states lean for the second i hit the gas. Ill get back with some tests though ------------- Orange 4.9 |
Posted By: orange
Date Posted: 13 June 2011 at 12:33am
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Ok so no data yet, i tore the engine apart and such. And made an interesting
discovery, all except 2 or my exhaust valve stems are white, but the back side of the valve is dark brown black. I know white valves are either lean, race gas, or fuel additives, but mine are just white stems. and my spark plugs looked normal but most or the cores were a light grey maybe white, and the two cylinders that didnt have white exhaust valve stems had black plugs. Any thoughts? ------------- Orange 4.9 |
Posted By: Romeo
Date Posted: 13 June 2011 at 8:23am
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Well, it could be that you're burning oil in the two, which the O2 is seeing as rich, and is consequently leaning out the other cylinders. Could also be something alot simpler that I haven't thought of yet. lol ------------- Never shift into reverse without a back-up plan. |