Check engine light
Check engine light
The last week or so, the check engine light has remained lit for 1 to 2 minutes after start up, on three or four occasions. The first time this happened, the car sat for about an hour after being driven in traffic, and it was a 90 degree plus day. Light came on again this evening, the car was cool. My wife bought gas the day before the first occurence. I need to make a 200 mile round trip tomorrow, I assume it is safe to use the car!? The nearest dealer is 100 miles away, I have a good local mechanic, but he would be the first to admit he is not real well versed in the Q. Open to any suggestions on the best approach to this problem. Thanks, Alan
Most fluid warnings involve other lights on the dash, or error messages in the display. Could be a simple reason, but don't ignore it; your car's telling you it isn't feeling well.There is a way to retrieve the numerical error code(s) from the ECU that will narrow down the error to the subsystem. You need the manual for the procedure and to translate the code. I can't remember it off the top of my head, but there is a set screw on the ECU that you need to turn back and forth with a screw driver, and then count the short and long LED blinks.
I'm no expert but most cars nowadays warn that if the gas cap is not turned enough to get a good seal it will affect the fuel system and give a check engine light.
Did you check that the gas cap is assembled properly? I live where I can pump my own gas but I know there are states where someone else pumps. We used to call them gas monkeys because they would always forget to replace the gas caps. Check that first.
Do you buy gas at the same station regularly? is the car performing normally?
Did you check that the gas cap is assembled properly? I live where I can pump my own gas but I know there are states where someone else pumps. We used to call them gas monkeys because they would always forget to replace the gas caps. Check that first.
Do you buy gas at the same station regularly? is the car performing normally?
Thanks all for the reponses. I don't see how low coolant could initiate "check engine", but hey, we were low. My eyes started to glaze over reading the emissions section of the manual, but I took your advice Deadalus, and looked over the procedure for retrieving the code. The manual is not so daunting when you go to a specific item. Okay, looks like the cpss (cpu) is in the passenger side kickpanel. Refering to the body section of the manual, I can't quite figure out how to pull that sucker off. Also, I did have a long drive yesterday and I have some more observations. The check engine did not come on on initial start in am. It comes on on subsequent starts now matter how long the car the car has been run. Does not seem temp related. Idle is a triffle ruff, rpm maybe a hair low, then everythin perfect, and light goes out, one to three minutes. As soon as I can get to the light, I will pull the code, anyone (Dennis, or other resident genius)want to guess in the interim? Thanks Again
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Stored codes are much more numerous than the few things that are considered so critical to the life of the engine that they illuminate the MIL .
Only 11 faults can turn on the light in a pre96Q:12 Air flow meter13 Engine temperature circuit14 Speed sensor circuit31 Ecu not passing self test [this can be a lot of things]32 EGR33&53 left and right Exhaust O2 sensor35 Exhaust temperature43 TPS open or not correct for condition45 Injector leak [ or unusual richness] sometimes O2 related51 Injector circuit [open or shorted] not drawing the appropriate ~~~1 ampere
32,35,45,51 apply to California cars only
The sensor can still work but their output can be significantly different from what the ecu expects at the time period. Crank, warm up, should be warm by this time. Same with coolant, should be 176F after 5,10 minutes still at -20F something is wrong Hey it was 176F 2 seconds ago now dropped 50F something is wrong.
The ecu has a short term 3 seconds ago memory to compare things now obviously a lot can happen in 3 seconds so ignores many things.Also it compares air flow to throttle position to rpm.....these things will always be within 20% of the calculated value for sealevel so if they are within 20% it assumes everything is ok cause you could be in Denver not LA or Miami.
Going above 6,000 feet may stress the ecu but since it occurs slowly it adapts and guesses you really are in the mountains.
Generally O2 are not EVER warm enough at idle but above 1500 rpm they should be switching back and forth after 5 minutes after crank....the ecu ignores them at idle and WOT unless the heater circuit is not drawing current [open heater element or a bad wire].
When the MIL light is on the ecu ignores what ever it thinks is a problem and goes into a strategy to still work somewhat if something is really critical it may limit engine rpm to 2,000.
Other sensors may do similiar things full explained in shop manual.
Only 11 faults can turn on the light in a pre96Q:12 Air flow meter13 Engine temperature circuit14 Speed sensor circuit31 Ecu not passing self test [this can be a lot of things]32 EGR33&53 left and right Exhaust O2 sensor35 Exhaust temperature43 TPS open or not correct for condition45 Injector leak [ or unusual richness] sometimes O2 related51 Injector circuit [open or shorted] not drawing the appropriate ~~~1 ampere
32,35,45,51 apply to California cars only
The sensor can still work but their output can be significantly different from what the ecu expects at the time period. Crank, warm up, should be warm by this time. Same with coolant, should be 176F after 5,10 minutes still at -20F something is wrong Hey it was 176F 2 seconds ago now dropped 50F something is wrong.
The ecu has a short term 3 seconds ago memory to compare things now obviously a lot can happen in 3 seconds so ignores many things.Also it compares air flow to throttle position to rpm.....these things will always be within 20% of the calculated value for sealevel so if they are within 20% it assumes everything is ok cause you could be in Denver not LA or Miami.
Going above 6,000 feet may stress the ecu but since it occurs slowly it adapts and guesses you really are in the mountains.
Generally O2 are not EVER warm enough at idle but above 1500 rpm they should be switching back and forth after 5 minutes after crank....the ecu ignores them at idle and WOT unless the heater circuit is not drawing current [open heater element or a bad wire].
When the MIL light is on the ecu ignores what ever it thinks is a problem and goes into a strategy to still work somewhat if something is really critical it may limit engine rpm to 2,000.
Other sensors may do similiar things full explained in shop manual.
My 91 with 185,000 and original injectors exhibits the same symptoms 3 to 4 times a year as your car. Check engine light on at start up, followed by a rough idle which usually corrects within a couple of minutes. Each and every time, the code was 51, injector circuit. A couple of my injectors (ones under the plenum of course) test slightly low at 9.8 ohms, and have the #8 fail completely. Test the resistance via the harness and check against the specs in the manual. Could be time for a very expensive repair:eek:
Sorry for duplicate post but it is morning here and head is still a little cloudy from too much Coors Light last night. To get to the ecu, you need a deep well 10MM socket and phillips screwdriver. Open the glove box and remove the glovebox door ONLY. Next, there is a little "tab" in the carpet at the back of the kick panel that covers the ECU. Pull the tab of carpet away and remove the 10MM nut. The rest of the panel just snaps away. There are 2 small phillips screws that hold the ECU in, remove the screws, and lift the ECU gently to pull away from frame. Turn the ECU around and follow the manual to retrive the codes. Long flashes followd by short ones. Check it 2 or 3 timnes to make sure.
You guys are terrific! Awards as follows: Best Guess- Doug Q45, Thanks for helping me get in there and you were right code 51. Most technical info- Dennis, you are amazing. So here is the next dilemma. I have a warranty that will cover injectors and the whole system, no charge to me. I am 3 hours away from the nearest dealer. Should I let my local guy do this work. Try a flush, what kind? Drive it for a while and get the work done before the warranty runs out? What are your thoughts? Alan
I would have the dealer do it. If I recall, injectors cost about $140 each, and there is a 50% chance that the plenum will have to be removed. At that point, I wouldn't trust anyone but a dealer if it's covered by warranty anyway. A 3 hour drive each way is worth it to have it done free and done properly.
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Presario12000
- Posts: 4
- Joined: Mon Nov 18, 2002 10:27 am
check engine light
hi guys,
I thought i share this with u guys.
I just recently bought a 90 s13 in almost mint condition (1 previous owner). Anyway, i put in KN and it was fine. But when i put in Bosh(platinum) spark plugs, the check engine light went on. I tried adjusting timing, checking for leaks but couldn't find any. So i took the Bosh spark plugs out and replace them with my original NGK spark plugs. The damnest thing, the check engine light went off the moment i pushed the car above 85mph. So, if any of u have problem w/ check engine light, might want to check the spark plugs first.
I thought i share this with u guys.
I just recently bought a 90 s13 in almost mint condition (1 previous owner). Anyway, i put in KN and it was fine. But when i put in Bosh(platinum) spark plugs, the check engine light went on. I tried adjusting timing, checking for leaks but couldn't find any. So i took the Bosh spark plugs out and replace them with my original NGK spark plugs. The damnest thing, the check engine light went off the moment i pushed the car above 85mph. So, if any of u have problem w/ check engine light, might want to check the spark plugs first.