"Check Engine" light is on! Need help troubleshooting it!

[ClydesdaleKevin]

Our RV is an 89, but it is carburated...Rochester Quadrajet, 454.

Anyhow, its flickered on before, but this last leg of the journey it came on and stayed on.  What makes it come on?  The engine water temp is perfect.  The oil pressure is perfect.  Voltage is good.  Transmission temp is better than expected towing, staying around 150.  Trans fluid and engine oil are perfect, belts are tight, power steering fluid is good too.  Power is perfect, runs as good as ever, so I'm sure the vacumm is fine, and fuel economy is still a very acceptable 7.5 mpg. 

What can cause a 1989 454 "Check Engine" light to come on if all else is good?  The only two things I didn't replace before we left were the fuel filter and the air filter.  The PO had just replaced the fuel filter when I bought it, so I didn't bother.  The air filter could use a replacement, but would that set off the light?

There isn't a computer in this RV except the ones we type on...lol.  Its a carburated 454.  What other sensors are there that could set it off?  Timing, crankshaft position, pinging I can't hear?  Should I even worry, since my gut tells me its minor and probably has to do with emissions?

Please let me know, as we aren't even half way there yet and have another 455 miles of driving to do tomorrow alone.  We are still 1160 miles from our destination.

Thanks ahead of time!

Kev

[Arberg0]

well Kev i spoke to my local car repair guy who has 2 towtrucks with the same carb setup as you have and he says air filter airfilter airfilter everytime even if the old owner said he had replaced it i would replace it again and the other one as well as he says its due to a air flow problem



arberg

[DaveVA78Chieftain]

Welcome to OBD1 (88 and later until OBD2)

http://www.troublecodes.net/GM/

It could also be nothing more than a mileage driven service engine soon light.

This is where you have to have the books in order to determine what the issue is.  Yes, they did use a ECM on a few carburated models.

Dave

[tiinytina]

Orange Check Engine is usually a "sensor" for air related (pollution) things... on my truck was a bad 0xygen sensor... Check air filter and snorkel etc.. may have sucked up debris etc...  We invested in a K&N reusable air filter in Gone (454 Quadrajet Edelbrock) and the cleaning fluids for it.... and a new flexible pipe that fit from snorkel to RAM air intake (ours was age degraded and meece chewed...

Red Check engine is "All stop" and usually oil related and or over heat etc....

Tina

[ClydesdaleKevin]

This only has one color light.  Reddish orange.  Anyhow, I'm having my awesome mechanics from last year in AZ go through this thing from one end to the other mechanically, so as long as it isn't serious right now and nothing is imminently in danger, I'm just gonna drive her there.  And I'm not entirely sure this has a computer at all...I looked all over the place under the dash and there isn't an OBD-1 port, or any other kind of port, anywhere I can find.

Ah well...if she keeps running great and the light keeps on, I'll just pull the lightbulb.

Kev

[Froggy1936]

Dont forget all that rain could have completed a curcuit for the light at a sensor etc.  Also tape is an easier way to block light  He  Frank

[RV Mech Tech]

Kev - RV's as well as 3/4 to one ton vans are considered extreme duty use and are not subject to the same emission rules as medium or lite duty vehicles  - in addition to the what everyone has said,  there may not be a computer on your coach but G.M. did have some emission control devices with separate small control modules that may be connected to this light in your dash - computers were scheduled to be installed in later years for the heavy duty applications so it's possible that you do have that light in your specific dashboard-  as Dave has said some carb engines did have on board computers but these were usually for the computer controlled carburetor versions (CCC) and some of the functions of the carb was controlled by an early version of a computer but if your carb does not have any wires going to it then you do not have this version - what you may have is some of the emission control devices like the positive crankcase system (PVC)  or the early fuel evaporation system (EVAP that controls the gas fumes from the gas tanks)  may have their own smaller control modules instead of a central computer like you see now  and when something malfunctions it will turn on this light to indicate it needs servicing - I owned a 1990  one ton extended Chev van with a 350 carbureted engine with three of these systems and no computer and it had the check engine light as well - so see what your mechanic finds - one other system they started using in the early 80's on heavy duty vehicles  without any emission equipment at all is an engine knock sensor - a sensor mounted in the side of the engine block (usually in the cooling passage drain plug  behind the front motor mount) that sensed when there was engine knocking which could cause damage and it was connected to a control module that then retarded the ignition timing so the engine would not be damaged ( without any other emission systems on the vehicle -keep in mind what was offered in Canada may be different than what you see on vehicles made for the  USA, not with what equipment was installed but what years they installed them and on what vehicles so that is why I'm suggesting to check and see what is specifically on your RV)  - the control module was also connected to  a 'Service Engine Soon' light in the dash so have your technician check to see what you have on yours - also verify that this is an additional light for these systems and not a regular warning light- hope this helps !   

[DaveVA78Chieftain]

And I will say again,
Get a copy of the chassis manuals. P30 set listed here:
http://www.classicwinnebagos.com/forum/index.php?topic=4974.0

Assuming you have a 89 built on a 88 chassis:
The title/pic of this EBAY listing syays 2 but the write up says all 3, so ask them because for that price the deal cannot be beat
http://cgi.ebay.com/ebaymotors/1988-GM-Chevy-Light-Duty-Truck-Service-2-Manual-Set-/320168047060?pt=Motors_Manuals_Literature&hash=item4a8b80b1d4

Manual set consists of
Service ST-330-YY
Unit ST-333-YY
Wiring ST-350-YY
Later years (started in 86/87) have a 4th book for emissions. ST-376-YY
YY = Chassis year
[SeaHag posted a picture of a complete set for 87 in the post above)


Dave

[ClydesdaleKevin]

Thank you everyone for your replies!  When we left this morning the light was off...and stayed off all the way through San Antonio and half way to Fort Stockton, where we pulled in for the night and where I am typing this.  It came on just cruising along the rolling hills of mid Texas, and stayed on till we got here.  Still running great, still all good on fluids and guages, just an annoyance apparently.

I'll definately have my mechanics take a look at it when they do the major tune-up.  I'll also look myself when we get to the fairesite since I'll have some time. 

Could be engine knock because we are using the cheapest gas on our tight budget, or it could be as simple as the air filter...but again, I'll check it all out when we get there.  As far as the manuals go, I'll definately get them when we can afford it. 

Thanks again everyone!

Kev and Patti

[fgutie35]

If I'm not mistaken, you have the California Emission System. This will include two air pumps, two exhaust valves thta attach to the exhaust manifold, and and extra EVAP canister. The light indicates that there is something wrong with the system and the manual specifies that the usual suspects will be a bad pump or valve. Other causes may be leaks in the system.

[ClydesdaleKevin]

Thanks for the input!  But to the best of my knowledge, this RV was purchased new at Holiday World, in NM.  Then the original owner moved to Colorado, where it lived for years...until it was sold on eBay to the guy from Massachusetts that I bought it from.  So it shouldn't have California emissions.  Its all good though...the light has been staying on all the time now, but all systems are good and we are only 88 miles from our destination, where I'll have time to really troubleshoot and/or have my mechanics look at it.

Thanks again everyone!

Kev and Patti

[fgutie35]

California Emission System is just a figure of speech. What I meant was that Winnebago made RV's to be sold in California and Canada where emission regulations are tougher. These RV's have an added emission system like the one I explained in my previous post. Those RV's were sold on other states. Mine comes from Kentuky and it had the system, that is how I know.

[ClydesdaleKevin]

Thanks!  I'll check it out when I can.

Kev

[ClydesdaleKevin]

Okay!  Mystery partly solved.  I read the 89 Chevy Owners Manual that came with the RV.  First, according to the VIN code, she doesn't have California Emissions.  In 89 the 454 came 2 ways, regular duty and heavy duty.  The regular duty had TBI, catalytic converters, a computer, and the check engine light was tied into the computer, O2 sensors, and a few other sensors.

Mine is the heavy duty model, which came with a Rochestor carburator, no catalytic converters, and thankfully, no computer at all.  The check engine light is tied into what they called the A.I.R. system, a primative emissions control whick basically just a valve with a small air filter and an air pump run by one of the belts and a pulley.  The light goes to a control module that monitors airflow at the valve.  So according to the manual, airflow is down...could be the pump, but I doubt it...the pulley still spins freely and noiselessly.  Could be the filter, which is the most likely cause according to the manual, or the module itself might be bad.  If its a cheap fix, I'll fix it.  If its something expensive, then I'll disconnect the light, since according to the manual it has to do entirely with the A.I.R. system and only effects emissions, not performance.  And Florida has no inspections or emissions...yay!

Once I figure out whats wrong, I'll post the final solution to this mystery.

Kev

[Froggy1936]

Hey Kev The AIR syestem just pumps fresh air into the exaust at the manifolds to make a mixture that will relight and burn any fuel not consumed in the clyinder there by reduceing emmissions of unburnt fuel  that process does nothing to help or hinder MPG which is all your concerned with unless you are going further west California might be a problem if the syestem is not operating as required by them. Frank

[GWINGER]

It's only a problem in Calli if you want to register it in the state. If you're just passing thru, no problem.
J

[defkaf]

We have an '89 Elandan on a P30 chassis with a 454. A few years ago our check engine light started flickering on and off, and eventually stayed on all the time. Had a Chevy truck dealer check it out and do the repair. Turned out to be a solenoid in the A.I R. system. IIRC it cost around $500 to have them replace the solenoid. If it happens again I think I would consider pulling the A.I.R system off the vehicle at this point.
Don

[Oz]

HEY KEVIN... I'm guessing your ck engine light has still been on almost 2 years?

[ClydesdaleKevin]

LMAO!!!  Nope, and sorry for not updating!  It was annoying so I pulled the light bulb out of its socket.  On a 1989 carbureted engine, the Check Engine light goes to a sensor for air pump volume.  After all my mods, its a moot point, so I pulled the bulb.  I might rewire it to tell me the steps are out...lol!

Kev

[eXodus]

Hey there,

I just after my last drive the "service engine soon" light on.
It's only on when ignition is in two and goes off immediately after starting the engine.

Can I just read trouble codes ?


Paper clip between A and B and count flashes ? How to reset if this is a mileage counter ?

[DaveVA78Chieftain]

No milage counter on GM OBD 1 TBI based system.
Key in RUN, engine OFF with light ON is normal.  Used to indicate power is getting to OBD 1 computer.  It is when it is not ON in that condition that you have issues.
Yes you can count stored light codes on GM OBD 1 by shorting A and B at ALD connector.  Standard OBD 1 call out where 12 is the standard everything is OK code.

Dave

[tiinytina]

i put a piece of electrical tape over Gone's light.. AIR gone means light is on most of the time... 
Tina

[DaveVA78Chieftain]

i put a piece of electrical tape over Gone's light.. AIR gone means light is on most of the time...

For a OBD1 TBI based system like he has, that's the last thing you want to do.

Dave

[Rickf1985]

What you are describing is a self test and is normal. As long as the light does not come on while running or come on and stay on it is fine and should have no codes.