Service engine soon light on Chevy Van?

[midhvac]

When I'm on the highway going up a hill, the engine seems to lose power and the "service engine soon" light starts flashing. When I crest the hill and hit level ground, both things stop.

What would cause that?

[WhoIsThat?]

Bad head gasket? (Do a compression test). Rarely, it passes and the head gasket is still bad.
Or, bad electronics telling the engine to behave that way.

I just lately discovered that my local library had a book on exam questions that people can use to bone up for their ASE certification exam.
This book has a lot of useful troubleshooting info, but it's not arranged in that order. Still, if you can wade through the questions and answers you may find exactly your symptoms and the cause.

There doesn't seem to be a generic troubleshooting book for cars, except for two volume sets that cost $600 and are vehicle-specific. Motor's and Chilton's used to publish books along this line but these companies might have become victims of the Internet.

Turns out it costs more money for the library to keep these kinds of books on their shelves than to sign up for online auto data services. If your make and model are in the library's version of the database, it might have some troubleshooting instructions. The older the car the more likely you'll find what you want.

I buy my $25 Chilton/Haynes manuals for my vehicles before I need them. Factory Service Manuals for new cars now cost $400 or so, and a lot of the procedures in them you can't do because you need special equipment.

Any time you work on your own vehicle you are paying yourself at least 30 tax-free dollars per hour, even if the job takes you the whole day.

[Tiger93rsl]

Take it to someone with a diagnostic interface and have them pull the code history and see what they come up with.

[Roscoe]

Catalytic converter........??.............or...............w ell ......it is a Chevy...............

[vmc1161]

Bad head gasket? (Do a compression test). Rarely, it passes and the head gasket is still bad.

I just lately discovered that my local library had a book on exam questions that people take to get their ASE certification.
This book has a lot of useful troubleshooting info, but it's not arranged in that order. Still, if you can wade through the questions and answers you may find exactly your symptoms and the cause.

There doesn't seem to be a generic troubleshooting book for cars, except for two volume sets that cost $600 and are vehicle-specific.
Motor's and Chilton's used to publish books along this line but these companies might have become victims of the Internet.
I buy my $25 Chilton/Haynes manuals for my vehicles, before I need them.

My truck has done the same thing for almost seven years, I was told what you are saying ...they checked and everything was OK. I then heard that the programming was updated and they just change an e-prong and all is well. I never bothered to get it changed, I only drive down hills now, seems to work ...



.

[Snapperhead]

When I'm on the highway going up a hill, the engine seems to lose power and the "service engine soon" light starts flashing. When I crest the hill and hit level ground, both things stop.

What would cause that?

I would start with a fuel filter. Has it lost its power in passing gear too ?

Back in the day that would point to a fuel pump going bad , but your is lectric now so Im going with the filter

[coolwhip]

Bad O2 sensor?

[timebuilder]

Bad head gasket? (Do a compression test). Rarely, it passes and the head gasket is still bad.
Or, bad electronics telling the engine to behave that way.

I just lately discovered that my local library had a book on exam questions that people can use to bone up for their ASE certification exam.
This book has a lot of useful troubleshooting info, but it's not arranged in that order. Still, if you can wade through the questions and answers you may find exactly your symptoms and the cause.

There doesn't seem to be a generic troubleshooting book for cars, except for two volume sets that cost $600 and are vehicle-specific. Motor's and Chilton's used to publish books along this line but these companies might have become victims of the Internet.

Turns out it costs more money for the library to keep these kinds of books on their shelves than to sign up for online auto data services. If your make and model are in the library's version of the database, it might have some troubleshooting instructions. The older the car the more likely you'll find what you want.

I buy my $25 Chilton/Haynes manuals for my vehicles before I need them. Factory Service Manuals for new cars now cost $400 or so, and a lot of the procedures in them you can't do because you need special equipment.

Any time you work on your own vehicle you are paying yourself at least 30 tax-free dollars per hour, even if the job takes you the whole day.

You probably found one of the ASE books I wrote for a major auto publisher. I did not ask for, nor receive a "by" line. I hope it helped you, but it is focused on test prep, and not check engine diagnostics.

You need a scan tool, either an OBD I or II, depending on the model year. Once you have the code, you look up the code in the appropriate manual, and follow the diagnostic tree. By the time you are finished, you will probably have spent more on the scan tool and the book that it would cost to take it to a shop and have them test the vehicle. Companies like Alldata are very good at preventing their info from being disseminated freely.

Older GM vehicles of the OBD I vintage can flash the check engine light when you short the A and B terminals of the ALDL connector.

Perhaps the least expensive and time consuming approach is to make sure all of the vehicle maintenance is up to snuff. Odd things can exist after that, like the innards of the cat sliding against the outlet of the cat when powering uphill and stifling the exhaust, and then falling away from the outlet when traveling downhill, allowing the exhaust to flow again. Or water in the fuel tank that gets sucked up at a specific angle can cause problems.

Start with maintenance, then take it in for diag when everything has been attended to.

[timebuilder]

My truck has done the same thing for almost seven years, I was told what you are saying ...they checked and everything was OK. I then heard that the programming was updated and they just change an e-prong and all is well. I never bothered to get it changed, I only drive down hills now, seems to work ...



.

GM pickups had an eprom update due to a knock sensor problem. Really irritated their customers, too. Of course, the recent "like a knock" problem that came from the abandonment of a "select fit" approach to engine building was a lot more irritating.

[edward301]

I am with coolwhip, O2 sensor starting to go bad...

[HeyBob]

Catalytic converter........??.............or...............w ell ......it is a Chevy...............

LOL......................Agreed! Hey! I found something on ebay that will make your cube van look better, bought a set myself.

Ford Factory Aluminum Wheels

You need to buy the rear caps for the full floating axle though.

[SJProwler]

Since it only does it going uphill with added load.... I'm putting my money on a misfire code. Go to AutoZone, they'll pull the codes for free. Misfires occur under heavy load with old spark plugs or a bad plug wire.

[timebuilder]

Since it only does it going uphill with added load.... I'm putting my money on a misfire code. Go to AutoZone, they'll pull the codes for free. Misfires occur under heavy load with old spark plugs or a bad plug wire.

That's why you check yourself on the maintenance first.

[Makinice]

My 01 did that also.

Turns out it was "carbon buildup". (02 sensor acting up) The dealer told me I drive to much like an old lady.

The fix was him flooring it in the parking lot to "release the carbon". I nearly tackled him.

He told me to either start running high test fuel, fuel additive, or start driving it like it's meant to be driven.

I started driving a little harder, and it never happened again.

[jpsmith1cm]

Every time one of mine has done that, the fuel pump was bad.

[Freezeking2000]

Every time one of mine has done that, the fuel pump was bad.

I would think fuel filter or pump, but we know chevy fuel pumps never go bad.

[freerider]

Badass van in your avatar, freeze.

[freerider]

Flashing is bad. Too many possibilities. That's why the codes are stored. Go to Autozone.

[timebuilder]

Flashing is bad. Too many possibilities. That's why the codes are stored. Go to Autozone.

Flashing is not "bad," per se.

It means that the engine control module (ECM, PCM, etc) is operating in its minimum operating mode. We used to call it "limp in" or "limp home" mode.

In this case, the vehicle is being prevented by some subsystem or systems from operating properly. A scan of the history codes will tell you the specific area that is setting the code, but be aware of this: the codes describe the AFFECTED systems.They are not always the CAUSAL problem. That's why every code has a diagnostic tree that should be followed.

Start with a review of maintenance, get the scan, and pay for a few pages of an ALLDATA printout from a service facility that will sell it to you. Do the pinpoint testing and work from there.

What is the model, year and engine for this truck?

[freerider]

By bad I mean not something you want to put up with. I have seen service vans that intermittenly had check engine light(steady) and ran fine, passing emissions. Chevy Vortecs leak sometimes in the injection spider, causing a bank rich code. However, if the light was off, they would pass. Never saw one pass when the light had flashed, even if it was off.