Evap IM
 

Ever since I did my lower intake gaskets on my 2003 Blazer L/S 4.3 liter I heard a air noise passenger side intake found noise to be coming from the evap control valve the small o ring below the valve.I fixed it now I am going on three Gm drive cycles still awaiting the evap im to stop blinking no hard code in commuter memory.In the Innova booklet it calls for three drive cycles and or 40 warm ups.Hope it clears soon its almost emission testing time.

One General Motors Driving Cycle, performed correctly, with no DTC's set before or during, will force ALL of the monitors to run and complete their tests. That's the purpose of the drive cycle. The "40 consecutive warm ups without a failure" will turn the light off, (if there is one), but it will not force any monitor to run. If there are incomplete monitors after the drive cycle, it was not performed correctly. EVAP is the most complicated monitor. Nearly every step in the drive cycle includes something for the EVAP system, which is why each step must be performed exactly as written. If the check engine light comes on before or during the drive cycle, it will abort until the problem is diagnosed and repaired, and the memories are cleared. The steps do not need to be performed in order, but they all must be performed. Trust me, if you mess up, even one time, it will know ;)

Ok Captain thank you for the quick response.Now like you said the gm drive cycle has to be followed to a T now my question after the 2 1/2 minutes warm up I used the heater instead of the air like it requires so i will try it again by the book but my question is after the initial warm up it says turn off every thing and my headlights are auto on will that make a difference were it says to turn off everything.

What they're looking for in the first part of the test, is to create maximum load on the electrical system, to make sure the alternator can supply sufficient voltage/amperage for the oxygen sensor heaters, (hence the reason for the AC to be turned on). When it instructs to turn everything off, before you turn the ignition on, apply the park brake to the first "click", that will keep the headlights off for the test.

Drive cycle
 

Ok Captain I get it now so today I set out to do a real drive cycle but one problem the temps here are 32 here and lower at night.And the air wont stay engaged so is the air conditioner the only way to do the drive cycle or can I use heater on full rear defrost all electrical for 2 1/2 minutes then click the e brake one notch for the rest of the test with everything off for the freeway part of it.?

That should be fine. It needs a heavy electrical load: high beam headlights, heater blower on high, rear defroster, wipers, etc.

Ok Captain I can do the warm up in my drive way 2 1/2 minutes everything on, shut off every thing drive to the freeway pull over to the side shut off car and head lights if e brake don,t work while running. apply e brake one notch if that works to shut off the auto light feature with engine running if it don,t can remove fuses left right headlight park lights and if you don,t touch the brake the lights wont come on.do the 3 min drive cycle coast to 20 mph accelerate to 55 for 5 minutes then coast to 20 mph and that should do it write.

The PCM is continuously "watching" for the driver to perform each requirement for each monitor. When the requirements in each step are met, the monitor completes. In other words, in step #4 you are instructed to go 55mph for 3 minutes; if you go 55mph for 5 minutes, the catalyst monitor, (step #7) will also complete. On the other hand, step #5 instructs not to touch the brake, if you do, the monitor will not complete. It will again start "watching" for the driver to duplicate the requirements in the step. Once the requirements are met exactly as written, the monitor completes.

Ok Captain now I know how to do it if I had a dyno it would be really easy.The E brake wont work for the head lights I can pull the left and right headlamp and the park fuses but for some reason that leaves the high beam indicator on at the dash don,t know if there is a way around it.But every thing else is possible so maybe the lights don,t need to be disconnected.I can hook up my Innova code reader put the car on heavy duty 3 ton jack stands start it run it for the warm up cycle shut off every thing accelerate to 55 mph hold for 3 minutes coast down to 20 mph again then accelerate back up to 55 mph hold for 5 minutes then coast down to 20 mph. and that should ready the evap monitor because like I said there isn't a hard code or a check engine light.It comes down to the head lights there has to be a way to turn them off without leaving a light on in the dash and one other question other drive cycles say use the speed control to keep the speed accurate do you think that would be ok or should i manual it.Also I don,t like the jack stand idea but it should be quite safe with heave duty jack stands and a 3 ton jack under it wont be driving off on me but it may take a little longer to coast down to 20 mph.

Cruise is ok to use.


No DTC's in memory.... If there are no hard faults in the EVAP system, it will not set an EVAP DTC until after the monitor runs, completes, and detects a fault.

No Captain like I said no DTC,s in memory at all and I am sure I have got the drive cycle rite more then once and I have kept the INNOVA code reader plunged in to see if the evap resets. I am going to call the dealer tomorrow to see if someone can tell me if you have to disconnect the auto headlights or not.I sure wish I had a dyno for 10 minutes that would make it so simple I really don,t feel comfortable cruising at 55 mph with no resistance at the tires.P/S also remember I had to fix the purge control it was leaking air at the manifold just a week ago.But besides that I had this issue once before I pushed the erase on accident and cleared all the im,s and it took forever it seemed like to reset the evap I eventually replaced the gas cap even though the cap and seal was good I put on a locking cap then after a number of attempted drive cycles it reset after about 20 warm ups that,s why I asked if they had anything to do with the im,s but you cleared me up on that.So Captain what do you think about raising the car up on 4 ton jack stands and I will keep the 3 ton floor jack under the rear end other then the free wheeling it will sure speed up the drive cycle even if I have to bypass the headlights.One last question Captain what if I disconnect the brake lights then maybe I could use the brakes to slow the rear end down with out canceling the test.

Ok captain since I don,t have a dyno the only other way I can complete the drive cycle in 15 minutes as stated in the drive cycle its self would be my jack it up do the warm up then the 3-5 minute freeway parts with out any delay and no touching the brake.Get them all done in 15 minutes and with the INNOVA tester plugged in and that should give me a completed evap system or a set DTC'.So what do you think Captain would you try it this way or is there a easier way to do it.Because after the warm up I am having to drive to the freeway and that is more than likely canceling the warm up with touching the brake.

EVAP monitor is the most involved monitor to complete. I've seen vehicles go days, even weeks, before the monitor will complete. Never tried that before. Let us know how it works out ;) Some of the high dollar scan tools can perform what's called a "service bay test" for EVAP. You don't even need to drive the vehicle!

Ok captain did it exactly as required 2 1/2 minute warm up jump on freeway take it to 55 mph for 3 minutes shut off cruse coast to 20 mph accelerate to 55 mph for 5 minute turn off cruse coast to 20 mph then accelerate back home failed again evap moniter still blinking after im sure at least 5 or 6 drive cycles done properly.still no dtc or srs codes

Ok Captain I will take your failure to respond to my jack up idea to not be a good one the more I thought about it the thought of blowing up mt transmission or rear end because of no resistance on the wheels. So that idea is off the table for good.So I was checking around online and a just ask mechanic said he would answer my question but what he didn't say was what if it didn't work do I get back my money.

Ok Captain I have run almost 200 miles trying to do the correct drive cycle and still no dtc,s Is there something else that can stop the im from running its test cycle with out leaving a dtc because I know I have the drive cycle down pat.Start vehicle all electrical on for 2 1/2 minutes shut off everything. Drive to freeway accelerate to 55 for three minutes coast down to 20 mph accelerate to 55 mph hold for 5 minutes coast down to 20 mph accelerate to 55 mph your done gm drive cycle. Evap im still blinking what would you do next Captain.I am not one to give up on a problem I like solving them I have started testing the electrical and vacuum valves with a new vacuum gauge and a multi meter.

Have you checked IM readiness/monitor status with another scanner? There might be a software glitch with the Innova. Seems like another member had a problem similar to what you're describing.

Ok captain Have tried everything other then a smoke test for leaks but if its not setting a hard code then its more then likely not leaking here is the answer from just ask that I was reluctant to try but am getting in patient to pass emissions so maybe you can comment on just what he meant because it sounded like no drive cycle was necessary to get the evap to run its cycle.
06 January 2016 03:51
Dr.Carz Dr.Carz
Chevy Mechanic
Well the fuel level must be between 1/4 and 3/4 full and the system will require and over nite soak or 2 this time of year when it gets cold it gets harder to run. It will pull a vacuum and the after 8hr soak or so will pull info on start up. If you have access to scan tool that can perform a purge and seal or evap test will help this monitor along. Here in NY you can have 1 not ready and pass Inspection. Good luck hope this helps driving for miles and miles will not help.Please remember to rate my service and Accept Thank You

Technically, fuel level must be between 15% and 85% for the EVAP monitor to run. 1/4 to 3/4 is a safe bet ;) What he's talking about with the "purge & seal" and "evap test", they are things that a high dollar scanner can command, (same thing that I mentioned in post #13). Neither of them will "help this monitor along". They are strictly for test purposes in the shop. If they are performed correctly, you can find out very quickly if the EVAP system can hold vacuum, or not, that's it. To satisfy the IM readiness/status monitor, the monitor must run, and complete. The only way to do that, is during a drive cycle. I've never, ever, heard of a PCM not recognizing the driving patterns of the drive cycle.


EDIT: Are there any DTC's in memory, or pending, before, during, or after you do the drive cycle?

So Captain just curious when will it run complete and set a fault if there is one and can you tell me what the specialist meant by warm ups draw vacuum and complete diagnostics on the evap and why 1/4 or 3/4 tank gasoline has anything to do with it.

The monitor will run its tests, and complete the diagnostics, (monitor will complete) when the drive patterns have been duplicated as described in the drive cycle, and all other requirements are met, (fuel level is correct, no DTC's in memory, etc etc).

When the monitor checks for leaks, the PCM closes the EVAP vent solenoid, (near the vapor canister), and applies a given amount** of vacuum to the EVAP system by momentarily opening the purge solenoid, (right side of intake manifold, near ignition coil). This is called a purge and seal. The fuel tank pressure sensor measures the amount of vacuum in the system. The PCM "watches" how long it takes for the vacuum to decay. Depending on how long it takes, if it's too rapid, the PCM will set one of three DTC's, large, medium, or small leak.


**This is where fuel level in the tank comes into play. Less fuel means the purge solenoid needs to remain open longer to "pull" (apply) vacuum on the EVAP system. With more fuel in the tank, the solenoid doesn't need to remain open as long. This is why the fuel level sender, and the pressure sensor, must be working properly.


This is just one of several tests in the EVAP monitor. Like I said, this is a tough monitor to run and complete, and it might take a while. You know exactly what you have to do, and you've gotta be coming very close to duplicating the pattern. Now you see why it can take so long for the "average driver" to complete it.

Yes Captain it just so happens I have one I got for a gift without abs and one with abs I bought for my current blazer.Both have yellow light on with the evap monitor blinking.

Are they both Innova? We're looking for an unbiased second opinion ;)

Yes there both Innova but I will go to the parts store and have them use there acuscan and let you know what it reads.

captain what do you think about the answer I got from the ase approved tech.
06 January 2016 03:51
Dr.Carz
Chevy Mechanic
Well the fuel level must be between 1/4 and 3/4 full and the system will require and over nite soak or 2 this time of year when it gets cold it gets harder to run. It will pull a vacuum and the after 8hr soak or so will pull info on start up. If you have access to scan tool that can perform a purge and seal or evap test will help this monitor along. Here in NY you can have 1 not ready and pass Inspection. Good luck hope this helps driving for miles and miles will not help.Please remember to rate my service and Accept Thank You.

Captain what do you think about what Dr.Carz had to say Its much safer than the drive cycle on the freeway yesterday some guy flipped me off and passed me on the right even though I had put on my four ways don't usually use then or blinkers because worried it will cancel the drive cycle but when coasting down to 20 mph It seems to be the safe thing to do especially if there are cars behind you when your coasting down.Even in the right lane.

This reminds me of a kid playing Mama against Papa. Just pick one specialist that you believe in and do what he asks. Don't ask one to expain what the other one says about a car that neither one has seen.......

Go back and read post #2. If it's not completing the tests there are two possibilities:

1. You are not doing the drive cycle correctly
2. There is some fault present that prevents the drive cycle from completing.

In post #1 you said there was no hard code in memory. Does that imply there was a pending code?

No and I am sorry if you think that's the case because the true fact is I just want to pass the emission test.Nothing more nothing less and I have tried the gm drive cycle about 8 times and I think I got it down unless it don't allow time between warm up and freeway cycle and if that's the case the only way to pass the drive cycle is with a dyno first start in the morning or park your car on the freeway over night then start test fresh and right after warm 2 1/2 minutes everything electrical on. Accelerate to 55 mph for 3 minutes coast down to 20 mph accelerate to 55 for 5 minutes coast down to 20 no brake gears and maybe even no four ways don't know.Do you.

Ok Lesmyer didn't mean to insult any feelings but I took the advice of trying a different scanner went to ORiley's used there Bosh tester and it said that the evap hasn't run complete with a extra code po102 mass or volume circuit low input.Now I know what and were that is I bought some cleaner for it first.And when I did the manifold gasket I removed that and the complete air box system for extra room when doing the lower intake gaskets and benched it then when finished put in fresh oil and filter and new antifreeze also new air cleaner element. Don't know if that had anything to do with the pending code or if it was just due 100000 miles now.2003 gm blazer l/s 4.3 liter

This is to you Captain thank you for all your help.But tonight with that new code and the evap still not running it got me to thinking of when I took off the complete cold air box and all to get extra room to remove the lower intake to replace the gaskets.And you know it dawned on me tonight the code low censor input that's low air input.When I removed the cold air input box the little extension
must have fell between the headlight and the front end because I looked down but didn't see it between the air box and the front end and sure enough no plastic exstention at all my guess would be it fell on removal of the filter box in between the headlight and the front end.So I guess I will be passing that emissions after all,and again thank you for all your patience.

This is to you Captain thank you for all your help.But tonight with that new code and the evap still not running it got me to thinking of when I took off the complete cold air box and all to get extra room to remove the lower intake to replace the gaskets.And you know it dawned on me tonight the code low censor input that's low air input.When I removed the cold air input box the little exstention
must have fell between the headlight and the front end

I know you are intentionally avoiding any thanks to me for getting you back on track and listening to the Captain, but that's OK. I don't have nearly the time invested in your problem that Captain does.

Although I don't know for sure how your fuel injection system responds to a pending P0102, it is certainly not beyond reason that any pending code could prevent your evap test from completing. Fix the P0102 so it is never pending and retry the test. Probably good to get a scanner that will display pending codes.

Good luck!

Continuation Evap system
 

Ok I am really getting frustrated with this emission controls that make us usually take our cars to the dealer.I did what Captain said took it to another tester a bosh and the result was PO102 Air volume circuit low volume input thought I had it figured out but the plastic exstention was there just couldn't see it.When I got home tried again my tester didn't pick up the code so today cleaned out MAF and also the Intake air temp switch dried it well after cleaning it with the MAF cleaner when I started the car it set a PO113 but I think that will go away as it settles in to being clean but the PO102 cleared itself when I tested it with my tester so I disconnected the wire shortly after it set its PO102 so plugged it in and this morning it wasn't there neither was the po102 code went back to O'Rilleys they said they cant erase codes so they handed me there Bosh went out and tested didn't erase anything but the tester said all codes were gone and evap had run but the INNOVA says it hasn't finished diagnostic,s.Captain can you sujest a decent tester for no more then $300.00 that has not only the codes on the tester screen but the information for repair,s

So, we've determined that the Innova is not too reliable, and that it has been leading the way on a wild goose chase.

$300 scanner with DTC troubleshooting ain't gonna happen. Most entry level scan tools will briefly explain what each DTC means. If you're looking for information to troubleshoot each DTC, get a genuine GM shop manual for your exact year and model vehicle, (ebay usually has used ones). Typically they include 2 or 3 volumes, with over 3,000 pages, compared to the 200 or so pages in Chilton/Haynes that halfass cover 4 or 5 model years.

Air Box Intake
 

Captain you would know the answer to this otherwise I need to go to wrecking yards to look for similar cars to get my answer.My 2003 gm blazer,s air box doesn't come up and through the front end sheet metal behind the head light like it looks like it should.Its just below the hole in the sheet metal and back in the engine department so my question is would that make the MAF have low input or would it make any difference.And if it would I should get some venting material and extend it to behind the head light and see if that helps the evap run it's diagnostic.This may all have started when I did the lower intake manifold gaskets maybe there was something below the box or the piece of plastic with two rubber dowels that is lose on the drivers side maybe it broke at some time or when I removed the air box to do the intake.

There is a separate black plastic piece that connects to the air box and kinda jogs to line up with the hole in the radiator core support. The piece is only ~5" long. I can guarantee you that it has nothing to do with the monitor, or the MAF sensor.

Thanks Captain I didn't think it would change anything but I thought I may have broke it when I did the intake.You know the INNOVA I have the 3150 only gives you codes and shut,s off the mil if you want to know what might cause the light to go on or what a code could mean you have to join there little club and pay $9.95 per code. That's why I have purchased the Actron CP9680 Auto Scanner Pro. When the light is turned on giving you a code it also gives a possible reason or reasons for the code all In the hand held unit its internet update-able.I believe it also has real time electrical reading and real time record like when the mil is turned on.So you can go back and check the conditions as to why the mil was turned on in the first place.I am not positive but I think the answer to the code is a on line cost feature just like the innova it cost 9.95 every time you called in for a code reason I am sure they all cost now that is what makes them in the business of making the code readers they couldn't possibility give you help for free that's not why the make them now I am not to sure I needed another code reader except the INNOVA didn't even recognize the code PO113 or PO102.P/S thanks again Captain for your help and thanks for the honest answers without a cost behind it. That's rare now a days.

Captain one last question for now does the car,s computer use the wheel censors to calculate the drive cycle.the reason I ask is in a shop they put it on a dyno so only the rear wheels are moving but does the computer get its information from things like throttle control rpm,s so on does it even know if the car is moving if the throttle control is correct and the rpm,s are what there supposed to be does it even care if the car is moving.

OK Captain
 

You did say ebay and for gm service or repair and can I get one just for my blazer or a number of blazers.I couldn't find just gm repair manuals they kept promoting Hane's and Chilton's but not gm.But I have been on the commuter for hours trying to get some answers because I would enjoy repairing it myself and not paying a shop for what I should be able to figure out.

Captain I will get a repair manual gm when I can find one I need to be able to learn more about what it is I am working on.But I keep kicking around thoughts of when I did the intake gaskets.There was one line that gave me trouble in trying to disconnect it.that was the evap control purge valve and the part I had trouble with was the connector from I believe came from the throttle body and hooks up at the purge valve.I remember because it had a white clip that connected at the purge valve and it needed to be squeezed on both sides but it just wouldn't disconnect and I took a pic tool and lifted it carefully but still broke one side of it and I thought it still clicked on as it was pushed on.And the other part of that valve as I told you I replaced the o ring and the air hiss stooped.But what if the line wasn't connecting correctly at the purge valve tomorrow I will try to hit it with soapy water in a spray bottle.But could the venture leak at the purge valve and not set a code would that cause the evap not to finish its diagnostics and that if I remember rite a hard line not a soft vacuum.And last question on this do you think they sell just that clip since everything is still in tack. Thanks again Captain without your help I would have never got very far at all, I sure do appreciate it.Oh by the way Captain I did a vacuum reading on my blazer and it was 17 out of a possible 23 not that it matters.