Idle too fast - not passing CA emissions

[rampage]

I have an 89 fullsize Jimmy with a stock 350. My problem is that I am not passing my CA emissions test because it is idling at 1425 rpm and aborting the test (and yes the engine is at normal operating temperature during the test). There is no "service engine" light on so instead of having someone charge me $100 to hook it up to a diagnostics machine I purchased one myself for an un-goddly price, but I will have it forever! Now when I view the output from my ECM I can see what the computer is seeing for all the sensors in realtime. What I see, amoung other things, is that the coolant temp is at 185 (normal), rpm when in gear at 0mph is 800rpm, rpm in park after driving for 30 mins is 1200 rpm. Immediately after I take the last rpm reading I turn the engine off and then back on and the rpm is now at 1425 again. What is the normal rpm at idle that I should be looking for and most important, how do I correct this so I can pass the strict CA emissions test. I have the service manuals but I need someones help fast who knows exactly what the problem is because I'm driving without a registration now!

 

[muddin4fun]

What kinda carb do you have? A quadre jet?

<A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>

 

[tRustyK5]

It would be TBI on an 89...
Throttle position sensor maybe?

Rene

<A target="_blank" HREF=http://jules.coloradok5.com>http://jules.coloradok5.com</A>

 

[rampage]

Sorry, I missed that info and maybe more too. It is TBI and fuel injected.

 

[muddin4fun]

I would try runnin a can of berriman's through your gas tank to clean everything up first, but if that doesn't help then I wouldn't be a whole lot of help. I'm sure it's some sensor. I've got a '79 and I like the simplicity

.

<A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>

 

[HarryH3]

Start looking for vacuum leaks first. The Idle Air Control motor can only do so much to restrict air from entering the engine. Once it's closed, it's closed.

Air entering through leaks can be enough to raise the idle speed.

<font color=black>HarryH3 - '75 K5</font color=black>
<A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>

 

[UseYourBlinker]

Isn't living in Cali a b!tch? Smog laws, Ha I spit on them....

<font color=blue> Yesterday was history,tomorrow is a mystery,and today is a gift. -Taproot- </font color=blue>

 

[sarazk5]

What part of cali are you in? I have a mobile mechanic rebuilding my carb right now, in northern cali. He specializes in carbs, fuel injection and emissions, did smogs for years and worked for GM, if you can handle him being a little scarey looking, he is extremely knowledgeable.

 

[rampage]

I live in Burlingame, just south of San Francisco ... and I don't mind scarey looking people, as long as he can get me to pass the test!

 

[elkboy]

Take a look at adjusting your TPS ( about 5 minutes with a multi meter). I had a bad one that was causing high idle speeds.

<font color=red> Elkboy</font color=red>

 

[muddin4fun]

Okay, I checked into this for ya. There is a solinoid on the throttle body that controls the idle. Usually called an idle speed solinoid. It is either sticking, faulty, or getting a bad reading from a sensor. The trick is to figure out which thing it is, but that might help narrow it down. It sounds like it's sticking which would mean you need to replace it.

<A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>

 

[rampage]

But wouldn't a bad solinoid also make it idle fast when in gear? It is idling at 800rpm when in gear but at 1400rpm when in park.

 

[muddin4fun]

I dunno. There's no tellin'. You might check into sensors that that solinoid runs off of. There's no tellin' what those things are telling it to do. Just my .02. I'm not really great at TBI. Well, not really good....well....I suck at TBI. I don't know which sensors it runs off of. Man! I need to shut up! I'm confusing myself! I'm just passing info along from what I heard somewhere else.

<A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>

 

[rampage]

I welcome any and all advice .. 1st, 2nd and even 3rd hand info. I'll be checking all the suggestions as soon as I can ... and get back in touch with the winner of the prize money!

 

[jarheadk5]

I'm thinking an Idle Air Control valve problem, or a Throttle Position Sensor problem. Maybe a leaking throttle body-intake manifold gasket?? I think you can spray a little carb cleaner around the base of the TBI and if the idle jumps up, you've got a leak. Here's one from left field... the Park/Neutral switch. My Haynes says the switch controls a few things and problems with it can cause "idle qualith will be adversely affected".

Semper Maintenance!

 

[rampage]

I'll try that card cleaner trick.
I don't think it's the park/neutral switch because the diagnostics readout indicates that it's not in gear, but ya never know!

 

[ChevyCaGal]

You ever consider it's the person doing the test? Two years ago I took my Blazer to a place...failed, guy wanted bucks to fix it. I got frustrated and left. I called a friend who does engine work and had him look at it to see if he could do the repairs cheaper. He asked me where I took it and told me to take it to another place. It passed there no problems. I am not trying to say anything bad here...but this first place got shut down here recently (I drive past it everyday going to work). I think they were BS'ing folks and got caught.....might wanna check that out for you as well.......

"I love the sound rice burners make when ya run over them"

 

[Nrose07]

Well since I haven't seen this posted yet so I will. Idle in park 750, in gear 600.
With your handy dandy little scanner hook it up when your Blaazzer is cold, start it up and watch your scanner, when the computer goes into closed loop operation see if your idle changes. If the idle dosen't change or at least by the difference you describe look at these areas. 1.Oxygen sensor, have you replaced? No, do it. 2. Check your exhaust manifold heat exchanger tube valve located in your air filter assembly. See if during your driving is becoming stuck in the open position, sucking in hot air. 3. Is your power brake booster developing a leak after some consistent use (after driving around for 30min)? 4.If you are still stuck find a deq place close, drive there, park, through a bag of ice on your motor, sit, sit, sit some more, motor cold? Go in have them test it, and hope they get done before your high idle shows up. Hope this helps!

Displacement, cubes, and did you say you drive a riceburner???

 

[Blazer1970]

If I recall right, there is a separate passage in the top of the throttle body where the air that goes through the IAC comes in. While the engine is idling high, you should be able to just put your hand over that passage, and block the air flow. This will tell you real quick if it is the IAC that is causing the problem. The passage is at the rear passenger side corner of the TB, right above where the IAC screws in. Otherwise, look real close for other vacuum leaks.

Tim

70 Blazer CST 4X4 350 SM465 NP205
87 Burb 4X4 350
01 GMC 2500HD 4X4 Duramax/Allison

 

[rampage]

ChevyCaGal : That's what I thougt at first too because before the guy did the test I had to wait a while for him to show up (maybe he was late to work that day), and I thought my engine cooled down too much. But when I got my diagnostics scanner it confirmed exactly what he said ... idle at 1425rpm. But I do think that they were going to rip me off with the repair bills ... $90 to hook it up to diagnostics scanner, 3 hours labor and a possible $250 for parts ... yeah, right!!! Do I look like an idiot?