1981 corvette idle speed

[alexdrastico]

Hello guys,
I've an idle speed problem with my car.When i start the engine the idle speed is about 650-700 rpm but when i lightly touch the gas pedal the idle speed goes immediately to 1000 rpm!!!For to lower it i've to push the gas pedal with a single blow and the idle speed return to 650-700 rpm,everytime i acclerate it's the same thing.What's it?

P.s. excuse me for a poor english

 

[Peer81]

Is it only with a cold engine (choke)? Or also with a hot engine?

Groeten Peter

 

[alexdrastico]

Always.

 

[Hib Halverson]

I'm going to guess there's either the throttle linkage, the primary throttle shaft or the TPS sensor.

What part of Italy do you live in?

I have friends in Milano and Firenze, both members of Corvette Scuderia Italia, who work on Corvettes. They might be able to help you.

 

[alexdrastico]

I live in Sardinian,an island of Italy.The car have this problem only when the engine is on,when it 's off the gas pedal works free!

 

[GerryLP]

Talk about distance troubleshooting...:L

Alex, allow me to first say welcome to CAC my L81 brother!

I would first ask you to remove the air cleaner assembly off the top of the carburetor to ensure that you have a clear view. Pay close attention to where the vacuum hoses connect and if your car still has the smog label (similar to this one

, then try to get a solid image in your head about how the hoses are connected. This will prove important in a bit.

So, now on the right side of the engine (passenger side of the car), look at the choke housing (that big round black cap on the side

Now loosen the 3 screws that hold the funny looking washer on top of the black cap, and rotate the cab while observing the choke plate (the cover on the air horn opening and closing.

This will let you know if, 1st - the spring seems to be in working order (i.e. the plate does not move then it is broken or disconnected -most likely broken). And when you first rotate the black cap, see how much travel you get clockwise and counter-clockwise. At any rate, the line or bump on the circumference of the cap should be aligned within two notches of the center (and bigger) notch on the choke housing).

Let us know what you find.

GerryLP:cool

 

[alexdrastico]

Thanks Gerry LP,today i'll do the work.

 

[alexdrastico]

Bad news from the carburetor,it's a screp iron!!!1st the primary throttle shaft is hard to drive,maybe there's rust inside!!!2 nd it's impossible to remove the chocke system ,cause it's close to the carburetor by rivets!!incredible,i think is better to buy a new carburetor.Somebody know where to buy it?Thanks

 

[JohnZ]

Hang onto that carburetor - it's the original! Someone will chime in with the name of a Q-Jet rebuilder that works on the E4ME electronic carb.

 

[GerryLP]

Alex,

Yeah...the choke housings came out with rivets on them. It was the way GM at the time was making sure to show if someone had tampered with the component (i.e. when new, and you took it to the dealership for a choke problem, then if the rivets were removed, it would have voided the warranty :ugh).

I will try to scan the page in the manual which shows you to drill the rivet heads (basically, you get a larger diameter drill bit than the inner diameter, and carefully remove enough material of the rivet head to remove it. It shouldn't take more than a 1/16 of an inch.

As far as the linkage is concerned, the secondary throttle plates lock-out is probably engaged. The lock-out prevents the secondary throttle plates from opening if the choke plate is in the semi-closed position over the primary side. See if while rotating the choke plate open from closed position, and by hand, the secondary linkage is released or operable. Try not to use an overbearing amount of force. But they should move with enough force to overcome the throttle return spring by hand.

By the way, if the lockout is engaged, this most likely indicates a broken heated element spring inside the choke housing. These are available from many catalog and parts warehouses.

GerryLP:cool

 

[alexdrastico]

Hello GerryLP and thanks for your help.

how can you see from my pics,the choke linkage it's completely lock out by a plastic band !!!!So it does'nt move and the choke plate is open all the time.

 

[alexdrastico]

Where can i buy an original E4ME carburetor for my '81 Corvette ?This is a californian aut. model whit the carburetor vin # 17081218.
Thanks

 

[Dunzvett81]

Ecklers sell them, I think around $400.00

 

[Yoda]

Where can i buy an original E4ME carburetor for my '81 Corvette ?This is a californian aut. model whit the carburetor vin # 17081218.
Thanks

Give Stingray6974 a shout or contact him via member search or here is Mike's website Click Here. Mike is one of the MORE Knowlegable folks when it comes to C1's ~ C4's and he is a GREAT Corvette Guy too.

Oh... and one of the best QuadraJet's mech. I've ever met

Good luck and tell Mike old Yoda (Bud) says

Bud

 

[GerryLP]

Alex,

That looks to me a like plastic zip-tie or something. That is not part of the carb.

Why don't you try to remove the carb (just keep track of the connections (vacuum, electrical, air) and take another picture from below...that looks too weird.

But like Yoda said, Mike can refurbish that carb for you in a jiffy, and this will help you keep your L81 stock and like it left the factory...almost

p.s. I wonder if someone had already replaced the carb, but failed to remove all the packaging clamps off of it? Or worse, some one is trying to make you part of an statistic...:L

 

[alexdrastico]

Hello GerryLP
I found in Italy someone that have removed all the electronic fuel system ,so next week i''ll fit it on my car to try if it's in good condition!Otherwise i'll buy one rebuild from ZIP Corvette,do you know how it costs in Italy a Rochester carburetor for my baby........850,00 €!!!!!!About 1000,00-1200,00 $, amazing!The black plastic zip lock the choke system,so it doesn't work.This is why my car ,when it's cold,doesn't start immediatly but after many trials.

 

[GerryLP]

Hello GerryLP
I found in Italy someone that have removed all the electronic fuel system ,so next week i''ll fit it on my car to try if it's in good condition!Otherwise i'll buy one rebuild from ZIP Corvette,do you know how it costs in Italy a Rochester carburetor for my baby........850,00 €!!!!!!About 1000,00-1200,00 $, amazing!The black plastic zip lock the choke system,so it doesn't work.This is why my car ,when it's cold,doesn't start immediatly but after many trials.

Alex,

Your choice, but what I am telling you is that the black zip-tie should not be there, and if you placed it yourself, then you don't have to deal with that. You can purchase the choke repair kit and we can help you get it fixed. I believe that the bi-metallic heated spring is broken, so a couple of things are happening: 1) It is engaging the lock-out, and 2) it is closing the primary side choke plate. You'll have to drill-out the rivet heads like I explained to you a few posts earlier, and install the new choke kit.

850 Euros is over $1,000 dollars American. You can buy two of those from Ecklers or other catalog store. If they don't ship it to you, then let me know, and you can ship it to me and I'll send it to you from my address. All you have to do is reimburse me for the shipping through Paypal (plus the nearly 4% they'll charge me for your reimbursement). You can send me a couple of american cents to verify that your paypal account is working if you decide this option. Let me know.

But I am still rooting for you to repair it or fix it yourself, you know?:ugh:eyerole

GerryLP:cool

 

[Dale Huff]

Would you happen to have a better image of the label? Im needing the idle speed settings.

Thanks.

Talk about distance troubleshooting...:L

Alex, allow me to first say welcome to CAC my L81 brother!

I would first ask you to remove the air cleaner assembly off the top of the carburetor to ensure that you have a clear view. Pay close attention to where the vacuum hoses connect and if your car still has the smog label (similar to this one

, then try to get a solid image in your head about how the hoses are connected. This will prove important in a bit.

So, now on the right side of the engine (passenger side of the car), look at the choke housing (that big round black cap on the side

Now loosen the 3 screws that hold the funny looking washer on top of the black cap, and rotate the cab while observing the choke plate (the cover on the air horn opening and closing.

This will let you know if, 1st - the spring seems to be in working order (i.e. the plate does not move then it is broken or disconnected -most likely broken). And when you first rotate the black cap, see how much travel you get clockwise and counter-clockwise. At any rate, the line or bump on the circumference of the cap should be aligned within two notches of the center (and bigger) notch on the choke housing).

Let us know what you find.

GerryLP:cool

 

[GerryLP]

Would you happen to have a better image of the label? Im needing the idle speed settings.

Thanks.

I tried uploading a pic, but would have to massage it smaller in size. How about if I post the info?

my label says:

catalyst. Transmission
air/BPEGR/QRC/OC
LOW ALTITUDE CERTIFICATION. AUTOMATIC

TIMING (deg BTC @ RPM). 6 deg @ 500 (dr)

SPARK OLUG GAP (IN.). 0.045”

IDLE SPEED SCREW (RPM)
(SOLENOID INACTIVE). 500 (dr)

IDLE SPEED SOLENOID (RPM)
(SOLENOID ACTIVE). 600 (dr)

FAST IDLE SPEED (RPM). 2200 (P) OR (N)


just make make sure your wheels are blocked. And not just one. I have always done as a minimum two wheels, diagonally opposed (blocked in front and rear of tire).

GerryLP :cool