Ecu? Aldl?

[85Silverado]

I have a '85 C10 Silverado and was curious if it has a ECU and ALDL and if so..where? I had a '85 Cutlass that had them so I don't think the computer controlled stuff would be left off of the trucks would it? I know I have a Computer controlled Q-jet, but like another guy on here...I want to do away with all the smog crap. Thanks for any info

[Piston]

Depending on the production date you could have the C3 setup.
C3 (Computer Controlled Carburetor) which has a mixture control soleniod in the carb and relies on a duty cycle (dwell in voltage) to maintain a good Idle mixture.

Cutting that system out wont help your performance. It's only function is to control Idle mixture, it has no effect on off idle performance. This type system also includes the EST (Electronic Spark Timing) which could cause retarded timing if not working properly. If your going to cut the system out, you'll need to replace the Carb and Distributer. There is a simple trick of jumpering 2 wires on the 4 pin EST connector but its best to replace the dist' with an earlier model without EST control.

Thats alot of work for a very little performance gain.

Also, most trucks incorporated a Vent Soleniod in the carb instead of a Mixture controll soleniod. I believe the Federal emission models had the Vent system. One easy way to tell is look near the front of the carb on the left side. Do you see a 3 wire connector going into the body of the carb? If yes, its a C3.

[85Silverado]

I know I have a connector on the front of the carb, but i have a vacuum advance canister on the side of the carb...if it was CCC i would of thought I wouldn't have one of those....my cutlass surely didn't. I looked all over the cab for the ALDL but have not found it. Also...as far as I could tell....I haven't seen a check engine or SES light in the dash but i just got the truck not to long ago and since it isn't licensed yet I haven't spent much time in the cab...but I know there's not check engine light when the key is turned...just the brake and choke light come on.

P.S. I'm not really doing it for performace, I want to get rid of the smog junk to clean up the engine bay....I hate the snake pit of vacuum lines....makes it hard to source a leak on the front of the engine....I just rather have an engine that runs by itself without the eye of the computer watching over it..hehe

[Piston]

If its the C3 system, it WILL also have a MAP sensor, Coolant Sensor and 2 electrical plugins on the carb (1 top, 1 front), an anti dieseling soleniod, Oxygen Sensor and a TPS.

In any event, sounds like your set on cutting it all out anyway... so cut away lol. Buy a HEI without EST controll (4 wire) and a Carb without C3 and your set.

Make sure there are no emissions laws where your at....

[85Silverado]

It doesn't have a Oxygen sensor or TPS but it does have a plug on the top of the carb...not sure if it's a 3 pin connector tho...will have to look. Thanks again for the info.

[Piston]

I was suspecting that. It's the standard Truck system... Vent at the top of the carb. It does look alot like the C3 system (looking at the pluggin at the top) because its a 2 wire blue connector. This type of system wont be affected unplugging the connector and leaving it off. This soleniod allows Venting while off.

[85Silverado]

So that means I have no ECU? Would I still need to get a new distributor if I take all the smog junk off? Thanks for all the info!

[Piston]

You have a EST or also known as ESC module. It's just to the left of the glove box near the firewall.
You can jumper the EST connector but I recommend getting the NON EST dist'. You can find them for $45-50 bucks OR better yet, get a performance HEI. Your cap/rotor/wires will work ok.

[85Silverado]

I forgot to put this in the other post.....There's no ALDL is there on this system?

[Piston]

Nope, there's no ECM... therefor no need for the ALDL (which is only a abreviation for DataLink connector)

[85Silverado]

Ok...Thanks a bunch

[swervin ervin]

The Electronic Spark Control (ESC) distributor only controls spark knock, nothing else.

Changing to a non ESC distributor

As far as the carb, 1985/86 Q-jets in U.S. trucks have dual capacity accelerator pumps. When the engine is cold, more fuel is needed for transition from idle to part-throttle. When the engine is warm, less fuel is required. Dual capacity pump solenoid (plug on top right front of carb) is activated by coolant temperature sensor (sensor in thermostat housing). At 170 degrees pump solenoid energizes, dual capacity pump valve opens and pump capacity reduces by about one-half.

So if you leave this wire unplugged, the pump will be in dual mode all the time. The solenoid needs to receive a signal from the sensor to open the valve.

[Piston]

DOH! You called that one right Mike. Here's a tutorial on this carb if anyone cares to read.

[85Silverado]

I'm probably just gonna convert mine for now. That's one thing down. Do either of you know the best way to remove the Air Injection System? Thanks again.

[Piston]

Yes, on the right side of the block just in front of the starter. It's actually in the Block Drain hole.

[85Silverado]

Sorry bout the edit....I wrote before I read Swervin's webpage..hehe But still would like to know the best way to remove the Air injection. Thanks

[Piston]

Well its ugly... but you can install brass plugs in the manifolds. Or swap them without a.i.r, or better yet, put headers on it.

[mckpaul]

Hey Piston, got a question on this same subject. My truck is an '84 Was wondering the same about it, is there an ECU? Since the motor has been changed (was originally and still is a 305) and all the emission stuff and no telling what else has been removed under the hood, is there a way to tell if there's an ECU? I know I have the electronic spark control, there is a knock sensor and a TIP IN vac switch on the firewall, but I suspect that's all there is as far as "electronic systems" so to speak. Any obvious tell tale signs under the dash or anywhere that would indicate I do or don't have more than just basic ESC?

[Piston]

Basicly the same would apply, if there is a TPS, MAP, Coolant sensor and Mixture control solenoid you'll have a ECM to control all this. If you only see a knock sensor (part of the spark control system) and a TIP IN switch (for the Overdrive) You will only have a spark control module and not an actual ECM.

[swervin ervin]

Do you have the ALCL (which stands for "Assembly Line Communications Link") connector under the dash on the left of the column? Do you have a service engine soon light? Do you have a O2 sensor in the exhaust pipe? If no to these questions, no, you don't have a ECU, only the ESC distributor. The only state that had a ECU was California, and I'm not sure what years had them there. The 305 California engine is a LF3, I believe. I do know for sure, if your truck had the LE9 engine, it only has the ESC and no computer. No LE9 came with a computer. All LE9 option code 305's were the ESC trucks.