1987 Chevrolet 350 tbi high idle

[iamtherealJayy]

The gauge is still getting above 210 it got up to the 3/4 mark before it dropped ive been keeping up the coolant because the truck stalled and coolant over flowed. Been squeezing upper radiator hose and it bubbles a little but I figure that’s just because when it drops it creates air under the snout. There is steam coming out of the radiator snout. I unplugged the est? I believe it what you all called it and slightly advanced the timing so it idles at 800 right now instead of 650. Everytime I touched the throttle it would suck down coolant then overflow when I let off.

 

[iamtherealJayy]

@AuroraGirl this is the belt oreillys gave me for the truck, I said what belt I needed because my alternator belt squealed so I replaced it. It’s not original belt it may be a newer one that’s just same style/suze

 

[Hugomartin]

oh god.

Please pay someone to look at yours and stop touching screws. your crankcase is pressurized from either combustion blowby/things escaping into the crankcase or there is a blockage somewhere in the ventilation that allows pressure to both enter and exit the crankcase.

Thanks where should I look for areas or sections of tubing for proper ventalation?

 

[AuroraGirl]

The gauge is still getting above 210 it got up to the 3/4 mark before it dropped ive been keeping up the coolant because the truck stalled and coolant over flowed. Been squeezing upper radiator hose and it bubbles a little but I figure that’s just because when it drops it creates air under the snout. There is steam coming out of the radiator snout. I unplugged the est? I believe it what you all called it and slightly advanced the timing so it idles at 800 right now instead of 650. Everytime I touched the throttle it would suck down coolant then overflow when I let off.

that behavior is rather normal on the coolant part. if you arent getting more bubbles and you have the thermostat opening and you squeezed hoses, its time to cap it and makesure overflow is rready too. also, 3/4 may be a result of your sender unit on the head, thats where you want to verify with a thermometer on the area around the engine sensor or you use your ALDL. Your ALDL gets basic data from the ECM but you should make sure the wires behind the connector arent hit or damaged. otherwise its a real low likelihood your software supports an 87 chevy truck tbi, but dedicated ALDL stuff would youd think. what program?

 

[AuroraGirl]

Thanks where should I look for areas or sections of tubing for proper ventalation?

i would start a separate thread so your posts dont get lost in the ones for his tbi. you can tag me with @ symbol. but if you do that, first post pics of your engine bay. 3 of them, 1 from the left, right, straight on. capture whats behind the carb or tb with the left/right in the photos.

 

[iamtherealJayy]

@AuroraGirl truing to use TunerProRT it’s what was recommended on the website for the aldl cable.

 

[iamtherealJayy]

Also, I could feel the upper radiator hoses like hmm? Pulsating? What the hell could that be? The thermostat finally opening and coolant flowing through?

 

[AuroraGirl]

Also I can’t get tuner pro to recognize my vehicle ive got com all set right it just won’t connect to vehicle

TunerPro doesn't seem to detect my ALDL cable. What's wrong?

Although TunerPro does automatically detect emulation hardware, TunerPro doesn't automatically detect ALDL cables (regardless of the type you use, including the Moates ALDU1). You need to specify the COM port your cable uses and set the cable type to Max232/2-Transistor.

What is ALDL/OBDI and what do I need to make use of it with TunerPro?

ALDL (Assembly Line Diagnostic Link) is a datastream used by the cars management computer(s) and diagnostic equipment. OBDI (or OBD1) stands for On-Board Diagnostics - One (there is also OBDII). Both of these combine to create a method by which a mechanic can acquire, change, and monitor information related to a vehicle's operation. Typical ALDL data streams contain information about the vehicle's speed, fuel delivery, spark operations, airflow, and mixture. There are generally two "speeds" at which OBDI vehicles communicate - 8192 baud (bits per second) and 160 baud.

TunerPro RT (currently) can communicate with 8192 baud OBDI data streams. In order to make use of TunerPro RT's ALDL communication ability, you will need an OBDI ALDL cable in either the 2 transistor or MAX232/233 IC configuration. These can be obtained through a couple of sources. See the Links & Resources section of this web site for information on where to obtain these.

You will also need an ALDL datastream definition file for your particular automobile. Included with TunerPro RT is a definition for the 1227165 ECM (typically found in GM '86-89 V8 applications). Your car may require a different definition. If you have your car's datastream information, you can create your own definition using TunerPro.

Once you have your cable, operation is as simple as connecting the cable to the vehicle following the cable manufacturer's directions (some cables require external power, some don't) and running the ALDL tool within TunerPro RT. Most automobile OBDI connectors are found under the dash of the vehicle. If your vehicle requires a 10k resistor to initiate 8192 diagnostic mode, be sure this is connected.

TunerPro and TunerPro RT - Professions Automobile Tuning Software

www.tunerpro.net

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I have very little understanding of any of this but it may be helpful. I found that screenshot for the definitions of ecm stuff for trucks, and it looks like depending on your engine (RPO code for your engine known?) you may have a different pin for data maybe...?

 

[iamtherealJayy]

I can look into it more, I just read the downloads and downloaded what it told me to then watched a tutorial. Note: once I reinstalled the radiator cap I can hear bubbling for a second in the overflow tank, is this fine?

 

[AuroraGirl]

I can look into it more, I just read the downloads and downloaded what it told me to then watched a tutorial. Note: once I reinstalled the radiator cap I can hear bubbling for a second in the overflow tank, is this fine?

it means the system has built pressure exceeding the caps rating and its purging to the overflow or the pressure its under possibly stopped boiling and its drawing in fluid as its made to. ithink. sounds fine to me.

 

[iamtherealJayy]

The trucks is running very rich right now it sounds like, after a few seconds of idling you can hear pops from the exhaust tip, it does start to stumble for a second then smooths back out. I’m working on getting a timing light to get it set at 0.

 

[iamtherealJayy]

Was talking to dad about the truck and he pointed out quite a bit of steam and moisture coming out of the exhaust, I’m hoping that’s just because it’s like 40° today and not a cracked head or blown head gasket.

 

[AuroraGirl]

Was talking to dad about the truck and he pointed out quite a bit of steam and moisture coming out of the exhaust, I’m hoping that’s just because it’s like 40° today and not a cracked head or blown head gasket.

well if you had a lot of running and turning off and things never got up to temp etc etc thats very possible to have a moisture buildup to evaporate.

 

[iamtherealJayy]

The truck after a few starts did settle down and quit the popping that was occurring. The idle seems too slow in my opinion, the truck doesn’t sound like it’s running at full potential, I feel like 750 would run better. The truck kinda shakes at 650 and if you accelerate and let off it bogs and runs rough then smooths back out to 650. The new IAC came in today will install in the morning just as an extra insurance.

 

[iamtherealJayy]

Tomorrow I plan on driving the truck down the road and seeing how the temperature acts. It was getting warm today but never got to 260 as far as I saw while trying to get air out of the system.