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Discussion Starter #1
Seems like cold weather is a trouble magnet...anyway I'd like some advice on a few issues regarding my 86 IROC LG4...

First of all, I've noticed on cold or damp days, until the engine warms up, there's a knocking or tapping noise, usually only hear it if I hold the RPMs around 2000-2500. It's hard to describe the sound, it sounds almost like someone's knocking on the firewall. Oil level/pressure is good...thought it might just be some mechanical part wearing, a rocker or something... any similar experience?

Second, but cause for more concern, I've been having problems with the engine stalling out or failing when I'm driving. Seems to have been happening since the weather turned cold. I'll be driving and suddenly I get no response from the accelerator.

Usually I can drift into a parking lot and the engine comes back to life after a few seconds in Park, but the other night it stalled out completely...I nearly hit someone cuz my power steering failed too. My guess was some kind of gas line freeze or vapor lock, cuz even when it did stall I could start it right back up. I put some Prestone winter fuel treatment in the tank, but it did it to me again today. What do you think? Water in the gas? Fuel pump starting to go? Related to the rapping noise mentioned above? This car is a daily driver, I need to keep it healthy.

Thanks for any info.
Mark
 

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Don't know about the knocking, but the stalling may be from carburator icing. Try removing the hose that goes from the air filter to the front of the car. Next check the door inside the air filter snorkel to see if it is closing. It should close on cold days so the engine takes in warm air off of the exhaust manifold. You might have to tie it closed and drive it like that durring cold weather and untie it when the weather gets warmer. This may not be your problem, but I've had 2 trucks and 1 car that did this. It is usualy worse on damp cold days.

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'69 RS/SS396 pro street
427/4spd/9"
 

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The knocking may be coming from the fuel injector area. I'ts a good chance that you have 1 or more bad injectors. Have your injectors tested, but don't take it to dealer! They will screw you easily for $50+. It happened to me last winter. They told me I had 5 bad injectors. I decided to get a second opinion, and found out I only had one bad. But I opted to change all of them since it was apart. Also if its your injectors, don't get them at a dealer. They charge $100 each, I got mine at summit for $450 for all of them.
 

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Discussion Starter #4
Gear Head:

I checked the "THERMAC" door on the intake snorkel...when the engine is running the door is open to the heat stove underneath. Unless for some reason it's closing too soon, I don't think that's it. Do these things close often close before the engine warms up? Also, my heat riser tube isn't clamped; it's just sort of positioned there. I don't know if this'd make much of a difference...any other thoughts?

Rods92: It's a nice thought, but the LG4 is carbureted, so there are no injectors...still, this worries me. If injector problems can cause the noise, could not enough fuel getting to the engine on a carbureted application also do this? Should I worry about losing my fuel pump with this combination of symptoms?

I'm also half a quart low on oil, gonna fix that straightaway and see if it helps.


Thanks for all help.
Mark
 

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Discussion Starter #5
Eerie coincidence...whenever the engine starts to stall out, it happens at the same place on the road. It's this place where I make a right turn onto an incline. Funny thing is it always happens on an incline, which suggests to me that it may be water in the tank...am I right? Or is it possible that it's just at that point the thermostat opens or something else goes into closed loop mode or something like that?

Also, if it stalls or almost stalls, there's mad bog if I try to accelerate.

Any ideas? Thanx.
Mark
 

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Discussion Starter #6
Another clue??? I had to pull the car out of the driveway a minute ago, when I pulled back in, it briefly spit what looked like a nice mix of water and black carbon on the driveway. Isn't doing it anymore, but I wonder if it might help determine what's wrong.

Mark
 

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#1) I'm going to assume you have an automatic trans. If so, check your converter bolts. Seen this happen before.

#2) Check the float level in the carb. That can cause a flooding condition if it's become water logged.

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67 Camaro LS6 454/TH400/12bolt 3.73
1989 TransAm 5.7L WS6 W/all the options

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Discussion Starter #8
Hmm...got underneath today...turns out my Early Fuel Evaporation valve on the exhaust isn't connected to a vacuum source. Without it, it may be causing my carb to ice up since I wouldn't be getting any heat to the carb till the engine warms up. I'm assuming this is only step 1, but does anyone know what vacuum port to connect this thing to?

BTW, where are the converter bolts, and what am I checking for...don't know much about transmissions.

Mark
86 IROC LG4
 

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In most cases there will be an inspection cover that you will have to remove. This will be two or three bolts. Once removed, you are looking for the bolts that connect the convertor to the flexplate.

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67 Camaro LS6 454/TH400/12bolt 3.73
1989 TransAm 5.7L WS6 W/all the options

www.geocities.com/akfourme/
 

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hi,
I am having the same problems with my 82 camaro that you are.If you find out why that water and black carbon is coming out from your car,please post it.my car also bogs down when I step on the gas(have you checked the acellerator pump?),the reason for my car stalling was becuase the automatic choke was not working correctly.
 

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Don't sweat the water and black carbon - that's perfectly normal for cold start; it's condensation in the exhaust system being blown out.

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JohnZ
'69 Z28 Fathom Green
 

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Discussion Starter #12
Okay well it's running again...someone suggested it might be an ignition problem. My ignition coil secondary resistance was reading kinda high so I changed that, the rotor and the cap just to be sure (cheap, whatever)...apparently when I did it I knocked it out of time...distributor nut was loose. May have been what was causing the problem in the first place. Since I timed it it's been running a lot better...still a little rough in the cold, but I'm starting to think that's normal. The Choke Pull-off seems to be working alright, I don't think there's gunk in the float needles or anything cuz the fuel pump still shuts off after a few seconds when I turn the ignition on before starting.

It isn't spitting black carbon anymore...still a lot of moisture coming out the pipes....I think it might've been bad gas that was stalling me out. I never fill the tank up with more than I need to get there and back a few times, so I was probably building up a lot of condensate...gonna keep an eye on it, just let it warm up a little more on these cold days.

Don't know how much more I'm gonna be driving it in the next few days...5-8" of snow due.

Leave it to winter to bring out the best in a good car and the worst in all the others.


Thanks again for all your help.
Mark
 

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If there's any time you want to keep your fuel tank over half-full all the time, it's in the winter - otherwise you're looking at possible frozen fuel lines and corrosion in the rest of the fuel system from all the moisture.

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JohnZ
'69 Z28 Fathom Green
 

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Discussion Starter #14
Could that be my problem?? The car stalled out again...virtually without warning. Now it's running rough again. This is ridiculous...

I guess I'll check my fuel filter tomorrow...if it looks OK I guess I'll try to tune the carb...

That's all I'm doing at this point...guessing.

I hope it's not anything too serious...I can't afford to buy new valve components or anything.


Mark
 

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Discussion Starter #15
Alright...put a new set of plugs in...turns out I had fouled out at least one cylinder...a lot of black carbon built up on the plugs. Running pretty good now, a little sputter here and there. I'm planning on taking the car to the shop where I got the carb rebuilt last year, have them check out the float levels and idle mixture.

Changing plugs is no fun.

Mark
 

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Discussion Starter #16
Since I've been buggin you all for help I thought I'd update you on my status...I put new plugs and wires on my IROC yesterday...I had the cuts and bruises to prove it.
Also re-timed it...it seems the distributor was loose again. Don't know what the overall problem was, but it seems like it's gone...took the car out today and it didn't stall or chug or foul or anything.

Only thing now is...I feel like I'm getting some hesitation in the accelerator. Also, I'll occasionally get this weird miss or backfire or sputter or something at about 3000RPM. Usually goes away as the engine warms up. Is this just "old age," cold weather, or a set of symptoms that indicates something else? I just put in new plugs, wires, rotor, cap, and ignition coil AND timed it, so I've ruled out ignition trouble.

Maybe it's paranoia setting in.


At least it goes now...I need this car to last till I get out of college and then I can sit it in storage somewhere until I have the money to put a REAL engine in it. Until then, I appreciate your feedback.

Mark
 
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