My '86 is Iroc is having some problems. First, let me list what I have done so far:

Distributor cap
Rotor
Plug wires
Spark plugs
Oil and filter
Transmission fluid/filter
New 195 degree thermostat
Radiator hoses and system flush
New harmonic balancer
Cleaned IAC
New gas cap
New fuel filter
New air filters

The car pulls strong, but when I come to a stop, it will want to die, if I was driving it hard. If I rev it once, the idle will go up to maybe 1200-1500 and then settle down to 1000 and stay there. Some times it will just idle rough at 750 or so and then go to 1000 and level off there. I cleaned the IAC, but I can't adjust it due to the fact that the idle won't go any lower. The idle screw is actually backed off all the way. The engine just idles at nothing less than 750. Huh?

I just replaced the spark plugs today. #8 had light colored carbon bridging the electrode to the ground. What's up with that? The new plugs and wires did give a performance boost.

When I turn my turn signals on, the battery meter moves with each blink. The car turns over fine, but when I hit the lights, brake, or turn a turn signal on, the meter drops a volt or so (temporarily). During the day it registers at what looks to be close to 15 volts, but at night with the head lights on it will show 13. I've just included this just in case it could in some way have some effect on the other issues.

I guess the temp gauge has a 100 mark, one above it, then a 220, then another blank mark, then a 260 or something (I don't know how else to describe it). While driving, it stays right around the second mark up, the one in between the 100 and the 220. When I have to stop and idle for a while, the needle will go up in the 230-240 range. Is this normal?

The fuel the tank seems to build up pressure. It doesn't happen much, but it does happen. I will start smelling gas and I'll notice some surging when taking off from a stop. If I remove the gas cap, there is enough pressure to have it actually push into your hand. If I let it vent, it seems as if it could vent for 15 minutes. I installed a new fuel filter, so we will see if that had anything to do with it, though I'm not sure how it could.

What kind of gas mileage should I be getting? When I'm nice to it, I get around 13.5. When I'm mean, I get around 13.5. I do a lot of around town, but it's not a "congested" around town. Don't get me wrong, I wasn't expecting economy, but if I'm going to max out at 13, shouldn't I get around 11 when I'm flooring it a good part of the time? We will see if my gas mileage will change now that I have new plugs in it.

I've been trying to figure this out, but I can't . I don't want to bother anyone with all this crap, but I have to figure this out. I appreciate any help or advice. Thanks.

 

i have heard having a bad head gasket will do this, but i dont know automatic's very well, so let some other people help you out on this one

the idle speed seems normal, mine idles at 800 with a t56, sometimes it will pause at 1000, then in a few moments idle down to 800, turning thr a/c on makes it increase idle speed

^ thats nothing out of the ordinary

^ temps seems good, i have a 160 degree t-stat in mine, but factory these things ran HOT (220+ i believe)

^ i get ALOT more pressure in my tank than any newer car iver ever been in, but its only a few seconds at most untill its released when i open the tank, maybe your charcol canister ( front, drivers side where the battery would be on the driver's side) is clogged? or a line to it?

^ u posted in the tpi section, so i assume ur tpi, and a 305? anyways, with tpi, 305 or 350 you should be doing better than 13.5 especially ith all new ingnition, i get 18-22mpg with a fairly built 350 tpi

^ the forum is here to Ask questions! hope i helped some, and

 

Some of your symptoms point to what happened to me prior to a "no-start" fiasco. Mine ended up being the injector switch fried closed and making the injectors stay on all the time. Ran great when running hard but idling sucked and starts had strong gas smell. New ECM fixed mine like brand new. Check out all the stuff I done and see if your voltage checks are similar.

https://www.thirdgen.org/forums/tpi/...off-major.html

https://www.thirdgen.org/forums/tpi/...rt-up-gas.html

https://www.thirdgen.org/forums/tech...-problems.html

 

Thanks to both of you. I appreciate the help. The car has a 305 with tpi. The car's symptoms are funny, because when it wants to die it will go down to 500-600, but then it's like the computer finally decides to bring it back up so it will stay running. Sorry I forgot to mention that when it does go low it goes down to 500-600.

Thank you for the links, tinyman. Man, I hope I don't have to go through all of that to figure this thing out! I know what kind of stress you went through. It sounds EXACTLY like my Eldorado.

I thought about the charcol canister.... I can get a new filter for a couple bucks, so I'll probably do that next (and check the lines). I just have to make sure the Black Widow is gone from under the windshield washer reservoir .

I was hoping to get at least 15, though I'd kill for 17-18 (not expecting it). Gas prices are going back up....

How do I read codes? I mean, I know that you jump the A and B terminals, and I know about the code 12 thing, but if there is a trouble code, how do you know that 4 blinks or something means a 43? I have a Chiltons but it's not helping much.

The Chilton's may not be helping much, but you guys are and I appreciate it. Despite these issues, the car is in real nice shape. The previous owner did install a new crate short block, probably around 5,000 miles ago. It's a fun car to drive. Thanks for your help!

 

jump the terminals, turn the key forward, itll pause, blink, pause, blink, blink. That means 12.

so 43 would be blink,blink,blink,blink(pause) blink, blink, blink
get it?

 

when my berlinetta's headlights would dim with every signal blink, i cleaned all the grounds and contacts on the harnesses going to and from the batt and the alt, it helped that. just a though

 

I'd check the charcoal canister for proper operation - they don't really clog so much as the valve fails to open properly, the gas cap, and the pressure relief valve for the gas tank down by the rear axle.
While you're down by the axle check to make sure you're not missing any heat shielding that goes between the exhaust and the fuel tank. Missing heat shields can cause the fuel to overflow like you describe.

 

Thanks for all of your help, everyone. Master_disaster, thanks for clearing that up for me. I checked for codes and there aren't any. When I bought the car, the ses light was intermittent. After fresh fuel (sat for a while) and a bit of driving, it went away.

85berlinetta2.8, thanks. I'll fool with the connections and see if it won't help any. It doesn't seem to be causing a problem, but if I can make it better, why not?

305 sbc, thanks for the help. Can a spray some WD-40 in the valve and fool with it a little with a little vacuum and see if that won't clear it up? I'd just go and buy a new one, but I would like to be sure that that's the problem. I use to just replace things in the Caddy when I suspected that they were the problem. Where did that get me? Usually no where. While I was under the car the other day, there was a large heat shield in between the tank and the exhaust. I have replaced the old vented gas cap with a new one.

If I drive the car normally, it won't build up pressure for quite a while (maybe 30 miles or so). If I drive it hard, it takes very little time for it to build pressure.

I filled up and I got around 14.5, rather than 13.5. I replaced the fuel filter during that tank and the new spark plugs and wires had been in for around 30 miles or so. Did those plugs/wires make that big of a difference? I mean, I could see 15 on the next tank.

Well, Rockauto sells the valve for around $28 and a new filter for the canister for like .83c. I'll be more than happy to replace them both if I can be sure. Thanks for all of your help. The car hasn't developed any true "new" problems in the 1000 miles that I have owned it, while the Eldorado cost around $1 a mile with everything I did (10,000 miles.....). I'm hoping that it will be a decent car. Thanks.

 

Ok, so I removed the littile valve and checked it out with a small, hand-operated vacuum pump. The valve that I'l talking about looks like this:
http://shop.oreillyauto.com/ProductD...pe=760&PTSet=A

It opened and closed properly (well, I guess properly... it held vacuum and opened the passage way so I could blow through it). When I removed it,gas came out of the line. Not out of the vacuum line, but out of the vapor line to the tank. Is that right? Should gas actually pour out? I thought that this was a VAPOR canister . It poured out and then line going to the tank gurgled.

Maybe you were referring to this valve:
http://shop.oreillyauto.com/ProductD...0&PartType=760

This looks like the one that's mounted on the canister, rather than the other that is suspended from three lines away from the canister. You can only see the top of the one in the canister, so I'm not sure if that last valve is it or not.

Well, I bought a new filter just in case, but I doubt that it will fix anything. Can I check my pressure relief valve near the tank? Thanks for the help.

 

You should have your radiator serviced at an experienced radiator shop every two years or less i do mine one a year around the first of January to keep it from being clogged. the charge problem sucks but i agree not unusual... I've herd steping up to and 100 amp alternator helps alot...

 

Thanks crmmaj9. I do need a professional flush. I did it myself, but the coolant still has a very dark color to it.

I actually removed the cap today and it sprayed fuel all over me. It ran pretty crappy while I was out as well. I think that the idle problem and this pressure issue could be linked. Any ideas on what I should do first? Gas actually will come out of the line going from the valve if I remove it. Any ideas? Thanks.

 

I don't know anything else that will do that besides something heating the gas tank.

 

Ok, thanks. Assuming it's not raining much tomorrow, I will have to jack it up and inspect that area to make sure that heat shield is completely there. It does have a cat-back exhaust (I believe) with a large flowmaster right under the tank. Thanks.

 

Well, I checked under there and the heat shielding is there. I have a pick-n-pull junk yard right near my house, so I may just run over there and pull a couple parts for the evap system, you know, to see if anything fixes it.

I replaced the IAC yesterday and that pretty much fixed the idle problem. It at 750-800 smoothly. It will go to 1000 at times, but like I say, it's smooth .

Ok, this may make me look a little dumb, but I have a simple question. On the center console, there are the two window switches, a hatch release switch, and some other switch. What is that other switch? Like I say, I feel dumb asking this, but I don't have an owners manual and I've been searching around a bit to figure it out. Thanks.

EDIT: Wait, could that be the rear wiper switch? Mine is missing the motor.