Help! Engine Problems 86 Regal 307

[rtanner68]

Firstly, thanks for the ideas. It helps me out in forming my plan.

Heres the issues: sporatic operation. She has the inability to idle. After she starts she'll quickly loose idle and cough out unless you apply throttle preassure, even with that the engine runs like hell. Shaking and everything. The same symtoms, but they have deteriorated a bit to this. Now, 1 week ago I started her up and she ran perfect-- no ticking, perfect idle. She warmed up for 8 minuets, then went for a 4 mile drive- perfect like new 307.

I stopped at a store, and when I came out 6 minuets later and started her-- ticking was back and rough idle... but still drievable to get back home. I think we are looking for an elecrtical problem... bad sensor/ ECM information.

- Great compression... new plugs and I pulled them today... super clean no carbon build up.

With the current settings this car ran like new 8 days ago for 20 minuets.

Also side question: on the intake manifold there are 2 sensors in the front cooling passage, I know based o factory diagrams that the one on left is coolant temp.. but what is the one 2 inched beside it? Same looking terminal connectors for it. Thanks

 

[84dragcutlass]

Id say u have some bad lifters and perhaps a bent pushrod in there. Belive me been there done that. One second u think uve got it fixed then it runs like crap. The car can run better when cold but when it warms up a bit its terrible. My car wouldnt idle right either and most of that was due to the lifters just not bein physically able to do there jobs right. As u apply throttle it kinda forces the motor to accept more fuel through the compromised space in the valve making it run but just horribly. Ur situation sounds identical to mine. Even explains the ticking. Best way to find out id say just take the valve covers off and start looking for loose or bent pushrods, obviously the "rebuilder" didnt know much

 

[rtanner68]

Ok, Im stumped and need any other possible ideas. Here is the full discription of the problems, I do not believe then to be what has been offered. Maybe this might help for better diagnoses. Thanks to everyone for their understanding, as I am new this these "new" cars. 🙂

First specs: 307 with the CCC diagnostics and ECM control. Full on emissions system including the AIR pump. Compression is good, fuel system preassure & flow is good, ignition system should be good.
I bought the car, and drove it 6 miles to my garage. I knew about the car 2 weeks before buying it, and knew that it ran well, but had this single constant "ticking" that changed with RPM. It drove well all the way to the garage. Just that ticking.

Now a day later when I go to start it... perfect. No ticking, perfect idle. Drove for 6 minuets to the store, and before that it was isling in park for 7 minuets. Perfect drive. No noise, only a well tuned sounding engine. Upon starting it up again after 10 minuets in the store.... ticking, rough idle. Still, it was driveable back to the garage.

Now its idle was a bit off at times, but very driveable. Same here. 2 days later I finally get to diagnose the problem. Nothing.

I did the full tune up- plugs, wires, coil, cap, rotor, fuel filter, oil, and a new battery. She really needed these things. Then started her up... still ticking but same ok idle. She idled for 10 minuets, then we went for a drive. She drove well, but tried to stall out at idle when sitting still. Got back to the garage and got out, walked back to the car in 2 minuets, and shes dead.

Started her up, had to fight to get her in the garage as she didn't want to idle well. Now here we are....

She will not idle. You start her, she runs for 3 seconds and like gravity coughs out. She will not idle. If I give her gas and work with her, I can keep her running, but not on her own. Above 1,000 rpm she stops chugging and runs well enough. I bring her down to 700 rpm, and then let go.. she dies off.

Plugs are super clean, I did not change any specs or settings since that perfect noiseless drive that day, or the 2 drives before it. I checked the diagnostic system, it works. I replaced an old throttle position sensor and a coolant switch just for age alone today, of course no change.

Now like today, despite no idle.... she didnt tick for 3 minuets while I ran her. 5 minuets later she was ticking.
I should also mention that yesterday when I first started her, she did idle. Maybe about 750 rpm which is too fast, then about 1 minuet she incresed her idle. I reved her down after 3 minuets, and like a switch flick- no idle. Since then she hasn't idled, just starts and dies out in 4 seconds. I am thinking maybe bad ECM???

Its not oil starvation, and these engines are know for spun crank bearings. I believe its not the case. I also checked the vac lines, previous owner had a few unhooked that did not route to anything, but still I didnt change it. All proper hosing is there, with no leak as I can tell. I cant do a proper vac leak test as she wont idle. Its just out of the blue this bad all of a sudden. I could really use some help here.

Thanks again

 

[jae]

As with everyone else you have to start at the basics. If the previous owner messed up the reinstall there's no telling what he "left off", buggered up.

You have to start by getting the vacuum lines in order, routed correctly. Next I would try the sugestion of spraying the base area around the carb with carb cleaner - idle picks up / smoothes out you got a leak.

Next, with the erratic idle your carb my be shot, particularly the primary side. The float bowls may be bad / out of adjustment, the throttle shaft could be worn (one of the most common problems with a Q-Jet), and the idle mixture screws could be hosed. Possibly the M/C solenoid is bad too. These can cause hella issue - so don't put it past the carb.

If you don't know the ECM is mounted in the passenger-right kick panel. If you're justing getting a code 12 it's not setting anything hard, which would lead to as others suggested, possibly a vacuum leak or EGR problems. Are all the emissions tubes on the manifolds connected, did you reconnect the air pump? Not that these were the most sophisticated ECMs in the world but whatever's happening it's not consistent enough to set a proper code.

I'm not sure if the O2 could be causing this much of an issue.

Could the coil be the incorrect one? Did you remember the ground strap, the button in the cap? Was the cap replaced and if so what does the contacts look like? Is it a good quailty cap, what's the material of the posts? A lot of the cheap-a HEI caps use aluminum posts /contacts and they build up corrosion fast & heavy. Also, if the gound strap is not placed back in it can cause havoc too. Could the cap have a crack in it? This makes itself known especially on damp / rainy days. Nice, dry warm days engine will run like a champ, a little damp or rain won't run for anythign if at all. Could the distributor not be getting advance like it should?

In terms of the ticking does it tick when cold as well or just when it's hot? If the ticking raises and lowers with RPM I'm thinking with the rest that it's a lifter(s) going. How's the oil pressure? What type of oil do you have in her? A heavier weight may help but eventually you may have to open her open to find out. As suggested I would pop the valve covers and take a look. It could be one or more of the pushrods are clogged - had that issue with an Olds 350 swap we did to the '81 Cutlass years ago.

Good luck & keep us posted.

 

[thedoctorisin]

I had a similar issue with my 79 with a 260, I couldn't run the computer codes because it doesn't have one but i replaced the entire distributor and vacuum lines still ran like crap. I had a "professional" look at it and all he said was maybe vacuum related. I parked my ride for a little over a year and then started playing with it again... in my frustration i found an LT1 for a 100 bucks so i decided that would be a much cooler engine to work on. After i pulled the 260 i started pulling it apart a bit. it was a dried out manifold seal along the intake and block right by the firewall so i couldn't see or hear it leaking...

 

[joe_padavano]

As noted much earlier in this thread, get a factory service manual and follow the troubleshooting trees in it. Most mechanics want to replace the ECM first. In my experience, unless you've applied a voltage spike, the ECM is RARELY the problem. Yes, GM had some issues with quad driver modules, but I've found that even when you get a quad driver code, it is frequently triggered by an external problem. The other thing is that people want to throw parts at a car like this without doing any basic troubleshooting. If you have that kind of money to waste, send some my way.

The CCC system is very sensitive to the condition and connection of the myriad of vacuum lines on the engine. One or two misconnected lines can cause all kinds of problems. Also, this is a pretty basic computer system and there are many, many failures that will cause the problems you have described without setting any codes. Get the manual and follow the steps in order.