Hi All,

I have recently purchased a 1989 caprice wagon with an Olds 307 engine. The problem I have with it is when I first start it up when cold it idles rough for about 1 minute and starts to smoke (black). When I start to drive it hesitates once in a while untill it warms up and then seems to run O.K.
When I first got it she would heat up and loose power under load if I was driving up a long steep hill and the temperature would climb very fast. I had the exhaust replaced because I thought the catalytic was plugged and the mechanic also agreed that was the case.
That seemed to solve the overheating and power issue but it failed the emissions test miserably. I then had the EGR valve replaced because the mechanic told me that that was the problem. After that it passed with flying colours. But now it smokes.

Does anyone have an idea of where to check in order to fix the rough start when cold?

Thanks,
Rene

 

Black smoke would mean it's burning oil thru the valves into the exhaust.

The Olds 307 isn't exactly the cleanest engine around, actually I think it's the worst or second worse emissions wise.

The rough idle, Carb issue?

 

Uhm, I'm no expert, but isn't black smoke fuel? Oil would be blue/white. Sounds like carburetor to me.

 

just a question to throw out there but was the 307 olds answer to the chevy 305.I have a 83 chevy malibu wagon with a 305 that is still strong but needs work rings seals due to stupidity from a dork that couldn't do his job right( when it was the familys car once it was taken to get the oil changed and the guy didn't remove the other oil filters gasket that didn't come out with the filter nuff said)causing the car to loose it's oil and now burns oil.We used to have a olds sedan that had a 307 dang thing couln't get out of it's own way lol.

 

The carb was just rebuilt before I bought the car but it could still be that they didn't set it up right. Thanks,

I am 90% sure that it is a fuel issue because it only smokes about 15 seconds after I start it and then for about another minute after that. The smoke comes in spurts out of the tailpipe.

 

Rene, the first thing I would say is that you need to find a new mechanic. If he replaced your catylitic converter and exhaust to "troubleshoot" a problem then he is a doofus. An 89 Chevy with a 307 should has a GM type 1 computer on it. This is a SUPER easy computer to work with.

If you were told the carburetor was rebuilt I would be wary. It sounds like you might have a carburetor issue. Does the check engine light turn on?

 

Being as it is a cold start/warm-up issue, I'm going to go out on a limb and say the choke needs attention.

 

This actually is incorrect. The Olds 307 was the last carburated American V8 because it ran clean. They didn't need to fuel inject to to cover up it's short comings in the emission department.

 

Black smoke is from a too rich mixture. When starting the choke will be closed on a cool engine. As soon as engine starts and vacuum supply is available a choke pull-off opens the choke flap a bit to eliminate rough idle, black smoke, and too rich a mixture. There could also be a second choke pull-off to open the choke flap even more after a short period. I would check the choke pulloff(s) and proper operation of choke flap to start.

 

You're right, it is an excellent engine. I had read somewhere that GM decided to use the 307 across the entire B wagon line in the last years because it was more cost effective instead of using the 305 and 307. It's turned out to be an incredibly reliable engine. Both of mine failed emissions this past year but my mechanic just did some adjustments and it passed with flying colors.

 

I sure am glad OK doesn't make cars do an emissions test. It is such a joke.

BTW, the 307 is a tough little engine. It might not be a torque monster like other Oldsmobile engines but it can definitely get around. I had one in my 1990 Buick Estate Wagon. It was a great car on the highway.

 

Black smoke indicates an overly-rich condition, NOT oil smoke. The VIN Y 307 has THE highest failure rate in emissions testing according to the EPA. This is not the fault of the engine, it is the fault of mechanics who have no clue as to how to properly diagnose, repair, and adjust the CCC system. There is a VERY specific adjustment process outlined in the Chassis Service Manual and it MUST be followed exactly. More importantly, there are miles of vacuum lines and a number of sensors and actuators. A problem with any one of these will cause the car to run improperly, and vacuum system problems will not usually result in a trouble code. Most mechanics today are "parts replacers" only - they read the codes and follow the flow chart. If the problem requires diagnosis skills beyond those in the manual, they ususally fail and end up throwing parts at the car unti they stumble onto a solution.

 

well that stinks I can do that (be a parts changer)and who said I need some guy fidding under my hood so he can break somthing else as they tend to do.I do most of my own work and use the books and manuals for the tuffer stuff though we have a friend in the family that is goood with Gm's so that comes in handy.

 

This is unfortunately true. Not only in the automotive industry but also in the military. I work for a US Army contractor that teaches operator and maintenance training to soldiers servicing FireFinder Radars. Parts are pluck-and-chuck to keep the system simple and easy to repair.

 

My 88 caprice had the same computer controlled Q jet carburetor, They work very well. It was one of my favorite cars. Though my caprice had the 305 the fuel delivery system was the same as the 307. Car was dependable and smooth running but the body died of cancer unfortunately.

 

i bet your gas mileage is sucking right now,too

take your air cleaner off and see if your CCC connectors are on the carb

if so,your carb is junk

go on ebay,i got a rebuilt one for $50 on there,it works great or look for one on here

i also recommend buying a factory service manual,and throw it in the trunk,so your mechanic can read it

every now and then one will show up for a 20

 

Right - I think the choke needs to be checked and possibly adjusted.

Not only due to incompetent mechanics but also to incompetent morons who set the test limits for the test machines. I have a news article somewhere that said the test machines had the "wrong data" for quite a few different cars and engines, causing mass failures of good running cars. Here is where shotgunning began. The check engine light was not even on in most cases.
I found this after my mom's 86 Olds failed 5 years ago and local "mechanics" did not even want to mess with it. As a result she traded it for a new car (GM at least) and her nice Olds was junked. For this reason, my 86 has never seen an inspection place ever since this dumb test was implemented here... In a couple more years, it will be exempt.

Most around here won't even bother, or they do not have the ability to begin with.......

 

No ability to read a FSM. That is funny.

Unfortunately, it is true in some cases.

 

Nor the ability to read "Pokey the Puppy" either...

In more cases than you'd imagine.

 

I took the air breather off to check the operation of the choke and started it up when cold. The choke was open at first about 1/16" or so untill I started it then it opened up to about 1/8" and ran for about 1/2 minute or so untill the choke opened up even a little more just like you said.
The funny thing is that time it didn't smoke so it might be a problem with not enough air getting to the engine. I have a K & N filter and it looks very clean so I will wait untill it cools down and try again.
Very strange....

 

Our inspections here used to be if the car was 20 years or older you didn't have to get it done. I am told that now this has changed and all vehicles built after 1988 will need to be inspected. This means that my 89 will need to be inspected every two years unless they decide to change the policy again.

This really stinks because one of the reasons for purchasing this car was because I thought that I wouldn't need to get the emissions test done. I guess that's what I get for not doing my homework and checking first.

 

Sounds like too much or wrong kind of oil on the filter choking airflow. Throwing in a paper filter would be a cheap, easy way to find out.

 

Good idea. I will try it tomorrow.
Thanks,