Hey, Im a friend of Daves posting here, I just fixed a small ignition problem, and had a few other questions (btw, it was just some loose connections)

-The rebuilder put in a camshaft out of a 350, now i beleive this is causing some un-nessisary flooding because of the loss in vacuum (the MAP sensor detects a loss in manifold vacuum, thinks the throttle is wide open or open more than it should be, hence it adding more gas)
>> is this plausible or does the EPROM (or whatever the computer is) rely on inputs from the TPS and the MAP before adding more fuel?

Any other suggestions as to why it may be idleling rough / flooding are appreciated (asides from the lumpy cam theory)

One more thing, the car is 'putting' at a steady rate throughout the RPM band, no immediate causes other than perhaps bad timing come to mind...so toss out a few suggestions if you can, the puts are probably at 1/3 second intervals at 1000rpm

Thanks

G

 

Sounds to me like it's running lean, the opposite of flooding.

What sort of car is this?

 

Camaro

no its not running lean..

 

its a 305 TBI....he has said on the ontario board that he smells gas and it really smelled like gas when he was trying to start it.

 

Yeah ... ok this fourm is kinda dissapointing at the moment .. I thought I would get more replies, I know there are tons of people who would know what the problem is, why dosent anyone give me some helpful input.. and yes its a Camaro im talking about, if it was something else I would say "some other car". not trying to sound like an azz but I want to fix this.

 

Ok to help you out, any 350 stock cam would not be too much cam for a 305. The lobe separation is large enough that the idle should be smooth, if not smoother than the peanut cam.

The fuel amount is adjusted mainly by o2 sensor readings, although the other inputs have to coincide with the o2 sensor readings else codes would be thrown here and there if even one reading does not coincide with each other within a variable margin.

Now if there is a real loss in vacuum, odds are its not the cam provided you have any of the stock cams in there. A vacuum leak at any point can cause this. There are connections to the brake booster, the air cleaner, the egr, the pcv I believe. check all of them for leaks. Plug each plug on the throttle body and see that it idles ok when you've done all that.

Next examine your plugs. Take them all out and examine if they are tan, white or black. tan=ideal, white = lean, black = rich.

If you are getting more fuel than necessary, these will be black for sure. Add to this fact is that when all fouled up, it doesn't allow the fuel to ignite well and a rich condition and stumbling will persist.

 

A Camaro....

305? 350? carb? TBI? TPI? some other induction system? etc.....

We're not mind readers, and we can't follow you from board to board guessing what car you're posting about under what name, just to be ready to come to your rescue. We can't see the car ourselves you know. That might be part of the reason you're a little disappointed with the results you're getting.

Tell us the whole story, maybe somebody can help out.

 

Man if im posting in a camaro fourm, than I have a camaro.
If it was something else I would mention it, And I have a sig that tells u what kinda engine. Im not asking you to be a mind reader, but at least to have some common sense.

88 SC

Bored 307 TBI
2.73 rear axle
what else would you like to know?

 

Thank you for the information. The "TBI" part was important, but we could have presumed that from fact that it is an '88 and has a MAP sensor. Making presumptions can be dangerous at times, though.

In defense of the other replies, with well over a million posts, we frequently get questions about other vehicles, vehicles other than those described in a poster's signature, etc. With no fewer than eight different engines made by either Chevrolet, Pontiac, or Buick, seven different basic fuel systems, and six different ECMs used across the production years, it never hurts to ask for a little more detail. Then there are always those modified cars with aftermarket carbs, aftermarket DFI, or custom modified systems from other vehicles. Additionally, I think you threw us all a little off track in the first post, stating that you were a "freind of Dave's" leading us to believe that the car in question was not the one described in Dave's signature.

Anyway, now that we are on track, your theory about a high MAP signal (lower vacuum) is plausible, and a high MAP would tend to adjust the mixture a little rich. However, a functioning oxygen sensor would tend to counteract that once the system was in closed-loop mode.

Do you have a vacuum reading at idle? That would be a good start. I'll agree that a stock 350 cam grind would make no real difference in the idle quality on a "bored 307". You also stated that the rebuilder installed this cam, but do you have any idea at what lobe centerline timing the cam was installed? If the builder timed the cam incorretly, you could have all kinds of idle and mixture issues. Has this been a condition that has existed since the rebuild, or something that has not been a problem but has occurred more recently?

 

Thanks for reply Vader, yah that was my buddies posting. My car wouldent start so he came by to look at it, and got it running.

Yeah I should of added a little more detail into the post before thats why I didnt really say anything, I now see why you guys are confusing about what car I was talking about. Yeah like I said that was just my buddy posting on my name for my car though.

yeah the car has been like this ever since the day I got it back from the shop. The guy has no idea what the problem is, he charged me extra just to try to get it working properly, but it dosent even do that. Its messed up, its been like this from the start.

Vader ill reply back to you after I show your reply to my friend.
Thanks