Popping and hesitation?

sparks · #1 (**permalink**) 06-13-2003, 07:17 PM

Just got car back the other day and all was fine, until today. Drove a few miles came home and then went back out again. It was fine at first and then started to hesitate a bit and also some popping on deceleration. When I stand on it it seems to run O.K. any ideas.....

Dan Semko · #2 (**permalink**) 06-13-2003, 07:35 PM

Here's the first thing that came to mind:
1. check your distributor gear, see if it spins after you remove the cap and rotate the shaft.
2. If you have a MSD, check your battery cables then all of the respective grounds. If your cable is loose, the MSD will initiate all kind of problems.
3. If all grounds are fine, check the MSD and the chip, if applicable. Change the rev limiter to the next highest chip and see if the problem reproduces.
4. Check the coil wiring for shorts against the block.

Start your car in a dark garage and watch the distributer cap, wires and coil. If anything is grounding, you'll see it.

If I was a betting person, the distributor gear would be on the top of the list.

Best of Luck.

PatBuckley · #3 (**permalink**) 06-13-2003, 07:48 PM

What was done to the car?

Also check for exhaust and vacuum leaks....

Rick Parker · #4 (**permalink**) 06-13-2003, 08:59 PM

Try spraying a little carb cleaner in the brass air corrector jets at the base of the venturi boosters in the carburetor sometimes they can get a small amount of dirt in one that can create a lot of havoc.

Rick

sparks · #5 (**permalink**) 06-14-2003, 06:52 AM

It was in for a new oil pan and change of plugs, and slight adj. of carb...At idle oil pressure is even down around 40 ?

TomH · #6 (**permalink**) 06-14-2003, 07:10 AM

Not knowing anything about your engine or what it just got back from; this is a real shot in the dark, but I would agree w/Dan and look at the distributor gear/shaft. Also, I would drain the oil and look very closely at the old oil and the filter (Cut it open). There have been a rash of distributor/oil pump related failures and these symptoms are sounding all too familiar.

CJ428CJ · #7 (**permalink**) 06-14-2003, 12:45 PM

If they adjusted your carb, that's probably the source of your problem. Check out this troubleshooting link: http://www.barrygrant.com/demon/default.aspx?page=28

That's for Demon Carbs but everything there should be applicable to Holley's (and other carbs?) too.

sparks · #8 (**permalink**) 06-15-2003, 08:23 AM

It seems odd that it was ok for 25miles or so? Put better gas in and i'll see what happens. If that doesnt work i will richen up the idle mixture since it only happens when throttle is hardley open. Thanks for adv. guys.....

Roscoe · #9 (**permalink**) 06-15-2003, 08:34 AM

Let me take a little side road here. The suggestion to look at the Demon Troubleshooting Guide was a good one. You should start with the carb. The additional suggestion by that post was subtle.
It said: "LEARN HOW TO TUNE IT YOURSELF!".

If you depend on someone else to tune your engine you will wind up marrying them. You will be disappointed many times and really won't enjoy the experience of owning a Cobra.

Understanding your engine is not rocket science. It is pretty easy and takes a minimum of tools.

My carb, from time to time, needs attention. Whether it is something clogged in the jets or something else. You have to change your filters periodically. Are you going to have your mechanic do all these little things?

Who is going to check all those bolts and nuts to make sure they haven't come loose?

If I were you I would invest in some books on your engine, get a timing light, vacuum gauge and whatever else is necessary and start learning what the car is all about.

Just a suggestion,
Roscoe

Janusz · #10 (**permalink**) 06-15-2003, 10:28 AM

Roscoe,

Good suggestions. Any recommendations on carb books or a specific trouble shooting guide besides the BG link? I'm a recent Cobra owner and have the same symptons as Sparks, some hesitation on initial acceleration, pulls well after that and popping if I come off the gas quickly. Plugs are dirty and have some fuel on them, but all are firing.

J

Roscoe · #11 (**permalink**) 06-15-2003, 10:44 AM

J,
Don't know what carb you are running but I would check either on the net or a large bookstore for books on your particular carb.
By the way, that Demon sheet is very helpful as a fine tuning guide; especially with your symptoms. It is usually an imbalance between the floats, idle mix and butterfly settings. However sometimes you will get that stumbling at light throttle because of debris in the carb.

Doing basic Google searches like the two below will get you some good sites.

http://www.google.com/search?sourcei...gine+tuning%22

or

http://www.google.com/search?sourcei...lley+tuning%22

Here's one on tuning with a Demon Carb

http://www.4secondsflat.com/demon101.html

Roscoe

George Snyder · #12 (**permalink**) 06-15-2003, 11:49 AM

Hey Guys,
Some good advise as always!
The only thing that complicates the matter is sparks never mentioned the brand of carburator he is using.

If he has a Demon,the tuning is sooo much easiler, as we all know! But!!!

Sparks,
If it is a Holley this may help also.
http://www.chevyhiperformance.com/ho...498/index.html

I hope you get your problem solved. I have been dicking around with one myself for a couple of weeks now myself. Good luck!
Bud

Lowell W · #13 (**permalink**) 06-15-2003, 01:56 PM

Dan and Tom,

I haven't had a problem but what's the deal with distributor drive gears? Do some motors just "wear gears"? Is there something that can be done to decrease wear? Have you tried the PEEK plastic distributor gears? Any info or advice on plastic gears?

Thanks,

Lowell

Hal Copple · #14 (**permalink**) 06-15-2003, 02:52 PM

you will get lots of suggestions, especially from drivers who have had this or that cause a similiar symptom.

If you are "popping" on decleration, then you have unburnt gas going out into your exhaust. While a worn distributor gear can cause late ignition, i agree with the above folks who suggest a carb issue. A distributor gear issue would not be intermittant.

I also agree that learning all you can about your carb is a useful place to start. I bought about four Holley books, and studied theory and application, but of course, still made errors when i tried to do things to my carb. But i got better in time.

My first suggestion would be to check your float level, remembering that the NUT does the adjustment, the SCREW is only to lock the needle valve. If you have not done this, ask for some suggestions on how to avoid a carb fire.

check your timing, too.

Tinker51 · #15 (**permalink**) 06-15-2003, 06:58 PM

I agree with Hal, this sounds more like a carb problem than a distributer gear. My gut reaction when I read the title of the post was a lean mixture or vacuum leak so that is where I would start for no other reason than you said you just had work done on the carb. On the other hand, I know two guys who have had distributer gear troubles recently so I would not rule it out. Can I cover my bases as well as any politician or what?

PatBuckley · #16 (**permalink**) 06-15-2003, 07:55 PM

Check for exhaust or vacuum leaks....

sparks · #17 (**permalink**) 06-15-2003, 09:37 PM

Thanks for all your advice guys. I turned out the idle mixture a 1/4 turn and it made a BIG dif....Every now and then I get a little pop but 95% of the hesitation is gone. They are high perf. engines and it aint gonna run like a lexus. Add a computor, some sensors and F.I, well it might be close? That demon web sites pretty helpful. Thanks again...............................SPARKS