94 cavy idles rough when cold

[schmark]

I have a 94 cavy with 2.2 fuel injected. When I start the car in the morning it idles and runs very rough until I get 2 - 3 miles down the road then it gets a couple bursts of power and seems to clear up. It then runs fine. This just recently started happening when it turned cold here in Michigan. Once I get to work which is about a 10 mile trip I park the car and it idles and operates perfectly. When I start my car after work for the ride home it runs rough again just like the initial startup in the morning. Has anyone had this problem and can someone please help. Thank you vey much, Mark

[Blue Bowtie]

Any check engine light? Has fuel mileage decreased?

I had a similar problem when one of my injectors was failing (134 CID just like your Cavvy). The injector did not spray fuel, but streamed it out the tip instead. The poor atomization at idle made it very rich, and it seemed like an almost completely dead cylinder. At RPM above idle it was just fine, and when the engine (head) warmed up, the extra temperature helped atomize the fuel better at idle and it was almost normal.

That may not be your problem, but the point is that it may not be something related to ignition. I'm guessing that most other people reading this would guess an ignition problem, and suggest that you check spark plugs for wear and gap, plug wires for conductivity and insulation damage, the two ignition coils for weak windings and flashover damage, and the primary connections. Of course, you should do all of that first, just to make sure the ignition system is in good condition. You should also check all hoses for vacuum leaks and the PCV valve for proper operation.

If all that reveals nothing, however, you might want to consider fuel delivery.

[schmark]

Originally Posted by Blue Bowtie

Any check engine light? Has fuel mileage decreased?

I had a similar problem when one of my injectors was failing (134 CID just like your Cavvy). The injector did not spray fuel, but streamed it out the tip instead. The poor atomization at idle made it very rich, and it seemed like an almost completely dead cylinder. At RPM above idle it was just fine, and when the engine (head) warmed up, the extra temperature helped atomize the fuel better at idle and it was almost normal.

That may not be your problem, but the point is that it may not be something related to ignition. I'm guessing that most other people reading this would guess an ignition problem, and suggest that you check spark plugs for wear and gap, plug wires for conductivity and insulation damage, the two ignition coils for weak windings and flashover damage, and the primary connections. Of course, you should do all of that first, just to make sure the ignition system is in good condition. You should also check all hoses for vacuum leaks and the PCV valve for proper operation.

If all that reveals nothing, however, you might want to consider fuel delivery.

Thank you very much for the information. There is no check engine light coming on but do believe I am burning quite a bit more fuel than usual. Is it a complicated job changing an injector and how do you figure out which is bad?? What you described sounds like my car and this problem didn't start until it got cold and I ran some fuel injector cleaner through my gas tank. One other thing I did not mention is that when I initially start the car and let it warm up it seems like it is not running on all cylinders and I can smell unburned unleaded gasoline that seems to be coming from the exhaust. is this consistent with a malfunctioning injector. Thank you for all your help. Mark

[Blue Bowtie]

Since the problem occurred only after adding injector cleaner, I'd suggest you live with the symptoms while you use the treated tank of fuel and can refill it. Fill with the lowest octane fuel you can find (87 octane or lower) and add about 3% two-cycle oil. Lower octane fuel contains more hydrocarbons and less additive, and is generally more volatile (which is why it can detonate more easily in a higher compression engine). The extra volatility can help clean up any moisture, injector cleaner residue, and accumulated varnish in the fuel system. The two-cycle oil will help lubricate injector pintles, since it lubricates by precipitating out of gasoline and coating metals that it contacts. If you run a clean tank of fuel through the system and the symptoms do not improve, you may have to perform a power balance test of the injectors to determine which one is the offender. Once you determine that, you can remove that injector and test it.

[schmark]

Thanks again for the taking the time to help me out. I will do as you say. You said 3% 2 stroke oil added to the gas tank. I did the math and this would be a little under two quarts/57 ounces in a 15 gallon tank(not sure on tank size of cavvy). Does this sound right to you? My tank is getting low and I will be able do this over the weekend. Any brand of 2 stroke oil be ok ?? By the way, my cavvy is getting much less fuel mileage. Thanks again

[schmark]

Here is some new info on my problem. I have tried the 2 stroke oil and have burned probably 5 gals of clean gas since. The problem still persists. During the time I did the fuel thng I have replaced the fuel filter, air filter, and had put new plugs in before I did the fuel thing. Any suggestions where to go from here??? I have a Hanes manual and in the troubleshooting section it says that if an injector is malfunctioning you can tell by putting a screwdriver to the injector and listening for a clicking sound through the handle. If you hear the clicking, then the injector is functioning. I tried this today and could only get at three of the injectors. They were all clicking. I will have to take off the take off the air intake to access the last injector but I was not able to get at it today out in the parking lot at work in the never ending blizzard we seem to be having. Any more suggestions would be welcomed and I hope some others are gaining some insight through this thread

[schmark]

Here is an update on my cavy problem. All the injectors were functioning. I tried a new(recycled) coil pack, that did no good. I started pulling off the spark plug boots one at a time to see if all cylinders were firing. They were not. I replaced the spark plug wires and my cavy runs lik new :-)