Mentioned this in an earlier post, but I don't think anyone had a perfect idea of what's going on here. As I accelerate, I get a surging. Up to about 3500 to 4000, it seems to pull reluctantly, then I get a large surge of power (more than just the torque curve kicking in). As I continue to accelerate, the power surges up and down until I'm at speed. There does not seem to be any surging at a constant velocity in 4th or 5th gears--perhaps just a little. I've tried to think of everything, but am stumped. I've recently changed the O2 sensor (Bosch) and distributor caps. So what's the forum opinion here? Thanks Andrew
I would check my fuel pressures and verify my CIS WUR is functioning properly from cold start through the warm-up cycle then while it runs. Your fuel pressure could be fluctuating causing the surge, just a thought.
No Birdman, it doesn't "appear" to be missing, just surging. As for the CIS WUR, uhmm, yeah, right. Uh. . . what's that? Andrew
* CIS is your fuel injection system (CIS = Continuous Injection System), the WUR is short for warm up regulator.
Ahh, well this happens well into a warm up as well as when cold. The surge is so "aburpt" that it could be an ignition issue (perhaps I should have it put onto a scope). This is just a bit unusual. Andrew
usually causes surge at steady throttle but i seen some old ones on bimmers that cause all kinds of bummers.
unplug your O2 sensor (very easy to do) and see if it still does it. I replaced my O2 sensor last year and my car did the same thing. It didn't before because it was never connected in the 10 years that I owned it. Once a new one was hooked up the surging began and it drove me crazy. I unplugged it and the problem went away again. It is going to STAY unplugged from now own too
Okay, I'm beginning to see that this might be an ignition problem. At lower rpms it pulls slowly and--I've now begin to notice that I get a single flash of my "slow down" light DURING acceleration at the lower rpms. If this means raw fuel into the cat during acceleration, then it likely is an ignition problem. (I'm thinking aloud here) As I said: at about 4K rpms, it suddenly pulls strongly BUT with a jerky power band. Coil wires, extenders, plugs, the coils themselves, etc? And don't answer "yes" to this question, lol. Andrew
Tommy, i am still learning a bit about Ferrari CIS ( i want a QV), but with the 02 unplugged, wont the car run dead rich? this would be bad for a cat equipped car i would think? i know some of us are exempt, but i would be careful with a cat installed, as a rich mixture could cause a fire . just wondering out loud. michael
I once had the very same issue on my carb car. The culprit was one bad spark plug out of a brandnew set. Since this may be the easiest solution, I would try this first. Replace all plugs and look whether the fault persists. Best Regards from Germany Martin
I suppose so but I ran a test pipe for years. I have a Hyperflow now. I have had problems with these O2 sensors on 3 cars with K-Jetronic. When I bought them YEARS ago(including the Ferrari) they were all disconnected and every shop I asked all said just forget about it. Leave it alone. I hooked it up again in 2 cars last year just to see and I got a terrible surging. The thing to do is make sure the CO is dead on correct and it should correct this problem but I never could get either one to smooth out. I disconnected them and, once again, they ran just perfectly again. You make a good point, though. Something to think about before you do it.
Well, I pulled the leads out of the coils and they looked old and weathered. I cleaned them up nicely and replaced them. I think it's working now! The surge appears gone! I really can't say too much right now because immediately after my first modest acceleration, I got pulled over by a cop 1/4 mile from the house. I took the car right back home after that. But this weekend, I'll test it to see if this is was a cure. If so, it's the 0 cent fix! Andrew
