Before stumpling on to the Spark Plug solution we expended a lot of intellectual energy trying to determine the source of our performance problems including a trip to the dealer and accross the "consult meter" for a analysis, looking for potential malfunction codes... no help.
Here's a look at the discussion that took place on-line with the experts at neons.org regarding performance issues with the 2002 Dodge Neon ACR. While none of us guessed right on this issue I can't thank the folks on-line enough for all the guidance an support over the last couple years.
SYMPTOMS OF POOR PERFORMANCE
At SFR SCCA Solo2 Event 9, May 29, 2004, on three of four runs, the Neon was much slower to accelerate in second gear than normal from around 3000-4000 RPM (I'm guessing on this as I didnít look at the tachometer). This occurred at the same spot on the course on runs two, three and four of the four run format. The place on the course where this occurred the car was on a level surface traveling in a straight line immediately following a hard left turn. The course began with a hard left followed immediately by a hard right, then the hard left, all 90 degrees and separated by 2 ~ 50" of straights. I shifted to second gear after the first left. There was no acceleration for >100' after the left, more than a simple misfire, the car would not get up and go.
OUR INITIAL SUSPICIONS
At least two of the three '02 ACRs autoXing in Northern California have at one time or another produced large amounts of oil smoke during a run. It began during G-Stock competition and only occurred when competing on competition tires (lots of grip) on sticky concrete. The oil smoke doesn't necessarily happen on the first or even second run but once it does it does so on each successive run, although in varying degrees. Competitors had commented that the smoke began after a sweeper to the right.
When this first occurred there was no apparent impact on performance. The day after I simply noticed a small amount of oil on the garage floor and the oil level a half quart low. The next time this happened performance was impacted and the car bogged and hesitated after the "offending" right hander. The smoke, while up until the last run I took had not affected performance I did get recognized by the Event Announcer, not positively, as it wafted through the timing trailer at the end of the course. This is not a incident without precedent, the 300 ZX does it as well. Competitors have been red flagged at events because course workers assumed a blown engine and oil on the course.
The theory as to it's source is that under sufficient g-force and body roll oil in the head gets sucked out the PCV. The supposed cause begins with the oil return passages in the head being to small, allowing oil to pool in the head. The PCV Valve allows oil to enter the intake manifold where it subsequently is burned in the combustion chamber. Adding a catch-can or switching valve covers to a gen1 style with the different PCV location, not legal for the Stock Class, are about the only things that can be done.
... sounds more like fuel starvation. It can happen when cornering hard left or right; my car does anyway. You sure you had enough fuel in the tank?
... very inclined to think that you are suffering from fuel starvation. Since you say that it happened at the same exact spot on the track each time, following a hard left turn. The same exact scenario happened to me, and I racked my brain until I ran the car on a full tank. Problem solved.
... it is definitely something worth looking into since a full tank certainly adds unwanted weight to the rear of the car. Fuel starvation in Neons is certainly not uncommon.
... if this is the case, my suggestion would be to buy a 5 gallon gas can. Fill it up at home so you don't waste a lot of time hunting down a gas station near the site.
My response: I always begin with a half tank, the same level the alignment was done with. After all the runs I still had 3/8 of a tank. Perhaps the diagnostics will point to something other than the oil ingestion? I certainly hope so.
... broken fuel pick up, the car would loose like all power coming out of turns as if starved for fuel.
My response: Iíll take a closer look at the possibility of a fuel pick up problem, it could of broken off like yours. I donít think itís the fuel level alone as this is the first time the symptom has occurred in 2 years and > 30 Event Days including Test and Tunes and as many as 4 drivers in an Event beginning in 2002. If the problem was fuel level the fix would certainly be easy. I'd also suspect that the extra weight of 6 gallons of gas would have less of an impact on performance than the stalling. Iíll look at fuel delivery as a possibility for the problem.
... I would certainly try this first before you go tearing down the fuel delivery system. If it works, and you can live with racing with an extra few pounds of fuel, it is certainly the cheapest route. It worked for me, and I've pretty much accepted this as a "characteristic" of my car. I know a guy who races a CRX who has the same problem and must do the same thing.
I took the car to the dealer to have a diagnostic run to determine if the computer has codes on the May 29, 2004 and look to see if something other than the ingestion of oil could be contributing to the faltering performance.
NO PROBLEM FOUND!
So, I was really surprised with a simple replacement of the plugs, we regained our momentum as we took the Regional Championship.
... I'd have guessed the secondaries might have been stuck open. But if the plugs did it, that's cool. I like my iridiums.
My Response: The only maintenance we did prior to changing the plugs was using carburetor cleaner but the symptom reoccurred after the cleaning and has not after the spark plug replacement. While not a scientific test the problem went away with the replacement of the plugs.
We've not been able to reproduce the oil smoke in over the last few rounds, a good thing, so if the performance issue is tied to oil ingestion the plugs are, perhaps, not a conclusive fix.
Perhaps the oil ingestion contributed to the premature wear of the spark plugs and the oil in the intake contributed to a sticking secondary. It might of taken a while for the carburetor cleaner to have an effect on the secondary, it freeing up in conjunction with the replacement of the plugs?