Contour Enthusiasts Group Archives Forums General Troubleshooting CSVT rough start and miss/hesitation low RPM/high

I have a 98 CSVT with about 79k miles on it. This past summer I did the LIM/UIM cleanin, cleaned the Tbody, MAF, IAC, replaced plugs, gaskets, etc. Car ran great for months. Recently had the cats replaced under warranty as well.

The car runs poorly at cold start and under moderate acceleration / lower rpms (under 3000-3500). It gets better the more the car is driven, say it runs better after 10 mintues than say after 5 mintues. Heres how it goes:

*cold start, starts OK runs fine for about 5 seconds at 1000rpm
*at about 5 seconds the idle drops, develops a very slight surge and idles very rough. Feels like it wants to stall but it never does. RPM hovers around 600rpm.
*runs like that for about 1 - 1.5 minutes and then the idle levels out and is much better. Normal idle is around 7-800rpm.

While driving:
*I need to take off at 1200-1500 rpms or the car hesitates and feels like it misses. Sort of feels like clutch slippage, but the rpms do NOT jump or rise suddenly. IT feels like a gear missing a tooth, best way to explain it.
*If I take off right and accelerate very slowly it does NOT do it
*Seems worse in 1-3rd gears
*Will do it in any gear if I try hard accel from under 3500rpm
*car feels fine and pulls great above 3500-4000rpm
* gas mileage has fallen to about 265 mile per tank from nearly 300 MPT in the summer. But that could be due to the winter blend gas and cold weather.

Try a new set of ignition wires from Motorcraft and check for vacuum leaks, and correct firing order. Also check for carbon tracks on the sparkplugs. That caused a similar problem for me. Use silicone grease to keep water out of the rubber boots and keep the socket clean so the plugs don't carbon track. These topics may be useful:

Spark plug topic, many good links there

Carbon tracking

Check the IMRC linkage and confirm that both sides close.

One of the plastic retainer clips may have broken.

Thanks guys! I will check those things out. I know its not firing order because the car ran great for 3+ months AFTER I cleaned the intakes and it hasnt been touched since then. From reading those links sounds like bad wires are going to be my culprit, 79000 miles on the original wires. But the plugs have 5-7000 miles on them. i think I may have put copper plugs in instead of the double plats though.

I had to replace the plastic bushing for the IMRC linkage when I did the intakes. Should the IMRC open the secondaires if you rev above 4000rpm with the car in neutral?

Im going to pick up a set of FMS or Motorcraft plug wires and some dielectric grease and swpa them out first. Can the rear plugs be removed with the UIM in place? Ill also check the IMRC linkage and see. Its just odd that its a low rpm problem not a high rpm/WOT problem.

Yes, you can change the rear plugs without removing the intake manifold. Some can do it without moving the coil pack, and others find it helpful to remove the coil pack. There is a FAQ about changing the plugs.

I just wanted to thank everyone for thier help. I installed Autolite APP764's and Magnecor 8.5mm wires today and the difference is totally remarkable!!! I cant believe how much better the car runs, its like a new car again! On cold start now it just fires up and idles, no surge or stumbles. When driving the car it is so smooth now, no misses, no hesitations even at WOT from about 2500rpm in 4th gear and I can actually feel the "kick" at 4000rpm's too!

Changing the ;lugs with UIM on really wasnt hard at all, once I took the coil pack out. Actually it took as long to install the new wires and route them as it did to change the plugs. Piece of cake.

However the condition of a few of the plugs has me fairly concerned. I will take pics and start a new thread for my questions though. They all have the brown "streaks" at the end of the insulator, I think 2 had "carbon tracks" and 2 others looked rusty, although the electrodes looked fine. They all came out withing spec as far as gap too. Oh, and they were Autolite single plats, not copper. They had maybe 10k miles on them too.