misfires, stalling, stellar handling!

Just bought a 2000 type SH a few weeks back (I've wanted one ever since I got rid of my old '88 2.0 Si), and took it for a trip up the west coast (talk about some UNBELIEVABLE roads for checking out the handling limits of the SH!). She ran beautifully. During the trip the CEL and ATTS light came on. Since I was in Canada and the dealer was in San Diego, I disconnected the battery to kill the lights. They came back on a few days later. Scan revealed misfiring on 3 cylinders, plus a fourth code that I think said general misfire or something. The car has also had a stalling problem the entire time, but only when I come to a stop (or nearly). If I take my foot off the gas and push in the clutch while driving and let the rpms drop, no stall. The only performance mod that I can see is an AEM CAI, which looks like it was installed properly. The car also does not always start right up - have to crank it for 2 seconds sometimes. There is a cracked cover on one of the vacuum nipples which seems to leak slightly, but have had 2 mechanics tell me this would probably not cause either problem. The car had 41k mi when I bought it, 45k now. Going to replace the vacuum cover today, but don't expect that will make much of a difference. Anybody experience this?


BTW the SH lude tore up the twisties better than I could even imagine. The limiting factors were always visibility or traffic, never the car. Never even get her to squeal, except twice in tight twisties when I let off the gas abruptly and the tail rotated (only slightly, then back in line). I'm an experienced driver, and was definitely pushing the limits of reasonable risk in the name of determining her limits, but guess they aren't to be reached on public roads..... I'm telling you, this baby is unreal. Only wish I had a videocamera onboard to record parts of the trip, although the footage would prabably make people sick! Damn this car sticks.....

There are a bunch of things that can cause misfires on all of the cylilnders.

First, you want to replace the cap / rotor / spark plugs.

I recommend either NGK copper plugs (and change the once a year religiously) or NGK Iridiums. The car comes with platnium plugs, but they are aobut $10.00 each... and the other two will work like gang busters.

Second, if that's not the problem, then you need to check out the coil with an ohm meter. This will determine if the coil is screwed up and causing poor spark. If that turns out ok... you may want to replace the wires... but they are not likely to be the problem.

Thrid, the EGR system can cause this too. If you remove the EGR valve... you can then clean it with carb cleaner. You'll need to take a small screw drive and chisle out the carbon on the port... then you'll need to move the needle side with your finger while spraying with carb cleaner. Even if you thing it's working fine... clean it anyway. It only take a little failure of the needle to work smoothly for this problem to arrive.

Forth, fuel pressure. Change the fuel filter, and if that doesn't work... then check the pressure at the rail.

The fuel filter is a PITA to change... and you'll need a set of flarenut crows feet to do it.

Gerhard

PS 5th Gen Preludes start like crap when they've got less than 1/4 tank of gas.

Thanks for the info...... especially the part about 5th gens not starting well (nice to know it's not an engine or related problem). Turns out the light went off on its own a couple days after I replaced all the vacuum caps. Stalling is still an issue, but I had to leave town (and my car) for a couple weeks, so I'll address it when I get back. Maybe now that the vacuum leaks are fixed the idle adjuster can actually be set with good results. Here's hoping, anyway......

About the idle speed:

With the Service Connector jumped, and the car warmed up... the car should idle at 700RPM +/- 50RPM.

If it's not... then something is wrong.