mikeinmichigan

Ok I finally fixed the bucking/surging between 40-50 mph a couple nights ago. One foggy day after an extended nighttime rain storm the engine was severely missing, and it didn't get any better when it was warmed up. I figured this was an electrical problem and ordered all the ignition parts. Saturday night I replaced the sparkplugs, plug wires, rotors, distributor caps, and coils. When I pulled out the plugs, I could see that two of them were not firing well or at all. It took about 4 hours to do it, but now the engine runs perfectly. I have 177k miles on it and for those of you who have a slight miss that gets worse in damp weather you might want to try this approach. Cost about 400.00 for all the parts. Mike

No one else has chimed in so I'll give you my opinion. I used to be into the Diamond Star turbocharged cars, Eclipse, Talon, Stealth, 3000gt... In our local Detroit club we went through well over a dozen clutches of different types. After trying a stage 2 carbon/ceramic clutch, and having it only last 10K miles till it disintegrated, I went back to a full face Exedy clutch which only grips about 10 or 20% more than stock. Now mind you, I rarely raced my TT Stealth and still only got a year out of it (the carbon/ceramic). That clutch cost me about 500.00 plus my labor to install it. It was also very hard to modulate on a launch or even casual driving. When it grabbed it really grabbed! Other members had similar results, even custom made clutches didn't last very long. My engine was making about 350 HP. Part of the problem was the AWD, it was very hard on everything, something has to give, the tires or the clutch. Launches with an AWD car are just brutal on drivetrains, stripped splines on T-case shafts & shredded clutches were normal. After the frustration and money spent, unless it is a dedicated race car or thrash vehicle that you don't mind throwing money at, go ahead and put a stage 2 in your car For the mods you are looking at, the stock clutch will work just fine, cost less, and last a whole lot longer. Keep in mind the stock clutch in my Stealth lasted for 160K miles..... Good Luck, Mike

I would try a place called Strutmasters, they might be able to get you a conversion kit. You would have to contact them though. Mike

Nope, that didn't fix it. It took longer, but she is still throwing the DTC 25 code in combo with the CEL/Trac Off. At least the heater kept me toasty warm this morning. For the minor inconvenience I might just live with it, as long as it doesn't get any worse.

Maybe I can add something that will be of use. 1992 SC400 175k miles. I had the surging/bucking @ 40-55 mph at a steady state or trailing throttle. I also had the CEL and Trac off light come on. The engine also didn't seem to be running at the proper temp (too low)and when I pulled the code it was "DTC 25 lean condition". Ok first I cleared the code, replaced the thermostat and test drove it. So far the bucking and surging are gone and no CEL or Trac off indications. The coolant temp is right in the middle of the gage now. Going through the troubleshooting in the manual enging temp is possibly tied to the DTC 25 code so hopefully that is all my problem was. I'm going to drive to work tomorrow and see if it gives me any more problems and will post again with the results. I know on the LS this is tied to the ECU programming causing "off throttle shock" but don't know if it affects our models as well. In addition, I have never had any idle problems whatsoever. This site has been a big help and it downloads faster than the other one, Thanks everyone. Mike

It sounds like a classis case of head gasket failure. With your current financial condition a used JDM engine might be the best bet if keeping the car is what you want. Ok, chill out! You don't need to spend 6 or 7 k unless you take it to the dealer. A used serviceable engine can be had for 1,500.00 or less and a mechanic would probably charge about 600.00 or so to replace it. So figure 2 or 3k will get you back on the road. I don't know how much damage has already been done to the bottom end of the engine, and that's why I suggest dropping a used motor in as an alternative. I had to do this on my old 92 Stealth TT AWD and it's a much more difficult job than the rear drive Lexus cars in my opinion. If you do go the used engine route have them replace the crank and rod bearings before they install the engine, also transfer your timing components since they are almost brand new. Change the oil pump as well. Good luck and don't despair, everything breaks sooner or later. Mike