Alright, had a little issue this morning. I got in the car with the wife to go pick some stuff up and everything started out okay. The car was a little rough on startup and idle, but this has happened before and clears up after a minuet or so. But this time, about 5 min. after we took off, I noticed that when I was stopped in traffic, the car felt like it kept trying to surge forward. When I was moving, it was fine, it only happend when I started to come to a stop and then stopped. Next thing I know GEARBOX FAULT is on and then right after came RESTRICTED PERFORMANCE. Both were amber, not red so I didn't lose it completely! Anyway, I managed to limp back home, and at lights I would turn the car off and on to see if it would go away. Well, the GEARBOX FAULT went away after the first turn off/on and all I had was RESTRICTED PERFORMANCE. Luckaly I was on a road with a slow speed so I didn't hold people up. Anyway, I figured it was something like a bad coil or plug, as I was planning on changing these soon. I found that when I was driving, if I put it in neutral at lights, there was no surging and only the engine was rough. This raised my hopes as I no longer think it is a transmission issue ( ). So, I got the car home, parked it, and we took off in my wifes car. Got home about 2 hours later and I went to my car just to move it to a different spot. Turned the car on, NO ISSUES. All warning lights gone, still a little rough idle, but nothing too bad. So, I'm thinking that I have a bad coil or plug (most likely coil). I don't belive that there is a transmission problem since I know that the ECU for the engine and transmission are closely linked and a bad misfire will send uneven power to the trans and that will make the trans think there is a problem. And since the gearbox light went away after I restarted the car and that in neutral the car still was rough I doubt it's a greabox issue. As well as the fact that at speed there is no issue and the car accelerated fine once up over 1000rpm before the problem started. I slipping clutch or bad transmission should get worse with acceleration, right? The car has 145,000km on it and there has never been any kind of issue other than the sometimes rough idle at start that went away after driving. I know that it is getting time to chance the plugs and as I mentioned I was going to do the coils as well. Basically, just wondering if you guys agree with my diagnosis or have any ideas what else it could be. I know that the smallest amout of water can mess these cars up, and now that I have to park outside and it is heading into winter, there is frost almost every morning and it has been wet and cool for the last while. Maybe water is condensing on something and since I usually start the car up and head out on the highway for a good drive, it heats up and gets ride of the water. Since today was stop and go traffic right away, maybe it just caused a problem since this happened before the car got a chance to get to operating temperature. Anyway, a bit long, but just trying to get all the facts in and see if anyone agrees with my diagnosis of a bad coil. I haven't got a scanner so I don't know what the codes are, but oddly the MIL light never came on. I also know that you can have a bad misfire and the MIL light won't necessarily come on. Thoughts? Comments?

 

Don't rule out the possibility that moisture is seeping into your throttle body. Your coils, plugs, and injectors could all be okay. But if even the slightest amount of water is finding its way into your throttle body, "limp home mode" is usually the eventual result....

I cleaned the throttle body in my 1999 Dodge Ram pickup (56,600 miles) yesterday for the first time ever. I removed the air cleaner housing assembly, held the throttle plates open with one hand while spraying Valvoline Throttle Body Cleaner with the other hand. Wiped up as much of the carbon-dissolved goo as I could reach with a clean rag on top of the throttle plates and inside the chamber. Reinstalled the air cleaner housing assembly and air ducts, cranked the engine, and drove the truck about six miles to test it. I was amazed at how much smoother and quieter the truck idles after the cleaning. I also replaced the crumbling and brittle original O-ring gasket that sits between the bottom of the air cleaner housing and the top of the throttle body. Because of the new O-ring gasket, the fit of the air cleaner housing on top of the throttle body is now much tighter and sturdier, meaning there is far less chance of allowing moisture to get in there....

Total cost for a new O-ring gasket and a can of throttle body cleaner at Advance Auto Parts was $5.90. Money well spent....

 

I used the Valvoline Throttle Body Cleaner to clean up the MAF sensor and the throttle body on my S-Type. Pretty easy to do and I noticed an improvement in smoothness as well. Also, I changed out the air filter. Overall, it took about 15 or so minutes. Total cost for everything was less than $30. Did the Great White Whale and that ran better also.

Mike

 

Mike,

When you removed your S-Type's air filter housing to get to your throttle body to clean it, what condition did you find the O-ring gasket in? Did you re-use it or replace it? I'm assuming that there is indeed an O-ring gasket there since I haven't attempted to gain access to our S-Type's throttle body yet. Our throttle body is still relatively new since it was replaced under warranty in mid-May as a result of my wife's "limp home mode" experience....

Given the tendency of these S-Type throttle bodies to collect moisture and experience problems, I would think replacing that O-ring gasket any time one decides to access the throttle body for cleaning would be a good idea. The better the seal, the more unlikely that moisture problems in the thottle body will occur....

 

Hi Jon,

I didn't notice an O ring gasket on the S-Type. The intake tube from the air cleaner to the throttle body is secured by hose clamps. You do have to remove the engine oil breather tube which is pretty easy though. After removing the intake tube it makes replacing the air filter pretty easy. Just pop the two outer tabs and the filter housing opens up like it's on hinges. The only tricky part is holding the butterfly open while you spray the cleaner inside the throttle body. You could probably use some silicone to coat the area around the connection but I haven't had any problems with moisture so far.

Mike

 

get the ecu read, the code should still be stored.

 

Well, I had considered my Throttle body or MAF to be an issue. I was thinking about cleaning them and it seems like a good idea. On the UK site that seems to be one of teh first suggestions to try. I know my plugs and such may be alright and it is water getting in somewhere, but since I'm close to the time to change the plugs and possibly coils I might just do them anyway. I'll see how things go today. I'm taking the car for a good drive and see what happens. Hopefully it'll take car of itself for now, but I'm still going to clean and replace these things!

 

Well, took it out today on the highway. Started fine, rough idle, just like a cylinder was not firing. Got it up to speed and got a flashing MIL for a few seconds, then it went away. This happened twice. Took it right back home and parked it. Felt and behaved just like my last car did that I had before this one when a coil went. The idle is the same as in that car. So, I am going to check the old fashioned way to see if I can find what coil it is. If that doesn't work I'll get it scanned since the MIL has now gone on and it will tell me what cylinder is down. Hopefully I'll be able to tell by disconnecting them one at a time and I'll hear a difference. I'm just glad the gearbox and restricted performance are gone! A lot easier and cheaper to fix a bad coil!

 

The flashing MIL is a warning that not only is misfiring happening but also that the cat may well be getting damaged.

I'd find and fix the problem NOW. I would NOT drive it in the manner you have done except to try to confirm a fix.

 

Well, I'm not using the car unless I absolutly have to. I only did that test drive to try and confirm a misfire. I am going to order a set of coils today and some plugs and change them as soon as I get them. I had to start and move the car this morning so I had to do about a 4 or 5 min drive. No flashing MIL but it is on now. I can smell fuel with the rough idle now so that confirms it! I'm replacing the whole lot of coils since I can get a set for $190 CDN and I have high Km's so not a bad idea to replace them I think! Or mybe I should just get say 2 or 3 just to replace the bad one and have a few extras incase more than one coil is bad?

 

All good points! If a new coil doesn't work, I'll have to check those things out. I can tell now that it should only be a bad coil (or two!). Hoepfully just one. The feel of the car is just like all cars I have driven with a bad coil. I'm going to get the car scanned at the local place today (hopefully) and see what cylinder's coil is bad. I am going to leave the plugs til the spring since I just don't have the time right now and it's getting too cold to work on a car! I was looking at coils and besides the dealer, here my only choice is to order online and get it shipped express, which would make one of the cheap coils cost about $70CDN. Called the dealer and they told me they can get me one tomorrow for $75CDN, so I just got one from them. I don't have time to wait for a cheaper one to arrive. I need my car! I should be able to swap it out tomorrow or Wednesday. This should fix the issue. Unless the car has some more surprises for me!

 

Ya, coils are easy to come by. I think that I'll clean and dry the bad coil and keep it as a spare. I am missing the top engine cover on my car (that covers up over the supercharger and such) which I have ordered. I don't want any water getting into where it shouldn't! So it is possilbe that water may have gotten into a coil and caused this problem. One of the covers over the coils is loose as well, so that leads me to believe that someone has been in there and not really known what they were doing. So, when I take it apart, I'm making sure everything is back in place properly!

 

If you are going to change the coils yourself, better make sure you have a deep socket (8mm). I have been doing some work in time for winter on my 2000 S-type V6 because it is getting frosty in Montreal. My standard "mechanics" ratchet set was not good enough for the fancy jag hex screws. I picked up the 8mm deep socket at canadian tire for $7.99

Oh and by the way, the coils I ordered over the internet work great !

 

Well, problem solved! As I suspected it was a bad coil. Got the coil yesterday, went home, and tested the old fashioned way for the bad coil by disconnecting each one and seeing if there was a difference in idle. Guess I got lucky since the second coil I tried was the bad one! I knew it was most likely one of the two that are nicely tucked away at the back of the engine. Tried the one on the left side first (facing engine), wassn't that one, then tried the one on the right. Bingo! I did disconnect some fo the other ones just to make sure there was only one bad one and so far it looks that way. So the culprit was the coil at the back of the engine on the right. The coil wasn't all soaked in water and oil. There was a little bit of oil on it, but since it is by the filler cap and I tend to be a little messy when topping up the oil it seems to be just a little bit of the spilled oil. Still, maybe between the previous owner and me spilling a little, it messed up the coil. I did wipe out the hole to get rid of any residual stuff, but it came up virtually clean. I figure if I did have a head gasket going (or something to that effect) there would be more oil. Anyway, 10min later and coil was replaced and everything was good! I am going to chance the plugs in the spring, so when I do I will check to see if more oil is there. If so, then maybe I will have to think about the head gasket. But I'm not too concerned right now. The car doesn't use that much oil between changes and there is no sign of oil where you would expect it to leak. Car seems to run smoother than the day I got it! Or maybe that is just me having to drive a 92 Honda Civic for the last few days!

 

And by head gasket I mean cam cover gasket! My bad!