I have a 2005 S-Type 4.2. I runs fine most of the time, including cold starts. But about 1 time in 4, it runs very rough for about 30 seconds after a hot start, setting codes P301, P303, P305, and sometimes P1313 and P1316. After 30 seconds, things smooth out and there are no more problems, even at full throttle acceleration. I've reset codes several times, and then within a few days on a hot start somewhere, they will reset. Dealer started by cleaning injectors, MAF, etc for a couple hundred bucks. Now they want to replace coils on cylinders 1,3,5 and change all plugs, but they want $1000 for that and say there's no guarantee it will solve the problem either. Any ideas?

I though maybe bad gas, but am on my second tank now since the problem started. Both were Shell, I'll try Exxon next time. I also thought remote possibility of weak battery. It starts ok, but is original equipment, 7 year old battery, so maybe voltage is weak for a few seconds after cranking until generator gets some current into the system. Have not changed battery, but am tempted to try that, as $125 with no guarantee is better than $1000 with no guarantee, and the battery will probably crater before too long anyway. Other ideas???

 

You likely have a vaccume leak. Check hose from air intake tube to cam cover (passenger side), check air intake box for proper sealing of top to bottom. Snoop around, but I'm sure its a vaccume leak, not coils and plugs.

 

Thanks, I'll check those tomorrow morning when I'm dirty again. But why would this cause only a hot start issue? There have never been any symptoms, problems, or codes set on cold start, normal operation, or at any time other than the first 30 seconds or so after a hot start?

 

It sounds bad enough to want to fix it but not bad enough to do it very urgently. I wouldn't rush to spend the $1K.

1,3,5 are all on the same bank (the RHS). If all started at the same time, rather than one or two of them and finally all three, then an air leak or contamination of coils (oil/water/whatever) would be my feeling.

By all means look & listen. You may well not find anything but it's free and you never know

Oil/etc in the plug wells on the R bank is a definite possibility.

Yes it could be the battery. There's a heavy peak current required for injectors & plugs and it must be delivered or trouble occurs.

I don't see why it would only affect one bank, though. Same comment applies to the gas.

Could be wiring-related as I expect the L & R banks have specific wiring from some point.

I'd get an OBD tool and use "live data" (make sure it does that), such as an elm327. Look at the fuel trims of each bank - they ought to be similar and near zero. Post them if you like.

If any engine-bay work has been done around the time the codes started, what was it?

How many miles on the car? (and thus plugs)

 

I’ve had several of those thoughts, most strongly, “why only one bank”, and “why only hot restarts”. At first, I thought perhaps there were separate fuel pressure regulators for each bank, but it appears to have a common one. Car has 71000 miles.

I have a code reader for my laptop that reads at least some real time data, but I have not gotten around to hooking it up in real time, so do not know if it will read the ones you mention. So far on this problem, I’ve only used it to read history codes and do resets. I tried the dealer because I didn’t have time to mess with it right away. The dealer said it did not fail for them while they had it. As you say, it’s not a critical problem, so I won’t take it back to the dealer until I’ve had some time to mess with it. I’m not in “ace mechanic” category, but I’m reasonably knowledgeable.

As far as recent work, the heater valve was replaced about 3 months ago. I had that done because of poor access without a lift, and I suppose it’s conceivable they knocked something loose, but arguing against that, it ran ok for 3 months before this started. The first occurrence was on the first hot restart after a gas fillup. But as you say, there’s no obvious link from gas to why only one bank and why only on hot restarts. Best I could come up with on gas is really reaching – higher winter vapor pressure of winter spec gas might make it easier for gas to vaporize in the fuel rail while stopped hot, and if that happened, it might clear quickly after car runs for a bit.

 

If OK for 3 months I'd ignore that work as a cause.

If it does any live data it'll include fuel trims. They may not read instantly but should after that. If it's an air leak it will show at idle and if you rev to 2500 they should head towards zero.

Oil/etc in the plug wells is what I lean towards but you'd have to look to find out.

At 71K the plugs are not due for ages so I really doubt it's them.

It could be the cat on that side and if so it's probably covered under the warranty (may depend on your local state laws and see where I am so I won't know!).

 

First do as JagV8 said. Until the spark plug wells are inspected you don't know what you have. Your inconsistent symptoms point strongly to oil in the plug wells.

It's easy to do yourself. The coils have a snap on cover and then one bolt and an electrical plug for each coil. Then just wiggle and pull straight up. If the boot is not nice and dry you have a problem.

Let the list know what you find out.
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Thanks for the ideas JagV8 and TBIRD6. I'll try them out, along with the earlier one from BFSGROSS and any more that get posted. I'll also report what I find. But it may not be right away. I'm in a very busy period right now, and as one of you observed, unless it gets worse, the problem is in the annoyance category, not an immediately critical problem. I figured it would take a while to get some meaningful replies, and am surprised and pleased that I got 3 so quickly. The only thing that continues to bother me a bit is that it's not obvious to me why any of the ideas would cause an issue only for 30 seconds after a hot restart. But one of the characteristics of intermittent problems is that their causes can be confusing. Meanwhile, anyone chime in with ideas or explanations that specifically address the aspect that it only occurs for 30 seconds or so after a hot start, and even that is only one time in 3 or 4.

 

Sometimes we look past the obvious. Walk away from the car, then return with fresh nerves. Good luck, please keep us posted.

 

I doubt you'll figure it out except by investigation, whether physical or OBD.

In case it's misfiring "gently" more than you know, it's destroying the cat.

 

I made the time to do at least a basic check of the suggestions this morning, and did not find anything. Plug wells dry. No vacuum leak found. Fuel trims low. Trouble is, I couldn’t get it to fail either. I only had time to let it get hot, sit twice, and restart twice, and both times it restarted ok. So the devil of my problem is that I have an intermittent issue, and even worse, even if/when I can get it to occur when hooked up to the scan tool, I’ll only have about 30 seconds to look at it until it disappears. So I guess for now, I’ll go ahead with the plan to try a different gas brand next fill-up, and perhaps replace the battery (I did not do that this morning). It may be that I’ll have to “wait it out”, until symptoms start occurring on most or all hot restarts, or at times other than a hot restart.

Having said all that, perhaps the most important thing I found out as a result of your suggestions is that this may be covered under the extended emissions warranty. I had figured that at 7+ years old and a bit over 70000 miles, it was way beyond any warranty. But when I looked, the big buck major stuff like ECM, TCM, cats, electronic ignition, etc, are covered to 8 years 80000 miles. Since the nearest Jag dealer is about 50 miles from me, I had taken it to a local shop for the clean out. But assuming it keeps happening, if I verify with the dealer that 1313 and 1316 codes qualify for the emissions warranty, I’ll take it to them. This should presumably keep me from incurring really big buck repair.

Once it all gets sorted out, I’ll post the outcome. Thanks again for the input, especially for prodding me to check the warranty provisions. Kind of hacks me off the local shop didn’t tell me that. The 8 year 80000 mile warranty is probably a federal requirement, so they probably knew and didn’t tell me. Guess it proves the old adage, let the buyer beware.

 

My wife's 05 4.2 is having a similar problem. We'd get a check engine light and eventually took it to our shop, and our mechanic has Jag software and pulled data out and found the misfire occurred at start up. The car has 88k on her now. We had a tune up with fuel filter and plugs, throttle body cleaned MAF sensor cleaned. There was no oil leakage around the plugs. Engine data showed the misfire occurred right at start up. The fuel filter was really dirty and mechanic speculates an injector may be leaking so that when the car shuts down ... some fuel leaks in, and a restart shortly thereafter causes the misfire. Generally 301 303 305 codes. Before tune up, we pulled the cat damaging misfire code ... but since tune up we just pull the misfire codes. Mechanic also thinks that with more ethanol in gas. We just bought the car a couple months ago so we don't know the fuel history etc. He put some strong injector cleaner in our gas and we've run a couple tanks of fuel through her. I'm running some lucas injector cleaner now, and pulling codes from the local part store. I did change the battery too (we'd checked it and it wasn't reading strong.) I guess I need to check the vacuum lines etc as a possible source too.

 

It's too soon to claim the problem is gone, but since since the last report, when I topped up the low battery water, changed brand of gas, and checked the plug wells (they were ok, but I suppose jiggling the wires during that operation could have helped a loose connection), the problem has not reoccurred.

 

You can change the plugs, boots, and coils yourself. It's pretty easy, and a lot cheaper. That should take care of the misfire if not, then it's a fuel injector, compression, etc problem.nThe code that was pulled should tell you exactly what cylinder is misfiring.

 

Here’s what I hope will be a final report, but given the nature of intermittent problems, might just be an interim chapter. A day after the last report, I had a mild incident. I say “mild” because only one cylinder’s misfire code was set, not several cylinders, and not the catalyst damage code. Since jiggling the wires and topping off the battery water had seemed to help a bit, I replaced the battery. It was still the original 7 year old battery, and while it had never failed to crank and start the car, I was at least a bit suspicious that the drain of starting with an age-weakened battery might make voltage a bit low for a minute until the generator pumped it back up. Indeed, the new battery cranks the engine noticeably faster, and there have not been any incidents since replacing the battery. I suppose Murphy ’s Law says that as punishment for posting this possible solution, it will set the codes again on the next hot start. But at least for now, I’m optimistic that the problem was indeed low voltage after starting with an aging, weak battery.

 

Sounds hopeful - but do post again if it's not the fix!

 

LDB...... anything further to report???

 

There still haven’t been any more incidents since replacing the battery, so I’m getting increasingly optimistic that was the problem. When I carefully read the forum prior to making my initial post, it seemed like the misfire codes were fairly common, but not a single thread that I saw mentioned my odd characteristic, namely, that it happened only in the first 30 seconds or so after starting. So my solution probably is not a general one. On the other hand, who knows? If indeed the battery was my problem, and it looks increasingly like it was, perhaps as the battery keeps deteriorating, voltage would go low at other times besides right after the drain of cranking. Idling with lights, AC, and other accessories running comes to mind. And relative to a trip to the shop, a $125 battery is cheap. So the way I looked at it when deciding whether to try replacing the battery -- I knew it was possible I was flushing $125 down the commode. On the other hand, I’d already flushed $300 down the commode on an intake and injector cleaning job that had done no good, and it was only going to get more expensive from there. So I figured it was at least a decent bet, and so far, it looks like it was.

 

Thanks for the report back. You are correct that this has not been a reported problem but as the cars age different issues will come up.

It also reinforces what we already know. If the battery is old just replace it. Cheaper in the long run and batteries do seem to last 6-7 years which is pretty good for $125!!
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