I currently own a 2002 Jaguar S-Type 3.0L vin M35400. Car always started and ran fine. I had a cylinder 3 misfire with code. I disconnected battery and replaced all 6 coils and plugs, checked plug gaps before install. Reconnected battery and car cranked but wouldn't run. Cleaned up tools and after approx 15-20 mins cranked car over and it started and ran engine miss was gone. Checked for obd2 codes had none test drove for 15mins or so shut car off. Went to start car again 15min later and again it cranked but wouldnt run. Once again I waited approx 20-30mins and it started right up and ran fine. Since then It may or may night start right up in morning. If it doesn't I can retry starting in 15-20mins and it will fire right up. If it does I can drive around fine until I shut it off then after sitting 15-20mins cranks but no run. It just keeps repeating this cycle.

Any help greatly appreciated. Thanks

 

Welcome to the forums ChappY41,

I've copied this question from your Intro to S-Type forum for advice from members with the same model.

Graham

 

I'd use OBD to check the two vital temperature sensors (ECT & IAT) are giving plausible values when it's starting OK & again when it's not. The car decides how much fuel depending on them (& MAF reading etc).

If they're not right maybe wiring was disturbed or the sensor gave up.

Our cars are quite like OnBoardDiagnostics.com - Engine Basics (but no IACV) to give you ideas about what goes on.

 

It may also be your "crankshaft position sensor" as these can fail and sometimes not throw a code.

 

Welcome to the forum. Note the clues you've given us. Previously all was good, except for a minor issue with one cylinder. You replaced all coils, and a brand new problem appears.

What brand of coils did you install? Many forum members have reported trouble with eBay specials and unbranded white box coils from the discount parts chains. The general consensus is to stick with name brands such as Denso, NGK, Bosch, etc. All six coils get power from a common source. It's possible, if one or more coils is bad, to draw down the available voltage so the others won't fire, but without drawing so much current as to blow the fuse.

Did you save the old coils? Five of them were still working, so you can use them for troubleshooting versus springing immediately for six new name brand coils.

The other possibility is an electrical connector was not fully reseated when you had the intake plenum off during the coil replacement.

 

Hi all, thanks for suggestions. Here's more info I can give. All 6 coils I used were brand new NGK brand. Plugs used were Autolite XP605. Checked gap on all plugs. After job was done I reconnected battery and car cranked fine but didn't fire up(run). But after sitting for 15min or so it cranked and fired right up ran fine with no engine miss. Next morning it fired right up, ran and drove fine on trip to store approx 15-20min. When I came out of store approx 15min once again car cranked fine but wouldn't fire up (run). I waited approx 20mins went back to car and it fired right up and I drove it home. Next morning it cranked over fine but wouldn't run. Tried again after 20-30min of 1st crank and it fired right up. It seems to be something with time between cranking and sitting. I checked all sensors related to engine temp, coolant temp sensor, Intake air temp sensor. I also replaced Crank sensor after problem started. No change. I tried spraying starting fluid (ether) into air cleaner box before MAF sensor no signs of firing up. One last note before cyl 3 miss appeared the security LED on dash would stay on dimly, but flash when FOB was pressed, alarm set. Now I don't see security Dash LED at all no blinking. I have 2 sets of keys and fobs both programmed and worked fine before problem appeared.

 

The PATS (security system) has, if I recall correctly, the capability to stop fuel, an ignition signal, or both from reaching the engine. Hopefully our PATS maven, Karl, will be along shortly to help with your issue.

 

PATS maven, huh? That title and $3 will get you a cup of coffee. Can't say I know a whole lot about PATS. I only know how the indicator light is supposed to work, and how to copy and paste:

For this intermittent situation, try the following when the engine is cold and seems to start fine, and then again the next time the engine won't start:

First, lock the car with the key fob. Press the lock button a second time to set the alarm system. The horn should chirp once. Watch the little red light. It should flash once every few seconds or so to show the system is armed. Now press the key fob unlock button twice to unlock all the doors. The red light should go out. Now hop in the driver's seat and turn the key to RUN (Not start yet). The red light should come on solid ONCE for about 3 seconds and then go out. If it flashes anything after that, you've got a stored fault and the security system may have inhibited the ignition and/or fuel pump.

Do you have a scanner or just a code reader? With a scanner, you can read live data. I'd suggest observing the fuel pressure and see if it is good even when the engine won't start.

 

Okay, phew, good to hear you didn't install Fling Dung or Wok Hoam brand coils.

Mostly thinking out loud, but I'm still working on the premise that somehow this new fault was induced during this recent work. NGK should be a good brand, but it's not impossible one of the new coils is bad. As previously mentioned, when you have a bunch of electrical loads (six coils in this case) out at the far end of a circuit, it's possible for a single bad part to draw the voltage down enough so the other components won't work. Here's the vexing part: this extra current draw may not be enough to blow the fuse. It seems to defy all troubleshooting logic, but I've had similar situations before.

Do you still have the original coils you removed? If so, try swapping them in place. I'd begin with the three easy ones, on the US driver's side, and see what happens. Won't cost a dime and will only take a few minutes. I'd hold off on the other side, just because access stinks with the big plenum in the way.

 

Can't help wondering if it is nothing to do with coils. I would suspect it is an electrical fault but is probably a sensor, actuator, or wiring to a sensor or actuator. Are all plugs pushed home fully? Are any wires pinched or chafed?

First systematically retrace your steps. Check everything you unplugged, if possible, while the engine is running. You can try the coil substitution thing if you want, at worst you will only have wasted a little time.

Check the fault codes. If nothing is found wrong, start checking sensor outputs, ideally at the ECU end of the wiring (yes it will be a pig of a job to get to, but that is traditionally the proper way to perform diagnostics). If you have the equipment, check the signals from the Crankshaft Position Sensor and the Camshaft Position Sensors. I don't have the data to tell you what the voltages peak to peak should be, but one of the Jag technicians on here might. It is not uncommon for tired CPSs to still work but give out a lower voltage (peak to peak) than the ECU requires to fire the engine. Also check coolant temp sensor, and every other sensor that is connected to the ECU. Pay attention to the throttle position sensor. The outputs from all of these sensors must be within the recommended ranges. Also check every earth and supply to and from the ECU is correct.

Doing all this will probably take hours of patient work, but it is part of the process of elimination. Possibly one wire or sensor was damaged, you just have to keep going until you find which one is showing the wrong voltage and then focus on that circuit. And yes it could be a wire to or from the immobiliser.

A word of warning, intermittent faults can sometimes be very hard to pin down. But as yours seems temperature related that might hint at a temp sensor or a solid state component. Both are well-known to work intermittently at different temperatures.

Good luck.

 

Before doing the awkward physical voltage etc checks, use OBD to look at everything you can - including pending codes and of course sensor values.

If you don't have pending (other than P1000/P1111) or actual codes, there can't be much wrong - but it's something critical.

Generally, bad things flag codes. Often multiple codes and you can be swamped. But lack of codes is something rare but critical as I've put.

Chances are that a sensor value will be wildly wrong but the PCM can't know that (whereas you can). E.g. ECT being -40 -- would ruin fuelling.

 

From the OP's "intro" in the New Members forum: "I am an ASE certified tech from New Jersey. I have approx 30yrs experience working on cars and trucks mostly American Big 3 and some European and Asian. You all are way more knowledgeable than I am about Jaguars."

 

Thanks Karl, Ill give that a try and let you know what happens.

 

Hi Everyone and thanks for suggestions. I have double checked all wiring and harness plugs. Nothing pinched or chafed. I have looked at sensor readings all seem fine based on temp conditions. As far as coils YES I do have all 6 that were replaced. Only problem is I didnt label them so I dont know which one was the original #3 with the miss and dont wanna pull intake off again lol. The reason I replaced all 6 was I figured if 1 went bad then maybe some of the rest would'nt be far behind and the cost for the three under intake was more than buying a whole set of 6. Individual coil price was between $20-$30 and I paid $100 for the 6 pack. It just seems weird to me that even when car had cyl #3 miss it still always started right up. But after I disconnected battery for approx 2 hrs to do the plugs and coils and reconnected battery it instantly cranked but wouldnt start but after sitting for 30min or so it fired right up and miss was gone. Next day it fired right up from a cold start and after taking for a drive to store. When i came out after 20-30mins it cranked but not run. So i wandered around store for another 30min came out and it fired right up and I drove home. Whats makin me crazy is if it starts and runs I can drive for 10 min or an hour fine and it will restart everytine after drive as long as it doesnt sit for more than 20-30min. Meaning if i run to store and come out in 5-10 mins it will start and run fine. But if i'm in store 30mins and come out it will crank but not run. But after crank no start I wait 30-40mins later it will start and run. Next morning it may or may not start. But if I wait the 30-40mins after that it will start right up. Sorry to ramble on but this thing is making me crazy. Over all my years of being a mechanic I have seen issues related to engine temp, ambient temp, bad sensors but this one is racking my brain. Thanks Everyone

 

I got to thinking about this one today. Spent maybe an hour, so if you wouldn't mind stopping by to do some yard work for an hour, we'd be even.

One thing that puzzled me is why the engine hasn't quit while running. You're getting the intermittent no-start, but it never stalls. If this was heat affecting a sensor or bad connection, you'd expect it to be worse while running. Granted, heat soak while parked could be a factor, but it's not consistent. And why does it sometimes happen on a cold start?

So I did some professional grade pondering. What's different while running? Battery voltage! Back to my theory of one marginal coil drawing a little extra current and pulling down the available voltage to the other coils. With the starter engaged, battery voltage drops down close to 10.0 under the massive load of the starter. This is perfectly normal and to be expected. But with the engine running, system voltage is closer to 14.0.

So my theory, offered for free and worth every penny, is your new coils are right on the edge of failure at 10 volts, exact reason unknown. One moment they work, the next they don't. But when the engine does start, the coils behave consistently at 14 volts.

When the coils do dip below the line and the engine won't start, the starter draw runs the battery down even further. But let the car sit 40 minutes and two things happen:

1) The battery voltage recovers to some extent.

2) The car enters sleep mode, with a big reduction in drain on the battery.

Could the battery itself be at fault? It could be a contributing factor, but not the primary cause as you didn't have this no-start problem with the old coils. To test my theory, try changing the battery every night for a week or so. I know it's a pain, but you'd begin each day with a fully charged battery. If the car now behaves itself, you'd know a factor was the interaction between the coils and battery voltage.

As far as swapping back to the old coils, I'd still try it on the easy side for now. If you inadvertently install the bad coil, it's no big deal. You'd just get a new misfire code and then you'd know which coil was bad.

 

Thanks I had that thought and tried charging battery with and without cables connected for 2 days each way. I'll try your suggestion for a week so keep cables connected? PS the battery was replaced with a new one approx 10 months ago. Also if it works ill do yard work or send case of beer or what ever you would like lol thanks

 

I would leave them connected. This reduces the hassle factor. And every time you disconnect the battery, it resets the OBD monitoring process. Some codes aren’t flagged until a certain number of occurrences have happened, so you might be losing important information.

 

That's a very good point and great logic. Should have thought of that myself. Let's hope your theory is right. Your theory would still stand if it was a damaged wire going to one of the coils causing a partial short.

 

One more thing to try, if my voltage theory is a factor. If you use the headlight Auto setting, try manually switching them off for engine start. Having the headlights on will further reduce voltage to the coils, in addition to the normal drop from the starter.

This might explain some of the seemingly random nature of the fault, if it occurs predominantly when the headlights are automatically commanded on. I use the Auto setting all the time, but it’s always bugged me the system isn’t smart enough to kill the lights during engine start. Lately, I’ve been manually switching the headlights off during start just to be nice to the battery. Not really necessary, as the battery should be able to handle the extra load, but why push it.

If this little trick causes your car to behave, then we know we’re on the right track. It’s not really a “fix”, just something free to try for troubleshooting.

 

What is the battery voltage across the terminals with the ignition in the OFF position when measured with a voltmeter during the 'no-start' condition?

What is the fuel pressure during the 'no-start' condition? There should be around 3 bar (300 kPa) fuel pressure when the key is turned to the 'ON' position prior to engaging the starter.