Engine high-pressure cleaned, now rough running and CEL

Cees Klumper · Post by **Cees Klumper** » 13 May 2016, 06:49

Yesterday I had to have my 2002 T6's engine and undercarriage pressure cleaned at a garage for the periodic check-up here at the Geneva DMV this morning. When I picked up the car, I noticed a very slight intermittent stumble at idle. I thought 'some moisture, it will dry up' and over the course of some driving, it did clear up completely. Then this morning I took it to the DMV, not a spec of trouble, and wouldn't you know it a hundred yards before I reach the DMV the engine starts missing badly, and throws the Check Engine Light. Needless to say it failed inspection with that light on, and the first thing the DMV mechanic said when I mentioned the stumble was "due to the cleaning" (this cleaning is mandatory before every inspection and I bet they see this problem all the time with overzealous mechanics blasting everything in sight with high-pressure steam cleaning)

So I limped home, engine running rough like it's on 5 cylinders. I pulled all the spark plugs and inspected everything there but there was no water, and all plugs looked ok, and all the same. Also checked all the hoses and electrical connections in sight, checked in the fuse box but that is also dry. I need to pick up my OBD code reader tomorrow, so can't read codes now, but I am thinking based on the symptoms it's a bad connection to either MAF, TCM, Oxygen Sensors or ? The fact that it was intermittent and slight at first, then cleared up completely, only to re-occur after having sat overnight and after having driven approx 14 miles, leads to me to think bad electrical connection but am grateful for any suggestions. Will post the results of reading out codes but can't do that until next Wednesday. Thanks for any tips.

Cees Klumper · Post by **Cees Klumper** » 13 May 2016, 07:18

P.s. just did the check mentioned in another thread:

"Turn key to pos II or start the engine.
Press and hold down [READ] on the the turn signal lever, and press the rear fog light button 3 times quickly.
Press [READ] to advance to the next item.

BCM - Brake Control Module
SAS - Steering Wheel Angle Sensor
SRS - Safety Restraint System
ECM - Engine Control Module
AUM - Audio Module
and so on.
Benefit will verify that you have a stored DTC in a system that may not be supported in the DIM window."

And I did get the message 'DTCS IN VEHICLE' so next step will be reading codes in a couple of days.

Cees Klumper · Post by **Cees Klumper** » 18 May 2016, 06:27

This morning read the codes: there were two, 3503 (cylinder misfire) and 3563: cylinder 6 misfire.

So I replaced the #6 coil and spark plug. But the problem persists and the code comes back.

I then took the old coil with a new spark plug, and with the engine running, held the spark plug against the engine block to see if there was spark at least this way: indeed no spark. I've searched here and elsewhere, and before I take it to the deaker to sort out, three questions:

- is the way I tested the spark, by holding the spark plug against the engine grounding it, with the coil loose-in-hand (i.e. not grounded to the engine) the right way to check for the spark, or should both the spark plug AND the coil be grounded?

- assuming I checked it properly, confirming there is indeed no spark going to cylinder 6, could that be caused by a bad injector on cylinder 6, causing the ECM to cut spark to cylinder 6, or would that mean I should get an additional error code, about that injector?

- if it's not the ECM cutting spark to 6 because of some other problem, then to me it seems the only other cause can be a bad connection/broken wire going to coil 6. How would I best go about checking where this bad connection or broken wire might be?

Thanks for your help, I'd really like to fix this issue myself. It seems like it should be something small, considering it started after engine cleaning, started intermittent and then next day became a permanent condition.

oldironsights · Post by **oldironsights** » 18 May 2016, 14:12

Do you have a 12v signal to the primary side of the #6 coil?

Cees Klumper · Post by **Cees Klumper** » 18 May 2016, 14:18

Just checked the resistance of injector no 6, and it was 12.5 ohms, same s a couple others I checked for reference. I plan to swap injector 6 with another to see if the problem moves to that cylinder. If it does, then it's the injector. If it doesn't, then it could still be the spark on no 6, OR the injector is not getting a pulse (wiring?). To check for that, I guess I need a noid light? Also plan on checking compression on no 6. Althoug a burnt valve seems less likely given how the issue came and went, then came back.
That's what I've been able to find in other threads. Would appreciate any comments.

Cees Klumper · Post by **Cees Klumper** » 18 May 2016, 14:20

oldironsights wrote:Do you have a 12v signal to the primary side of the #6 coil?

Thanks for your reply; will go and check now. Not sure where the primary side is, but will try with my multimeter and report back next.

Cees Klumper · Post by **Cees Klumper** » 18 May 2016, 14:50

Checked the no 6 coil and on the white-and-green wire I do get 12 volts, same as another one I checked.
The spark plug was dry even after running without firing for a while which tells me it's not getting fuel?

Cees Klumper · Post by **Cees Klumper** » 19 May 2016, 07:28

So today I checked the no 6 injector and it also has 12 volts to one of the terminals with the ignition on. So both the coil and the injector have 12 volts, although we don't know whether they get their signals as they should.

As I wrote above, there does not seem to be a spark, but I am still not sure whether I have checked that properly: putting a new spark plug in the new coil, and with the engine running holding the spark plug against the engine block for earth. Can someone please confirm this is the right way to check whether I get spark? I've searched youtube and this forum and I can't find the answer to this most basic of questions, so I would appreciate someone helping me out with that.

Lastly, I swapped the no 6 injector with the no 4 injector, to see whether my misfire would follow the injector. Cleared old codes, short test drive and codes still say *misfire cylinder 6*. So we can rule out the injector as being faulty or dirty, but now I'm still unsure as to whether:
(1) coil is not getting its signal
(2) injector is not getting its signal
(3) there's a compression problem

At an auto supply shop this morning I ordered a signal tester and a compression gauge. Supposed to come in tomorrow (auto supplies stores here in Switzerland/France are not as plentiful as in the US and they don't carry such excotic testing gear in stock).

At least I have eliminated the coil, spark plug and the injector as possible culprits. Remaining are (1), (2) and (3) above, or am I missing something else here?

Thanks for any help!

Cees Klumper · Post by **Cees Klumper** » 20 May 2016, 04:34

Well, today is my birthday and I got a nice present this morning: decided to triple check the spark, and lo and behold turnd out I had installed the new coil wrong, the 'sleeve' had gone past the spark plug rather than over it, and so was not making contact. Engine now running sweet as ever, cleared the fault codes and none came back so problem solved. It turned out to be the first thing I suspected but almost went on a wild goose chase because of my own sloppiness. Another couple lessons learned.

oldironsights · Post by **oldironsights** » 20 May 2016, 17:51

Happy Birthday Mr. Klumper!

Glad you solved your problem.
When I replaced spark plugs on my S80 shortly after purchase, I noticed #6 ignition coil saturated with oil from the nearby filler cap. It came apart in my hand. Still worked but I replaced it anyway. I have driven it 13,000 miles since joining this forum in October.
I will give my two cars a rest tomorrow & commute on my FJR1300.
After Hurricane Katrina I sold my two remaining motorcycles(BMW R100CS & Moto Guzzi LeMans) & immersed myself in the shooting sports.
I have some old Swiss rifles that I like to shoot. M1911 & K31's. I like your GP-11 ammo. Very accurate combination.
Enjoy!