intermittent P0301

[azharj]

Miles: 360,000

P0103 CEL not flashing sometimes turns off itself and then comes on. First time it came on speed breaker. But later comes on smooth roads also. Good start no driveablilty problem. Good gas average. OBD momitor 6 type A misfire all cylinder is 0. Cylinder events 0. Freez frame Data ECT 85 RPM 2091 VSS 34 km/h FEULSYSA CL SRTFT 1% -2.3 SRTFT 2 % -3.9 LONGTFT 1% -4.7 LONGTFT 2% 1.6

Everytime the Data is different. The code is no reproduceable. Plug motorcraft paltinum changed 12000 km air filter changed 6000km feul filter changed feul filter changed 120000 km

[phil-l]

This almost sounds like it could be a wiring harness problem. An intermittent electrical connection can do all sort of strange things. I'd start by hooking up your monitor - and have a second person wiggle portions of the wiring harness to see if the data monitor starts changing when one part of the harness is moving. Begin with the wiring harness that goes to the MAF. Also be aware that wires can bend where they enter a connector; at 360K miles, those wires have been moving for a long time.

[azharj]

Thanks good suggestion

[azharj]

I checked all wires and the harness to MAF, TPS and Camshaft sensor and Crank shaft sensor moved the wires but no code came up. Any other idea??

[Mustang_Driver]

try changing the coilpack...i thought i dropped a timing chain and all it was was the coil pack 50 bucks later the van ran fine just had a coolant leak at the factory press on fitting

[scubacat]

Coil pack failure is very common and tricky to diagnose. With any mysterious misfire, I'd swap that before spending any more time on this. If it's been a while, change the spark plugs and wires, too, while you're in there.

[azharj]

Thanks all. I changed the coil in 2011. Because of engine stalling randomly. I read that coil works in pairs. There should be 0301 and 0305. Cylinder one and five work together, 2 and 6, and 3 and four I may not be correct in these no.

[wiswind]

Also plug wires. Sometimes, if you have a dark place at night. Lift the hood while it is idling and see if you can spot any glowing / sparks. A spray bottle to spray a fine mist of water may help in that. If the wires are old, I would just replace them as well as the coil pack, which is now old from 2011. You don't want to replace much only to find out it was coil pack or plug wires. Fuel system cleaner would be my next guess.....dirty fuel injector can cause this also. A good dose of Berryman's Chemtool in a tank of gasoline. If you have a period where that tank of gasoline will last a couple weeks, it will be even better as the solvent has time to soak.

[azharj]

Finally the culprit found.
Thanks for all the friends resposes
The CEL was coming on and off during driving. The code pulled was always P0301. It was intermittent. Clearing the the code after third cycle, monitor readiness used to become green. There was no driveability issue with good gas average. Each time, among the various parameters shown in Free Frame Data like STFT, LTFT VSS, etc. the ECT was always near 90C. It never happened when it was cold. I forgot to mention that coolant used to decrease by one litre after highway drive about 400 km and in city, after a week. I had changed the No. 1 spark plug and plug wire. Injector cleaner I, already, had tried, no use. I was palnning to change the coil. I bought the original motorcraft coil pack.
Two week back following a leisure trip of about 2300 km, engine lost power and huge steam came from the engine bay. I am frequently watching the temprature gague. The temprature was normal it never overheated.
Since it happened first time, I was suspecting head gasket, but different mechanics were not convinced. So referring to the post, http://www.automotiveforums.com/t310...8l_engine.html, I guess the problem was slow leak of gasket of the cylinder one, which blew completely. Today, I have changed the head gasket. All cylinders were full of coolant. The egr port were clogged except to the cylender No. 3 and 4. Tomorrow I will take a test drive.

[azharj]

Test Drive after change of head from junk yard and gaskets.
No missing STFT and LTFT of both banks nearly +2 to +3 equal. Before one bank always + upto 13 to +15 and the other negative. coolant is not lost any more but, three weeks ago the coolant reservoir cracked small leak. Today I have received new coolant reservoir from ebay for 75 USD including shipping, will change it and see.

[azharj]

The New coolant reservoir was installed in 27 July 2023. Now there is almost no water leakage. Only 100 ml water, I have to add after 1000 KM. I changed spark plugs platinum tipped from ebay on November 2023. Now it runs great I have to add 250 ml engine oil after 500 to 1000 km. So the culprit was the leaking head gasket.

[maxwedge]

Thanks for posting back. Good to hear good news here.