M42 puzzle
-
After unplugging assorted things the issue may be the O2 sensor even though throwing no codes.
Smooth idle cold, after a few minutes stumbles, cel flashes and almost dies. Disconnect O2 sensor and idles smoothly, give it throttle still runs smoothly but cel flashes.
Cel flashes on throttle with or without O2 sensor connected. No codes stored. Think it's time to try a new O2 sensor.
Coil packs check out fine, cps as well, cam sensor, tps and icv, afm (tried with and without the resistor harness).
Replaced fuel filter, spark plugs, intake boot.
Checked plug wires. Resistance on wire 1 is 15.33; wire 2 is 5.76; wire 3 is 5.74; wire 4 is 5.98. Meter set at 20k. Not sure what values should be.
If anyone can think of something I've missed please let me know.
-
Thank you sir. Bought one this morning. Haven't installed it yet. Did find one possible intake leak source. One of the multiple hose pieces between the crankcase and the throttle body on the m42 the only one I hadn't replaced turned out to be cracked. I picked up some crankcase hose when I bought the sensor and will try that first to see if it makes a difference.
-
Hose replaced, smoothed it out a bit. O2 sensor replaced, smooth idle cold and warm with no CEL. Give it throttle and cel flashes, no stored codes. Even checked the bulb to see if it was loose. All good.
I'm stumped. Car runs fine. I've got an oil leak at the filter housing maybe this?
-
Does it depend on how aggressively you accelerate? (AFM pegging out),Does it depend on the RPM range you are in?(O2 sensor losing connection), Does it only occur at a particular throttle position? (worn spot on the TPS)
If it were related to the Main ECU relay having a bad connection/loose relay the car would stumble when it happend
BUT, it may be worth checking into the o2 sensor relay since the car would still operate normally under open loop and perhaps a code for o2 heater voltage or o2 signal wouldnt be stored because the duration of the malfunction isnt long enough. This is just me theorizing and thinking out loud, some ECUs require a certain number of malfunctions within a certain timeframe to store a code and a certain number of start cycles with no malfunctions present to clear the codes so having a time/duration based code storage criteria is something that makes sense to me as a possibility (my theory/me thinking aloud).I am also curious as to whether it is AFM related, such as a dead spot on the resistor track or a weak spring, or a wiper arm that needs adjustment since a vacuum spike within the intake tract while accelerating could peg out the AFM with one of those problems and cause it to read out of limits.
-
Tried smooth and hard acceleration and same result.
Needed a muffler shop to get the O2 sensor out. On the way home cel would flash but under load up a steep hill doing 35-40 did not flash. Once on a more level grade would flash. This might mean something but I'm not sure what.
Rpm range flash starts around 1500 and will flash up from there. Highest I revved it was over 4k, and still flash.
Swapped out the O2 sensor relay early on but since it didn't make a difference put the original back in. Since the O2 sensor has been changed I'll try th
-
Does it happen on a cold engine during warmup enrichment?
When you hear of a blinking CEL under load with no stored codes that initially makes me think misfire but you say its running good.
Have you tried disconnecting the battery for a few minutes to reset the ECU?
-
Stupid smart phone...
I'll try the new relay.
Could be afm. I've been driving on Milwaukee roads with lowered suspension enough to rattle teeth. Maybe something knocked out of whack.
A quirk in the ecu itself? I've got an extra one I can try.
This uphill on a steep grade though has me curious.
-
Well... Maybe solved.
Still same cel issues this morning, cold and engine warm. Except when going up a steep hill with throttle.
Gas gauge showed about 3/8 of a tank and I hadn't added any since this mess began in case I had to pull the pump. So added a container of HEET, put in 5 gallons of 93 from the local SA. No change for about 10 minutes then I got on the throttle hard, cel blinked for a bit then stopped blinking.
Drove around for about a 1/2 hour fine. Turned it off for about 10 minutes. Started again and ran it again for a 1/2 hour. Side streets and highway. Fine. No cel.
Letting it sit for the rest of the afternoon and we'll see what happens later.
Like I said maybe...
-
Sat for 5 hours, just took it out again. All good at idle and at speed. Go figure.
Bad gas (Shell premium though) or condensation in the tank after running it down to the warning light before I had filled it up. Add in the old O2 sensor, a few marginal hoses, older plugs. etc etc???
-
Or just go to west allis on the corner of 76th and Lincoln. They sell 110 octane
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login