A high speed (indicated) miss could be a lazy O2 sensor or a lazy crank position sensor.
The computer uses O2 timings to measure for a miss by somehow figuring out which exhaust pulse is which cylinder (I didn't think the PCM was fast enough to do that, but I digress). A lazy O2 sensor at high speed can make the PCM think there's a miss.
A lazy crank sensor will actually cause a miss, as it will throw off the fuel sync and spark timing. This is then picked up by the O2 and reported.
The computer uses O2 timings to measure for a miss by somehow figuring out which exhaust pulse is which cylinder (I didn't think the PCM was fast enough to do that, but I digress). A lazy O2 sensor at high speed can make the PCM think there's a miss.
A lazy crank sensor will actually cause a miss, as it will throw off the fuel sync and spark timing. This is then picked up by the O2 and reported.
Quote:
The computer uses O2 timings to measure for a miss by somehow figuring out which exhaust pulse is which cylinder (I didn't think the PCM was fast enough to do that, but I digress). A lazy O2 sensor at high speed can make the PCM think there's a miss.
A lazy crank sensor will actually cause a miss, as it will throw off the fuel sync and spark timing. This is then picked up by the O2 and reported.
Thing is, i have already replaced both, 02 sensor and crank sensorOriginally Posted by magnethead
A high speed (indicated) miss could be a lazy O2 sensor or a lazy crank position sensor.The computer uses O2 timings to measure for a miss by somehow figuring out which exhaust pulse is which cylinder (I didn't think the PCM was fast enough to do that, but I digress). A lazy O2 sensor at high speed can make the PCM think there's a miss.
A lazy crank sensor will actually cause a miss, as it will throw off the fuel sync and spark timing. This is then picked up by the O2 and reported.
Apart from that, last weekend i unplugged the o2 sensor, i felt sluggish while driving and guess what, it did it again!!! So, i dont think the o2 sensor is causing this.
What i did was to put together a table with the misfire counters that i have been getting when driving at high speed, this is what i came up with:
Interesting things
- Always its at high speed
- The jerk thing doesn't happen at the same time as when the solus is displaying misfires but this may be due to the Solus not really presenting the misfire data in real time
- Its almost always the same cylinders
- Taking a closer look, all cylinders missing present about the same number of misfires, is not like one has considerably more than any other
Another thing i did was to check the firing order:
If I sort the table by firing order (instead as by cylinder number) this is what i get:
Interesting fact
- Its always like one fires, next one fails, one fires, next one fails
If you have any ideas, let me know
My next step will be to swap the injectors from the cylinders that are miss firing to the ones that are not and vice versa
Quote:
Wasn't there a write up on spark plug wire routing to keep them from arching off each other or something like that?? It sounds like a lean surge, but if it's missing it's gonna show it's running Rich because of the unburned mixture. What temp coolant does the ecm show?? And what temp air does the ait show?? If you can get those readings on your scanner.Originally Posted by HeyYou
How old is the crank sensor?
Quote:
Have replaced it alreadyOriginally Posted by rebeltaz83
Have you done anything with the coil? I've seen them do some funky things after they get hot, and put under a load.
Quote:
Like 7 or 8 months, that is the first thing i replaced when the issue startedOriginally Posted by HeyYou
How old is the crank sensor?
Quote:
Yeah, there is a TSB, i did it like 6 years ago and have been routing my wires as per the TSB ever since.Originally Posted by rebeltaz83
Wasn't there a write up on spark plug wire routing to keep them from arching off each other or something like that?? It sounds like a lean surge, but if it's missing it's gonna show it's running Rich because of the unburned mixture. What temp coolant does the ecm show?? And what temp air does the ait show?? If you can get those readings on your scanner.
Here is a snipe of the Solus with some of the important PIDs, the blue line shows when the issue was present:
Quote:
1 degree ECT and 3 degree IAT oscillation is rather normal and won't affect anything noticablyOriginally Posted by HeyYou
I am curious why the two temp readings jump around like that...... or is that just the way the tool graphs them?
It's always good to stay with the Mopar sensors- 02/cps/cmps/tps/map .Off brands are well known to throw off readings ,especially if multiple sensors are the off brand =new trouble.
(-the 02 moreso).
(-the 02 moreso).
Registered User
So after reading the whole thread did you ever get that problem figured out?
I'm basically in the exact same boat with my 98 5.2l dakota and its been driving me nuts. Pretty much replaced every sensor and tuned everything up that I could think of and its still having this exact issue. I'm waiting on the new aluminum plenum plate from hughes to see if by some chance the factory one is causing an oil leak thereby causing it to go rich and cut fuel way to much in closed loop hwy driving.
I'm basically in the exact same boat with my 98 5.2l dakota and its been driving me nuts. Pretty much replaced every sensor and tuned everything up that I could think of and its still having this exact issue. I'm waiting on the new aluminum plenum plate from hughes to see if by some chance the factory one is causing an oil leak thereby causing it to go rich and cut fuel way to much in closed loop hwy driving.