Lean Misfires at 2700-2800 rpm

[badass3000]

If you have the money then go for it!
BTW I have a different CAS on my car now, just cant seem to get the rest of the car together to test it.

[DoctorDex]

Well it looks like I've committed myself to buying a DLI. It'll be a couple of weeks before it gets here. I'll let you know if it has any effect.

Originally Posted by badass3000

BTW I have a different CAS on my car now, just cant seem to get the rest of the car together to test it.

Apart for more upgrades? I'm curious as to what else you could possibly do to that car, its pretty sweet. If you don't mind, keep me posted re: the CAS and any other changes you've made.

[DoctorDex]

I know I mentioned this before, but I continue to experience many small misses and occasional large misses while cruising @ ~ 2650 rpm. The large misses are usually coupled with a relatively large manifold pressure spike, measured with an electronic boost gauge (ie. from -10cm Hg to 0.00 and then back to -10cm Hg). Not sure what to make of this. ? Mechanical issue? Valve not closing all the way prior to the initiation of combustion? Anybody know what to make of this?

[StealthCRF]

do you still have egr

if so, just try disconnecting the solenoid connector and going for a drive

edit: oh and one more thing... if the egr connector and purge flow solenoid connector are crossed this WILL happen.. same w/ vacuum lines

edit2.0: just saw your first post. try disconecting purge solenoid if you still have it (noticed you have egr delete)

[DoctorDex]

I still have the EGR, which _might_ explain why I'm seeing manifold pressure fluctations (ie. unburnt fuel from the miss entering the rear manifold, igniting, and then causing the pressure spike.) I have tried disconnecting it before in the past and it didn't make a difference, hence the reason I reconnected it. This time, I'll disconnect all of the solenoids to see if it makes any difference and I'll report back.

[DoctorDex]

Went for a drive tonight with all of the solenoids disconnected. No effect on the missing.

Left the EGR disconnected and drove for ~ 15 minutes and tried to make a manifold pressure spike/low load knock by driving in the "miss zone"; preliminary results show no pressure spike and no knock. If these results do prove to be consistently true, it would lend support to my theory that unburnt fuel is entering the rear exhaust manifold and igniting causing manifold pressure spikes +/- low load knock. I'm going to keep the EGR disconnected and I'll be driving for a number of hours tomorrow, so I will be able to better test this theory. Will report back with more info.

[StealthCRF]

awesome, hope i was able to help fix the problem

[mopargirl24]

My car did this after overheating on the way to Colorado in 100 degree weather (the shoulder of I-70 is really the place I'd wanna be in this sort of weather...). Anyways, it fried all of my plug wires. We changed the wires and the problem was solved. Exactly what I wanted to do on my vacation. It also limited my time with my brand new nephew. Dang finicky little car. Good luck!

[brattesani]

any updates?

[DoctorDex]

Sorry, I've been away.

Here's the latest update re: the possible implications of the EGR:

It does seem as though the EGR is implicated in the manifold pressure spikes I would occasionally see while cruising @ ~ 2600 rpm. Since disconnecting the EGR, I no longer see spikes from - 10 cm Hg --> 0.00 --> -10 cm Hg.

However, I am still experiencing occasional episodes of low load sustained knock while gradually accelerating @ ~ 2600 rpm. During the most recent episode, I saw a sustained 12 counts which continued, despite 7* of timing being pulled, for a number of seconds until I was eventually forced to let off the throttle.