Okay so Monday me and my friend decided to convert my car over to speed density, we did the GM IAT sensor and OMNI 4 Bar Sensor. We started tuning the car and it ran great WOT. But @ crusing RPMS est. 2k-3k, the car breaks up and starts hopping or shaking violently. I also have the problem where on a cold start the car brakes up @ low RPMs when going into 1st.

My friend says he's researched and found that some cars the tune on Speed Density have this problem, i just wanted to post this hear to see if somebody had the same problem and found a solution.

 

this is a known issue with the SD patch, there are a lot of experienced people working on this. Its a small little issue but the pros outweigh this minute detail. the problems are not as exaggerated as you make it seem. when you cold start youre car let it warm up, there are maps that retard timing based on coolant temps.

 

did you look the car in open loop?

my car runs better than stock with SD - WOT and cruise.

 

well i dunno when i was driving home from work yesterday the car while cruising started shaking so bad that i heard the clutch engaging, disengaging engaging, disengaging. Sure u can get off the gas and get back on it and it might help but sometime it'd do it again

 

You did not hear the clutch engaging and disengaging.

You may have heard the springs and disc jolting around with the clutch engaged.

 

My car is running SD and I've experienced the known issue. It's nothing like what you are describing. It's very subtle. It sounds like you have a much bigger problem. Are you sure that the AFRs aren't running super lean when it's running rough?

 

+1. Check those AFR's when it starts to break up and see what it's doing. Mine breaks up a little cruising but it's not really violent. WOT is perfect. And I let my car warm up everytime before I drive anywhere. If not, it is damn near impossible to drive.

 

Well 1 solution to my problem is im going to buy a remote start to get'r started and running correctly. Now im going to investigate today about the cruising AFRs

 

Remote start would be nice for the mornings your in a rush. Just make sure you don't park the car and leave it in gear! lol

 

Where I live, I need to get out of the quiet neighborhood as quick as possible. No time for warm-up.

I have not noticed that my car runs more poorly cold with SD than before. For you guys having issues, you might want to raise the coolant temp trigger for going into closed loop. Also, double check that your cold start ignition tables have been adjusted, particularly if you changed your load scaling. Your cold temp timing table too needs to be adjusted too. Otherwise, you'll be pulling 10+ degrees in load ranges way above what the stock tune intended.

 

This.

I have the Viper 5701 w/ remote start. It has some safety feature which does not allow the car to remote start if a certain sequence is not performed before turning the car off. This was never enabled on my car tho, but since then I rarely use the remote start unless it's cold but even then with e85 in the winter, the remote start can sometimes take multiple times to actually start. I have noticed that the remote start will drain the battery quicker if keeps on trying to start over and over. I have a mini battery btw.

 

Battery in the trunk FTW!

 

Good info even though it's off topic lol. I have a mini battery too.

 

I have an AutoPage alarm with remote start, mini-battery, and E85. Multiple starts when morning temp is 65 degrees or less. But, usually starts second or third try when the battery is fully charged. Using a trickle-battery charger overnight helps. Using a Baker battery now, which is slightly bigger than the AMS. Also had an Odyssey mini-battery that was crap... only lasted a few month and would hold a charge.

 

I don't think the permanant fix to SD related start up, cold and low RPM driveability is auto start, although it's a cool thing to have as well.

The reasons why these things are happening is that the VE is probably not correct for the condition.

Why this is happening could be tuning (set-up) related, patch related or even other tables affecting it (cold timing/ cold enrichment/enleanment TPS delta aysnc/etc). these tables are poorly understood (by me at least) and seem to be the key to getting SD working like stock.

I ran this patch most of the summer and experienced all of the above issues and followed JC bank's thread on how the patch worked and how to fix them, most of which where over my head, but he got it to work.

I am still picking through it though and when I set it up again, hopefully on V7 I will have my current set up dialed in and then carefully plot VE off that. By then I am also hoping that more people will figure out the tables to make cold starts and low RPM drivabillity smoother.