24 replies to this topic

[blk09rt6sp]

up until yesterday the car has been running great, feeling really string. On Thursday I did a 4th gear run in cooler weather to see if there was any difference with the solo broken in over the summer. The result was great - one of the est TTDyno charts to date.
 Sept162011StockTuneSolo16Celcius4th.jpg   131.5KB   34 downloads

On friday on the way home, I did another run just for a comparison - car was feeling strong again, but as I was getting into the power band I felt a noticeable dead spot, then power picked back up and pulled to 5600 or so. That has never, ever happened in 4th before. This is the graph.

 Sept16_22011StockTuneSolo16Celcius4th.jpg   131.55KB   36 downloads

For some reason at about 3500 RPM I got a huge amount of knock - knock ST retard was 12.5!

Again, this has never happened in 3 years with the car. I have like 50 logs of pulls and none have knock like that. Nothing was changed between the days, same gas, same road, same temp even. I took it back out last night with the wife and went to about 4k in 4th a couple of times. Once, it felt totally normal and once again there was some hesitation although not as pronounced as in the afternoon.

I'm a bit freaked out by this - but have no real idea where to start to look for causes. The only thing I'm thinking is maybe plugs? They are still original - I was going to change them this winter but maybe the time is up. There is no noticeable miss and it doesn't seem to be running rough at all though - hence the wtf?

Comments / suggestions welcome.

[HemiSam]

One thing we've seen with the stick cars is the tune CAN (doesn't mean all the time) go wonky if it's a custom tune. The canned tune you're using is effectively a form of a custom tune. So as simple as this sounds, I'd start by reloading the canned tune. Run the car for your errands...half a day, whatever you can do but for a few cycles, and then reload the canned tune or whatever you're using if it's aftermarket. You might just find that this fixes it.

Note it's likely cooler where you are so your AFR has leaned..you're getting cooler air and more of it through the system. The car likes the cooler IATs, etc... Lean is mean...real easy to remember. Not so much you have to worry about it with your setup though. It's possible your plugs could need to be looked at but not likely unless you've got a lot of miles on the car or they've been fouled. It's also possible, depending on the miles and the fuel, that your fuel filter in the basket could be ready for a change. You run a bit lean and it hits you with ST Knock and the Knock Retard (the nannies kick in and pull timing, dump fuel, all the bad medicine).

Go back to your stock tune as suggested and see if it does the same thing. If it does, then you'll have to turn your attention to other stuff. How many miles on the car?

HemiSam

[Jay6spdRT]

Also, try putting into dyno mode, drive a bit, and take out of dyno mode. I've been told dyno mode resets all those nasty adaptives the computer 'learns' without having to disconnect the battery or the 'fuse trick'. Keep us posted.

[blk09rt6sp]

Sam - I am running a modified version of the stock tune. I dunno if you remember a year and a half or so ago I had a thread on CT about the canned predator tunes being worse than stock on my car - they still are as of r28 so i just kinda gave up on them. I also haven't been running my DCX tune all summer because my CALID got updated and now that tune won't load.

So, it's the stock tune with the following modified:

* All fans set 40 Deg lower for the 180 t-stat
* rev limit set to 6k
* speed limit set to around 180mph
* throttle boost at 5%.

It's got 69,000 kms on it now, which is why I was going to do plugs this winter - but also why I was thinking plugs now. I guess if a plug started to misfire under load that's pretty much what you would expect right? Also, where is the fuel filter in our cars - for some reason I think I read under the back seat, is that correct?

I'll try running in dyno mode and then resetting the tune and see if that clears it up.

Thanks for the suggestions guys!

[Jay6spdRT]

Keep us posted - and I think maybe losing the DCX Depot tune could be a good thing from what I've read about that company. I seriously doubt any of the changes to your stock tune should cause issues - speed limit, zero effect - fan temps, zero -effect, and rev limit - zero effect. I dunno about throttle boost - I don't have it as an option - not sure why you do.

[HemiSam]

For grins, get you a fresh tank of gas. Then, reload the stocker tune as it was and drive it around. Try what Jim suggested about dyno mode. Neither one will cost you anything but a few minutes.

Plugs are to be changed at 30K miles if memory serves me. You don't have to use what Dodge does...you've got options.

If you're up for it, the fuel filter is under the rear seat, on the driver's side. The toughest part is cracking open the locking ring.

Looks like this once you peel back the sound deadening material/protection for seat cushion and you've popped off the black plastic cover. I've got the clip with the power supply removed in this pic.



You don't do this until you're as close to empty as cool...say 1/8th tank. You'll have to take a drift and something like a 3lb hammer to turn the locking ring....look at it and you'll see the direction you need to go. The top of the fuel basket is on springs and will come up. Once you unhook the electrical connector at the top (before you remove the locking ring) and then under the hat, you'll see this (never mind the dual pumps in this setup).



You'll need to disconnect a couple of worm clamps on the flex hoses that cross over from the passenger side of the tank. You can see what they look like in this pic



Filter looks like this...


Should be able to pick it up from the dealership for a few bucks or you can find them on line cheap. I'd have it in hand before you start.

Finally, I wouldn't do this right out of the shoot. I have a feeling it's got more to do with your tune and if you want to change the plugs I'd try that first. Seems odd that it's happens at a certain point in the power band and then picks back up if it's plugs.

HemiSam

[Knownman]

That filter looks like it's off a HD softail? I never seen a car with that setup.

[Jay6spdRT]

Damn - the Challenger fuel filter is in the fuel tank? What a pain in the ass. What's the recommended replacement interval? (too lazy to go to garage and get manual out) That would be an expensive maintenance item at the dealer I bet.

[toofart]

Damn - the Challenger fuel filter is in the fuel tank? What a pain in the ass. What's the recommended replacement interval? (too lazy to go to garage and get manual out) That would be an expensive maintenance item at the dealer I bet.

What do you mean? It takes six seconds to remove the rear seat "cover", then you unplug the fuel pump connection and yank it out. Easier than jacking the car to reach an external filter which is full of road grime.

Stu -- do the plugs man. I'm coming up on 30,000km and I'll be changing them out this winter.

For your DCX tune and cal ID, email both the stock backup (with the new cal id) and the DCX tune to mike at diablosport and he'll update it for you no charge.

Speaking of plugs, Sam, what do you recommend I use on my mildly boosted junk? And what should blk use on his car?

[HemiSam]

Denis,

I've been through some plugs and what started it was thought were the plugs getting blown out. I was running relatively high boost that was rising and it turned out that it was going up for a couple of reasons. We accidentally ended up with a smaller blower pulley after shipping damaged the original and we didn't know it. Temps were cooling which exacerbated the effect so at peak I was seeing 14's. At WOT in 3rd or so it would hit a wall occasionally. I knew it wasn't going lean and it wasn't mechanical so the thought turned to plugs. I turned to a colder plug and gapped a bit tighter. The problem went away but it turned out it had more to do with weather, we just didn't know it at the time. We finally figured out right around Forum Wars that I was hitting 2bar on the MAP sensor and HAL would basically shut things down when that happened. Now we have a fix for that.

So back in Oct 2010 I switched to these Iridiums. I don't believe you need to spend the money on the Irridiums knowing what I know now but this will give you the heat range. The heat range is designated by the "6" and it's one step colder than what came from the factory. Dodge being Dodge tries to confuse us and state a hotter heat range in the manuals for an R/T vs an SRT but that's NOT what the factory was installing and it's NOT what you get if you go to the dealership so assume an equal heat range for the R/T's and the SRT8's. Makes all the sense in the world with the compression ratio with the Eagle heads as compared to the SRT8's...not much difference.

http://www.amazon.co...duct/B001RLRXPQ

So here's what I think. If you want to step down one step colder for a blown application, I think that's good (but not absolutely necessary) and that plug I provided a link to does that. I wouldn't go any further down unless you're spraying nitrous. I'm now running Brisks that are colder for the spray I will likely use at the Mile. I need to check them to make sure they're not fouling. I was pig fat rich until recently on the race tune and my street tune is way rich.

HemiSam

[blk09rt6sp]

Sam - thanks for the great info as always. I reset the tune last night and got a full tank today. Seems ok - no hesitation in 4th when passing a couple of cars but haven't had a chance to do a full run in 4th yet to be sure. To tag onto Denis's question, which plugs should I go with? From what I've read previously it seems like replacing with OEM is as good as any for a stock 5.7?

Jay - will try the dyno mode reset tomorrow as well.

Denis - Doing the plugs for sure buddy. How do you pull out the back seat btw? I think I'll do the filter this winter - may as well. I've taken a sending unit out of a truck tank previously so I should be able to tackle this as well. Thanks alot on for the tip about the tune, I will do that for sure! I had wanted to compare it but obviously couldn't. I'm def hoping this was just a little hiccup as I was starting to get ready for a trip to Luskville on the 24th - hence the tune comparison, ttdyno runs, etc. The car in general has felt great the past month or so and it seems linked to the solo really getting alot deeper a growl over that time as well. That pull I did on Thursday generated basically the best #'s the car has put up for torque and hp combined and then fri when it fell on it's face I freaked.

Even though this (hopefully) isn't anything major I definitely appreciate all the suggestions guys.

[toofart]

Stu -- just grab one side and pull forward and up towards the front of the car. Do same on other side.

Let me know ahead of time if you do Luskville on the 24th. I'll go too if I'm not swapping an axle

[blk09rt6sp]

Stu -- just grab one side and pull forward and up towards the front of the car. Do same on other side.

Let me know ahead of time if you do Luskville on the 24th. I'll go too if I'm not swapping an axle

sounds good - I'll let you know mid week.

[HemiSam]

No prob, bro. Stock is all you need. No difference between the SRT8's and a 2009+ 5.7's plugs so jump on in. Just let us know if you need any info on changing them out, gapping, etc...

One thing that's in the back of this big ole roulette table is weather the cool weather you're seeing up North leaned you out and that's what caused the hiccup. Prob not but I'm just slinging stuff on the wall at early hours...

HemiSam

[mjf6866]

damn guys, thats some good info!

[Jay6spdRT]

sounds good - I'll let you know mid week.

How'd you make out with the problem?

[toofart]

How'd you make out with the problem?

We're still Monday dude =)

[Speedy]

That sock filter on the filter in Sam's pic is just the sock filter. This has been on nearly every fuel pump I've fooled with. I've never changed one, just leave them be and my Accord has nearly 200K on it.

The other cars I own have a real fuel filter external to the tank. I haven't checked the Challenger yet as most don't need changing very often unless you just have really poor gas quality in your area.

On plugs, for what it's worth I'm still running the stock plug in mine at 12psi of boost. I've checked the plugs a time or two and they looked good. I will likely swap to 1 step colder when it's time for a plug change.

[Jay6spdRT]

We're still Monday dude =)

That was changing the fuel filter- - I wondered if dynomode or reinstalling the tune fixed his knock issue

[blk09rt6sp]

quick update - I still haven't tried dyno mode yet, definitely will tomorrow but this is how it looked Monday with a new tank of gas and the tune reset.

 Sept192011StockTuneSolo18Celcius4th.jpg   130.93KB   20 downloads

Much better than the crazy knock, but not as good as earlier last week. Here is an overlay between the good last week (dotted line) and good this week.

 Sept2011StockTuneSolo4thComparison.jpg   135.64KB   21 downloads

Look at how much more torque I was making last week from mid 2k up. I could really feel that difference, the car was pulling like crazy. So now I'm wondering what the hell is with these fluctuations!? Absolutely nothing has changed on the car other than gas and obviously the tune reset. Maybe somehow adaptives did get reset? Is there really this much variation on any given day?

To answer Sam's final question, you're definitely right that the temp has fallen here a bit, but it was still 16 - 18 Celcius when I did these runs (in the low 60's F) and within a couple of degrees of the same temp each time.

Anyways, going to Luskville Sat Denis as long as there's no rain - if you can make it that would be awesome! What's up with your axles btw? Here's to hoping it's a 390 ftlb torque day for the car !