Hi all, recently had my 2000 Supercharged and it will surge around town. Does not happen when throttle is varied but will when constant. Installer says normal but it does not seem normal to me. It is an A&A V3SI. Thank you in advance.

 

even though mine is a c6, mine drives 100% stock when driving normally. No surge.
Your tune probably needs tweaking.

 

Are you talking about blower surge or the engine surging? If it's blower surge, you have one problem, if it's engine surge, it's another.
Engine surge is tuning issues.
Blower surge is dependent on how the bypass valve is configured. It needs to make a straight shot back to the intake manifold, or to a tee directly off the brake booster line and not anything downstream.


I agree if it's engine surge and not blower surge.

 

I had the same problem on my 2000 also with A&A V3SI. I just received the car back today with the problem solved. The spring supplied with the A&A kit was too strong. Tony at Finish Line Performance - Naperville IL replaced the Blow Off Valve spring and the surging is gone.

Jim

 

Need to confirm if it's blower surge on decel or if it's engine surge sitting at idle.

 

Opening this back up as I have the same (or similar) mild but a little annoying issue. Setup is a bone stock C5 M6 LS1 with A&A V3si (great kit b/t/w). When cruising under very very light load or when going down a very slight hill, I get a little bucking. I do all my own tuning and have everything else working great but it would be nice to get rid of this minor issue. Thoughts on what I might look at in the tune since that would be super easy to tweak (and free)?

Thanks in advance!

 

Scan and watch the timing during the bucking, it might need to be smoothed out. Check the over and under spark tables make sure they don't create a bucking condition. Might also watch the injectors m/s during the bucking, might need to increase the minimum injector pulse and short pulse adder.

 

I figured Josh might chime in - you guys are always so helpful.

I will do as you suggest if over the weekend and see what I find. Thanks you!

P.S. Josh, I am getting a C8 in about 5 years and am counting on A&A having a well vetted (pun intended) kit for sale by then!!!

 

Ken you didnt have surge originally after the SC install, correct? Is it possible a tube or maf connection is loose?

 

Tony,
It is a minor bucking or surge (not sure which lingo is correct) but only happens low rpm cruising on flat or slight downhill grade in. It has been there since the install so I think it is a minor tuning issue I have not dealt with. Very minor but time to see if I can fix it.

 

ahh, got it..thought it was a new issue...good luck

 

Too little spark advance caused surging at low load and low RPM in my Subaru, so I wouldn't be surprised if the same is true for other engines. It would be interesting to load the RPM and load (g/cyl) where you get this surging, and compare your current tune's spark advance in that area to the factory tune. Detonation is pretty unlikely at such low load, and the supercharger isn't really doing much at such low load, so I suspect that you can safely run the same advance as factory.

If you are already running the same spark advance as factory, then this is probably not the problem.

 

I think it will be fuel injector tuning related - or just an issue with the 80lb siemens deka injectors that don't like low pulse widths.... I could swap the factory injectors and data in (if I really wanted to) to see if the problem persists or not - that would I.D. if it is injector related - or not. Sun will be out tomorrow so I will scan it and work on it a little.

Thanks!

 

T4L, I had the same issue you're describing with my turbo build, so I don't think it's related to the supercharger. 30 MPH in 3rd gear, less than 10% throttle were the conditions I found it happened the worst.

I had Siemens Deka 60s with Greg Banish's data on a mild 5.3L. Look at your AFRs while the surge is happening--if it's the same issue I had, they will be swinging rich-lean-rich-lean. I ended up ditching those injectors and going to faster/smaller Bosch injectors which fixed the problem. My injector pulse widths were getting down to around 1.5ms, that seems like the point below which the Siemens Dekas no longer work well.

 

I've tuned a lot of cars with Siemens injectors from 60lb to 220 and been happy with them. Often times, part of the problem is that the injector data is incomplete and there are other things needing to be changed to control fueling according to when it's needed.
Simply putting in Banishes data doesn't cut it unless you happen to get lucky.There are many other related tables that require attention to get the injectors to do their job most effectively.
Once the engine is completely warmed up and in closed loop, the O2 voltages are supposed to be swinging from rich to lean and back, constantly. This is known as O2 switching and it's used to help keep the catalysts happy. Sometimes the swing can be too much and sometimes the fuel trims will over respond to the normal/typical O2 voltage swings. When running larger injectors it's sometimes necessary to modify the PID tables that control the responses to rich/lean conditions to get what you want.

 

My data for the 60# injectors themselves IS complete. The trick is, there's more to properly calibrating an engine than just swapping in injector data.

The LS1 PCM is limited on the maximum value one can enter for injector flow rate, MAF, and g/cyl, so a proper scaling exercise is required to correct all of these. Properly done (NOT just IFR and stoich point!), is allows the calibrator to go forward with confidence with fixing things like transient fueling and spark. In this case, he'll probably also need to adjust the minimum fuel transient mass allowed, re-map the VE in that range, and then verify that he's got the appropriate (MBT) spark at light load.

 

Bret and Greg - thanks for the responses!

I have the Siemen Deka 80's. I know Greg (from reading lots of other posts on the internet) and others (including me) find them to be inconsistent - especially at very low pulsewidths. It maybe just as good as the 80s are going to get (and the light throttle mild bucking (M6) going down slight grades is really is not that bad - it is just not perfect so I am working on trying to improve it). Adjusting the minimum fuel transient mass allowed was absolutely required to just get the car to idle at stoich with the 80s!

If you have any more input regarding the SD80s I am all ears. I will investigate what has been suggested and report back with what I find.

Thanks!
T4L

 

Bingo. There's just a LOT of variability (part to part, and even shot to shot on the same part) down low with the 80's. I can't fix that with average characterization data.

Remember that 8 of the Deka60's at 4 bar (they actually flow about 72#/hr at LSx presure) should be good for about 1000hp flywheel on gasoline, so many people don't really need 80's here. I always recommend running the smallest injector you can that still has the top end capability you need. This gives you better resolution at idle and cruise. Trying to sip from the fire hose is sometimes difficult.

 

Point well taken about the 60's ability to support 1000hp on gasoline (probably needing meth in this installation though). In my case I got the 80's because I have E85 all around me and I was thinking I would eventually move my V3si supercharger up in boost and need e85 to get MBT out of it at WOT without being knock limited and without using Meth. We always want more HP right??

As it stands, the 80's work pretty good, decent gas mileage and most drive-ability is very good and injector duty cycle is at 83% at WOT 6500 RPM's. I am running a blended fuel (I check it regularly) at E33 and am able to trap 130 in the quarter (cool fall air) with a bone stock LS1 and stock exhaust with the only mod to the engine being LS6 valve springs to handle the higher RPM's. I went with E33 as I know the boost a pump with stock fuel pump will not likely deliver enough fuel for full E85 and at the end of the day any more octane (and cooling effect from higher ethanol content) than you need to meet the requirements of your set up is just overkill. E10 93 octane allowed only 12 degrees timing at peak torque whereas E33 so far allows 16degrees (maybe more) and has rewarded me with higher trap speeds vs 12 degrees.

 

I meant no disrespect Greg. I guess it would've been better to say that the data that you publish is correct, but there's way more to it than that and it's not reasonable to expect to be able to put your data in, dial in the idle airflow, start up, VE, Spark, MAF, transient fueling and spark tables and be done. While it's possible that someone can experience good drivability after going through all that, there are many circumstances that can require that you know and do much more with fueling before you can enjoy good drivability. While shot to shot, there may be elevated variances in fuel yield with the Siemens's 80's, as long as they're not some counterfeit junk and they've been acquired from a reputable source, I've been able to work with these injectors to the point where they're not causing issues. There are many circumstances to consider and I'll share/mention 2 that quickly come to mind when it comes to entering your data and it not being enough to go tune the rest. One is compensating for the voltage delta between the PCM and the injectors.
its not uncommon for the injectors to see 1/2 volt difference from what's the PCM displays in the log. At low pulse widths, the difference in offsets, percentage wise is fairly significant. Although I consider the valve events to be the driver for EOIT changes, it's often needed to get things to settle down. There are so many things that can affect these kinds of issues.
I'll add one more. I rarely have a car come to me for tuning that's mechanically and electrically ready for tuning. Cracked spark plugs, defective plug wires, exhaust leaks, blown O2 heater fuses and the list goes on.
It's not uncommon for me to have to spend days on a car that I didn't build, before working on the tune.