I was thinking that the surging you guys are talking about ( i also have the issue)was caused by the wipe pattern being worn in the AFM and the "needle" not making great contact in the area where you drive a lot. Haven't I read that bending the needle so it "wipes" on an un-worn section improves the surge behavior?

his sounds like a neat option, wish I could try it.

I think you are correct. The AFM contact arm can lose reliable contact and cause throttle control problems. I had my AFM rebuilt to address that problem and was supplied with a nice, smooth electrical trace of its new performance. This helped a great deal, but there is still a problem that feels like an off/on threshold event. I don't know but it sounds like fuel shut off and abrupt resumption may contribute.
Thanks,
Dave

I agree dave the surging feels very much like a fuel off switch. Dave where did you get your AFM rebuilt and what was the ~ cost if you dont mine sharing. I did not think they could be serviced.

Hey Sal, I will not be making a purchase till Mid November but please send me your information to get a hold of you please. berkmk5 (at) gmail (dot) com

Berk

Wear on the AFM track does have an effect on this. I saw noticeable improvement in low speed running when I re-tracked the AFM. But the abrupt on-off jerk remained.

I may be biased as Sal has been helping me a lot with tuning my car (manually, I want it dialed in before having my chip tuned).

First of all, product aside, I 110% agree that a wide band gauge is huge. I would still be deep in the dark without mine. I went AEM, and it has paid for itself in spades.

Second, Sal did not mention this, but his customer service is excellent. Heck, I just bought a set of rebuilt injectors from him (not the type in this thread), and he has been a fountain of fast, patient, accurate help. He was helping me out with non injector related issues when I was not even a customer.

Finally, great video and I appreciate the honesty on the hp part, although I am sure the atomization is worth something up top (even with diminishing returns)... science wins.

Thing is, with the price of injectors (about 250$ Canadian each), or comparable custom chips, 800$US is kinda crazy good value. It is a custom chip and the injectors are free. Throw in 200$ for a AFR gauge (worth it!!!) that you will be shocked you ever lived without.

Let me see what I can work out. I have appreciated your help so far Sal, and I know you have dealt with a build very similar to mine... so I am quite interested.

What you are describing is Kangarooing or bucking at very light loads and low RPMs. I call this behavior the parking lot jerk and I know what causes it and how to eliminate it. When I bought my car it did the same thing, seems a lot of cars with exhaust changes or aftermarket chips exhibit this behavior. It's not all related to decel fuel cut, other things are at play here as well. I can easily help with stock chips or my chips but I will not touch any aftermarket chips. If you are having problems with a aftermarket chip I suggest you contact that vendor about the issue but before you do you should put a stock chip in to see if the issue goes away. My bet is that the stock chip will be a lot better in this problem area. Another common complaint with open exhaust is popping sounds on decel that are also very annoying I have remedied issues like this as well.

On the bucking and kangarooing issue you can try unplugging the idle switch, this will disable the decel fuel cut completely. Of course it will idle high, I just suggest this test so you can tell if the bucking goes away, if it does then maybe it is the decel fuel cut. However, I suspect she will still buck at those light loads and lower RPMs. Try it and let us know the results.

Sounds good Sal, what about a set up with headers, that's what l currently have in my car and it runs best with its single NBO2 on the left bank disconnected. Would you say to add a bung to the right bank and have dual WBO2 inputs? Or just run open loop.

Headers are not an issue. My advice is run open loop with no O2 feedback to the DME.

Then do get a WBO2 gauge, of course you could get 2 gauges for LHS and RHS banks, others have done this. However, you could also have a bung installed into the center of the Muffler and put the WBO2 sensor in the muffler where it sees exhaust from all 6 cyls. Having the sensor just on the LHS bank is also very acceptable and most folks use this option.

I used Bavarian Restorations. They have a website. I think the cost was $150 and included disassembly, cleaning, lubricating re-tracking the wiper arm and electrical analysis for other problems. They specialize in BMW but it's the same AFM and they will take care of you. Send them an email on their contact link.
Very good guys.
Dave

Thanks Sal,
I have SSI's and a Dansk sport muffler, 964 cams and 10.3 JE pistons, and over-sized throttle body and chip from Steve Wong. I like the idea of your modern injector and chip. Can you accommodate my system and replace my current chip and injectors while addressing the parking lot jerk? Also, how difficult is the injector swap?
Thanks,
Dave

Hi Sal,
One last question. I know you have a MAF system for the 3.2. What is the cost comparison for that vs. the injector only upgrade?
Thanks,
Dave

Dave,

I sent you a PM, I don't want to derail this thread with MAF system. But the MAF is $2200 while Injectors with Chip is $800. The reason the MAF is so expensive is that you also get A special DME for MAF with changes in that DME to handle MAF input signal. Will chat more with you privately about MAF if you like.

Thanks, Sal. The price makes the injectors and chip sound very attractive.
Dave

Interesting. If I had a stock chip to try, I'd do it. I bought my car with one aftermarket chip in it, and a different aftermarket chip in the spare parts box. No stock chip. Darn!

But this I will try. Might be a few days, or maybe sometime over the weekend.

Sal - would you be so kind to explain the fuel model pre and post re-programming?

The factory air fuel model is crude and uses fuel trim tables. My model is far more acurate, has volumetric efficiency built in and my fuel tables are true lambda tables, I command a AFR in a table and that's what I get at the tail pipe. If you want to see the exact math I used buy 2 books by author Greg Banish, look him up on Amazon. He explains modern day fueling very well in those books, he assisted with the math in my system. It was built for my MAF setup and then re-purposed for the new AFM + injector offering.

OK so your using a VE fuel model with lambda table, thats all I wanted to know.

The original fuel model uses a traditional 'pulse width model'? I.e no injector characterisation, simply greater pulse width more fuel - based on load and engine rpm (+trims).

Yes, VE based and full injector modeling including low and high slopes.