I am about to have my cam swapped in my 93 z28 and I wanted to know if anybody had any recommendations on who to go with for a tune. Ive read good things about some of the mail order places, but have not heard how they are with speed density tunes. I just wanted to get some peoples input before I decided on where to go.

BTW if anybody knows of a good place in the Houston area too go, I would prefer that.

 

PCM4less completely failed me, tune was way off. Gained over 90RWHP with a dynotune. Tunder said they hardly added fuel over the stock map, I was way lean, making no power at first. It took about 25-30 points (values) more in the PE Tables to get AFR to where we wanted.

 

I might just keep looking around for a good place in my area, and get it dynotuned. Its good hearing this from someone else with speed density. Thanks for the info.

 

The only way to get speed density (or anything else for that matter) right is to log the car being driven around and make changes based on the data collected. That is in order to get part throttle tuning correct. Wide open throttle tuning is easy to nail down on the dyno. But part throttle is where you'll spend 99% of your time and unfortunately to do that right is a cut and check type operation, and sadly mail order probably isn't going to get it there.

 

My understanding of speed density is that it must be checked, rechecked, and then checked some more. IE lots of data logging. If you want to get a "tune and forget" tune, you're probably better off with closed loop.

 

Speed density can be run in open loop or closed loop. In either of those cases it won't have to be altered if its set up properly and tuned as close as it should be. Also since he has a 93 speed density is the only option he has since they came from the factory with no maf.

 

+1 on above, best not to mix regular driving tuning w/WOT tuning. When running regular driving (99% of the time) in SD/closed loop the O2's are going to keep the AFR at 14.7. Yes it's good to tune the VE table to keep the BLM's close as possible to 128, and it may help smoothing things out. But in your '93 that means burning and installing a new chip whenever you change something (unless you have an expensive emulator setup). WOT is a different story the PE tables take over and then the rich/lean problems kick in. You need a dyno w/a wideband to get that correct and again a chip burn. Your biggest problems after the cam will be idle speed, closed TPS timing, and transition from low RPM to the higher RPM's where the cam is happy, also getting rid of surge if it pops up.. After that then you need to insure your timing matches you new cam's power curve AKA: performance tuning. A good mail order tune in a box is may work out OK and solve these problems. A local tuner that does both normal, performance and WOT tuning obviously will be much better and cost more.

 

The reason I suggest so heavily to have it tuned on the street to get the ve maps very close for part throttle is because of time spent in open loop. A car that is way too lean or way too rich in open loop can be very annoying to drive if it will even start. If your ve tables are where they should be your open loop air fuel ratio will be right on target and you will then be able to avoid problems. Also your gas mileage on short trips will improve a great deal, and engine wear will also improve considerably as well.

 

Tuning a cam is generally really needed for timing since that is not self tuning and always WAY off after a cam swap. 02's can with 20-30mins of driving, learn and take care of the fuel as long as it's close and the cam isnt too big for the 02's to read correctly, but ideally you want your VE tables tuned in (speed density) so you dont have to wait for the 02's to correct everything.

02's save long term fuel corrections in the PCM's short term memory which the PCM will use to fuel each open loop event (cold start) however the first start (and every other really) wont be as good as they could be, including any time you reset the PCM (dead batt). Now, some mail order tunes wont get the VE's as good as you could get if your did that part yourself and used the VEMASTER program a few times.

People dont choose to run speed density because it sounds cool (well maybe some do) and people dont choose to run open loop because it also sounds cool (well maybe some do).

People have to run Speed Density because some MAF setup's run out at 3000rpm and the same setup usually runs like a diesel volvo in closed loop (extremely sluggish and overall crappy) when the 02's begin taking control and leaning out the AFR after a big enough cam messes everything up.

Choose your battle. If it runs great with a MAF and closed loop keep it that way (once it's tuned). If it gets shaky at the higher boost level then ditch the MAF and save the motor. If it starts running generally shakey and less responsive down low and runs great everytime it's reset then ditch the 02's.

 

What do I need to record the data in order to have my 93 Z tuned??

 

What type of cam are you talking about? If your going with something off the shelf, hotcam, 305 etc. then going with someone like PCMforless would be fine. He has lots of files for something like this. It's more when you get into the real big cams, complete engine builds etc where your more likely to need repeated tweaks of the tune.

My first round of mods about 10 years ago was stage II heads, shorty headers and a mild 211/219cam and my pcmtune was near dead on first try, just needed to be leaned a bit up top which was no big deal and done all thought the mail. I send him a log and dyno sheet W/AF readings and he touched up the tune. My Blower/383/2-Bar was not so easy!

I data log using TTS software and cables from Moates. I also bought the chip burner so when I was tuning my 383 setup Alvin would send me the tunes via E-mail so we didn't have to deal with sending chips back~n~fourth.

 

I'm having AI's 226 / 234 cam put in right now. I also just decided to have my mechanic install some dart heads(cant remember the specs at the moment) since he found that one of the valves on my stock heads was warped. I'm probably going to get a mail order tune at first, because work just got slow, but I would like to eventually get it dyno tuned.

 

I talked to a place near me about a dyno tune, but they didnt have the software for my car, but they recommended pcmforless. So I ordered a tune from him. Thanks again for the help.

BTW, does anyone know about how long it takes to get the chip from them?