mdpalmer

iTrader: (1)

Hey guys, I just got my car running. I'm new to LS1 PCMs. I have experience tuning rotaries (from the Rx-7)... so I'm no stranger to electronic fuel injection speed density tuning. Looks like the LS1 has a MAF and MAP input to the PCM... I'm not familiar with MAF based setups.

My question is: is it "bad" for the setup (engine itself, cat converters) to putt around in w/o a tune? It seems to run just fine, although I don't have a wideband, or fuel presure gauge (yet), which I know are very important to monitor... I would like to think that the MAF would be able to better compensate than the MAP inputs with breathing mods (cam/heads/intake/exhaust)... but not sure by how much. If it's running too rich it will mess up my new cats. If it's running too lean I could burn a valve or ping... but I would tend to think that happens with more load on the engine. If I drive like Miss Daisy I don't think I would have a problem...

The tuner suggested to start the car, let it come up to temp, and tow it to them, BUT...

I want to make sure the entire car is sorted out, besides the tune of course, before I take it to the tuner. It's a fresh motor, fired right up w/ open headers... just got my exhaust done today, from headers back to muffler. It starts up and idles great, 30 psi oil pressure warm. I just drove it around the block at about 30-40 mph, and it seems to run just fine (@ 10-20% throttle, any more than that the car seems to jump out of its own skin... I'm not used to v8 power, this thing feels ridiculous and I haven't even given it any gas). Check out a startup vid I made.

http://www.youtube.com/watch?v=V0Kwklg4qwY

I have stock f-body manifolds with replacement cat converters that are CA legal, has cam/heads and custom intake. Here's the setup, I just copy and paste the whole list of stuff even tho I know some of it is irrelevant:

-1993 Mazda rx-7
-120k mile '02 z28 ls1 block
-T56 is stock with new slave cylinder, and pilot bearing
-MGW shifter
-7/8" bore willwood clutch master
-micropolished crank
-new rods, rings, and pistons (ls1 OEM GM)
-katech rod bolts
-improved racing oil pan baffle
-new cometic gasket set
-all new clevite bearings
-new ls7 lifters and trays
-new ls2 chain, new ls6 oil pump
-dual oil coolers (on car, not hooked up yet)
-ls6 intake manifold, air filter in front of radiator
-arp head bolts
-ls7 clutch pp/flywheel/disk
-cnc ported and polished 5.3 heads with larger valves and double valve springs. similar to the tsp stage 2.5 heads
-TSP hardened chromoly pushrods (7.4")
-comp cams trunion rocker arm upgrade
-comp cam 224*/228*, 0.568"/0.588"
-NGK TR55 plugs
-NAPA plug wires (new)
-4.10 final drive (mazda rx7 rear end)
-f-body cat converters & stock exhaust manifolds
-custom exhaust after cats... to y pipe to 3" muffler
-ls6 intake
-ls6 PCV system
-stock 28ish lb/hr injectors @ stock fuel pressure (58 psi)
-f-body power steering, no A/C
-new water pump & ARP hardware
-180* hypertech thermostat
-dual spal fans & custom radiator
-5/16" fuel lines up to fuel rail
-denso fuel pump (280 liters/hr @ 13 volts... I think)

Do you think it's OK to drive it to the tuner or should I tow this thing?

salemetro

iTrader: (5)

I can't imagine risking catastrophe on a fresh engine. I would get a flat-bed, and tow it to the tuner after you have all the other stuff done on the car since you are not able to monitor it correctly.

Ideally, you'd want the car "street" tuned (with a wideband) without the cats in it (in case it's too rich)....and then once you have it close, put the cats back in and go to the dyno.

But you allready knew this, did'nt ya

I know it is tempting to drive it, but I'd wait.

BTW....killer swap! I'm doing this to an '01 Miata in a few months, once my current project is done. Seeing your youtube video has me itching to get started on it.

mdpalmer

iTrader: (1)

lol... it is SO tempting. I mean... it starts, idles OK...

It's only been about 4+ months since I pulled the old rotary, but I'm dying to drive a car with some *****. The way it feels just putting around the street... holy ****. I'm not used to having torque @ idle. I let the clutch out and the car just pulls itself uphill, with ZERO throttle, it's the weirdest thing for me.

But you're right, I was just trying to find any excuse to drive the car until I get it to the tuner Can't let emotion trump logic

I've been reading about and watching vids of ls1 miatas, that's power-to-weight ratio right there!!!! God damn, that will be a handful. About a month ago I went on a cruise with some rotary/rx-7 guys and when people were getting ready to leave, I hear the unmistakable sound of a v8 start up... and guess what, it was a Miata! My eyes lit up, it was so funny because my girlfriend and my other buddies knew what my reaction would be... the guy took off and I was grinning ear-to-ear knowing I would be making the same sound soon

Good luck with the build, it is so exciting, I know I'm so stoked to get the car running! Make sure to post a build thread, I would like to see how it comes along.

2xLS1

iTrader: (25)

With what you listed it will be fine to drive it.

mdpalmer

iTrader: (1)

Thanx man. I just talked to another guy who had a bigger cam and longtubes and he did the same thing... even gave it some throttle on the way to the tuner.. not that I would ever condone doing that! I made a quick walk around clip to hear the exhaust/motor... it's idling a little high because it likes to stall if I drive it when it's cold. Totally untuned, running off stock maps.

http://www.youtube.com/watch?v=K_BsAhXxMb8

YellowToy/A

iTrader: (1)

Lean is hot. I would never drive it without a wide band. How much would it be to rebuild the engine? What is internet advice worth? If air/fuel ratio is good, then u are good. Buy a wide band. End of story

99Bluz28

iTrader: (35)

You could easily overheat the cats, and then their garbage.
BTW, how far away is the tuner?

2xLS1

iTrader: (25)

Do you guys telling him he can't drive it even have a clue about tuning or how these PCMs work? It has a stock MAF, stock injectors, stock fuel pressure, O2 sensors. STFTs that can correct the 14.7 closed loop A/F +- 50% and LTFTs that can correct it +- 25%. It will be fine to drive it at part throttle and idle. I'm going to guess you were no where around pre 2003 when we modded the crap out of these cars before there was even tuning suites to tune them with.

mdpalmer

iTrader: (1)

FWIW, I talked to another local tuner today. This guy is supposed to be real good from what I read on here and some other lsx enthusiast forums. He's about 15 miles from my house, not really far at all. I emailed him my mod list as I posted here. Talked to him on the phone.

He told me, "if it starts and idles OK, and you can putt around w/o any weird stuff happening, you can drive it part throttle. may run a little rich, your gas milage will suffer, but you'll be fine. just don't floor it. see you soon."

I'll tell you one thing, turbocharged rotaries are very hard on cats as they must run rich to maintain safe air-fuel ratios. EGTs are generally higher than piston motor too... 1800+ *F. I was in the high 10:1 air-fuel ratio range all the time with the old motor under heavy load... that cat was fine after about 20k+ miles worth of that kind of abuse... and I could even pass smog

2xLS1

iTrader: (25)

You are talking about open loop PE A/F ratios, not closed loop.

rockinace6

iTrader: (1)

i drove my truck that was turboed on a stock tune over and hour away at part throttle and it was fine. never took it into boost. also drove my truck without the cam tune for 2 days just putting around and it was a good size cam. it ran fine. thats a high lsa and the STFT's will correct most of it while driving around. as long as u dont take it above like 30-35% throttle it WILL BE FINE!!!! btw, ur motor is noisy, what springs are in it?

gen 3 pcms are some the of smartest computers ever designed (some may disagree). they learn and relearn over and over and if something is wrong it wont run for ****. just get it to him and let him tune it. also, hook up a wideband and fuel pressure gauge as stated before me asap.

YellowToy/A

iTrader: (1)

With wide bands for 250.00 I would not drive my car without knowing the a/f. I have seen more that a few engine after they run lean. It is not good and did not take long to hurt them bad. If you spend big money on the engine I would not take that chance. It may all work out for you. I hope it does.

mdpalmer

iTrader: (1)

Thanx for the feedback guys, really appreciate it. My plan was to have a pro tune the car first and then I can get involved with tuning/tweaking it myself. Have the tuner sort the car out and then I would add the WBO2 and fuel pressure monitor...

What WBO2 do you recommend YellowToy? I used to run a PLX M-300, but my display crapped out on me. Where do you guys put the O2? Do you monitor each cylinder bank (meaning 2 O2s)? I have a y-pipe to a single exhaust... I also have a bung in said y-pipe, feet downstream of the cats, I think I will put it there, although I have heard that off-the-shelf WBO2s need to be closer to the motor to provide better readings... have to read up on that too.

Also, about running lean: when I had the turbo rotary, it was open loop MAP controlled. I tailored air-fuel ratios and timing to keep the motor happy and safe, as lean as I could. I ran it real lean in cruise (16:1) and sorta lean at idle (13:1), and part throttle as best I could (12:1). Any leaner than that (I experimented with this) under those conditions and the motor would stumble, real bad. No ping, no detonation, maybe it was running hot but I never had a problem. Running it lean under WOT... well that's how rotaries blow apex seals.

Not saying it's smart to drive the car w/o a WB, as I think it IS smart. Once you mod the motor it's important to monitor things like air-fuel ratios, etc.

Thanks again.

mdpalmer

iTrader: (1)

I thought it was noisy too. I have double valve springs.. not sure from who. The guy who built the motor picked up the 5.3l heads (706 casting) from someone else and they built the heads basically like the TSP stage 2.5 setup... I have hardened pushrods, ls7 lifters... the "noise" is def. coming from the top end of the motor.

These are the TSP heads.

http://www.texas-speed.com/shop/item.asp?itemid=84

YellowToy/A

iTrader: (1)

The wb should be before the cats. The cats will change the air/ratio some. Not sure how much, I have never had them. An LM1 or LM2 gets the job done for under 300.00$. 14.7 is stoichiometric, that is what you should cruise at. 12.5 to 13 for WOT.

ebk06

iTrader: (5)

I finished my ls1 with 228r, supporting mods, and a new yank 3200. I dropped off the ecu for a base tune but I had no choice but to put the break in miles on the converter. all 150 of them before I could get a dyno tune. The car is running a little rich but no smoke or anything crazy. The car never knocked or drove bad and nothing has felt odd on it. I'd say its safe to drive to a tuner but dont try racing it all over the place. I wouldnt put 1000 miles on it but a few hundred conservative miles I would think would be ok. I am dropping off the car wednesday for a dyno tune finally.

KSLAYR73

iTrader: (2)

I am going to be in a similar situation when I am finished with mine. I have a new FLT lvl 4 4l60 on the way with a new 3400 stall. Motor will have a slightly larger cam than yours, 236/232 .608/.595 110 lsa, Fast 90/90, MTI lid, 38lb injectors, fully ported 241's, lt's, 3" Y, gutted cats. I will need to break in the convertor and everything else before strapping in on the dyno for a full tune. What do I do here? Get a generic tune to get it around for awhile before the dyno time?

ebk06

iTrader: (5)

For sure have a tuner throw in a base tune to keep the air/fuel ratio somewhere decent so you dont screw up the motor. Any good tuner should be able to pull up a tune from a similiar setup to get you in the correct neighborhood. Maybe you can even work out something with the tuner if you take it back to him for a full tune once the break in miles are done.

01ssreda4

iTrader: (96)

I remember throwing in my cam, letting it idle for 10 minutes, then stomping it as I pulled onto the street.

mdpalmer

iTrader: (1)

^^ Awesome I'm not sure how different the situation would be for an automatic car, like some of the other guys are posting. If you use different injectors, I would be surprised if the motor would run at all w/o modifying the PCM maps.