1995 GTP Performance Chips?

[Dueling Ponchos]

My '95 GTP is my first computer controlled car and I want to try and get some more performance out of it as easily as I can. I haven't found any chips for any DOHC 3.4 after 1993. If you know of a good one that doesn't turn on the SES light I'm open to suggestions.

[Mach10]

Welkommen

Just so you know, "performance chips" don't usually do jack squat except lose you a bit of fuel economy.

Stock programming does it's best to keep the mixture stoichiometric, so while the engine isn't actually pulling any more air, altering how much fuel goes in isn't going to do a whole lot. The only thing you might expect even a hair of benefit from is a more aggressive timing advance from the DIS, but unless you're running AvGas or race fuel, you won't be able to see a lot of difference.

There really is no such thing as "free performance," unless you are willing to open the motor up and change things internally. The only time an aftermarket chip or reprogram will help you is if you've already modified the motor internally, and have changed the air flow characteristics (and I'm not talking about a cone filter) of the engine.

If you are up to that, you can dork around with cam phasing, as what's been experimented with here in the past. You'll have to do some searching for that, though, since I've never done it myself.

How fast you go has always been mostly tied to "How much money you got" and to a lesser extent "what can you do with your own hands."

Other than that, a good tune up, new plugs, wires, and cleaning up the intake etc will do more for a car than any "high performance chip" without the mods to back it.

[SappySE107]

My 91-93 chip gives a stock DOHC 8-10 hp. Wish I still had a dyno sheet for it but its been proven and you can definetly tell the powerband is extended.

On that note, im mostly done with a 94-95 chip. I have a setup for removing the MAF screen and changing the cam timing to 6 adv intake/6 retarded exhaust. However, im about done fixing up a stock 95 cutlass so that I can do dyno tuning so that I have a dyno sheet for this chip. Ill also be messing around with the shift points which will help with the feel of the car im sure. So far I only know that on a bone stock 95 DOHC setup, with the screen removed and too rich a mixture it gained 6 hp over stock. I had retuned everything but WOT for the MAF screen removal which is why it was still pig rich.

Chip can work, but only if someone actually takes the time to tune a real car...not make generic changes that don't do anything like the major companies. Spark is a major thing they like to change, and they don't gain any power from doing so. That takes care of the spark advance power theory. Sorry but the above post really bothers me cause its wrong and its repeated a hell of lot.

[RednBlack]

Uh, wrong. Better see sappyse107. He chips the 94-95 LQ1. And it is totally tunable. Chip is available in the store.

I have one and it kicks ass. Performance and fuel mileage both benefit.

One up for you.. HaHa! I'm late...Move this post up 1.

[SappySE107]

94-95 chips aren't on the store yet cause i wanna dyno tune it before I add them. Ive sold 1 chip though, owner liked it, but has now sold the car for something else

I promise ill have it done as soon as I can, cause now I have a test vehicle any time I want it...after I put the intake manifolds on and time the motor that is:P

[RednBlack]

But anyway...it does exist now.

[GTP_MuNkY]

Once he is done testing it, I fully plan on buying the chip from sappyse107, I also plan on doing some other mods to the engine maybe getting more out of the chip.

Jamie

[Mach10]

I'd have a seriously hard time forking over $150 to Hypertech to give me a 160º closed-loop, so I'll agree with you there.

I'm too old fashioned. I won't accredit it unless I can see results, and not just from the ass-o-meter. Timeslips, dyno, that'd be fine. I'm not a sticker; If you can give me some honest before and after numbers, I'll accept that at face value(not having any real reason to doubt). "Pulls better" won't cut it. "I ran xxx until I did this, then I ran xxx" is better.


As for the rest, I stick by it based on all that I I've learned over the years on different motors. I'll grant that each application is different, but I've seen enough corollaries to be confident in my answer. I'm no expert, but I get very suspicious when someone says something that goes against pretty much all I've seen in the past.

Now, I know that the 3.4TDC is a strange motor. It has bizarre flow patterns, and doesn't seem to make power like other motors. I'll grant that there is LOTS about this motor I don't know. As I said, I made my claims based on what I've seen before. And what I've seen, without exception so far, is that a reprogrammed chip without internal mods will do very little if anything at all. I'm still trying to decide whether changing the shape of the MAF sensor qualifies as "internal mod." I'm inclined to say that it does, since it changes the air flow path... But then again, maybe only a bit more than a different filter?

As for spark advance, it really depends on what the burn characteristics are like for this motor, and what the final advance works out to be. In general, stock tuning tends to be more concerned with NOx emmissions rather than performance. I've seen anywhere from 1 to 20hp (crank) picked up by fine-tuning the timing, although I freely admit that this pertains to small-block fords, chevy, and BOP motors.

For the rest, I will take what you say into consideration, but I have a hard time believing that GM was so far off on it's mixture calculations with this motor that you'd be able to pick up any amount of power by simply changing the tables on an otherwise stock motor.

Granted, the 4-valve OHC heads will give a pretty efficient flame-front, but timing has always been a critical performance component. Basically all you're saying is that the stock timing curve is sufficiently aggressive. I can live with that.

Now, I don't do chip programming (obviously). As such, I've never seen a wide-band dyno pull on a stock motor. Are the fuel curves that far out of whack? How about burn patterns on the stock pistons?

A final note is that I don't hold much stock with changes that only show 2-3% changes. Even if they are repeatable, most measuring equipment has a built in acceptable margin of error that's larger than that anyway. All too often someone will post numbers about a mod, but forget to add that, "Oh, while we installed the part, we put new plugs in, new wires, changed the air filter (or ran without it), cleaned the intakes, de-carboned the cylinders etc etc etc". 3% overall increase (and more) barely accounts for normal operating variances.

I'm not trying to be offensive... I'm just a skeptic. Don't burn me at the stake for it. Correct me if I post something wrong (I'm a big boy, I can admit it!), but don't assume I'm jumping on a band-wagon and vomitting someone elses post. My post above was of my own making, based on my own experience. If it doesn't apply to this motor, fine, tell me why.

Peace!

[SappySE107]

http://www.60degreev6.com/store/images/Chip/31dynochip.jpg

Thats the 3.1 chip that I sell, stock, and hypertech. Thats fine if you dont want to believe that I can do more on the DOHC than the 3.1 since I dont have a dyno...but im not a liar and I have way too much at stake to be lying. Of course, companies do lie and make up marketing crap so I fully understand your postition. Perhaps someone will dyno their chip, or perhaps ill revert mine back to stock someday and can dyno just the chip.

[Mach10]

No worries. I'm not calling you a liar.

But perhaps you can elaborate on what it is exactly that you're able to optimize on the DOHC?

[HayesPerformance]

I STAND BEHIND CHIPS ALL THE WAY!!!!!!!!!!!

Chips do work!!!!! I got the ford chip burner and its amazing what you can do to ANY computer controled vehicle.
I support sappyse107 his comments on the chips! As I said I KNOW TOO!!!!!! I BURN THEM ON ALL THE FORDS.

Best Regards to all,
David Hayes

[Mach10]

Ok, now I REALLY have to know.

We have two people here who are claiming gains with custom chip burning.

Fine. I find it easier to make friends if I don't scream bullshit every time I hear something contrary to my beliefs

But, but, but... How come nobody seems to want to elaborate beyond that? I understand if you don't want to give away trade secrets...

But,

First of all, are these gains coming as a direct result of disabling emmissions features?

Second, If the timing maps for a stock motor are fine, and the mixtures are pretty close... WHERE are you getting power from?!

I'm not trying to be deliberatly obtuse... But there isn't a whole lot of sense being made here.

A GM ECM doesn't control ANYTHING on the motor except the timing advance and mixture trim. As I understand it, at WOT, it falls back on pre-determined fuel maps and pretty much ignores everything but the TPS and the knock sensor... As far as I understand it, there isn't a lot of emmissions controls at WOT to interfere.

If the mixture is too rich, leaning it out some on the WOT table will give you a little more power...

Lowering the closed-loop temperature of the car (and putting a cooler thermostat) will net you a tiny little gain from increasing the charge density ever so slightly. I run a cooler thermo. Makes sense in a Fiero which runs hot at the best of times.


WHAT ELSE IS THERE?

The ecm doesn't control cams. It doesn't control intake runner length. It doesn't control the throttle-body bore size. It controls fuel and spark. It's a REACTIONARY system. It takes what is given my the mechanical parts and tries to figure out the optimal amount of fuel and timing advance.

Nobody will answer me. I've pulled my plugs after a few WOT runs on my motor. The plug electrodes were a lovely shade of tan. NOTHING to indicate either a rich or lean mixture.

So either help me to understand, or beat me to death with a gold brick. Either way, I'm happy

[SappySE107]

Who said the mixture was fine at WOT? Not I, cause thats a lie. OBD2 computers are lean from what I hear, and I know OBD1 memcals that I tune are pig rich. Fuel is what I tune but no, no secrets from me:P

I can't tell you what the fiero does as I dont tune that computer.

The computer uses TPS only for how fast it moves, past a certain point to allow WOT (as well as MAP reading), and for decel along with again, the MAP readings. WOT uses preset tables for AF ratios to be calculated, but it bases this on the long term fueling that was established from cruising around. Custom tuning for mods comes into play here substantially from drivability to the WOT fueling. Tune idle, then cruise/decel, then WOT power.

Colder stat will allow a few degrees spark advance more but really, I dont look to it for any real gains.

Ive shown you a dyno graph...honestly I dont know what else I can do to prove that I get performance gains from retuning. The only thing changed was the chip.

[Mach10]

**THANK YOU!***

I'm running an ODB-I 1992 3.4TDC in my fiero, with a stock manual PROM. The Fiero 2.8 is a dog. It's raspy, it isn't particularly reliable, and it runs out of breath WAY too quick. I wouldn't have wasted my time trying to tune it.

As I said, I'd not run my own car on a wideband, so all I had to go on was plug color (not much good 'cept for determining pig-rich or anorexic), and for determining an overall average lean or rich condition (i.e., in all conditions and ranges, averaged together.



hehehehe...

Regardless. Are you saying you optimise the block-learn-mode code to get a better trim, or do are you tweaking the constants to narrow the variablity in range? I know that GM puts a huge margin in there so that the motor will "run" in all kinds of conditions. This makes for sloppy tuning, but from a reliability stand-point "too rich" can be less dangerous than "too lean." Well, to a certain point, anyway. Besides which, I don't know of many sub 30k passenger cars that REQUIRE razor-edge fuel mixtures, and I'm sure GM didn't want to waste the resources in making it so.

As I said, I cheerfully eat crow if it's presented well enough. The parsley around the edges is a nice touch. Pass the ketchup, please!

[SappySE107]

A DOHC in a fiero setup uses a different exhaust routing and shoud be better flowing than the W body setup. It may be better tuned stock for your setup than it was for a w body. I don't touch the BLM range unless I have the car to do. WHen I tune a car, I set it up so the BLM is locked (after I get it decently close). Then its just tuning the short term fuel trim. For the chips I sell, I don't change the BLM range as I cannot know what the car is doing either. Different plugs, wires, carbon build up, cat condition, etc change all that stuff so its impossible to 'tune" a car without having a datalog to make changes/repeat.

Still, I can get 8 hp out of a DOHC in a w body. Might not be the case for a fiero running a DOHC...I dont know till I try.