Georgia Fiero Club Forum
All Things Fiero => General Fiero Discussion => Topic started by: f85gtron on February 10, 2015, 11:48:40 am
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I'm curious about tuning. I'm running an 85 ecm and wonder if the benefits switching to a 7730 ecm are actually there. Anyone with experience please chime in. I'm dangerously close to gathering materials for a 7730 as we speak, but am a little nervous about buying a chip that i have no experience with these chip burning companies.....or should i burn them myself?
Ron
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One of the benefits of the 7730 is the speed of upgrade and response. It's about 10 times faster than the stock ECM. You may not need custom tuning of a 7730 chip and you probably won't get the same performance out of a tuned stock chip.
If you don't want to install an aftermarket crankshaft sensor and DIS on the engine, you can run the system off the distributor, add a knock sensor in place of one of the freeze plugs, the fan switch, or in place of a bolt about mid-block on the muffler side of the engine. With the 7730 setup you would remove the problematic vacuum EGR system and install the digital EGR valve using (drumroll) the Digital EGR Adapter Kit sold by Georgia Fieros.
Raydar has done some chip burning, maybe he'll offer some info and advice.
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Everything is built to a price point of cost, reliability, and performance; which doesn't mean technology won't move that point somewhere else.
My concern is the reliability-point. Adding another 20 HP puts more strain on a 30 year old engine: its gaskets, valves, cylinders, etc. Is 20 HP enough of a performance (speed/response/mpg) boost to offset reliability concerns? Is torque affected?
Does the performance boost justify the cost? Would it be better to apply the cost to a 3.8L SC?
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Personally I don't believe you would realize 20 hp gain on a 2.8. Remember that the 3.4 is only a 20 hp gain and it has a better ECM than the Fiero or probably even the 7730, DIS and a larger and better flowing throttle body and intake.
The 7730 does resolve some issues over the stock ECM and makes the engine more driveable due to faster sensor input and analysis by the ECM. Maybe even a slight gain in mpg, too. Probably the gain wouldn't be enough to really harm an engine.
The conversion to the 7730 would require the ECM, a knock sensor, a digital EGR and adapter and a wiring harness. All could be had for somewhere about $350 or less, assuming you continued to use the distributor for pre-88 engines. Pullapart prices for the ECM and EGR would be only $45 at the Augusta yard. I've seen the conversion harness go for as little as $150, but currently that vendor cannot be reached. If you're good at wiring and schematics, the pinouts are available online for free.
A 3.4 serviceable drop-in long block will cost you about $350 and about $150 for a full set of gaskets. Add $60 for a starter relocation jig and you've got that added 20 hp. High lift rockers or cam, headers and free-flow exhaust might bring another 10-15 hp for an additional $400 or so. Then add DIS because the engine already has the crank and sensor port, and a harness for a few more hp and you're getting probably 190 max. Maaaybe a little more.
A 3.8 NA will likely cost you $650 or more for a drop-in, plus ECM and tuning, harness, custom engine mounts, heavier clutch and another flywheel, custom transmission mounts if using an automatic, a newer transmission because the stock auto trans won't hold up very long to the 3.8. Then about another $350-500 for custom exhausts and you've only gained about 50 hp over a stock 3.4.
These are my guesstimates of mostly do-it-yourself prices for much of the labor that a non-professional hobbyist mechanic might be able to do.
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I'm happy with my 2.8, but would like to tweak it a little. Mechanically, I've done all that i feel comfortable doing and keeping it a daily driver, but i haven't messed with the computer yet, other than aldl readings and such.
I'm sold on the 7730 now now, feel comfortable with the wiring, but have a couple questions...
What is this aftermarket crank sensor?
Oh...i guess i only had one question.
Ron
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The engine must have something to trigger the spark for fuel combustion. In our case, it's the distributor with it's stator and reluctor wheel. The engines which use a Distributorless Ignition System, (DIS) need other provisions. Normally it's a crankshaft position sensor and in the case of the 3.4 for example, that sensor is in the side of the engine block.
But what does it sense? Take a look at this crankshaft and pass your cursor over the image to enlarge it. Pay close attention to the center wheel on the crankshaft and you will see notches. These are timing marks that the sensor uses to trigger ignition. The 85-87 Fiero doesn't have this. Neither does the 88, but I'm told that the 88 crankshaft is the same but because there isn't a provision in the block to install the sensor, you must go to the harmonic balancer and timing cover.
http://shop.advanceautoparts.com/p/crankshaft-rebuilders-remanufactured-crankshaft-kit-10570/19950006-P?navigationPath=L1*14923|L2*15030|L3*16014
There are aftermarket timing sensors that can be installed there. I believe a new balancer has to be cut with correct notches for the sensor to pick up or a bolt-on plate in some cases. Having your ignition triggered off the crankshaft is much more precise because it eliminates slop and lag of the timing chain, and other worn components all the way up to the rotor button and cap.
The 7730 also manages the fuel pump, the AC and the engine cooling fan and allows the removal of the CSI. It's also more tuneable than the stock ECM in part because it has more features.
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I forgot another expense. Getting over the 200 hp mark will probably require a brake upgrade, too. The big brake kit at The Fiero Store sells for about $350. Add $100 for braided lines and probably would also require the big bore master cylinder, too.
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WHOA! EASY TIGER! One thing at a time! All this talk about busting 200hp is doing my head in! :o
Ron
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Sorry. The 200+ hp was referring to Paul's comment about a 3.8.
A 2.8 can be bored and a 3.1 crank installed and it will increase the torque, but by the time you did that, you could pick up a good 3.4, install a crank kit and cam with bearings and get your extra 200 horses right there. I'll let each of you drive my 3.4 on Sunday to see what you think.
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Any power increase from using a 7730 ECM is not going to harm the engine at all. In fact, it may last longer. That's because the knock sensor will back off on the timing if any knocking is detected -- something the stock ECM can't do.
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I don't want to drive your 3.4 because then I'll know what I'm missing. That wouldn't be fair to my wife, who has put up with my endless tinkering and cussing in the garage for months now.
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OH, what technical terms you must be teaching Sophia. Got the bump stops and ECM in the car for you.
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sometimes, it's necessary to learn a different language...just to cuss in it. Ha ha. When she's around, its a lot of gritting teeth and sweet talking.
Ron
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7730's on its way, along with wiring harness, so get ready for questions in the tech tips! ;D
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Should I bring a digital EGR valve and Adapter Kit, too?
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Hold off for now.... supposedly, the egr is deleted. I think it would be better with one, but the deletes vs egrs can't agree one way or the other. I can always add it in, right? Ok. Bring them. What's the damage?
Ron
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Is this 1MohrFiero's package? If so, I just see that there's no EGR included, even though the pigtail is there. That indicates it's wired for it. The EGR can be tuned in or out on the ECM. Even if the EGR is there and plugged in, it can be turned off with programming.
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It's the one from Riddick85. It's set up for a 4speed dizzy and he claims no egr, but it would be easier to pin one in before i install the harness. I suspect I'll have to get the tune modified, so they can enable egr when that takes place. Unless it's better without it. What do you think?
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...That wouldn't be fair to my wife, who has put up with my endless tinkering and cussing in the garage for months now.
When the wrenches and the "words" start flying, my wife reminds me, "Remember... This is what you do for fun!"
She's like that.
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Kick you when your down, right? Lol
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Some have removed the EGR and blocked it off I think mostly to eliminate the problems associated with the vacuum style EGR. There's no gain of hp or mpg by disabling since the valve and solenoid don't work full time. Pontiac went to a lot of time and expense with the system, so there's a good reason for it being there. Some have reported burned pistons after removing or disabling it.
The Digital EGR could be mounted and wired in, but turned off in the ECM and turned back on when you wanted. I'd suggest having it installed, whether you use it or not.