GP964

Hi All,

Just picked up an 928 prod. date of 4/84. I took the car to Power Chip to find out if they could chip the car for more HP. Unfortunately I have a car was made a couple of months too early. My 928 uses the Jetronic ECU which according to them you can't tune.

But I was told that they have seen some 928's made in 83 and 84 that has the newer Motronic ECU. I wanted to ask if it is possible to plug-in a Motronic ECU in my car. I know that 84 928's had the same engine size. I was being offered a Euro 84 928 ECU by 928 International, but wasn't sure if it would work.

Has anyone have any suggestions?

Thanks

GP

ViribusUnits

It all depends. Is your car a US car, or a European car? (Edited in, do note that the below information only applys the the 84 year model.)

The US cars used a analog L-jetronic ECU. No tuneing, cause it's not a digital system. The US cars also used the older style pointless distributer, with mechenical advance for rpm, and vacuum advance for part load applications.

The European cars got the digital LH-jetronic ECU system. The european car also had a digital ignition control system. The digital systems means they could be "retuned" for more power. Theoreticaly speaking anyways.

The two are not interchangeable. Easy check, does your motor have one distributer? If so, no retuneing with a chip set.

If your intersted in how to retune your car w/o a chip, we can get into that. But it's a little more complex, and requires that your willing to get your hand dirty. Plus be willing to gain some understanding of how the car works.

Drewster67

Contact Rich9928 - Rich Andrade is our local 928/Puter Guru. He has a business of repairing controllers, he would know for sure.

I do know that some Controllers are not chippable 84-? (is that a word?) - BUT, I also heard that you can piggy back those controllers. Dunno if thats true or not.

Rich9928p

ViribusUnits called it ... L-Jet is used for '80 - '84 US Spec cars, Euro cars went from CIS to LH-Jet in 1984. LH-Jetronic modules have the ROM chip. Also keep in mind that the LH-Jet cars have a separate ignition control unit too; EZF for early LH (Euro '84 - 86 and US '85 - 86) and those can be "chipped" too.

I advise caution when changing to high performance chips. Porsche wasn't stuipid, they designed the engine control for ALL driving conditions an to meet pollution requirements. Aftermarket performance chips may cause engine damage due to detonation or the car may fail emissions testing.

Rich9928p

Drew mentioned "piggy back" tuning.

My understanding of this concept is the use of a circuit board that holds both old and new ROM chips and has a switch so the "personality" can be changed on demand. Companies make piggyback boards for Porsche 911s and 944/951 Motronic modules [Motronic combines spark and fuel control into one module]. While it is technically possible, I am not aware of such mods for 928s. Remember, that later model 928s have separate spark and fuel controller modules. So any work of this kind is "doubled" ... if there is a desire to upgrade spark and fuel profiles.

It isn't possible to interchange L-Jet and LH-Jet controllers ... also be aware that there are different generation LH and spark controllers. Early generation modules are 25 pin and later generations are 35 pin modules. Later model year LH modules have different calibrations and diagnostics capabilities.

GP964

so you are saying it is almost impossible to convert from analog to digital? how do i get more horsepower???????

i already have k&n air filter, timing set at 18 deg advance, magnaflow exhaust, also i use only 91 octane

willing to do anything to gain more hp!!!!!!
thank you for your info.

2V4V

GP,

If you're willing to spend some $ and some time, you can do anything.

You can easily switch from L to LH. This requires more parts than I would recommend as a good investment, but hey, it's doable. I really don't see any return on investment, and you're still stuck with a very limited selection of chips. Lotsa $, not much more HP.

As Rich pointed out, Porsche wasn't stupid- hampered a bit by emission regs- but not stupid. The best chips will try to "push the envelope" a bit. There's really very little envelope to push with regards to the ECU on an L-Jet car. There's not a lot on the LH cars either. There are no "limiters" to up or anything, so they try to richen up the mix at certain points to beyond what the O2 sensor can correct for. This will give some more HP (not much mind you) but some more. There have been some folks on the board who have had some luck with chips, but they really are a moribund technology - price on stand-alone management drops everyday, and most of the OBD-II stuff is field flashable.

Currently I am trying to finish up testing/tweaking on 2 different things - an L-jet meter replacement, and a plug-in ECU that's programmable to replace the L-Jet ECU. Neither will have a terribly high price point (like well under what just a decent standalone computer would cost).

If you REALLY want HP, the quick, easy and (ok, not too cheap but cheap for what you get) mod is the blower. Check out Quick Carl's www.928Motorsports.com set-up for the 16V. (No, I don't get a cut. Yes, I've seen his stuff. It's quite well done.)

Greg

ViribusUnits

Well, you want more power uh?

1st, get the car up and running right. You might be surpsied. Go through evverything, injectors, plugs, plug leads, distributer cap, etc. I'd dump the K&N. The stock filter flows more than enough air for the engine, and the K&N is known to be poorer at filtering.

Next up are headers, and maybe Euro S2 intake parts and cams.

Once you do that, your next options are to find a diffrent engine, maybe a Euro S CIS motor. 300 hp out of the box, and nearly a drop in replacement. If you can get it that is.

You can talk to Andy about a positive displacement supercharger, John... for a twin turbo set up, or Quick Carl at 928 motorsports for a centrifigual supercharger set up. I thought Tim and the folks at F.A.S.T. are putting a centrificul set up together too.

Another option is to talk to the folks at Devek.net for a stroker, or a bored engine. You can bolt a 5l bottem end to the US heads and intake. Devek has built 6.4l stroker bored motors with simply insane amount of torque, and hp. I belive their base motor for the bored strokers was the 5l S4 engine though. They offer a crank that will make your 4.7l motor a 5.7l motor. You can do the 5l bottem end, with the stroker crank to get a 6l engine, and mate it to the Euro S top end. Some really sweet stuff comes out of their shop I understand.

If your really insane, you can talk to the folks at renagade about figureing out how to wedge a 454 Chevy in that engine bay. Maybe even a supercharged 454 chevy.

Many options there, if there is enough money. What do you want?

ViribusUnits

Additional thoughts.

You may think about comeing off of that very advanced timeing. I'm just about willing to bet that you went to far with it, and it's now makeing less power than more. Unless you've verified that it's makeing you more power.