cougar motor in a stang

blk88lx · 06-17-2001, 02:31 AM

Hi all,

I've got an 88LX with a 5.0 out of an 88 cougar. Thing runs like crap. Wondering if the stock computer can read this engine. Anyone know?

84_GT350 · 06-17-2001, 02:58 AM

The cam is probably different for starters. And that would probably make a difference in an SD car. There may be some other differences as well. If you have a mass air upgrade, then your guess is as good as mine. But I'd definitely recommend a mass air upgrade if you don't have one already.

------------------
1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

blk88lx · 06-17-2001, 02:11 PM

The cam is different and my engine is not a roller motor. How would mass air help?

Jayson

Unit 5302 · 06-17-2001, 02:54 PM

Well, the cam is probably messing with the SD a little. You may want to try and pick up an ajustable FPR and play with the fuel pressure. If it can deal with bigger cams, I don't see why it wouldn't be able to deal with smaller ones.

It may just be a hell of a lot easier to swap the computers with an 88 T-bird computer. They are probably a direct swap.

Just a thought, unless of course the 88 Thunderbird already uses MAF?

[This message has been edited by Unit 5302 (edited 06-17-2001).]

Unit 5302 · 06-17-2001, 03:04 PM

As far as the way MAF would help, it can actually read the amount of air coming in.

Speed Density injection systems have no way of measuring air, or fuel for that matter. They go off a baseline of stored information in the database. They use a BAP sensor to determine air charge density, a temp sensor to determine coolant and air temps, and a TPS to determine throttle position. Based on that information, it changes the injector cycle based on parameters it has stored.

So, when you change a cam (which makes a big difference in airflow), the computer is trying to inject fuel at the rate for the stock roller cam, not the new smaller cam, and you run rich. If you get an adjustable FPR, you can turn down the fuel pressure so it will be injecting less fuel, and get the engine back within the adjustment tolerences of the SD computer. Even though SD is pretty damn good at adjusting, it can't cope with cams and heads without a little tuning help.

MAF uses an actual MAF sensor, which measures intake charge temp, density, and actual airflow so the computer can adjust the injector cycle accordingly. It's not very good at making adjustments though. There isn't a whole lot of ability to compensate if something isn't jivving.

An example of MAF's limitations would be adding 24lb injectors to a 5.0. With MAF, there's a damn good chance the car won't even run. SD will run, albeit rich at startup, and it'll have a bit of idle surge. So SD has more ability to compensate internally, but MAF is far better at actually measuring data.

Of course that pertains to keeping the stock MAF. MAF sensors can be recalibrated to show data for larger injectors as well.

[This message has been edited by Unit 5302 (edited 06-17-2001).]

06-17-2001, 02:31 AM	#1
blk88lx Registered Member Join Date: Jun 2001 Location: Fort Leonard Wood, MO Posts: 179	cougar motor in a stang Hi all, I've got an 88LX with a 5.0 out of an 88 cougar. Thing runs like crap. Wondering if the stock computer can read this engine. Anyone know?

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06-17-2001, 02:58 AM	#2
84_GT350 Registered Member Join Date: Apr 1999 Location: Overland Park, KS, USA Posts: 1,631	The cam is probably different for starters. And that would probably make a difference in an SD car. There may be some other differences as well. If you have a mass air upgrade, then your guess is as good as mine. But I'd definitely recommend a mass air upgrade if you don't have one already. ------------------ 1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

06-17-2001, 02:11 PM	#3
blk88lx Registered Member Join Date: Jun 2001 Location: Fort Leonard Wood, MO Posts: 179	The cam is different and my engine is not a roller motor. How would mass air help? Jayson

06-17-2001, 02:54 PM	#4
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Well, the cam is probably messing with the SD a little. You may want to try and pick up an ajustable FPR and play with the fuel pressure. If it can deal with bigger cams, I don't see why it wouldn't be able to deal with smaller ones. It may just be a hell of a lot easier to swap the computers with an 88 T-bird computer. They are probably a direct swap. Just a thought, unless of course the 88 Thunderbird already uses MAF? [This message has been edited by Unit 5302 (edited 06-17-2001).]

06-17-2001, 03:04 PM	#5
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	As far as the way MAF would help, it can actually read the amount of air coming in. Speed Density injection systems have no way of measuring air, or fuel for that matter. They go off a baseline of stored information in the database. They use a BAP sensor to determine air charge density, a temp sensor to determine coolant and air temps, and a TPS to determine throttle position. Based on that information, it changes the injector cycle based on parameters it has stored. So, when you change a cam (which makes a big difference in airflow), the computer is trying to inject fuel at the rate for the stock roller cam, not the new smaller cam, and you run rich. If you get an adjustable FPR, you can turn down the fuel pressure so it will be injecting less fuel, and get the engine back within the adjustment tolerences of the SD computer. Even though SD is pretty damn good at adjusting, it can't cope with cams and heads without a little tuning help. MAF uses an actual MAF sensor, which measures intake charge temp, density, and actual airflow so the computer can adjust the injector cycle accordingly. It's not very good at making adjustments though. There isn't a whole lot of ability to compensate if something isn't jivving. An example of MAF's limitations would be adding 24lb injectors to a 5.0. With MAF, there's a damn good chance the car won't even run. SD will run, albeit rich at startup, and it'll have a bit of idle surge. So SD has more ability to compensate internally, but MAF is far better at actually measuring data. Of course that pertains to keeping the stock MAF. MAF sensors can be recalibrated to show data for larger injectors as well. [This message has been edited by Unit 5302 (edited 06-17-2001).]