Motronic tuning

[dmcummins]

I now have a 3.2 motronic and I'm curious on what I can do, and what tools I need to get everything out of it I can. Ive searched and really haven't found much.

According to Waynes book I guess there are the two screws that adjust the A/F mixture and thats about it. So what do I use to check the A/F mixture to know if it needs adjustment?

I also assume that I need a pressure guage to check the fuel pressure at the test port.

So is that it? I also assume that I need to check that the various sensors and switches are working so a voltmeter would also be used.

Any tips or suggestions? Of coarse I'm asking these questions because I don't believe that I'm getting all I can from my engine.

[88-diamondblue]

Steve Wong and a dyno. Everything is controlled by the chip except for the idle mixture.

[stlrj]

Originally Posted by dmcummins

According to Waynes book I guess there are the two screws that adjust the A/F mixture and thats about it.

Hint: type in "air flow meter" in the search box and make sure you're sitting down.

[911st]

Second SW's 911chips.com.

Get the custom chip option. Then when you get your chip, take it to a dyno and get the Air Fuel ratio info to send to him to see if it needs any correction.

I put a cat bypass on mine. With the chip it goes good.

If you are running in some type of race class where you can not use a chip, it is possible to tune the car by playing with adjustments on the Air Flow Meter but not a great idea. And using the fuel quality switch on the DME.

Also, check under the drivers seat for a brown wire. If it is plugged into its self, it is triggering HP robing smog parameters for California and Japan. Un plug it.

Unplugging the O2 disables Lambda correction and you can pick up a few HP at the expense of fuel mileage.

[craigyirush]

Originally Posted by 911st

If you are running in some type of race class where you can not use a chip, it is possible to tune the car by playing with adjustments on the Air Flow Meter but not a great idea. And using the fuel quality switch on the DME.

"Using the fuel quality switch . . ."

How?

[Bart_dood]

Wait a few weeks for the release of my MAF for the 911! (see sig)

[911st]

Originally Posted by craigyirush

"Using the fuel quality switch . . ."

How?

Depends on your needs.

The fuel quality switch should give you a gross adjustment from about 4% less to over 6% more fuel.

I would think using that first to get the area after 5200 rpm right first. Then use internal adjustments on the AFM to get the area up to 5200 rpm dialed in. They might have to be played off against each other.

Exhaust changes if permitted are a good way to get the richness out of the top end.

Still, this dose not give you access to the ignition side where much of the opportunity might be. I suspect one could cheat this by putting a resistor in line with the AFM temp sensor.

However, the best way to make em rock is a chip.

Not an expert, just my thoughts.

[carolinatrophy]

Originally Posted by craigyirush

"Using the fuel quality switch . . ."

How?

Whoa, whoa, whoa. I'd leave that switch alone if I were you, unless you have some kind of very specific reason to play around with it, and you know exactly that you are doing.

I don't remember what the exact values are for the different switch positions (although I'm sure Steve does), but it's something like: Position 2 = -2 degrees timing, Position 3 = -2 degrees timing and +5% richer mixture, Position 3 = +2 degrees timing, etc. (Again, those ARE NOT the actual values, but the switch does things LIKE that.)

Either way it is an extremely coarse and crude adjustment that applies to ALL data points, and changing the switch position almost never makes the car run better. If you think you have an ignition advance and or fuel mixture problem, figure out what it is and correct it, don't use the switch to try to mask it.

If you don't have a problem and just want more power, the switch will not give it to you. You will get all the power and response you can possibly get by working with Steve to get a good, correctly-tuned chip in there.

I have a Steve Wong chip and cat bypass on an otherwise stock 3.2L Carrera and the car runs like a scalded dog, all the way up to the rev limiter in fifth gear.

My advice? Leave that switch alone. At most, check to make sure it's in the stock position and then forget it's even there.

[DRACO A5OG]

I assume you want to spend least amount of money but I too recommend the Steve Wong Chip, it is "day & night" to OEM stock chip.

Stock Chip will never get rid of the Dreaded "Carrera Lag" especially in 1st

Here is my cheapo list:

AFM check/adjust if needed
1. Pep Boys has a Flex Screw Driver with a 3 MM Hex that is perfect for the A/F port. Sears sells one but the Hex attachment is too wide to fit the port and you will need to grind and weld.

Before you mess with the adjustements get a reading first, of course. Counter Clock Wise is LEAN vs. Clock Wise RICH. The base setting is 2 turns out from all the way in.

You also need to check to see if the protective cover is off, if not. you will need to drill a hole and pull it off. You can leave it off. Some (like my PO) drilled a 1/8" in hole in a 45 degree angle on the side facing the rear.

2. Good DVM with proper resolution and OHM's level, you can go Fluke but no need I got mine from a local Electronics shop for $45 works perfectly. I suggest getting the insulated gator clips, you will know why.

To Test A/F Ratio, ghetto style, after the car is WARM, disconnect the O2 Sensor at the harness. If your A/R is correct, there should be little to no change in idle. If it goes up you maybe too rich vs. rough too lean. To verify, connect the red lead with the insulated gator clip then the black lead to a good ground. I found the top of the ICV's harness clamp to be a good location. Turn the DVM to measure voltage id "DC" (do not buy those auto voltage finding featured DVM's, they do not have the proper resolution). Your reading should fluctuate from 0.20-0.80. If you get 0.81 or higher, you are too RICH vs. below 0.19 indicates too LEAN. Adjust accordingly.

Of course if you are made of Money by the LM1 or borrow one from a buddy. This will verify your finding and allow for a more fine adjustement to the A/F ratio. You can also drive with it hooked up to verify full range of throttle.

Base Idle: Verify/Adjust
1. 4" piece of 14 Guage Wire, half inch stripped of both ends aka "B/C Jumper" Special Tool. I crimped male bullet spades on mine to obtain a tighter fit and I used solid copper wire for rigidity.

2. 7 MM socket and driver handle (screw driver type).

I assume you do not have a RPM diagnostic machine so your Tach will have to do.

Base Idle Settings, Stock Chip is 780-800 RPMs, years 84-86, 880 RPMs 87+. SW Chip is 880 RPMs for 84+.

Use the Jumper tool and locate the port on left side of the engine compartment, if you have the plastic protective cover remove it. It will look like a empty recepticle for a Round Bosch Relay, it is suppoed to be empty. As you look at it, you will see 4 female connections on top and one at the bottom. Connect the the Jumper tool to the bottom receiver and the 3rd one from the left as you face it. You may notice your idle change. Take the 7MM socket and place in on the idle adjustment point located above the ICV and right below the huge 90 degree ribbed hose. It may be covered with a plastic cap. Counter Clock wise to increase vc clock wise to lower RPMs. Once you are happy with the RPMs remove the Jumper tool. Note turn off all accessories, lights, radio, dome light.

Brown Wire under Driver Seat:
On California and Japanese Models to pass emissions, there is a brown wire near the DME that may be connected. If it is disconnect the harness and use electrical tape to tuck away but also to insulate it. This Brown wire from what was explained to me was to retard the timing. Do not cut it off it you need to pass smog. She will drive like crap but you will pass smog if everything else is proper.

Full Thottle:
Check your Full Throttle is operating properly. With the Car off but ignition in on postion, insure the throttle click at full throttle. If not adjust per Bentley.

Also Check to see if at the Pedal there is no slack. Have a helper press the accelerator while in the drive seat then go to the engine and see if the idle lever goes further out. if so you need to adjust this.

Well this is my $2.02 worth of cheap max performance on a budget.

But I'd still go SW Chip, CBP and maybe K&N filter.

Sorry if this was TMI

Originally Posted by dmcummins

I now have a 3.2 motronic and I'm curious on what I can do, and what tools I need to get everything out of it I can. Ive searched and really haven't found much.

According to Waynes book I guess there are the two screws that adjust the A/F mixture and thats about it. So what do I use to check the A/F mixture to know if it needs adjustment?

I also assume that I need a pressure guage to check the fuel pressure at the test port.

So is that it? I also assume that I need to check that the various sensors and switches are working so a voltmeter would also be used.

Any tips or suggestions? Of coarse I'm asking these questions because I don't believe that I'm getting all I can from my engine.

[dmcummins]

Thanks! Ive at least now got a start of things to look for. I'm just trying to get my 3.2 swap sorted out. I'll check that switch to see where its at and I also remember a brown wire comming out of the DME, something else to check. And I agree on the SW chip but I think I can do better with what I have for now. I also need to take a look at my DME again to see what I have. It has someones sticker taped on it and the car was federalized at some point. I have a euro car but there was wireing for a 02 sensor so I hooked that up also.

[stlrj]

Originally Posted by dmcummins

And I agree on the SW chip but I think I can do better with what I have for now. .

You'd be amazed how much performance is locked up in the stock chip once you get your engine sorted out. You seem to be on the right track.

[dmcummins]

Here are a few things that I have found out. First the two brown wires are not connected. Also there is currently a Weltmeister TC-6000 chip installed. I do not know if I have a Euro or USA DME. Can anyone tell from the pics.






The switch is in the 0 position, full counter clockwise.

I also removed the A/F meter to take a look at it and to see where the screw was set at now. It was 13 1/2 turns out. If two is the base setting and out is lean isn't this alot?

[911st]

Draco, great into.

If that is not a euro chip you may be taking a risk. Get the number off the chip and make a new post of it.

I would not run it or run it hard until you have this worked out. I do not know but in the short term you might get away with reducing the timing using the fuel quality switch or add some race gas to the mix.

Just my thought, I defer to the experts.

[BReyes]

The 3.2 has stronger top end with a chip, exhaust and K&N. It then revs beyond 6500, actually much more but told to keep it at 6500. The motronic has a mind of its own and owners that really know will tell you she is mean too. Your skill level will determine if you shift it to max its power and never hurt it. If you get a reason to open it up you can tear up vast majority most of others cars, and can do that by its sound at idle to majority.

Sounds like a good build you are putting together there!

Regards,

[carolinatrophy]

I agree that you should figure out what kind of chip and box you have in there.

I damaged the Motronic unit last year on my previous European 3.2L (the alternator started overcharging and fried it.) When I sent the DME in to be rebuilt, it turned out to be a DME out of a BMW 735i, apparently changed when the car was federalized. There was no telling what the chip was! Once I got the proper DME in there with the proper Steve Wong chip, the car came alive.

[DRACO A5OG]

That is a Weltmesiter Chip and Yes, she has been totally LEANED out to the Maximum Point. This was the same set up as my car from Tennessee.

I would send that pic to Steve WOng he can tell you if the DME is Euro or US.

The AFM had failed so the PO tried to compensate by LEANING her all the way out. I bet if you hook up the DVM on the O2 Sensor she will run above 0.80 at top of fluctuation or LM1 will verify this or visa versa.

Do not mess with the fuel quality switch, it will effect negatively in all RPM range. I was going to do this becasue it lowered the RICHness but I was told by Steve not to mess with it.

There is a way to test teh AFM, search for AFM Testing by IANC, a 944 guy had figured out how to test with a 9 volt battery. Do the test before attempting to re-adjust the Potension Meter Arm. If you have to re-adjust make sure you have the tester on to insure proper contact. I just went through this and discovered after all the time that it was a faulty AFM.

[dmcummins]

I pryed off the AFM cover and I will move the wiper slightly as there are definatly grooves worn. But I an not the first to have taken the cover off. There was clear silicon caulk holding it on and it was a pain to get off. You could also see where the cover was pried on before. I wonder what was done?

[DRACO A5OG]

Before you mess with the arm. Set up your test rig and test to insure it has proper readings.

0 degrees = 0.50 volts DVM (closed)
110 degrees - 8.50 volts (WOT)

In between readings should be gradual and steady with no spikes or severe drops

[Steve W]

13.5 turns on the AFM idle screw is too many turns out. The screw after all only has 11 turns before it will fall out. A stock properly maintained 3.2 with no intake air leaks normally is only from 1.5-3 turns out.

Also, it looks like whoever open your AFM cover did so to lean it out. It looks like the clock spring has been tightened by 3 teeth clockwise.

[DRACO A5OG]

Hey Steve,

It looks like he will have the same situation as me. I mean Welt Mesiter and all the way LEANed out?