HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Porsche 944 Tachometer Modification

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Porsche 944 Tachometer Modification

Post  944-LT1 on Wed Sep 08, 2010 10:12 pm

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Porsche 944 Tachometer Modification

WARNING/DISCLAIMER: This procedure involves removing your instrument cluster and manipulating the electronics of the tachometer. If you don’t know what you are doing, or are unfamiliar with proper electronics safety, Do Not Attempt This Procedure. You are the only person responsible if you are successful or not!!!

Tools:

24mm Socket (for steering wheel)
Phillips Screwdriver
Flathead Screwdriver
5, 6, & 7 mm sockets
Alcohol wipes (or alcohol and q-tips)
Light bulbs Sylvania 194 bulbs (3.78 watts)
22K ohm resistor
Soldering iron, solder, desoldering braid
Personal grounding strap (Highly recommended)

Procedure, Cluster Removal:

1. Disconnect the negative battery cable
2. Disconnect the fuse for the instrument panel (yes, I know, paranoid, but better safe than sorry)
3. Remove the steering wheel
4. Remove instrument panel trim piece
5. Unscrew the instrument panel
6. Carefully disconnect the three cables from the instrument panel.
7. Remove the instrument panel from the car
8. Take the panel and your tools to a clean, dust free area where you can sit and work.

Procedure, Tachometer Removal:

1. Place the panel face down on a padded surface (clean towel works well)
2. Ground yourself using a ground strap.
3. If you have them, now would be a good time to change out all of those instrument panel bulbs.
4. Remove 9 Phillips screws from the rear of the gauge cluster and separate the cluster from the display case.
5. Carefully remove the tachometer needle by pulling up on it gently.
6. Remove the 2 flat head screws that hole the tachometer face to the gauge and set aside.
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7. On the reverse side of the cluster, seven brass 5/16” nuts hold the tachometer to the cluster housing as well as act as electrical terminals to the circuit board. BE VERY CAREFUL HERE!! Do not crack or tear the circuit board when removing these nuts! If a nut is reluctant to move, you must use your best judgment on how to remove it. I’ve found that a q-tip dipped in WD40 and applied to the nut and area helped.
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8. Remove the tachometer from the cluster.

Procedure, Modifying the Tachometer:

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1. Remove the stock OR/BL/OR 32K ohm resistor with your desoldering braid.
2. Solder in the new RD/RE/OR 22K ohm resistor in its place.
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3. Reinstall the gauge into the cluster. DO NOT OVERTIGHTEN THE BRASS NUTS AS THIS WILL TEAR THE CIRCUIT BOARD!!! Reverse order of disassembly, but do not reinstall the display casing as you will need to check operation of the gauge before final assembly.
4. Although there are many ways to calibrate the gauge, the preferred method is to use an automotive multimeter that has an RPM meter. Run the engine and trim the potentiometer until the RPMs are correct at 2000, 2500, 3000 RPM. As an example, across my Pot is 3.48 K ohms; although yours may differ.
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5. Reinstall the cluster display housing and reinstall into the car.


Last edited by 944-LT1 on Mon Apr 11, 2011 7:04 am; edited 1 time in total

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Re: Porsche 944 Tachometer Modification

Post  944-LT1 on Wed Sep 08, 2010 10:29 pm

My gauge cluster was sent off to RH back in 97 for this modification. They sent it to North Hollywood Speedometers and then sent it back to me. The price they charged me was 250.00 plus shipping (shipping was quite a bit considering I paid to send it to RH, from RH to NHspeedo, back to RH, then back to me!!!!). Laughing

Please let me know if something is off above. Also, there are signs that the pink metallized polycarbonate film capacitor thingy behind the potentiometer and next to the replaced resistor may actually have been replaced as well...If your gauge has this pink square thing in it, PLEASE RECORD THE NUMBERS ON IT AND POST THEM!!!!

On the side of the pink metallized polycarbonate film capacitor thingy, it says: W8/ MKC1862 and on top it says, 0.1J100-.

Also, please share any other ideas on this or best ways to calibrate!

Thanks fellers! Very Happy

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Re: Porsche 944 Tachometer Modification

Post  Bluemach1 on Thu Sep 09, 2010 9:05 am

What is the purpose of this modification?

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Re: Porsche 944 Tachometer Modification

Post  Admin on Thu Sep 09, 2010 9:17 am

T make the factory tach work properly with the LT1 motor

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Re: Porsche 944 Tachometer Modification

Post  xschop on Thu Sep 09, 2010 9:18 am

Wiki time.
I may do this instead of sending my PCM back to SSP for a reflash since I am going all LED lighting in the gauges anyways and looks like I need a new odometer crown gear also.....fekkin great write-up LT1 Cool

My Tach is idling at 1900 now. After the install can I calibrate the POT to 950 RPM at idle and call it a day?
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Re: Porsche 944 Tachometer Modification

Post  cfgioja on Thu Sep 09, 2010 1:24 pm

will this work on a LS1 or just LT1?
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Re: Porsche 944 Tachometer Modification

Post  spence on Thu Sep 09, 2010 1:44 pm

Don't the LS1's put out a 4cyl signal? I think the truck LSX engine's put out a 8cyl signal (according to xschop) and would need the tach re-calibrated. Otherwise, this is just for the LT1 (and the LS truck engines).
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Re: Porsche 944 Tachometer Modification

Post  xschop on Thu Sep 09, 2010 2:21 pm

NO the truck engine PCM's ALSO put out the correct 4 cyl. signal. It's just that SSP wiring flashed it for an 8 Cylinder tach by accident Shocked
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Re: Porsche 944 Tachometer Modification

Post  spence on Thu Sep 09, 2010 2:49 pm

Gotcha...
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Re: Porsche 944 Tachometer Modification

Post  944-LT1 on Thu Sep 09, 2010 5:37 pm

I should have included in the title this is for LT1 engines.

My Tach is idling at 1900 now. After the install can I calibrate the POT to 950 RPM at idle and call it a day?

Im not sure if you can trim the pot down that far without replacing the resistor. You can try and post back the limits of the pot...this I dont know yet. But, if youre already in there you can play with it with one of those adjustable resistor pots. Cool

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Re: Porsche 944 Tachometer Modification

Post  xschop on Thu Sep 09, 2010 5:39 pm

Yes, I meant after installing the resistor, then adjusting to 950 rpm while idling.
Thanks for this write-up.
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Re: Porsche 944 Tachometer Modification

Post  944-LT1 on Thu Sep 09, 2010 5:42 pm

No problem!

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Re: Porsche 944 Tachometer Modification

Post  xschop on Mon Oct 04, 2010 10:29 am

Wanted to post up what I did to the tach this weekend. I bought a pack of 5 of those 22K ohm resistors from radio Shack ($0.99) and took appart the gauges, installed a new odometer gear and LED bulbs and resprayed the gauge reflectors with silvercoat....yada yada.
Then came the Tach mod......turns out my tach has an LPG/MPG meter on the bottom and it is a different tach than what LT1 posted here (guts wise). The resistors are about 1/3 the size although I measured the ohms across the resitor feeding the middle pot at 20K ohm. I took a guess that the lone pot near the 5k mark on the dial was the one out of the 3 pots to adjust, so I just turned it all the way down counterclockwise and hooked up the tach/gauges and started it up.......it is only about 50 RPM too high and is idling right at 1050 now (Idled at 2000 before in 4 cyl mode)......
So it seems that the tachs with the MPG/LPG gauge included are adjustable 4-8 cylinders?


Last edited by xschop on Mon Oct 04, 2010 10:55 am; edited 1 time in total
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Re: Porsche 944 Tachometer Modification

Post  spence on Mon Oct 04, 2010 10:46 am

Thats awsome!! Sounds like I have the same gauge as you too.... I might try this before it gets too cold out...

How was changing the odometer gear? Mine needs to be repalced too...
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Re: Porsche 944 Tachometer Modification

Post  xschop on Mon Oct 04, 2010 10:54 am

The odo gear changes by removing the 2 E-clips on the gears and removable slip-pin in the 3rd lower gear after taking apart the housing. I think someone has been into mine and replaced a resistor for the drive gear motor as when the odo gear locks up (due to $hitty plastic) it locks the drive motor and something has to fry. So now I'm not sure if the speed gear in the tranny is the culprit or if the drive motor in the odo gauge is toast. I'm going to put in a new tranny speed sensor first to diagnose. I'm still tickled that the TACH adjusted all the way down. This is good news for SBC/ LT1-4 swappers....
Also FYI, LEDS are 1-way polarity. Test them with the gauges installed and the gauge cover off so you can reach in and flip the LED's by hand until the polarity is correct.
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Re: Porsche 944 Tachometer Modification

Post  87-944S on Mon Oct 04, 2010 9:33 pm

Hey XSChop, what LEDs are you using?
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Re: Porsche 944 Tachometer Modification

Post  bluehellfire666 on Sun Apr 10, 2011 7:42 pm

i did this tach mod today, the tach works well, but i think it's off a bit

After i replaced the standard resistor with the 22K ohm one, i hooked the tach up and it read just under 2K rpm, so i turned the pot. all the way down, and when i first start the car it idles at about 1200, after it runs for a bit it'll idle closer to 1000, but it seems to rev up faster than the engine is, and it seems to jump up above 2K rpm fast...maybe i'm just not used to having a tach work, but it seems like it's reading pretty damn high when it's off of idle

any ideas? it doesn't really bother me, i've been driving without a tach for almost a year now, so just having one is awesome!
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Re: Porsche 944 Tachometer Modification

Post  Dawgz83948 on Sun Apr 10, 2011 8:35 pm

I just bought a tach adapter for $79 and didn't have to screw around with the electronics. DakotaDigital is your friend.

bluehellfire666 wrote:i did this tach mod today, the tach works well, but i think it's off a bit

After i replaced the standard resistor with the 22K ohm one, i hooked the tach up and it read just under 2K rpm, so i turned the pot. all the way down, and when i first start the car it idles at about 1200, after it runs for a bit it'll idle closer to 1000, but it seems to rev up faster than the engine is, and it seems to jump up above 2K rpm fast...maybe i'm just not used to having a tach work, but it seems like it's reading pretty damn high when it's off of idle

any ideas? it doesn't really bother me, i've been driving without a tach for almost a year now, so just having one is awesome!
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Re: Porsche 944 Tachometer Modification

Post  bluehellfire666 on Thu Apr 14, 2011 2:34 pm

well, this cost me all of 5 bucks and took me a couple of hours, plus i think it's closer than i originally thought, so i'm liking where my bank account is sitting right now (and yes 79 bucks is a big deal to me, that's a tank of gas!)
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Re: Porsche 944 Tachometer Modification

Post  Dawgz83948 on Thu Apr 14, 2011 2:47 pm

bluehellfire666 wrote:well, this cost me all of 5 bucks and took me a couple of hours, plus i think it's closer than i originally thought, so i'm liking where my bank account is sitting right now (and yes 79 bucks is a big deal to me, that's a tank of gas!)

Plug into your obdc connector and check the actual rpm with a scanner. Well my solution cost me 79 and took me 3 minutes. My time is worth more than $40/hr not including the time it'll take you to tweak it. Laughing
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Re: Porsche 944 Tachometer Modification

Post  bluehellfire666 on Thu Apr 14, 2011 5:11 pm

there's the rub...my time is worth much LESS than 40 dollars an hour....sooo yeah. i need to rewire my OBD2 connector because i think something isn't right in it, it won't connect to my scan tool, but the scan tool connects to other cars, so it's gotta be the wiring/plug, that's for another day though!
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Re: Porsche 944 Tachometer Modification

Post  kelleysj on Thu Apr 14, 2011 5:55 pm

is this what you are referring to?

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Re: Porsche 944 Tachometer Modification

Post  Dawgz83948 on Fri Apr 15, 2011 10:15 am

kelleysj wrote:is this what you are referring to?

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Yes, I think summit had it cheaper when I bought it. I bought this 5 years ago when I did my Early swap and just replaced the tach back then. This time that wasn't an option so I used the tach converter and it worked like a champ.

@bluehellfire: I was just kidding.
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Re: Porsche 944 Tachometer Modification

Post  bluehellfire666 on Fri Apr 15, 2011 9:55 pm

lol dude...i know man i was just playing along! But honestly...right now my time is worth about 8 dollars an hour (lol, at least that's what i get paid at my part time job, it's money right? anythings better than nothing for a poor ass college student like me!)

One of these days i'll pull it all back apart and fire up my data program and see how close i can get it...unfortunately i think it's as close as it's going to get, which is kinda weird, it idles at about 1200 (according to the tach) and i think that's a bit high, but the real problem is at higher rpms, because i think the tach revs faster than the motor. I guess i should just count this as a blessing because it'll keep me from breaking stuff! I also do have a pretty short geared trans in there right now, so it may just be that.

I can't wait for this summer, i'll actually have a well paying job and be able to put the kind of money into this car that i've wanted to put into it for years now!
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Re: Porsche 944 Tachometer Modification

Post  joecitizennn on Sat Mar 10, 2012 4:59 pm

what is the procedure for an early 944/924 guage?

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