924Board.org

Zuffen · Posted: Tue Jan 07, 2003 2:50 pm Post subject:

Smoothie you need to test that resistor, it may be out of spec or nonfunctional.
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Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

Smoothie · Posted: Wed Jan 08, 2003 2:29 am Post subject:

Yeah, I haven't forgotten about that. I did take a reading of it, but while in-circuit. I got 26.34kOhms. Of course, being in circuit, the rest of the circuitry could affect the reading. Anyway, from the looks of it I'd be real surprised if it's still within its' rated tolerance and if I read the color bands right, it should be 28kOhm with 5% tolerance. Not too sure about the second color though (partly color blind) - it could be anything from 25k to 28kOhms. If anyone has an open DITC real handy, R16 is in the area diagonally opposite to the vacuum/pressure sensor. (The other end of the board, diagonally.) A verify of the color bands and an in-circuit resistance reading would be very useful. The colors as I read them were red, grey, orange, then gold for tolerance.

The new coil should be arriving today. That's the next easy thing to rule in/out, so I'll know tonight or tomorrow if that's been the problem.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Wed Jan 08, 2003 8:22 am Post subject:

No, it wasn't the coil. Popped the new one in and the car runs exactly the same...so I have a spare coil now for troubleshooting. Luckily, found probably the cheapest one available for a 924T - $14.99 from Autozone. 'Tis nice to get a break on the price when playing hit 'n miss.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

924RACR · Posted: Wed Jan 08, 2003 8:45 am Post subject:

Fortunately my DITC is still open and out. R16 is brown, grey, orange, gold to my eyes. I'm afraid I don't know my ratings, been too long, but I'm sure you can figure it...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Smoothie · Posted: Wed Jan 08, 2003 9:12 am Post subject:

Muchos gracias kind sir. Not too suprised - brown is a color I've had trouble with - it's between some shades of brown and green that I sometimes can't tell which it is, but red... guess I have trouble with that too now. Anyway - the DITC just became my most easy next thing to work on again, so I'll be back in there, maybe tomorrow.

My little cardboard cheater from Radio Shack indicates brown-grey-orange is 18kOhms.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

924RACR · Posted: Wed Jan 08, 2003 10:56 am Post subject:

FYI, I have updated a bit of the info on that link (posted earlier). Trying to spend my time working on updates to the Tech Section, instead of wasting my time killing flames on the board...

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Smoothie · Posted: Wed Jan 08, 2003 12:12 pm Post subject:

A new twist to my little saga - Radio Shack doesn't sell 18kOhm resistors, not alone and not in an assortment pack. The closest they come is 15k and 22k... They do have 56k though...maybe I'll use 3 of them soldered in parallel. 18k x 3 = 54k Close enough? - or how about a 15k + 2.2k + 1k soldered in series?

Just kidding.
I think.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Wed Jan 08, 2003 1:18 pm Post subject:

Vaughan - I took a look at the ditc addition to the tech section - good stuff, crispy pics. My brother just got an HP 812 digital camera - I'm suprised at how sharp it is - shot some pics in and under my car today. It's great that you can get the camera into tight spots, shoot, then see right away if you got what you wanted, try again, etc. Anyway, back to the ditc board - I'm still curious about a coating on it. Mine looks like it was dipped in lacquer or some kind of clear glossy finish, the whole thing -both sides, resistors, chips, caps, board, etc after assembly. This would make reflowing the solder on the entire board difficult, wouldn't it? Is that the residue you mentioned that you removed with circuit board cleaner? I didn't have a camera handy while I had my ditc disassembled, so I scanned it instead. I'll get the scans uploaded to my website later. They'll look pretty much the same as your circuit board, but glossy. I can't really tell from the pics if your board has the same glossy finish.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

924RACR · Posted: Wed Jan 08, 2003 1:51 pm Post subject:

Yes, mine has a bit of a glossy finish, just re-adjusted the setup to eliminate the glare from the flash. Yeah, the camera is great for working on these cars, especially sharing info!

It came resonably clean with the spray cleaner and toothbrush.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Smoothie · Posted: Thu Jan 09, 2003 3:28 am Post subject:

I got those ditc scans onto my website. Look at the top of the lower left-hand picture at the chips and you can get an idea of the thickness of clearcoat they put on it.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Sun Jan 12, 2003 1:12 pm Post subject:

I put the CIS pressure tester on the car today and tried the cold test. (engine cold and wires to the WUR disconnected) The air temp was 38F. I got system pressure = 89psi and control pressure = 30psi. Both are high. Take 15psi off both of those numbers and they'd be within range. Control pressure of about 15psi would be ok for 38F and system pressure should be between 65 - 75psi. Wonder if there are enough shims in the fuel pressure regulator to remove to get it to drop by 15psi - then if system pressure is lowered by 15, will control pressure go down by the same amount? I'm guessing yes, but according to Haynes, I'll have to remove about 1.5mm of shims (.1mm of shims per .9psi pressure change).

I don't think this has anything to do with my 3kRpm/4psiBoost problem though.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

wdb · Joined: 02 Nov 2002 Posts: 2024

smoothie wrote: I don't think this has anything to do with my 3kRpm/4psiBoost problem though.

it could be part of the problem . if your emissions stuff is still working ,the EGR valve (porsche has another name for it ,I forget ?) anyway , the EGR valve is open at idle and doesnt close until intake vacuum drops at a certain throttle position . it could be compensating for the rich air/fuel mixture caused by the high fuel pressure . and when the EGR closes, your running way rich and loosing power . try disabling the EGR by removing the vacuum line to it so it wont open . then see if the car runs badly and hesitates when you hit the gas . it seems odd to me that your fuel pressure gets higher when parts get old , maybe your return line is bent, kinked, or clogged .

Paul · Posted: Sun Jan 12, 2003 1:43 pm Post subject:

2 bar (30 PSI) at 10 degrees C is normal for the control pressure.

Normal system pressure is 5.8 to 6.5 bar. (roughly 90 PSI).

Your car is within spec according to my Porsche shop manual.

The turbo motors run higher pressures than the N/A, make sure you are not using N/A numbers.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Smoothie · Posted: Sun Jan 12, 2003 3:06 pm Post subject:

Good point - and thanks. I did have 90psi in the back of my mind, but the Haynes kept saying 65-75 even in the back of the book where it covers later models. Anyway, if the thing ain't broke, I won't fix it.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Paul · Posted: Sun Jan 12, 2003 3:12 pm Post subject:

I did the same thing the first time I used the Haynes manual. It does have the correct info at the beginning of the chapter, but the numbers in the text are not for a turbo.