924Board.org

[Vince Ponz]

I made a mistake and I meant to say the oil pressure gauge. Put the lights on and the pressure drops. I changed from synthetic to dino and it is a little better.
When hot I really get to worry. Uses no oil and runs great.

[larso]

The oil pressure sender may need to be replaced, I would get a generic one from pep boys or NAPA or a porsche one if you insist (80 bucks). I would have liked to drive one of these 924s when they were brand new, did they have any of these problems when brand new, because every single 924 has the same problem over and over, unlike other cars.
I noticed that all the dash lights and the oil pressure gauge were connected to one basic ground, so i would run a seperate ground wire to anywhere on the body, if the new sender unit doesn't completely solve problemo.

[Smoothie]

I've noticed that when the engine is warmed up, (and lights are on), if the tach is on 1 (1000 rpm) the oil pressure gauge will be about on 2 (2 bar). When the tach is at 2, the oil pressure gauge will read 4. Tach 3, oil gauge 6, etc.

Also - it seems more likely that the oil pressure gauge problem we're looking into here is with the wiring and probably the ground. I would take the easier and less expensive route first (I understand it's tough to get at the sender back between the firewall and cylinder head.)

In addition, my 931 consumes little (actually none that I can detect) oil. Doesn't leak any either. It's the best car I've ever had in that and in most other respects as well. Also, I use synthetic oil - which I've read is more likely to leak past seals than regular oil. (Of course that's not why I use it.) I use it because it's less prone to coking in and around the turbo's bearing. (Not wanting to do another turbo replacement very soon.)

_________________
'82 924 Turbo, Home Depot boost control, blue windshield washer fluid water injection

[ This Message was edited by: smoothie on 2001-09-23 14:27 ]

[Smoothie]

Vince - Here's a link to a post concerning the oil pressure gauge. It's not the one I was looking for, but; it's helpful:
http://database2.planb.com.au/924org/viewtopic.php?topic=993&forum=10&1

[Smoothie]

One last note on the original topic: I'm starting to feel confident now that the problem is fixed. It's been running good for 2 weeks now. Looks like the unplug-clean-reattach connectors to the ignition module and control units is what corrected the problem. Thanks again, excellent dg!

[Vince Ponz]

Thanks Mr.Smoothie.I will test the gauge.That is what I like about this site.

[924RACR]

Hey, can you guys please email me info about your use of the Delco alternators? Specific model #'s and installation tips? Any mods or rewiring required? I'd like to add them to the website - please email them direct to me:
vaughan@vaughanscott.com

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

[numbers]

Vaughan, I posted the complete instructions for using the Delco in the 931 a couple of years ago. It should still be around.

[TonyMechanic]

Whoa VINCE!
did you say that you switched from Synthetic to Regular? be careful with that buddy, it'll eat away at your oil gaskets/seals. just watch your Oil pressure and make sure theres no spots on your garage floor.

[wdb]

hey smoothie,just a word of caution.that blue windshield washer fluid is made with methynol(sp) and is poison (Highly toxic) and can be absorbed through the skin,and mucus membranes (lining of nose and mouth)be careful around that stuff,getting it on your hands and breathing the vapors can make you blind. you probably new this but I had to be sure you were aware of the dangers

[Smoothie]

Thank ya Dubbya Dee, you are very correct - nasty stuff there. Let me just say to all that I do not condone the use of blue windsheild washer fluid for anything other than its' intended purpose. Do not wash your hands in it. Do -not- use it as a mouthwash, nasal spray or eye drops. Do not concentrate the contents and inhale (for fun or any other purpose). -Do- only pour it straight from its' bottle into your windsheild washer fluid reservoir. If you're stupid and you know it or if you're smart, but; others seem to indicate you're not or they come right out and say you're stupid, stay away from the stuff. If you didn't understand that last sentence, you may have already been exposed to too much - get away from it. Just because it's pretty and maybe smells good is no reason to get all over it or to let it get all over you. Thanks all, for your attention in this matter. Good health.

[ericj001]

the voltage input wires are the key to fixing the "dancing" gauges. when you combine small gage wiring, age, and corrosion over the years , its difficult to get a constant voltage to power the gauges. its worse if youve added a high power stereo using the original wires. as stated above, the fix is either renewing the wiring harness, or splicing in a new power wire of heavier gauge. and ofcourse making sure your gounds are solid, "t"ing in a an extra groud wire to the circuit also helps considerably. I did this in my 78 and it made a huge difference. I think adding a capacitor to the system would also help allot by stabilizing the voltage, but i havent tried it yet. i replaced the clock in my 82 with a stock voltmeter, using the same power wires. its all over the place especially when the radio is on. proof positive of the varing voltage, the more accessories running, the worse it gets..ive some rewiring to do...
Also, id caution against using a higher output alternator, lest we forget your wiring was spec'd to handle only a certina amount of juice, and its properties have degraded over time, reducing those parameters. go too high and your wires will develope more resistance, get hot, and posibly even ignite..any upgrades to the power transfer system should be carefully monitored...

[ This Message was edited by: ericj001 on 2002-02-14 00:34 ]

[Smoothie]

I didn't complete my bachelorate degree program in electrical engineering (didn't even start), but; I think I have a good enough understanding of things electric not to do too much damage. I'll have to try and muddle through this in laymans terms. Mostly because those are the only terms I have. Of course I'm open to any corrections if we have any real electrical engineers out there. My understanding is that it doesn't matter how many amps are coming from your power source, be it a battery or a generator or alternator, it's the device being powered that determines how much juice flows through the wires and that determines the wire size needed. As an example, lets say we have a small 12 volt dashboard lamp. Whether your power source is (8)AA batteries (12 volts, ? amps (very low amps)) or a 75 amp 12V alternator or a 200 amp 12V alternator it doesn't matter, as long as the power supply is putting out 12V, the lamp will draw the same in volts and amps and require the same minimum size wire. (I realize the (8)AA cells may actually be putting out 12.5V or less and the alternators may be at approx. 13.5V, but; given a theoretical 12V from all of the power sources, the bulb will require the same minimum size of wire for all.) Given a wiring system designed for a 12-14V power source, if you were to put in an alternator that puts out more volts, say 20V, then you should be worried about burning wires. Adding an electric device that draws 2 amps to wiring that's sized to handle something that draws only 50 milliamps will also likely burn wires. Putting in a 12V alternator with a larger amperage capacity shouldn't overstress the wiring. If the wires are old and have built up enough resistance, then you could have the same problems whether you have a 75A or 200A alternator.

P.S. My car is running with no new electrical problems for about a half year now with the alternator upgrade. No burnt wires, actually all that's changed is my weak battery problem has been solved. Thanks for the other wiring suggestions - still have to check the grounds behind the dashboard. Saving that for the next time I'm in there to work on the speedometer.

As for the original topic of this string, "Runs good, runs bad, tach flops around...", the problem reappeared once breifly several weeks ago. I started it up and the tach was weird again and the engine was running rough. I just shut it off, got out and pulled that connector to the box that's behind the radio, plugged it back in and it started right up. It's running like a charm since.

[larso]

Hrm...I had this problem for about a week. It conked out on me, I coasted a bit...then the car restarted...then it conked out again. The symptoms were: tach flopping around.

I did nothing...I've been driving for about 3 months since, and it hasn't happened. It's weird. I did put methanol in the tank, I don't know if it was just my fuel pump and dirty fuel. I also changed the fuel filter. It was definitely NOT the fuel pump relay, as I have a spare 931 relay that I put in while it was happening that one week. I don't know whether it was air in the fuel, a bad coil, connections or what, but the problem has not happened since. I was also guessing that the ignition switch was bad, because it sometimes occurred only under hard acceleration (bumpy, causing the ignition switch to short out maybe). I've heard of NEW ignition switches being bad, they are a little flaky. I still do not know what the problem was though. I hate the problems that you've fixed, for a year, but don't know what the hell you fixed or how you fixed! I'm hoping it was just the fuel filter and the fuel, since that's all I really tried. I never changed the coil...Oh I also cleaned the distributor cap, but I doubt it was that. And NO it wasn't the over boost switch..I grounded it out and the problem during that week still happened.

[Smoothie]

The original problem that I started this topic about was this: the tach pointer flopped around wildly, engine ran rough, backfired and stalled. I found the solution in the FAQ here: http://www.924.org/techsection/GarageFAQ.htm#931backfire (The connector to the digital ignition control box behind the radio - just needed to disconnect, clean, reattach)

_________________
'82 924T

[ This Message was edited by: Smoothie on 2002-06-27 18:29 ]