Bizarre Instrument Gauge Problem

[aggerz]

Hi Folks,

I will do my best to explain the situation I'm getting here so bare with me

Gauges were fine when i got the car, I have since had a full alarm and new stereo installed. Since getting that done my problem has been there.

Problem - The car seems to take forever to warm up as indicated by the gauge... it will *eventually* get to half.. and if left idle its possible to get it up to 3/4 and then the thermo fans come on as they should so it seems that the cooling system is doing its job but if you trust the gauge it takes much much longer than it ever used to. Driving around, freeway or urban etc it might take around 45mins before it really starts showing much life above cold!

-- Meanwhile! - the oil pressure gauge is maxxed out at 5.. from the time i turn the key.

Now the bizarre thing - As the temp gauge starts to rise a little .. the oil pressure gauge will start to lower a Little... say to '4'.. and will function properly but with a limited range ie. from 4-5... the warmer the temp gauge gets.. the more "play" the oil pressure gauge gets... 3-5 etc..
But it doesn't ever get back down to 1 like it used to.

I took the car back to the alarm/stereo place and he went over the car top to bottom and insists that the wiring has nothing to do with the dash and it should not be interfering.. and that he also checked any other stock wiring around dash etc and it appears fine.

So Any ideas/Thoughts would be appreciated!

Thanks, Adam.


'90 S2 Cabriolet

[Enthuzed1]

hey there, I don't know about the temp but i know that for the oil, at idle and normal operating temp, 3-4 bar is about right.....going down to 1 bar, i don't think that's good......

[livewirevoodoo]

I would start to worry if the oil pressure gauge ever went below 2. I get 5 on startup, 3 to 4 during city idle, 5 at WOT, and about 2 at idle after about 45 mins on the highway. Also.... My pressure was a bit lower during the winter when I was using a thinner oil. You're oil gauge sounds fairly typical, but be concerned when it drops below a 2 after some hard driving.


With that bieng said...

The one thing you didnt mention was your battery voltage guage. What sort of voltage is bieng shown? Stereo draw would definitely effect this. I finished up a killer stereo install on the car a few months back. Running right from the battery, in addition to the voltage needel drop when the bass hit, I believe the current draw (ever so slightly) effected the oil and temp gauges. When the bass would hit, oil pressure gauge would decrease, temperature gauge would increase. Ever so slightly. After about 2 weeks, I added a capacitor to the setup and havent noticed the issue.

I don't think a stereo install would by nature screw up your gauges. Nothing in the stereo wiring looks like instrument cluster wiring, or vice versa. What would influence your gauges would be if they are getting enough juice.

[SoCal Driver]

When the wires on the oil pressure gauge are backwards you will get the gauge jumping to and staying on 5 bar. There is a colored mark by one of the two connectors on the oil pressure sender. One of the wires is the same color and should connect to that lug.

You will have to use a seperate temp sensor to check the gauge.

It's quite possible that the alarm is connected to the wrong parts of the wiring harness. The S2 uses a ignition interface module between the DME and the coil. Real easy to screw the wiring up.

[aggerz]

thanks for your replies guys.

As for the voltage meter that seems to be fine.. It sits around the 13v mark when running and i put a new heavy duty sealed battery in less than 1 week ago.

Perhaps i am mistaken about the oil pressure ever dipping to 1 as I have not had the car that long and its been stuck on 5 more than it has been below that....

I am more concerned about the temp gauge if the car is actually warming up properly.. as far as i remember Pre-alarm install etc it never took that long for the car to warm.

Its like i have to drive for almost 1hr before the gauges look normal.. I cant imagine that the car would take 1hr to warm up.

I will check the wiring as SoCal suggests and see if this helps.

Cheers, Adam.

[livewirevoodoo]

1 hr... ya... far too long... even in the dead of winter, around 20 degrees F, idling till normal temp only takes me about 15 mins.

after 1/2 hr, if you can touch the cam cover and hold your hand there something isnt right.

SoCal raise a good point with the DME interface. I hadn't thought about it. Could very well be stemming from there.

[SoCal Driver]

Worried more about warming up than having oil pressure?

Both are important. I would put the oil pressure above warm up.

[aggerz]

Socal - Hah yes you are right.. oil pressure is more important i just meant in that i was confident that what is happening under the hood is correct its just the gauges are not telling the truth.

Is there anything blatantly obvious that would keep a car from warming up in a reasonable time? thermostat?

[SoCal Driver]

Bad temp sender. These cars are notorious for getting too hot too soon.

[bobcat0]

SoCal Driver (a/k/a Hugh a/k/a Obi-wan) mentioned that the oil gauge will show a constant "5" reading when the leads are reversed...I have the same problem...what's the best/easiest way to make them right and where do I need to switch the leads...remember, I'm a comparative "newbie" and need some guidance...thanks...

[SoCal Driver]

Just below and behind the oil filter. Gold colored "can" about two inches in diameter with two threaded lugs. Thought I saw a leading picture in a thread where it was shown clearly.

[SoCal Driver]

Yeap. In one of Dan's threads:

Most 951 Knowledgeable Shop in L.A.?

[bobcat0]

Thanks, Hugh and all.