Instrument issues
Thread Starter
Heel & Toe
Joined: Sep 2015
Posts: 18
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Instrument issues
Hello from the UK. I own a 94 C4 Corvette coupe that I bought 10 years ago now. I love the car, despite the poor stopping and handling...because it looks a million dollars, and the engine and transmission are just great ! Further more, you don't see too many of them around here, so it collects a lot of admiring looks wherever I go.
It has developed a slight fault, which I wonder if any of you guys have encountered before? The speedometer is under reading dramatically.....it hasn't always done this, it's something that started a little while ago. When I checked my speed with a satnav, the car was reading at least 25 mph slow when the satnav was showing 100mph. Also, strangely, and I'm guessing possibly connected, the rev counter is over-reading. I noticed that it has been showing a lot more revs than it used to, and if I really apply the gas hard, the needle goes clear off the gauge as the engine peaks.
Anyone got any ideas what's gone wrong? Assistance very much appreciated.
It has developed a slight fault, which I wonder if any of you guys have encountered before? The speedometer is under reading dramatically.....it hasn't always done this, it's something that started a little while ago. When I checked my speed with a satnav, the car was reading at least 25 mph slow when the satnav was showing 100mph. Also, strangely, and I'm guessing possibly connected, the rev counter is over-reading. I noticed that it has been showing a lot more revs than it used to, and if I really apply the gas hard, the needle goes clear off the gauge as the engine peaks.
Anyone got any ideas what's gone wrong? Assistance very much appreciated.
Team Owner
Joined: Sep 2003
Posts: 25,361
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If your car has C68 A/C you can confirm MPH and RPM using the AC control panel. I would check both using that panel and post back.
Here's enough info to get you started:
I doubt they're related issues. How about the balance of the gauges? There are parameters you can check also with the AC panel other than RPM, MPH and AC faults.
If you don't have C68 you'll need a scanner.
Here's enough info to get you started:
I doubt they're related issues. How about the balance of the gauges? There are parameters you can check also with the AC panel other than RPM, MPH and AC faults.
If you don't have C68 you'll need a scanner.
Thread Starter
Heel & Toe
Joined: Sep 2015
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at tick over, I had a value of 27, 28 or 29 showing on the screen, whilst the rev counter was showing a fairly steady 1000 rpm.
as for the speed, it's difficult to compare the value showing in the small screen to the speedo while driving along, but just a short drive around the block, and the heater control screen number seemed to be always less than showing on the speedo to some degree.
What's next?
I should point out that no system faults were registered, as at the outset of this procedure the screen showed "00". It's also worth mentioning that within seconds of starting my engine, from hot, or stone cold, the engine fans fire up every time followed by the "service engine soon" emblem lighting up.
Last edited by lucepac27; Sep 13, 2015 at 05:55 AM.
Race Director
Joined: Mar 2015
Posts: 15,926
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Thanks WV....I had a go with this procedure yesterday, and as I said, my heater control buttons do seem a bit unresponsive, but I did manage to work through it....
at tick over, I had a value of 27, 28 or 29 showing on the screen, whilst the rev counter was showing a fairly steady 1000 rpm.
as for the speed, it's difficult to compare the value showing in the small screen to the speedo while driving along, but just a short drive around the block, and the heater control screen number seemed to be always less than showing on the speedo to some degree.
What's next?
I should point out that no system faults were registered, as at the outset of this procedure the screen showed "00". It's also worth mentioning that within seconds of starting my engine, from hot, or stone cold, the engine fans fire up every time followed by the "service engine soon" emblem lighting up.
at tick over, I had a value of 27, 28 or 29 showing on the screen, whilst the rev counter was showing a fairly steady 1000 rpm.
as for the speed, it's difficult to compare the value showing in the small screen to the speedo while driving along, but just a short drive around the block, and the heater control screen number seemed to be always less than showing on the speedo to some degree.
What's next?
I should point out that no system faults were registered, as at the outset of this procedure the screen showed "00". It's also worth mentioning that within seconds of starting my engine, from hot, or stone cold, the engine fans fire up every time followed by the "service engine soon" emblem lighting up.
on the 94 you can jump your ob connector with a paper clip and read the check engin codes with your speedo. look it up on youtube. as far as your fans comming on if the AC is on your fan will come on if it is off might have a air bubble in your coolant there are two bleeders by your thermostat do not get your opti wet.
do some reading should not have poor stopping and handling other than breaking loose the rear end that is just a learning curve
Last edited by antfarmer2; Sep 13, 2015 at 09:29 AM.
Thread Starter
Heel & Toe
Joined: Sep 2015
Posts: 18
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on the 94 you can jump your ob connector with a paper clip and read the check engin codes with your speedo. look it up on youtube. as far as your fans comming on if the AC is on your fan will come on if it is off might have a air bubble in your coolant there are two bleeders by your thermostat do not get your opti wet.
do some reading should not have poor stopping and handling other than breaking loose the rear end that is just a learning curve
do some reading should not have poor stopping and handling other than breaking loose the rear end that is just a learning curve
When it stops raining, I shall go out and bleed the coolant system and see if that stops the fans from coming on. Thanks again.
Race Director
Joined: Mar 2015
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Thank you for your help Antfarmer.....and comments about handling and stopping. I fitted "greenstuff" pads up front, and EBC in the rear, and for normal driving the car stops well, no complaints, however, problems arise stopping it from big speeds...I'm talking 140 or more. I live near a big dual carriageway where doing these speeds is not a problem, but stopping the car hard overheats the brakes, and the pedal just turns to wood.....it's not something I do very often, so I can live with it. As for the handling, you need to know that roads here in the UK are very different to those you guys are used to. Ours are very much smaller, and can be quite bumpy. On smooth surfaces the car handles OKish, not well...but on the bumps it's no good at all, as it feels like it's scudding along the tops of the bumps, and going quickly is out of the question, but again, I can live with it, as I like the car.
When it stops raining, I shall go out and bleed the coolant system and see if that stops the fans from coming on. Thanks again.
When it stops raining, I shall go out and bleed the coolant system and see if that stops the fans from coming on. Thanks again.
try bleeding the brakes replaceing the fluid would be best. And I understand the bumpy roads they do not like this.
Le Mans Master
Joined: May 2006
Posts: 7,708
Likes: 266
From: indy indiana
That wouldn't be the airstrip near Wesham/Blackpool would it? have some good friends there that fly a Huey Helicopter in the airshows there. BTW, WV knows his stuff about Vettes and has helped many folks in here.
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Thread Starter
Heel & Toe
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