90SteelBlueCoupe

I've run accross this a few times on here but still have yet to get a straight up answer... Short of replacing the whole instrument cluster (which can get expensive) ... is ther any way to make the tachometer accurate???

There is no filter on the 1990 car... at least if there is I can't see it... it's not on the engine like the 1984's are... I don't want to have to replace the whole cluster ... what other things are there to check.... I am totally lost on what to look for ... Could the dist. be wrong and malfuntioning and if so how can I test this with simple tools....

Please HELP!!!!

skateparkdave

If you look at the top of the distributor there's two wires and one is labled "tach" follow it down and there should be a cylinder shaped unit in line on that wire. Thats the tach filter. However, replacing mine on my 90 did nothing.

I had the local GM dealer order me a GM refurbished cluster, for around $169 if memory serves, that fixed me right up. I did the install which saved me alot I'm sure. I dont know of any other fixes short of an aftermarket tach. Best of luck to you.

Dave

Blower91

My 91 has a filter and I think yours should have one too. Look behind the engine close to the distributor. The filter is a black small box taped behind one of the "main" cable harness... at least this is the case on my. Almost impossible to see but you can reach and touch it if you are agile.

Hope this helps

VAHROOM

Why do you believe the tach is inaccurate? The symptoms may help troubleshoot this issue. A 1990 does have a filter from the factory.

My 1990 had a tach issue. The tach would show idle just fine. As the RPM increased, the tach would go wild and peg while I was just turning around 300-3500. It was the filter. The filter wasn't bad, it was just loose on the ground connection. Tightened the connection and all was fixed. Hope yours is just as easy.

90SteelBlueCoupe

At idle my tach reads 1500 to 2000 rpm and cruising in OD at 40 mph it reads 3000 .... when I step on the gas... the needle pegs out when I actually punch it and it gets to 4000 or 5000 actual the needle goes to zero and when I slow down it drops back to reading high.... I'm not a mech. but I can tell the tach is wrong... I was thinking about putting a aftermarket tachometer on the steering wheel .. any ideas on which one would be small and accurate... I was looking for one to put in a guage pod but can't find a tach.... any ideas????

I feel like ---->>>>

VAHROOM

Oddly enough my 90 was Light Steel Blue like yours. Mine had a similar problem. Just follow the white wire from the distributor like skateparkdave said. Mine was not a black box. Mine was a device that looked like an old points style condensor, if you remember back that far. It had a white wire out each end and bolted to the bell housing with one of the bell housing mounting bolts. I removed the bolt. Cleaned the corrosion off the filter where it bolted to the housing and replaced the split type lock washer with a star type (because I dropped the old one and couldn't find it) and all was well.

90SteelBlueCoupe

Thanks VAROOHM

I'm going to try that... My wife's 84 has that cylinder looking thing at the base of the distributer... I just looked on mine and didn't see it there... I'll have to look a bit closer and dig a bit deeper... I didn't look as far down as the bellhousing.... Thanks....

Blower91

Interesting, I've tried figure out when they started to use the "new" 3-wire filter. Since my 91 uses 3-wire and from what you say it seems they started to use the new filter 91 then.

Odd that GM moved the filter down to the bell housing in 90, maybe they had a good reason? I thought the 89 and earlier was on the engine? By the way, the 91 filter is also close the bell housing... not very convenient when you want to replace it.

VAHROOM

Though the filter on a 90 looks like a 2 wire, the mounting bracket is actually a ground that attaches to the block. When I tried to get one from GM, I was told they were discontinued. It would have been nice if they kept making them since so many of them seem to have issues.

Blower91

I think you can buy filters for 92 and newer, 89 and older (but not 90-91) from eg Corvette Central. I do not understand why those two would not include 90-91! Anyway, I built my own filter. It is made of 2 resistors and two capacitors and the exact values of the componets are not that critical.

By judging from the location of the filter I would guess that GM thought that this filter would not break down.