Taco reading wrong?

Recently bought an 85 323i, but the taco is reading far above what it should. It has the standard gearbox, which in my other 323i does 80km/ph at 2000rpm in 5th.

My new car reads approx 3000rpm.

There is a definite pattern of the rev 'boost' it follows an extra 50% to what it should.


Could this be because the instrument panel has been replaced with a 4 cylinder one? so it is reading 50% more ignitions?

Also, just replaced the timing belt, tensioner, adjusted the valve clearances and gave the dizzy a clean, will i have to re-time the engine?

I want to get the car and everything in it running well, as i just passed my blueslip/ roadworthy inspection today.

Thanks

just because they are both 323's doesnt mean they have the same rear diff ratio

If you are certain that the tach is from a 4 cylinder car, then that is probably the reason.
If the entire cluster is from a 4 pot car , then the coding plug will also be the wrong piece.
You'll be looking for a six pot cluster to be certain of the correct revs.

m

I like taco's.

Me too. 'Specially shrimp tacos. :yum:

4 cylinder cluster in a 6 cylinder car will read 50% over actual RPM, just like pilot said

My taco usually reads ok it read about mid level meat cheese and lettuce

Wicked Fast Entertainment

TACH!!! Or Tachometer. None of them are super accurate. Swapped eta to 7k Tach in my e30 before the M52 swap and noticed it was off. Many others have said BMW Speedo's and Tach's are all just off. Friend with a E90 his is 7mph off. Eta/M52 is 5mph off.

Originally Posted by Tkaczuk

TACH!!! Or Tachometer. None of them are super accurate. Swapped eta to 7k Tach in my e30 before the M52 swap and noticed it was off. Many others have said BMW Speedo's and Tach's are all just off. Friend with a E90 his is 7mph off. Eta/M52 is 5mph off.

speedo and tach or different. speedo can be anything from tranny gearing to how worn your tires are

tachs are off the pulses to the #1 cylinder, so alot more accurate

There are ways & means to calibrate your speedo to be accurate, especially these pulse driven ones
Then your Odometer is usually out afterward
Most Tach's are very accurate untill somebody works them

So they are the pulse powered types? Tacho* not taco.. i guess i was hungry.

Originally Posted by hornhospital

Me too. 'Specially shrimp tacos. :yum:

4 cylinder cluster in a 6 cylinder car will read 50% over actual RPM, just like pilot said

I prefer Latina errrr Mexican.

all of this taco business and noones answered the problem

OP, assuming you still have you 323i cluster, on the front of it and also the 4cyl one, you will see a white part. this can come out, and can be swapped over. the cluster itself is actually the same, its this white module that tells it whether the cluster is in a 4cyl or 6cyl car.

Originally Posted by _Ethrty-Andy_

all of this taco business and noones answered the problem

OP, assuming you still have you 323i cluster, on the front of it and also the 4cyl one, you will see a white part. this can come out, and can be swapped over. the cluster itself is actually the same, its this white module that tells it whether the cluster is in a 4cyl or 6cyl car.

Well, I wouldn't recommend something that doesn't apply to him Andy.


You DO know when the coding plugs were introduced right? His car is an 85 M10 318i chassis.....

Originally Posted by SWISS

Well, I wouldn't recommend something that doesn't apply to him Andy.


You DO know when the coding plugs were introduced right? His car is an 85 M10 318i chassis.....

when did they start the coding plugs?

Originally Posted by downhiller

when did they start the coding plugs?

late 87

I did not know that, i have never owned or wrecked a prefacelift so not familiar with all their differences.

Originally Posted by SWISS

late 87

mine had one and it was an 86. but it was only for the "taco".

i was having a fun time driving around with my tach was way off when i change my si board from a 90 ix to my 86 e on motometer cluster.

Originally Posted by downhiller

mine had one and it was an 86. but it was only for the "taco".

i was having a fun time driving around with my tach was way off when i change my si board from a 90 ix to my 86 e on motometer cluster.

Probably was swapped due to bad SI's or odo before you got it. There may have been oter idiosyncrasies I am forgetting but some of the OG's know I deconstructed the motometer and VDO early and late clusters years ago and had a table to show compatibility. When I was troubleshooting my 87 325 in 06.

Coding plugs also were phased out in 94 in lieu of a rewritable module.

i had this problem when i changed the speedometer. the rpm would go up to 3000 when it should be 2000. so it turns out the chip on the bottom right (the white part that Ethrty-Andy is talking about) had to be changed.
the 4 cylinder one has "003" written on it. you need to get the 6 cylinder one that has "002" instead and it should work.

Originally Posted by Tkaczuk

TACH!!! Or Tachometer. None of them are super accurate. Swapped eta to 7k Tach in my e30 before the M52 swap and noticed it was off. Many others have said BMW Speedo's and Tach's are all just off. Friend with a E90 his is 7mph off. Eta/M52 is 5mph off.

I put an S52/ZF 320 in the E30M3. Decided to use a Dakota Digital tach signal converter until I get a six cylinder cluster.
The tach is 50% optimistic at idle and gets worse as the revs go up.
Watching the tach needle slam past 8k and then bounce is just silly.

m

Originally Posted by SWISS

Well, I wouldn't recommend something that doesn't apply to him Andy.


You DO know when the coding plugs were introduced right? His car is an 85 M10 318i chassis.....

I dont have the old Tacho, i bought the car and it reads wrong. So you recommend pulling out the cluster and checking?

it's a 323i '85 chassis/motor, but with (what i suspect to be ) a 318i cluster.
It's not that bad, it just looks like i live on the redline..

Originally Posted by 7pilot

I put an S52/ZF 320 in the E30M3. Decided to use a Dakota Digital tach signal converter until I get a six cylinder cluster.
The tach is 50% optimistic at idle and gets worse as the revs go up.
Watching the tach needle slam past 8k and then bounce is just silly.

m

I had the same issue when I swapped my 1.9L Z3 for a 2.8 M52. idle was normal but the revs climbed so fast and the needle flew past 7K. Coupled with loud MAgnaflow exhaust it raised some eyebrows.

Originally Posted by van31

I dont have the old Tacho, i bought the car and it reads wrong. So you recommend pulling out the cluster and checking?

it's a 323i '85 chassis/motor, but with (what i suspect to be ) a 318i cluster.
It's not that bad, it just looks like i live on the redline..

Late model clusters are backwards compatible throw a moto meter in there from a 87+ 325i and you should be money.