tachometer

One of my 2.3 mustangs' tach has recently gone haywire it will drop way down while driving like say when your cruising at 70 it drops from around 2900 to 1000 rpm the car still runs fine and the tach still works just not on the right scale and when you slow to a stop the check engine light comes on. Any ideas has to the problem? Thanks in advance!

Why is it that every time I post on this forum nobody answers? I dont have this problem any where else! :confused:

check if your battery terminals are dirty. it has happened to me a while back ... but in my case the whole cluster went crazy ...

give that a try .. see what happens


Greg

Well if any body is interested I pulled the codes today and got 181 223 224 not sure if these would affect the tach in this manner but I havent been able to catch the light on to check codes. Already checked and replaced the terminals any other ideas?

I would hook up another tach, and see what happens.

I have found ths website that would be usefull to any mustang owner. I belive it has all the codes in the world. Give this a ry hopefully it will offer an explenation.

http://proficientmustang.com/ecm_codes.htm

Greg

Hey Hormonx If I were you I wouldnt use those codes according to my manual the are not the same has a mustang the site said they were for a truck. For instance if you dont belive me the manual for mustang says that code 181 is "fuel at rich adaptive limit at part throttle: system rich" but this site says its "lean" . Just keeping a heads up!

This might sound like a really crazy question, and I may be way off the wall here, but before going out and spending $$$ on the gauge I was wondering if the engine had a miss??? The reason I ask this is because the tach is tied directly into the primary ignition system.
(Primary= battery, pickup coil, crankshaft position sensor, ign mdle, and primary windings on the coil.)
(secondary=coil wire, distributor, cap, rotor, plug wires,plugs,etc.)
Mechanics use the "TACH TRICK" all the time to first determine if the ignition problem is in the secondary or primary ignition system. If you have this problem and a miss post reply and I'll explain how to diagnose.




Why is it that every time I post on this forum nobody answers? I dont have this problem any where else! :confused:

Well Said, Hey uncatchable, Not to knock this website as I DO LOVE IT, I was wondering where else do you post? automotiveforums has been great for posts with my Yukon. However, with my 91 Legend and this mustang I have had no luck. With the 91 Legend there was a site called acura-legend com and it was great. I'm new to the mustang world, Just bought a 302 GT a few weeks ago. Is there another mustang forum I don't know about?

Well Denaliman I am not sure on the miss problem but I'm betting it is a posibility seeing has it runs for lack of better terms "rough" when the tach mess' up. Has for the other mustang forums I havent found one yet but I will and you can bet I'll let you know where to go, maybe then we'll get some help instead of being ignored!

Well Denaliman I am not sure on the miss problem but I'm betting it is a posibility seeing has it runs for lack of better terms "rough" when the tach mess' up.
I am 99.95% sure that there is a problem with your primary ignition system. This can be a good thing.--killing two birds with one stone
I would recommend going to autozone and running a scan tool diagnostics and testing the battery. These are free-bees. They do it for free in hopes you will buy the parts from them. If you have no luck I would then, First, thouroughly check all your ground wires and connections both on the battery terminals and through out the ignition system. Another free-bee. Next use an ohm meter or multi-meter to check the coil wire. yet another free-bee. Or purchase of the tool. Simply test on the ohms setting. I'm not sure what your vehicle specs are, but Good rule of thumb is no more than 1000 ohms resistance per inch of wire. The wire is usually not the cause, but is worth checking.
Now that all the free-bees are up, you have two choices. Process of elimination or find a shop to diagnose the problem. (They have really expensive equipment that can easily pinpoint the cause) If you decide in the process of elimination route, I would recommend first Replacing your pick up coil in the distributor and/or your ignition coil. I priced these two items @ autozone. I used an 89 2.3L. The pick up coil is $17.00 and the ignition coil is $13.00. Would probably be one of the other. If these items don't help, I would condemn the Ignition control module, around $30.00. Good luck and happy hunting.

May even want to check TSB's (technical Service Bulletins) or call the dealer to see if there is a common problem with one of these parts. Good Luck and Happy Hunting.

Well, a simple search and I found one. www.stangnet.com Just clicked over there curretnly 800 stang owners online in forum rooms. very active site.

i have the same problem not all of those codes tho and althou i haven't fixed it because simply i didnt have an autozone to near me and wouldnt have a ride there...but neways...
From what I've read it is very likely your ignition module, check the connections to that and make sure its good and clean, but yeh you can bring the module into most autozones and have that tested, and like denali said, if that isnt it it is probably the coils. I just never did anything because a new ignition coil for mine was like 100+ and $100 wasnt worth a working tach to me =P

i did have a question for you thou denali, wats the best way to test the grounds, or does autozone do this for you?