[jdwill13]

I am new to this site and I have a question. I have a 1991 Mustang with the 2.3 and a T-5. Just recently while driving to work on the highway my tachometer would start reading half of what the actual RPMs were. I was cruising at 2500 RPM and the tach just dropped to 1200 but the engine was still running the same and the car did not slow down. The car has been doing this more often here lately. Now it will throw a check engine light and start to run shaky. But, once you kill the engine and restart it, it will run fine and the tachometer will read fine. My friend told me its the DIS because it controls the tach signal. Any ideas? I hate to pay $150 for a new DIS and that not be it. Thanks.

Jeremy

[b_chandler]

That's a typical symptom of a failing DIS module. You can do a search here to confirm that.

I ran into the same problem with my '91 and a new DIS module took care of it. Your check engine light probably comes on from time to time and if you were to pull the codes you'd get codes 223 and 224. Both of those codes point to respective coil packs, but it's been found that the problem really lies with the DIS module.

I agree that the price of the module sucks.

[RICESKI]

Originally Posted by jdwill13

I am new to this site and I have a question. I have a 1991 Mustang with the 2.3 and a T-5. Just recently while driving to work on the highway my tachometer would start reading half of what the actual RPMs were. I was cruising at 2500 RPM and the tach just dropped to 1200 but the engine was still running the same and the car did not slow down. The car has been doing this more often here lately. Now it will throw a check engine light and start to run shaky. But, once you kill the engine and restart it, it will run fine and the tachometer will read fine. My friend told me its the DIS because it controls the tach signal. Any ideas? I hate to pay $150 for a new DIS and that not be it. Thanks.

Jeremy

Did you ever get your 91 fixed? I have a 91 that when I replaced a non working electrical fan the new one refuses to work naturally. I have it hot wired on all the time but this is not what I want.

ALSO - this car had the water pump - timing belt - and thermostat [195] replaced and still it never moves the gauge to the middle. I have not put a numbered temp gauge on it but wondered. the old thermostat did the same thing. Well at least it isn't over heating and the heater works good.
There you have it - any ideas on this is appreciated [ well a little - hahaha ]

Thanks

[nofxintx]

You can take your DIS in to get checked just like a battery or alternator. Autozone does it for free. I hate that stupid DIS!!!

[Lowerednjuiced]

Check ebay for used ones. I sold out of them in my ebay store but I had 5 listed for $25 including shipping. I have some heat sink blocks for the TFI, just not listed.