engine miss & no tach

ol'stupidcoupe

Registered User
My vehicle is a '90 S/C with auto trans. I am experiencing an intermittant engine miss/buck & even will stall with hard restart. Within 1-2 miles from home & after filling with fuel this morning, with symptoms present I replaced the DIS (although I dropped 1 of the screws - rear near s/c) & the engine had extended crank to start & then still bucked 2-3 times in my 20 mile commute to work. Upon starting to come home, had extrended cranking & then engine shut off as if key was turned off when I truned on a/c - restarted again with extended cranking. On the way home, within 1-2 miles, the engine miss/buck returned & the tach started to jump & drop to zero. I pulled over to check - all connectors tight. This time the crank time was longer - I cranked for several seconds 2-3 times before engine would start. When the engine started the tach did not work for several seconds & then jumped up to idle speed. Ran O.K. for a few miles & then miss/buck returned as well as erratic tach. I then replaced back to the first DIS & changed the missing bolt to front outside bolt hole & now vehicle drove fine the rest of the 20 mile commute. The first DIS used is a Motorcraft that I purchased several years ago & have had on the vehicle since. The DIS I used as a replacement was a new aftermarket Standard make. Now for the guts, is the cam sensor starting to fail? Could it be that the ONE bolt I lost for the DIS was the ground & by changing it to another location suppleid the ground needed? More whacky Supercoupe problems, must be why we love 'em.
 
i had the same problem. cam sensor was no good
My vehicle is a '90 S/C with auto trans. I am experiencing an intermittant engine miss/buck & even will stall with hard restart. Within 1-2 miles from home & after filling with fuel this morning, with symptoms present I replaced the DIS (although I dropped 1 of the screws - rear near s/c) & the engine had extended crank to start & then still bucked 2-3 times in my 20 mile commute to work. Upon starting to come home, had extrended cranking & then engine shut off as if key was turned off when I truned on a/c - restarted again with extended cranking. On the way home, within 1-2 miles, the engine miss/buck returned & the tach started to jump & drop to zero. I pulled over to check - all connectors tight. This time the crank time was longer - I cranked for several seconds 2-3 times before engine would start. When the engine started the tach did not work for several seconds & then jumped up to idle speed. Ran O.K. for a few miles & then miss/buck returned as well as erratic tach. I then replaced back to the first DIS & changed the missing bolt to front outside bolt hole & now vehicle drove fine the rest of the 20 mile commute. The first DIS used is a Motorcraft that I purchased several years ago & have had on the vehicle since. The DIS I used as a replacement was a new aftermarket Standard make. Now for the guts, is the cam sensor starting to fail? Could it be that the ONE bolt I lost for the DIS was the ground & by changing it to another location suppleid the ground needed? More whacky Supercoupe problems, must be why we love 'em.
 
My vehicle is a '90 S/C with auto trans. I am experiencing an intermittant engine miss/buck & even will stall with hard restart. Within 1-2 miles from home & after filling with fuel this morning, with symptoms present I replaced the DIS (although I dropped 1 of the screws - rear near s/c) & the engine had extended crank to start & then still bucked 2-3 times in my 20 mile commute to work. Upon starting to come home, had extrended cranking & then engine shut off as if key was turned off when I truned on a/c - restarted again with extended cranking. On the way home, within 1-2 miles, the engine miss/buck returned & the tach started to jump & drop to zero. I pulled over to check - all connectors tight. This time the crank time was longer - I cranked for several seconds 2-3 times before engine would start. When the engine started the tach did not work for several seconds & then jumped up to idle speed. Ran O.K. for a few miles & then miss/buck returned as well as erratic tach. I then replaced back to the first DIS & changed the missing bolt to front outside bolt hole & now vehicle drove fine the rest of the 20 mile commute. The first DIS used is a Motorcraft that I purchased several years ago & have had on the vehicle since. The DIS I used as a replacement was a new aftermarket Standard make. Now for the guts, is the cam sensor starting to fail? Could it be that the ONE bolt I lost for the DIS was the ground & by changing it to another location suppleid the ground needed? More whacky Supercoupe problems, must be why we love 'em.

You might be getting ready to replace your harmonic balancer and crank sensor. I had a similar problem: intermittant stalling and hard starting until the evening I went to pick up the pizza and it fell on it's face and was not going to start until it gave me another lesson. The intermittantness was caused by the rubber core of the harmonic balancer gradually comming loose at the center. As the balancer wobbled it hit the crank sensor, shorting out the signal and killing the engine. The sudden additional load of an A/C compressor comming on might cause the serpentine belt to affect a balancer on it's way out. After getting the car home and trouble shooting that it was the crank sensor I started to remove parts to get at it. As I pondered what to take off first I noticed a shiny spot on the hub of the balancer. I removed the belt and found the balancer spun on the hub. As the engine was running I figure, the rouge balancer finally let loose enough to hit the crank sensor and smash it to death. I went to the local junk yard for mine. I paid 20 bucks for a used balancer. I inquired about the after market balancer and found hat it is'nt as good as some say. The dealership quoted me abou $400 for the new OEM. I want for the used one. I could've bought 20 of them before I matched the dealership's deal. Good luck

Madison
 
You can test this. For the balancer you just look at it while the engine is running looking to see if it wobbles. Should be a noticeable wobble if there is an issue causing what you report.

Cam sensor you test by disconnecting the wiring harness from the sensor. The car will start and run, but it will be hard to start with it disconnected. Drive it with the sensor disconnected for a while and see if the other issues clear up. If everything but hard start clear up, the Cam sensor is bad.
 
Drive it with the sensor disconnected for a while and see if the other issues clear up. If everything but hard start clear up, the Cam sensor is bad.
Will the tach work with the cam sensor disconnected?

Kurt
 
Will the tach work with the cam sensor disconnected?
Nope.

Note: With the cam sensor disconnected, if it doesn't start within 2-3 seconds, key off and try again. Whats happening is the EEC has to guess and its chances are 33%. :cool:
 
I had to try and crank mine about 3 seperate times before it would run when my cam sensor died. It ran fine however, no misses or stumbles, but the tach didn't read.

If you lose the tach and it's running rough..... DIS Module.
 
The reason why you disconnect the cam sensor to look for a change, even though you have odd running conditions is that if the sensor is failing in an odd way, it can send incorrect information to the eec, or intermittent information to the eec.

Disconnect it, and any odd input will be gone. It should be hard to start when disconnected, but otherwise run fine. (power may be down, so no wot blasts) If it still runs odd with the Cam sensor disconnected, it isn't likely the cam sensor.
 
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