Power cutting out Tach fluctuating

Flex

Registered User
Hey guys,

A new issue has popped up. Yesterday and today as I was driving the car was fine until I gas into it, then it cut out a couple of times like it was running out of gas and the tach needle bounced back and forth between 2500-3500 rpm. When I let of the gas and ease back into it it is fine.

The fluttering tach and power cutting out has me thinking DIS. Any thoughts?
 
Hi Branko,

It sounds a little like when my DIS module went bad. ...

However, the misfire only only hard acceleration sounds more to me like plugs or wires. It could even be that a plug boot has worked loose. (I suppose there could be a chance of a misfire from the coil pack, but those don't seem to go bad too often.)

When my DIS went bad, it was more like a total cutout of the tach, or crazy bouncing around. And it didn't go away based on throttle position - it felt random.

I hope you get it worked out without too much trouble.

Have a good one, man!
 
Thanks Steve. It just started doing it. My brother's car started like this before the DIS went. I don't remember the tach though as I wasn't really watching it. When it happens, the tach jumps around pretty good.

Steve give me your email address. The pictures are large so I need to email them to you.
 
If it is the DIS, you could get the bucking and misfire due to low charge rates on the coil pack which would result in low spark energy, and likely misfires under load.
 
I had the same problem recently with a set of Bosch platinum plugs and a premium set of plug wires from AutoZone. They only had about 5000 miles on them so they were not suspect. I went through the usual DIS, crankshaft sensor, and camshaft sensor and still had the problem. I finally replaced the coil pack and the problem got worse. When I replaced the coil pack, I dressed the plug wires to look nicer and number 5 plug quit firing completely. I loosened the dress point on the plug wire and it ran fine.
I bought the Autolite double platinum plugs and Motorcraft plug wires like everyone recommends. I've been changing the valve cover gaskets but am confident it will run fine.
What a fuss to get a clean shot at the valve covers.
Cheers, Harold
 
With the new plugs and wires, the engine runs perfectly. Also no more oil running out of the valve covers.
Another hint: To keep the valve cover screws from loosening use lock washers and flat washers. Install the flat washers with the burr side toward the valve cover. The flat washer keeps the lock washer from digging into the valve cover when removing the next time and the burr will keep the flat washer from turning.
They should stay tight indefinitely.
Harold
 
The flat washer keeps the lock washer from digging into the valve cover when removing the next time and the burr will keep the flat washer from turning.
They should stay tight indefinitely.

Not necessarily indefinitely. Fastener technology is moving along and lock washers are not a preferred method when dealing with vibration leading to loosening. The issue with the valve covers is you are not supposed to tighten those bolts very much, due to impact compression has on the standard valve cover gasket. If you can't tighten the bolt enough to properly engage the threads and create a clamping force, they will always loosen up.

http://www.boltscience.com/pages/vibloose.htm
For example, conventional spring lock washers are no longer specified, because it has been shown that they actually aid self loosening rather than prevent it.

The best thing you could use is something like a loc-tite thread sealer, perhaps the medium strength. That will plug the threads making it more difficult for the fastener to self loosen even with minimal load on the fastener.
 
Sounds alot like my DIS symptoms. All three (or was it four?) instances that I had one go out, the car (mis)behaved a little differently.
 
Hi i have the exact same problem i never thought it would be plugs im going to change them today but y would tach drop like that what my 90 xr7 is doing is bucking when my tach drops to zero then i can turn off and its hard to start but she starts then some times my tach will come back sometimes not when it dosent car runs fine and eventuly it comes back i changed the crank sensore and ing contr module
 
I was experiencing this same problem. The tach would show idle at around 400-500rpm, when this would occur the car felt like it dropped an anchor and had a hard time accelerating. When I was under low boost the car would buck and cut out. If I let the car idle, it would eventually clear up and the tach would return to normal. I went after the cheaper, but more difficult repair first, spark plugs. I had already changed the wires while replacing a/c compressor. I should have changed plugs also at this time. I found the ceramic insulator on one plug cracked from top to bottom. Replaced all plugs, problem solved. Hope this helps
 
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