Severe Engoine Miss during Warm-up

[wvsvx]

When driving from a start when engine is cold, during warm-up at about the 3-7 mile point, the engine misses with a noticeable jerk in the car. After a mile (and more warm-up) it ceases. Any thoughts?

[Beav]

Don't let the jerk in the car. :D

Seriously, if you think it's temperature related check the temp sensor - it could have a mid-range glitch. Otherwise start with the basics first, how old are the plugs, are there any vacuum leaks, etc.

[Landshark]

could a mis-fire be temp sensor related? its only done it after work, when the car has been sitting in a parking lot in the cold all day, not in the morning when it comes out of the garage. reports a mis-fire code. :confused:

its happened twice, but today i let it warm up extra long, and no mis-fire, which leads me to believe that cold temps are involved.

[Beav]

Depending on OEMs and specific vehicles, etc. a temp sensor can cause some weird problems. Later model vehicles aren't as prone as the earlier computer-driven cars.

When does the miss occur? During acceleration? Idling? Steady cruise?

Today I had two Explorers in the shop with the same problem, undoubtedly made worse by our recent cold temps (why did I ever leave Fla.?) the intake manifolds are two piece plastic units and stretch/contract at a different rate than the aluminum heads and cast iron block, creating a vacuum leak. Usually the engine management can compensate a bit for a small leak but, with the more extreme temp today, the leaks are becoming too much for the computer to correct. They both ran poorly - no power, very bad idle and stalling. First vehicle had codes P0304, 305 & 306 (cylinders 4,5,& 6 misfiring - left bank) second vehicle had P0300 - P0306, all cylinders misfiring AND a random misfire code.

The reason I'm mentioning this is becuse it's a good example of how far flung a problem can be. Just popping down to the parts store for a psychic scanner reading won't always give you much information.

While I'm on a roll, here's another: Neon. Has all signs of a bad computer - engine spins easily but will hardly start, very erratic idle and stalling, sometimes runs as if nothing's wrong. Igniton, injectors and auto-shutdown relay o.k. Found that someone had changed the starter but failed to reattach the battery ground wire to one of the starter bolts. Now, answer me this - how on earth does a starter find enough ground to spin and draw 130 amps yet there's not enough of a ground to allow the engine to run? (probably less than five amps) It doesn't make much sense on the surface, does it? I know why, but I work with this stuff constantly.

This is why I don't answer some posts, the problem is too wide or vague, etc. I usually wait until it's been researched a bit farther.

BTW, before someone starts taking pot-shots at Ford, they did do the right thing and extended the warranty on the manifold gaskets to more than double the original warranty - from 3/36 to 7/72.

O.K., I'm done now. :)