something's missing

[andrew383]

ok,ive put maybe 1000 miles on the gp in the past year.when i was home last month i was drivin around and i got on it a few times but its got a dead spot rite around 4k rpm's.also the tach cuts in and out ,after i drive it for awhile it'll get better.
could the timing sensor be bad? what else would cause this?
thanks andrew

[pocket-rocket]

If the tach dies out too I would think either the crank position sensor or the ICM, as both are used (at least in OBD1 cars) to drive the tach. But it's kind of odd it only does it at 4k, and no where else. Maybe someone else has had this same problem and can shed some light in on the subject.

[andrew383]

ill check out the cps when im home in a few weeks

[andrew383]

back from the dead ... It still has a prob at 4200 rpm...It'll cut out a few times then keep going but rarely does it in first at WOT,and some times it wont do it at all...Ive changed the plugs and everything and it still does it.There is nothing else wrong with the way it runs,hell we drove it on a 2000 mile trip just a month ago and got 30mpg's at 80 the whole time....... im just really stumped by this

[DefEddie]

Verify that it is at 4200 rpm's and not your throttle position.
TPS flat spots are common.

[RedBird]

hey, i have a very similar problem on the 92 v6 bird that i'm driving right now. plugs and wires didn't make it go away. weird thing is, it DOES seem to be throttle position related for me, but swapping in a known good one did nothing for it. same shudder/miss at the approx. same throttle position.

[Superdave]

if the tach is actually cutting out then it's probably the ICM...

[asylummotorsports]

The tach is the give away on this.

CPS or ICM.

When I was having problems with my external pick-up (cps) the tach would go crazy.

[andrew383]

The tach shoows the mis and you cann feel the motor missing,its like a plug wire is off for a split sec..Wish i could get video of it but the car home in indiana and im in tx.Also ive only had it happen at WOT,never a part throttle or any other rpm.

[Superdave]

I would guess the CPS or the CPS wire then.

[RedBird]

mine happens as i'm on my way to WOT :P liek if i gently sweep my foot to the floor you can feel it shuddering in the 50-75% throttle range

[Superdave]

mine happens as i'm on my way to WOT :P liek if i gently sweep my foot to the floor you can feel it shuddering in the 50-75% throttle range

that still could be the AE in the tune, once it gets a little colder out you might have to bring it by for some datalogs. Those injectors are going to be a challenge this winter...

[RedBird]

actaully dave this problem is on my brothers stock 3.1/auto. i dunno what the damn issue is but it doesn't matter, since i finished my car finally, and ALSO, blew a brake hardline in it, so i won't be driving it much anyway unless/until i fix it. damnit.