come and go missing?

[Dony409]

i started having this issue the other day... the car would be running and randomly start missing on #2 like all the time toally consistant. i have good spark. in fact soo much that it arc'd through the insulation into my hand (time for new wires haha) so i pulled the cap and almost all of the contacts were pulled out a little so i pushed them all back in and no change... on my way home it started missing on 2 cylinders not jsut one and when i turned around the corner it started running perfectly again. again this morning when i was going to school the mis started when i started the car. this time still consistand but when in acceleration boost (3 psi ish) it would shutter a bit as you felt the cylinder grab a stroke, then it all went away and ran good again! it pulls 15 of vaccuum at idle normal and about 13 with the 1 miss. the only thing that changed was the valve cover. i was thinking injector harness??? as well as when the car is not missing it pops hard on decel around 2500rpm (like a crappy carbed little ricer)

car is a 89 shelby z with a 89 2.5 t1 motor (and t1 computer) only mod is a 3" and a garrett

[turismolover22]

15 in/hg of vaccum at idle is pretty low. At a minimim it should be between 18-20 unless you have this car cammed out pretty crazy. Are you sure cam timing is spot on? With the low vac and random miss you sound off time (mechanically)

[cordes]

Agreed. Is that 15" with the car in drive?

[Dony409]

Sorry...That's 15" according to my factory gauge which almost reads 5 when the cars off it's clearly not accurate so 15 would actually be more than when it says 15 on the gauge. The car idles great but it just misses od like that sometimes. Sorry and by randomly missing I meant that it would occur randomly... But when it was missing that cylinder would not fire at all (like if I pulled the plug wire)

[85boostbox]

HEP intermittently acting up?

[cordes]

HEP intermittently acting up?

If that's the case then the tach should drop out when it happens.

[Dony409]

Is that symptoms we see from these? Cause I heard either they work... Or they don't...

[85boostbox]

If that's the case then the tach should drop out when it happens.

Not if it is the side of the HEP that controls the fuel injectors. Ask me how I know....

[cordes]

Not if it is the side of the HEP that controls the fuel injectors. Ask me how I know....

I've never had one go without the tach cutting out. Tell me more!

[85boostbox]

http://www.turbododge.com/forums/f4/...g-gurus-3.html

Sort of a long thread with some BSing cause I was still a admin at the time. But I did ALL diagnostics on the car ended being the HEP. I had the same thread on here just never updated it.

[cordes]

Thanks. That's pretty interesting.