Weird boost/tach problems......
 

Hey guys, my cars actin' up on me bad. I'll try to explain the wierdness the best I can.
While daily driving with no boost (shift at 0psi), the car runs fine.

When I hit about 4-5psi, guy car hits a fuel cut and jumps around like a bucking bronco untill I let off the gas.

While coasting downhill in 3rd,4rth, or 5th gear, the tach will jump to 5400rpm and hover there untill I touch the gas, then it goes back to where it should be (around 2800 - 3200rpm) as long as I'm giving it 1% + throttle.

Sometimes during traffic the tach will just go wacky again during slow acceleration and would jump to 4k then all the way to 0rpm . This is when I hear backfiring (no cat).

If I punch it while rolling in 1st slowly, I can go right upto 10psi, shift to 2nd hit 10psi again, shift to 3rd and still hit 10psi with no wierd fuel cut.

It did this problem before when I tried using 2step colder plugs, but wasnt this bad.

I was thinking it might be the distributor, since its sending the tach signals, but what does the distributor know about how much psi I'm running?

I've tried burning .bin files on different versions of Uberdata. Tried making brand new bin files on different versions and using a brand new chip also.

Additional info:

Replaced Cap + Rotor
Running 1 step colder plugs
NGK wires

Re:Weird boost/tach problems......
 

So my friend came over today and I swapped over his distributor and went for a test drive, didn't do anything. Same weird ----.

So I swapped over his P28 ecu and went for a drive, same weird ----.

So then I tried gapping my plugs tighter like .22 (they were at .30). This time when I went driving around, the car boosted perfect . After doing about 6-7 pulls in all gears from 1st to 3rd, I stopped to make a turn and went to boost again... same ---- AHHHHH!!!!

The car just dies at like 4-5psi and the tach jumps to idle rpm's. Then once I let off the gas it'll start going again. This is driving me nuts. I don't see how it can be my O2 sensor because ppl drive around with CEL codes for O2 sensors all the time and they run fine.

If its some kind of loose wire, how can it suddenly work right after I do something to the ignition system, then after some boosting it goes back to crappin' out?

Any other idea's?

Re:Weird boost/tach problems......
 

damnnit, i just got done typin up 4 paragraphs referencing problems with chevy and mitsubishi distributor system and got the "you're not logged in message" - 180 minues was up.

----, that was shitty, see what I get for not being on my home computer.

to sum it all up for you man, check your coil and plug wires (if you haven't already). I will go into more detail and work out something tomorrow or so, see what can be figured out.

-ryan

Re:Weird boost/tach problems......
 

When the tach jumps, does your engine stay the same revs so its just the tach stuffing?

Re:Weird boost/tach problems......
 

i think he was saying that the motor is normal and the tach surges.. the tach signal is a frequency response, so this thing is getting complicated.

Re:Weird boost/tach problems......
 

yeah, if it was just the tach Id say ignition. Check your coil and stuff.

Re:Weird boost/tach problems......
 

it seems like people are afraid of this thread man, only me and u posting.. i'm also kinda avoiding full tackling the problem, i just want to do one word answers tonight, i'm tired.

Re:Weird boost/tach problems......
 

yeah, everyonce and awhile my tack fucks ups too, quadnie, the coils is in the dizzy, so it can't be the coil. If I were you, i'd try spark plug wires.

but, since your problems only arise durring half throttle boost, there could be something wrong with your tune aswell.

Re:Weird boost/tach problems......
 

yeah, I just figured that if the tach was connected to the coil terminal, it might be just getting a w00ted signal and screwing off

Just buy a new car. Seems to fix all the problems I have

Re:Weird boost/tach problems......
 

how old are your plugs?

makes me think it's the ignitor or the coil.

Buy some new sparkplugs and gap them or clean the hell out the old ones, THEN try both distributors. It's possible for both you and your friend to have weak coils.

in other words the weakened coil will work fine running n/a(out of boost) but once you go into boost it starts blowing out the weak spark produced... and it's quite possible that both of those distributors have a weak coil but your friend doesn't notice it on his car. Is he n/a by any chance?

damn i'm good.

p.s. sparkplugs do go bad quicker in turbo cars so it might be time to replace them.