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

 

It looks like you're dealing with a couple of problems all at once.

Can you boost normally on a regular basis?? Whats you fuel setup? What you described as a 'bucking bronco' could be your getting fuel cut cause of your setup.

The tack dealy could be that you have a loose ground some where or that you have a wire grounded. Are you talking about your factory tack or do you have an aftermarket one??

Not sure if this helped

 

I can only boost normal if I punch it in 1st through to 3rd. Once I start driving normal for a while then it starts cutting fuel or whatever around 4-5psi.

Its a stock tach. My fuel setup is 450cc DSM's, Uberdata, Walbro 255lph.

It had been running fine for some months now. Then all of a sudden I goto lunch from work and its cutting fuel or spark . Someone told me to check out the ignitor in the distributor. Makes sense but why would it cause **** to go wrong right around 4-5psi? Hmmm....

 

Well it could be that your fuel settings are fine but if you ignitor is weak than the amount of fuel comming thru just drowns out your weak spark.

Just curious what do your spark plugs look like?? Always check your plugs for a quick answer.

With Uberdata did you just burn someones pre-exsisting program and are running off of it or did you modify the values with in the program?? What are your fuel settings at?? And did you mess with the ignition retard values??

 

That's weird, maybe someone did the chipping wrong or something is not soldered right. I'd open the ECU and make sure everything is secure, including the wiring going to the ECU, make sure there are no splits that could cause shorts.

 

Well i think it safe to say that your setup for fuel is good enough.
The tack problem is probly do to a grounding issue.

The only thing that's over looked is Uberdata. Who installed it?? Who tunned it?? If possible tell me what the ignition settings and fuel settings are set at. This is the only way others are gonna be able to help.

 

I chipped the ecu myself and tuned my map myself with my wideband. It was running great for the past 3 months. Then one day i'm boostin' on the way to work and everythings fine. Go for my lunch break 4hrs later and this **** happens.

Oh btw I tried punching it in 1st, still cutting spark or whatever. So I can't even do that anymore.

I replaced my rotor and cap last week and the problem went away for one day, then came back .

I'm thinking its cutting spark because when it happens, the tach goes to 750rpm while the car starts jerking around. Daily driving is getting messed up aswell, when the tach starts jumpin' around while i'm just drivin' normal. I can tell the car isn't giving the correct fuel/timing when I start to accelerate.

I'm going to swap over my friends distributor this weekend and see what happens. Anyone have anyother suggestions besides checking for loose grounds? Any help is much appriciated, thanks.

 

check your sensors, my cars tach did the same thing while i was either stopped or driving under different load conditions and it ended being my o2. My friends greddy system on his b16 also acted up when it was on 0psi and he figured out he needed an extra injector, but you're system obviously has a good fuel system in it.
good luck

 

UPDATE:

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?

 

Have you monitored your map sensor input when all this is happening?

 

I've got the innovative WB. Can someone tell me what voltage #'s to put into the program so I can datalog the map sensor?

 

a stock map sensor is 2.6v at 0", and more or less from there

 

damn my car bucks like a bronco too, and it sucks not knowing what the problem is. When a car bucks is it usually the fuel or spark?

 

Not sure if this is it but you should be able to tell through your spark plugs. By the sounds of it when you slipped in the new ones they ran well for awhile then suddenly they stopped working (something seized them from working) and the other ones weren't working at all. Seems that something is getting to them eventually which is causing your problem. I guess just scan the plugs and anything from that should give your answer.

Ive had some weird stuttering and sometimes the car will all of a sudden die with the uberdata, but once i go WOT or let the car warm up completely the problems are no where to be seen, car drives smooth with a 12.5 afr all the way up to redline.

I say your problem lies in your spark plugs. Check your ignitor (maybe the coil) aswell....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by patdemps &raquo;</TD></TR><TR><TD CLASS="quote">
I say your problem lies in your spark plugs. Check your ignitor (maybe the coil) aswell....</TD></TR></TABLE>

Except that he said he already tried replacing the distributor.

 

UPDATE:

This morning I tried taking apart the distributor and cleaning all the connections inside it with sandpaper and then put some dielectric grease on all the connections and tightened them back up. While I was putting the distributor back I noticed that the wires that are grounded onto the thermostat housing weren't fully tightened down So I took out the bolt and sandpapered both sides of the ground connection and the spot on the thermostat housing. Then topped it off with the dielectric grease and bolted it up nice and tight.

Went for a short drive for about 10mins and I was boosting fine But I'm not gonna say that my problem is completly fixed because the last couple times I did anything to the ignition ie: (change the cap, re-gap the plugs) the car boosted fine for a short period of time. So I'll drive around for a couple days and update again.

This time I tried:
Tightened the ground wires on the thermostat housing
Cleaned and dielectric greased all the connections in the distributor

 

 

Ok, the car runs fine now. Amazing how one little loose ground wire can make such an impact. Thanks everyone !

 

Boost is addicting!! Glad you got the problem fixed now puff puff pass my turn to drive your car.