random misfire CEL no spark on coil2/3 once cel occurs, ECU problem?

[Attack Eagle]

ok
so I recently replaced the front 02 and did the 02 bypass which got rid of my CEL. (thanks to conicelli for a great deal and R.I.P.).

I pressure tested last week and found that I had two hoses disconnected and the fitting/coupler/adapter between the sidemount and the stock UIP was leaking so badly that I could not pressurize past 2psi.

today I fixed that issue (after about 5 tries) with a piece of silicone tubing, and cutting down the original filler section out of the middle of the OEM coupler. (though I am still only getting 10 psi)

Now I wish i hadn't fixed it. I had to jump start the car b/c I had left the lights on inside and outside when I was working on it (thought it would be a 30 minute job...)

I'm now getting a random misfire CEL... just as I was completing my first shakedown run with still a leak I got a CEL... and when I slowed and pulled in the driveway it ran rough for a second or two until I got to the top, then tried to idle at 0-200 rpm, but it went away after I tapped the throttle. So I cleared the CEL and put it on the charger while I pressure tested and tried again to get rid of the leak.

after fixing the leak (about 2 hours later!) on the second shakedown run as I was slowing down at the last stoplight near my house the CEL came on again, the car started idling at 200 rpms (according to the tach) and was behaving like it was loading up with fuel, or not firing correctly or out of time, and backfired (popped on deceleration)

I revved it up (it did not want to) and at about 3k all of a sudden it started firing cleanly and drove fine. I immediately headed to Autozone to get the code pulled and they said it was random misfire. when I started the car it again was acting like it was out of time or loaded with fuel or not firing on all 4 cylinders... and did that all the way home... popping on decel, idling like crud, no power at all.

As soon as i got home it pulled the plug wires off with it idling (it said at 0-200) and they all appeared to be firing. it sounded smoother after i finished and when i looked inside the tach read correctly at about 700 rpm so the problem disappeared again

again i pressure checked the system and the UIP-IC was fine and for the first time I could actually build some pressure but not more than 5 psi... it appears the Throttle body is leaking (under the spring) at about 3-4 psi and by five I am fighting a losing battle.

I set the battery back to charge just to be on the safe side and cleared the cel while I was pressure testing, and once i was done the battery was fully charged and even my radio presets and album titles had been lost this time (the first time I have ever lost them).

3rd test drive was fine... went to the store and on the way back decided to give it full WOT throttle... car ran fine but when I looked down as I decelerated the CEL was on again... Its too late to go to AZ to find out what it is this time but it's probably the same one again...

any ideas (my boost guage has always read 10psi and then falling towards readline (even when the o2 were out) but acceleration and spool feel faster and feels more solid now that the ic coupler isn't leaking...) on what might be all of a sudden causing this random misfire problem? I have not changed the plugs yet since fixing all these things b/c I have not found anyone in town who carries NGKs and has the right ones in stock, nor have i changed the wires... but until I fixed the boost leak tonight I did not have a CEL even at WOT... I will fill up again tommorrow, maybe I got some "dregs" in the tank from the last tankful? Ifthat were the case whay did it not do it when I came home before fixing the leak though? the first shakedown was just 5 minutes around the neighborhood annoying people with the extremely loud spool sound caused by the leaky ic coupler.

I am really puzzled here guys...

Can the TB be rebushed? if so does anyone do it on an exchange basis? This is our only vehicle with A/C + I have to drive 30+ miles to work everyday and 30+ back + errands so I can't afford any downtime... and I was just about to try and pass inspection so I can finally register it since i got rid of the CEL. Now that it is back it's an instant failure again so I can't register the car yet again afer 4 months

 

[Attack Eagle]

ok further info and testing....

one: it won't do it after a reset UNTIL it throws the CEL then it starts immediately or after.
two: it did it when I first started leaving work this afternoon so I tested somemore (T/S intermittent probelms when they occur.. right?) NO spark on 2 and 3 fine on 1/4... pulled the battery off for just a few seconds and again tried to start (with cel still in memory) and same thing on second start, and on third restart. Then I reset ecu and purrs like a kitten full power etc... I fear the ECU got damaged last night due to the low voltage start attempt, or the jumpstart...
3 once reset it will run fine again until about when it should go closed loop and start checking everything, then the problem recurs... keep driving it and the car will occasionally give full power and the tach will read correct particularly if you can ever get it to high rpms (5k+) but once you let off it may or may not resume... it will be fine for a little while 2-3 minutes and then again will have the problem for 5-10 minutes with occasional tach reading right and full power.


beats the ever loving petucas out of me if it isn't the ECU... why would it clear up by resetting the ecu if it were a physical problem like wiring bad coil pack etc... and it is always 2/3 that has no spark... I might flip the coilpacks just to double check myself but I see no reason whythe coilpacks would "reset" if the ecu cleared its cels.

also if i am not mistaken the tach is ecu driven not coil driven... if it were and a coil stopped firing you would expect to get either 0 reading or a correct rpm reading, not 1/2 or 1/3rd reading or bouncing between the two...

anyone ever see this problem before or even hear of it?

wish i had a pocket logger, but so far I've barely got enough to get basic maintenance and my $10 boost guage... at least give me a chance to make some money, fix all the little issues that have creeped up over the last 3 years and 45k I haven't had the car and I'll get one!

I guess black was not such a good color after all... its a black hole for repairs and $$$ but I still love it.

maybe I can borrow an ecu to confirm that it is the ECU itself? I know a friend down the street still has his engine apart...

any other ideas for what else could cause these symptoms?

 

[jb95gst]

Have you figured out what the problem is? I am having a similar problem, and can't figure it out. I tried the plugs, wires, O2 sensor, ecu and still can't figure it out.
Thanks for any help, JB

 

[R3dR]

The second gen you have has a trigger on the intake cam, and if the ecu is having issues talking to this trigger you will have issues with the 2/3 but never the 1/4. (The sensor is on the head and the trigger is on the cam and the sensor is what talks to the ECU)When you reset the ecu you are clearing the issue but the issue is still there so as soon as the ecu re-sees the issue it starts acting up.



#1 pull the coils and have them tested to be sure
#2 have the trigger tested

 

[bmxrider154]

I am having the same problems with my 1st gen. I have replaced the coil, power transistor. next step is the cam angle sensor tomorrow. wierdest thing ever.

 

[jb95gst]

I figured mine out, it was a power transister.
Thanks, JB

 

[Attack Eagle]

mine was a combination of fouled plug and boost leak... fixing the leak cause a misfire due to the fouled plugs severe enough to trigger limp mode... 1000 miles later no cels no more issues.