First of all, Hi! Long time lurker, first time poster. I'm mostly over at vwkd, but i've been reading a lot over here as well. I hope to get some help with this, heres my situation:

I've got a 1972 standard beetle with an OBDII 96 ej22 engine and computer. It's had it's teething problems, mainly me leaving the starter wire input for the computer hooked up to 12v, lead to some weird idle issues. I got that all sorted out and it looked like blue skies and sunshine from then on.

Recently, though, i drove through a very heavy rain storm (this may have had something to do with it, it may have not) from then on it's been acting funny. Heres how:

While you're driving, and only after it's totally warmed up and above 2krpm going down the road with very light throttle or backing off to light throttle or sometimes just off closed throttle it'll chug, hesitate, buck, basically run like dog mess. It's not always repeatable, but when it's 'in the mood' it does it every single time you get to part throttle. Once it's past a certain throttle range (in fact, in lower gears its a *higher* throttle amount to get it out of it's 'funk') it'll just jump out like you flipped a switch. If you drive it hard it wont do this at all, only when you're sedately cruising (and i sometimes do like to sedately cruise).

The reason i'm asking you guys is, i really am out of ideas of things to try. This is but a partial list:

Stiffened the intake tube (flexible hose, maybe it was resonating?)
Checked the coil resistances cold and hot (both check good)
Patched a eraser sized hole in the intake hose (thought i had it that time)
Ran GM top engine cleaner through the IAC intake (just made a bunch of smoke, didnt help)
Changed the spark plugs (old plugs were white, i dunno what that signifies in an EFI system)
Checked the fuel pressure (slightly low, but it's always been slightly low, peaks up just fine when i pinch the return line)
Verified and re-did all the power feeds and grounds for the computer
Reset the computer umpteen times
The coolant temp sensor is brand new
Unplugged the tps and it seemed to improve for a bit, then came back big time about 5 minutes later
Unplugged the MAF and it got ALOT! Worse
Sprayed ether all over the intake and fittings to check for vacuum leaks, nothing

I forget what else but quite literally i'm out of things to try, things to check over. So i'm punting this to you guys, any chance to help out a clueless american?

Ben

there should be two green plugs on the loom just near the computer. plug them together and turn the ignition on. it will run a diagnostic program, then give you the codes the engine has an issue with. try that first.

btw, is the engine fault light coming on when the motor starts behaving in this way?

when you mention "heavy rain" as the start of the problem, it tells me you have an intermitent short of some sort. I'd check all your earth straps and then unplug and replug every plug on the motor/loom, spray some electronic cleaner in them, then blow them out and re plug them.

if there is no simple fix with all that, pull over as soon as the fault begins and try to acertain whether it's a spark or fuel issue.... which make me ask this qu...

is the fuel pump controled by the ECU and is there an issue with it getting wet?

I'm thinking worn TPS (if it has one ?)

The way it's acting keeps making me think its ECU related, i've replaced the ecu with a good one and it doesnt change. It's just odd that at idle it's perfectly fine, and WOT it's perfectly fine, its just right off idle it misfires and stumbles so bad. I wish there was a way to figure out if its ignition or fuel related...
I have a cable and software that i'm supposed to be able to look at the data stream in the ecu but i havent gotten it to work yet :/

What is the ecu seeing as far as throttle pos. Maybe the idle stop or reference to 0% is off.

I don't know, that's a good question. Presumably it's reading it correctly because it does it whether or not the TPS is plugged in or not. I tried re-indexing the tps and it didnt change what it was doing. I'll put a meter on it and make sure.

stab in the dark, but what are you're voltage readings like in the ECU supply and the alternator output?

could it be that it's mucking up coz of that?

also related, is power shorting somewhere? that would explain a bunch of stuff.

I'll check that as well. Good point.

Gah, i'd really like to do some logging with this but the people who sold me this cable havent been a whole lot of help. Theres almost a dead zone when it comes to US my96 ecus... Older ones have support, newer ones have support, but it seems like 96's got left out of the loop.

If you can find a local dealer with a helpful parts person, often they can be really good. alternatively, call subaru service and try and get onto a service tech high up in the organization. don't tell them it's a conversion to start with, then if the guy seems good value, tell him what you've done. the Aussie tech I spoke to thought it was awesome what I was doing.

Anyhow, the way I see it, you are down to three basic problems;
1. fuel supply - which you say is no drama
2. spark supply - which you say is not effected
3. power supply - to the ECU or sensors.

once you can pinpoint which one is the issue, you can lick the problem

personally, the description to me sounds like the car is running our of fuel or the ignition is dying.

I'll have to honestly 'i dont know' on the spark issue. I can measure the fuel pressure, but i have no way of measuring spark quality. I have a feeling that its losing spark but thats from my experience with aircooled lumps, fairly easy to lose a spark due to an overrich mixture. I have no idea with these computerized ignitions if that's even possible.

I verified and reset the TPS today (.045 to .050 volts), no change. I'll address the power supply to the system next. I've got a somewhat hokey setup for powering the loom, i'll go to a hard-wired battery bus bar for the main, fan, and fuel pump relays and use the coil power wire to power the computer. Right now it's all ganged off the same wire, can't help things, and wont hurt to correct it

I still think i should try logging with it... I'm poking around for the subaru select monitor plug, its one part i didnt pull out of the donor car. My cable wont work with the OBDII plug, so it might with the SSM plug. If not i've got some choice words with the supplier of my cable

Well, good news and bad news. Good news is its not doing it anymore, bad news is i have no idea why. All that's changed is the weather, it's -much- colder than it has been for a while.

Uhg.

I did get the intermittent wipers up and running though

Quote:

Originally posted by Inane Cathode I did get the intermittent wipers up and running though

Quote:

Originally posted by Joel Quote: Originally posted by Inane Cathode I did get the intermittent wipers up and running though bout time it showed up

What about a bad 02 exhaust sensor? might explain why it does it light to part throttle (when in closed loop mode looking for the 02 sensor feedback), then when you floor it, the ecu goes open loop and ignores the 02 sensor. In saying this, i would have thought a bad 02 sensor would throw a fault code from the ecu. Maybe unplug it altogether and see what happens?

Interestingly enough i've got a brandy new front o2s. The old one quit responding so i had to replace it. Oddly enough, with the o2s unplugged (well, the old one at least) driveability wasnt really that different. I honestly couldnt tell if it was unplugged or not. I'll put a meter on this sensor and see whats up. If it's bad too i'll blow a damn gasket these things are expensive!