2001 WRX Miss

drof351 · Post by **drof351** » Mon Feb 22, 2010 8:39 pm

Gday guys, I got a problem with a 2001 WRX. Heres as much as i can think of about the car, just rebuilt the engine, fitted forged pistons, serviced heads etc. It is running an autronic computer, greddy digital boost controller, big front mount, vf34? turbo, full mandrel bent exhaust etc. When its cold it drives normal, as soon as it gets a little temp into the engine there is a miss at 3000rpm and wont really rev past it. Have tried coil packs, new plugs, checked fuel pressure, Checked cam timing again. Idles fine. Codes present are 11 13 34 and 42. Any ideas would be appreciated.
thanks

RSR 555 · Post by **RSR 555** » Mon Feb 22, 2010 9:15 pm

I'm not at the workshop to check those codes but I'd check the Airflow Meter.

drof351 · Post by **drof351** » Mon Feb 22, 2010 9:30 pm

its running a maf less tune so no air flow meter. i'm getting different answers for the codes but 11 crankshaft sensor 13 camshaft sensor 34 egr 42 throttle position sensor, or idle switch

steptoe · Post by **steptoe** » Tue Feb 23, 2010 8:51 am

one sick ECU. Is it bad earth?

drof351 · Post by **drof351** » Tue Feb 23, 2010 9:37 am

I have checked the connectors and earths. All seem ok.

RSR 555 · Post by **RSR 555** » Tue Feb 23, 2010 10:06 am

ok.. then next step is to check the TPS and you mentioned that the ECU had been retuned? Can this lose it's memory?

drof351 · Post by **drof351** » Wed Feb 24, 2010 9:06 pm

Thanks for your input rsr, I've checked the voltages at the throttle position sensor, they aren't as the book suggests but if i disconnect it the exact same fault occurs. Its an autronic computer not sure about forgetting its tune tho.

RSR 555 · Post by **RSR 555** » Wed Feb 24, 2010 9:55 pm

Not sure if the Autronic ECUs have the same codes as a factory ECU (I doubt it) but if the car brings up the same code whether the TPS is plugged in or not, then I'm definately thinking TPS, as the code should disappear when a good TPS is connected. The factory ECU will only keep it in the memory not as a current code.

drof351 · Post by **drof351** » Thu Feb 25, 2010 8:30 am

All the codes don't disappear tho, wonder if theres a common earth or plug that contains, cam and crank and throttle position. Haven't had chance to look at it again but I'll get onto it after i get this engine in a 2004 liberty.

RSR 555 · Post by **RSR 555** » Thu Feb 25, 2010 9:24 am

Yeah.. it's a good idea to double check that all the engine earths are connected. Also have a look and see that the 5v system is working to all the sensors, like TPS, Cam and Crank Sensors, Air Temp Sensor and MAP sensor.

drof351 · Post by **drof351** » Thu Feb 25, 2010 9:32 am

Whats 5 v system? Each sensor should have 5v to it?

drof351 · Post by **drof351** » Thu Feb 25, 2010 9:34 am

If i unplug cam or crank it doesnt run so you'd think they're working and air gaps look good.

RSR 555 · Post by **RSR 555** » Thu Feb 25, 2010 9:59 am

Yeah most but not all sensor use the 5v system. To check these and any sensors on the engine, we have the ignition turned on but the engine not running, then use a multimeter to check the sensor plugs (disconnected from sensor) one by one, ensuring that once you've checked it you make sure you plug it back into the sensor.

RSR 555 · Post by **RSR 555** » Thu Feb 25, 2010 10:03 am

DISCLAIMER... I'm not an Autronic mechanic but offering experiance from working on the Subaru system.

bobbyjimmy · Post by **bobbyjimmy** » Thu Feb 25, 2010 10:38 am

You said it was just rebuilt?
Might be stupid, but is the negative terminal on the battery tight?

drof351 · Post by **drof351** » Fri Feb 26, 2010 1:11 am

bobbyjimmy wrote:You said it was just rebuilt?
Might be stupid, but is the negative terminal on the battery tight?

Not stupid I'm thinking after everything it has to be stupid!!!

drof351 · Post by **drof351** » Wed Apr 07, 2010 6:54 pm

Gday guys time to look at this one again, i've ignored it long enough. Any fresh ideas? I've checked the wiring from the cam, crank and tps back to the ecu all good. Same codes are still present. Tried another crank sensor in it no change.

steptoe · Post by **steptoe** » Wed Apr 07, 2010 10:42 pm

OK my experience with ECU's is limited so this is my disclaimer. The only fault codes I have ever pulled and found to be correctly identified was with my EA82T 3 plugger. I have failed on Falcons and Bitsamiisins.

I wonder....what if you supply the feedback to the ECU on the various sensors, one at a time. Feedback is resistance isn't it? Need to find what range the ECU is expecting and see if you can dial it up on a dicksmif resistance wheel or just simple resistors rigged up with switches. Surely must be some electronics guys in here to assist in some part numbers to use to wire in to the return signal wire.

I wonder if your AFM bypass is the problem? Can you add a working AFM or MAP sensor to the ECU to try??

steptoe · Post by **steptoe** » Wed Apr 07, 2010 10:45 pm

When its cold, measure the resistance of engine temp sensor at cold and duplicate that in a permanent supply from a resistor instead. Spark plug type and match correct?

drof351 · Post by **drof351** » Wed Apr 07, 2010 10:54 pm

thanks steptoe, i have unplugged the temp sender and it didnt make a difference. It ran perfectly before except for cracked ringlands. Rebuilt the engine now trying to get this miss gone before i get it tuned again.