!Gn|T|0n

Yesterday I extracted codes 157 and 334 from non-volatile memory during an EEC-V KOEO test. The procedure was simple enough but when I went to do a KOER test I found that I could not get anything other than fast codes!

I’d start the motor and the computer would run through its base timing rigmarole holding engine revs etc. I did not see an engine code, only the fast flashes on my test lamp which I recognised as fast codes similar to those I’d seen preceding the normal codes I’d read earlier during the EOEO run. I couldn’t provoke it to perform a cylinder balance test either.

I tried another KOEO run and found the same thing. I couldn’t repeat the normal code extraction procedure finding only fast codes followed by inactivity.

Even if I’d erased the memory codes I’d still expect to see a code 111 (all ok) after either a KOEO or KOER test run but all I could observe was the fast flashes and then absolutely no activity on the test lamp. What is wrong? I tried running the car in normal mode for a bit and then re connecting the test jumper and read codes again but still only managed fast codes then nothing. Is this defined behaviour? I’ve yet to try it again today.

It is noteworthy that the tests still seem to execute as I can hear the thermos spin up and down during KOEO and the base timing procedure is repeatable during KOER.

Additionally, code 334 (EVP sensor was high) means what exactly? I’ve searched for EVP but couldn’t meet the search expression requirements. I’m chasing a problem where symptoms include a flat spot between 2,500 RPM and 3,500 RPM and rotten fuel consumption. The 157 (Mass Air Flow signal was low or grounded) may have resulted from my swapping from 70mm to 55mm MAF electronics recently.

Thanks for your help.

GT 0909

Not sure why you're not getting 'Slow codes', but your EVP stands for EGR Valve Position, 334 being your closed-valve voltage is higher than expected. sounds like the sensor on the end of the EGR valve is suspect. They are available as separate items. Two tests you can do here:

1. EVP resistance: Key off, disconnect EVP sensor connector. Connect ohmmeter to connector at EVP SIG and VREF (look at your workshop manual for correct wire colour codes). Disconnect vacuum line to EGR, connect vacuum pump and increase vacuum. You should get 5500 ohms to 100 ohms as vacuum increases to 33kPa (10 in. Hg). If not, EGR or EVP sensor may be faulty.

2. VREF at EVP Sensor: Key off, disconnect EVP sensor connector. Key on, measure voltage at vehicle side of harness between VREF and SIG RTN. You should get 4 to 6 volts DC. If not, wiring or EEC-V module may be faulty.

Your 157 (MAF Sensor circuit below minimum voltage) sounds like your MAF sensor is faulty. With the MAF connected and engine idling, backprobe the MAF connector between MAF SIG and Ground - you should get between 0.6 and 1.2 volts DC - if not, sensor maybe faulty. I had this on my Mustang a few years ago - at idle, I was only getting 0.05 vdc (about a tenth of what I should have had as a minimum)! No wonder I was seriously down on power.

I hope these checks reveal something concrete for you to go on.

__________________
BA GT #0909 - Manual, Citric Acid, Stripes, Sunroof, Premium sound, FPV Steering wheel and Mats.

!Gn|T|0n

Cheers GT 0909. I tried again last night. The first attempt gave me only fast codes again but the second attempt gave me code 334. I could not repeat after that. Every time a ran a test I only got fast codes then nothing. WHAT IS GOING ON?

!Gn|T|0n

So no one has seen this before?