Weird one...engine miss for specific time?

firehunter · Jul 2, 2013

Back again folks with an issue I don't remember ever reading about here.

Turn key on, all gauges and lights are normal - SES light stays on. Engine cranking is normal, even starts normally. Once it is running it feels like it has a dead miss, SES light is lit for exactly 40 seconds then, bam, cylinder fires, RPM's jump slightly then idle normalizes and SES light goes out. Runs perfectly fine the rest of the time.

It just started doing this yesterday and did it on every start throughout the day, hot or cold engine. 40 seconds every time. Any position on the chip. Already did it this morning too.

Thoughts? (other than "scan for codes" which should happen later today)

firehunter · Jul 2, 2013

OK, just started it again today, this time engine idles pretty darn smooth but still the SES light for 40 seconds then, idle jumps a couple hundred RPM for a second, SES light goes out and runs perfectly normal. Weird...

CSIPSD · Jul 2, 2013

IDM...

Thats my first guess.

or a loose harness issue, but if its exactly 40 seconds every time, that seems more like an IDM/specific injector issue.

firehunter · Jul 22, 2013

Thanks for the input Joe, I did read your post when you put it on here, just been very busy with fires...

Finally got it scanned today. What is happening is upon starting ICP is defaulting to 750 psi for exactly 40 seconds, ICP spikes, then sensor appears functional and ICP drops to around 480 psi - which I assume is what is commanded by the tuning. The long-time Ford mechanic I went to is no stranger to 7.3's but has never heard of anything like this. He says it is almost like the computer (he said "memory") is not "seeing" the ICP sensor for 40 seconds, then reading it just fine after that. We unplugged the ICP sensor and it STILL spikes the ICP at the 40 second mark then returns to 750psi (sensor still unplugged).

The only codes that came up were one for EBPV (deleted), IAH (deleted), and P1280...

P1280 ICP circuit out of range low Open/grounded circuit, biased sensor, PCM

So, going by that code, a new ICP sensor is on the way (there is oil in the plug), but I have my doubts that is the issue since it still does it with the sensor completely eliminated from the circuit. PCM??? Boost, EGT's, smoke are all normal for my set-up.

Dafuq?