Back story on my motor, 152k miles.
Mods are, hfc, DC headers, 3" single, 3" intake with blox velocity stack filter, 5/16" spacer. Replaced oem injectors with injectors off an hr with around 40k miles on them. Knock sensor harness replaced also with a z1 harness.

Known wear items are timing chain guides and possibly tensioners, oem af sensors, as far as I know oem cam sensors and crank sensor.

The issues are difficult to figure out, back wheen I got tuned about a year and a half ago the car would not take timing. This was during winter and it was relatively cold. Best the car would do was 228 hp and 216 torque on an awd mustang dyno. Timing from 2k to WOT was almost flatlined at 20 degrees, maybe peaking at 22. This was at 12.8afr.

Fast forward to today and I just got retuned after headers and the 3" single I built and the car showed the same thing. It was also 90 something degrees today. So I am really stumped as to why the car will not make any power or take timing. My tuner (Steve kan) trys something for ***** and giggles and sets the afr target to 12.0, and sure enough the car will take more timing, 26 by redline to be exact, and the car picks up 10 hp and 6 tq, so now it is at 238 and 224.

The first few pulls were only showing around 22 degrees max timing, and when we richened it up even more to 12.0 it allowed us to dial in 26 degrees.

Issues before tuning today were p1273 and p1283 codes popping up under low load and idle conditions, which I thought was from the headers, so we turned those off as I have a wideband in the car.

If you know Steven kan you know that he is a great tuner, and having tuned alot of vqs he knows that they should run around 30 or so at redline, he was telling me the possible causes which do make sense to me.

So we are thinking:
Vct is not working as it should. (Cam phasers maybe, maybe vct sprocket, or sensors)

Excessive blowby causing detonation on the passenger side and pulling timing. (Cc filled up about 3/32 every oil change)

Injectors clogged or not flowing right. (Have not tested these injectors from the hr that are in the car, condition unknown)

Spark plugs fouled or bad(changed 15k miles ago with ngk iridiums, stock heat range, pulling tonight to check condition)

Bad crank pos sensor.

Car throws no sensor codes, widebands were reading fine in uprev.

Things I will be doing:
Another compression test(previous was 167-170)
Checking plugs.
New sensors all around.
Reassembling plenum assembly to eliminate vac leak possibility.
Potentially swapping to test pipes.
Checking entire fuel system.
And if I have to tearing down the motor and pulling the pistons to check clearances and ring/cylinder condition.

Someone with knowledge please chime in, I am a little stumped by this and I am contemplating just buying a low mileage long block and swapping it in.

Apologies in advance for the text, I am mobile.

 

Plugs are fine.

Did some 4th gear highway runs and it was showing 24-26 degrees of timing by redline.

One pull showed 28 for sure, for some reason and possibly 30 I wasn't sure I didn't have my logs going for that pull, afr sat around 12.6 and it pulled super hard, this does not make sense at all to me. I am getting fed up and depending on compression test results tomorrow I may put the money down for a haltech.

This makes me feel like there is a fault in the timing harness, vtc solenoids, or cam sensors somewhere, or a fault in the ECU itself.

Maybe I am being too picky, dyno numbers translate to around 270-273 corrected for dynojet which I think is above average for a de with my mileage.

 

270 is pretty good for corrected numbers I ran like 240ish corrected without a tune without test pipes yet..

But I do belive that compression is kinda low I see most people around the 180-190 range

 

things may just be wore down, steve is a very knowledgeable guy, and cool as hell. he tuned my car and i had no complaints

 

Yeah i know what you're saying trav and i agree.. I am either buying a used long block or an lq4/ls1 this winter whichever i can get easier and in better condition.

Im not sure how much longer the motor will be good for but its served its purpose i guess. Hopefully i can figure out this intermittent timing stuff.

Minimum compression is 142 psi, so shes still in good shape and runs smooth, I think the electrical gremlins are starting to show up though.
Regardless of the power figures though, i feel like the car should be running quicker, something funky is going on with timing and the way the ecu advances it.

 

what do you mean, wont take any more timing? You tell it to run 30* and it wont? have you tried unplugging knock sensor?

 

I got a long block in 2013 from eBay for under 1k

 

Yeah exactly, i havent tried unplugging the knock sensor, the harness was replaced around 5k ago with a z1 harness, but i never thought to unplug the sensor. Sometimes the car will run 24* sometimes it will run up to 29* by redline, its so intermittent that i dont even know where to start troubleshooting because of the timing jumping around. There will be times where the car will FEEL like its running full timing and it will pull all the way through, but then times where you can smash the pedal as hard as you want but you can feel the timing plateau after a certain rpms, so its really difficult for me to pick a direction to go with my troubleshooting lol.

Its set at 26* because anything after caused to car to trigger the hi det map even though we could not hear any pings or knocking, and it bugs me that the afr at wot is around 12.6-12.8(according to my freshly cal'd lc-2) but the target afr is set at 12.0-12.2 in uprev.

Also, short term fuel trims are a little messed up, bank 1 is adding more fuel than bank 2 most of the time, sometimes around 6 to 7%.
Long term so far are around -3% bank 2 and -5% bank 1.

I am buying a long block soon for a winter swap and rebuilding the current motor while its out.

 

Subscribed. Experiencing the exact same thing.

 

I dont like the P1273 and P1283 codes, those shouldnt pop up just because of headers. Maybe the O2s are worn or the header gaskets are leaking?
I like the knock sensor check and the possible blow by. But that doesnt sound like a lot of blowby.

 

If the ECU is set for 30 degrees of timing, the only thing that can retard timing is knock. Before you unplug the knock sensor, you could try some lead free race gas and see if the timing returns, in which case it is possible the knock is really due to true detonation (possibly due to gas contaminated with oil). In which case, you really do not want to unplug the knock sensor or run more timing. Just be happy with it. The difference in 20 hp is meaningless.