What determines the onset of stupid-rich

[Barge]

A cynical thought for you. Between warranty issues and protecting the Prestige of the Premium SVT power ratings (something like 170Hp SE vs 190Hp SVT-depending on year) - which is more important to Ford?

Obviously, warranty. But I would argue that running richer than 10:1 was absurdly un-necessary.

Finally, from personal experience running calibration on an engine-dyno I can state that even on air-cooled engines (NA) running any richer than 12.2:1 will cause torque to fall off. Running lower than 11.5 will begin quenching combustion and <9.7 rich misfire predominates (excluding cold-start).

Well i'm sure it's a line between warranty and performance but the fact that some amateur can throw a tune onto an SVT and gain 10-15hp means that they didn't try to eek all they could out of it.

I agree that richer than 10:1 is absurd...

I run my WRX at around 11.7:1 - 12:1 with water injection. From the factory it runs in the 9:1 range at high load areas.

Edit: If your engine is knocking there should be an indication that you can log. Either a knock sensor reading or timing correction or just the timing vs. what the timing should be.

 

[SicSE]

Edit: If your engine is knocking there should be an indication that you can log. Either a knock sensor reading or timing correction or just the timing vs. what the timing should be.

Ford took the knock sensor pid out of their datalogging software sometime last year :nonono: , and I don't believe there is a table for timing advance because of all the factors involved in calculating it.

 

[sleepr]

I did 3 dyno pulls today ... Stupid-rich happened at about
5600 RPM on run 1, then about
5400 RPM on run 2, then shortly after
5200 RPM on run 3.

The runs were all within 10 minutes of each other...

So what we're seeing is:
Detonation is causing an immediate drop in power, the processor requests a fuel dump, then the sensor sees rich A/F, and we see the corresponding lag between the drop in power and the rich A/F on the data-log, right?

The fact that detonation is happening earlier on each run does indeed suggest heat soak in the intake tract.

 

[SicSE]

So what we're seeing is:
Detonation is causing an immediate drop in power, the processor requests a fuel dump, then the sensor sees rich A/F, and we see the corresponding lag between the drop in power and the rich A/F on the data-log, right?

The fact that detonation is happening earlier on each run does indeed suggest heat soak in the intake tract.

That's what I see happening. I'm hoping to verify & possibly remedy it this weekend. Gonna pick up some octane booster, reinstall my CAI & see what happens.

 

[Keyser]

He means the temperature of the catalyst monolith or brick. There is a specific temperature at which the ceramic structure (the monolith) inside the steel casing begins to fail. This temperature is measured by placing a thermocouple in the middle of the brickwhile running on the dyno and in-car during development. If kept at too high a temperature for too long the monolith melts and plugs the exhaust.

Again, I'm not familiar with the fueling strategy in the 'Tour, but this suggestion makes a great deal of sense. While fueling cools the combustion chamber, it also cools the exhaust - same gases-different place and now without water-cooling.

The important part here is that since the PCM is dumping fuel, it is for protection of some component. Because the spark is not being retarded, the protection is aimed at either the Catalyst or the exhaust-valves.

The reason I say this? Fuel takes a specific amount of time to burn at any given A/F ratio, so if the spark is retarded the fuel will still be burning as the exhaust-valves open - dramatically overheating them in short order.

Think of running important bits in the hot part of a blow-torch. Not good if you want to keep the bits intact for a long time.

The same thing will happen to the close-coupled catalysts which are less than a foot away from the exhaust-valves. Either way, the fueling is there for a reason. That reason appears to be temperature reduction of some component either in the combustion-chamber or downstream of it.

Not sure of a solution just now. Hope this spurs further thought though.

The force is strong with this one. There is a specific entry in the GUI to turn off cat protection. Once turned to 0 the extra fuel went away for me.

 

[SicSE]

The force is strong with this one. There is a specific entry in the GUI to turn off cat protection. Once turned to 0 the extra fuel went away for me.

I'd actually rather NOT turn it off. There is solace in that extra protection... gross power-robbing solace, but solace nonetheless.

I bought the most expensive octane booster at AutoZone, (NOS), but unfortunately, it didn't help. It did a nice job of tinting the porcelain of my plugs... but didn't help the full-rich situation.

I'm wondering how much my gutted precats are playing a role in this. That big open space where the cat element used to be would seriously slow flow out of the cylinders. I'm thinking that a more efficient escape path for the hot exhaust gases could help lower cylinder temps. Looks like it may be time for some headers.

 

[Keyser]

I've done a few Contour dynos. 10:1 is just plain silly stupid money out the tail pipe rich. 12.5 is about the leanest I'd suggest you lean it out if you are a bit paranoid about the motor. 11.8:1 would be the richest. Even if it's not the cat protection it would behoove you to lean it out.

That NOS you bough is most likely filled with MTBE which turned your plugs orange. The gutted precats are fine, don't worry.

 

[SicSE]

The gutted precats are fine, don't worry.

Well, it's my understanding, when dealing with flow through a conduit, that any increase of pipe diameter slows flow. From the head exits to the size of the precat is a rather large increase in diameter. Theoretically, headers should allow the high velocity exhaust gasses to maintain speed, aiding in cylinder scavenging of gas AND heat.

 

[Keyser]

Sure, I agree more velocity, but enough to justify the expense of headers? IMO, no but that's just me. I made 183hp through my gutted cats on the 2.5 on a dynojet with just an AFC for tuning. How many header 2.5's have made over that and how many hp over?

 

[Ray]

Well, it's my understanding, when dealing with flow through a conduit, that any increase of pipe diameter slows flow. From the head exits to the size of the precat is a rather large increase in diameter. Theoretically, headers should allow the high velocity exhaust gasses to maintain speed, aiding in cylinder scavenging of gas AND heat.

The flow IN the larger diameter would be slower. and it would remain at a somewhat slower speed from there on (even if it went to a smaller diameter later on it wouldn't have the original speed) but a larger gutted pre-cat AFTER the heads isn't slowing the speed of the exhaust gas as it leaves the heads themselves.

It may affect (albeit not much) the speed of the gas IN the cats versus a smaller diameter cat and it also will affect the speed of the gas through the REST of the exhaust, but how will it slow the gas down coming from the cylinder any slower than its being expelled from the engine?

 

[SicSE]

It may affect (albeit not much) the speed of the gas IN the cats versus a smaller diameter cat and it also will affect the speed of the gas through the REST of the exhaust, but how will it slow the gas down coming from the cylinder any slower than its being expelled from the engine?

I'm thinking back pressure of sorts. Think of exhaust pulses as having a head, (positive pressure), and a tail, (negative pressure). With a header, the tail of an exhaust pulse of one cylinder helps "pull" the head of the exhaust pulse of another cylinder, perpetuating directional flow, and helping maintain exhaust gas velocity. With the stock manifold, these pulses are pretty much colliding, head-to-head in the open area of the exhaust manifold, before being able to flow through the rest of the exhaust. This is less of an issue at lower RPM's as there is more time for the exhaust pulse to expand in the manifold, then continue it's journey through the rest of the exhaust system, before the next cylinder spits out it's gasses. But, at higher RPM's, there is less actual time for the process to take place. This could allow a positive pressure to be present in the exhaust manifold as the positive pressured head of the the next cylinder's exhaust pulse is being expelled from said cylinder. This would further slow flow and encourage heat retention in the exhaust portion of the head, IMO.

 

[Keyser]

You're obviously set in your mind as to your next move. Go for it. I just think $500 for 5whp is kinda silly. Besides that the origional Nautilus kit bolted on to factory gutted precats and ran just fine. Regular exhaust gas plus boost made it through the precats.

 

[SicSE]

I just think $500 for 5whp is kinda silly.

This is not about getting more power. The end result will gain HP, yes, but this thread is about finding out what exactly the PCM is seeing that is causing it to command the full-rich fuel strategy.

Besides that the origional Nautilus kit bolted on to factory gutted precats and ran just fine. Regular exhaust gas plus boost made it through the precats.

You're talking a whole other world from N/A. Plus I am running an untuned SE PCM... I doubt that they slapped a turbo on a 3L hybrid with a factory calibrated SE PCM. Boost with 11+:1 compression? Man, we're not even in the same book, let alone on the same page.

It's fine if you disagree with my theory, but let's keep comparisons logical.

 

[Keyser]

You're talking a whole other world from N/A. Plus I am running an untuned SE PCM... I doubt that they slapped a turbo on a 3L hybrid with a factory calibrated SE PCM. Boost with 11+:1 compression? Man, we're not even in the same book, let alone on the same page.

It's fine if you disagree with my theory, but let's keep comparisons logical.

Reread my post you aren't comprehending. My point is that more cfm can fit through the gutted precats than the NA can throw at it. Even a hybrid.

 

[SicSE]

My point is that more cfm can fit through the gutted precats than the NA can throw at it. Even a hybrid.

Agreed... but this isn't about CFM.

 

[Keyser]

I'm not trying to be an ass, I just think I misunderstand the whole point of this thread. I think you are saying that the head is getting too hot from exhaust backing up, causing the ECU to add fuel. Is that it?

You asked what determines the onset of stupid-rich originally. I'm telling you, the ECU has parameters that are not tuned to your advantage, especially when you say you are now hybrid. All that research that Ford did to tune that ECU is now no longer the right calibration.

My whole point/opinion through this whole thread, take it or leave it, is to spend $500 on a tuner, not the headers. If you have enough for both then by all means do both. Good Luck with whatever you do.

-Chris

 

[SicSE]

The original question in this thread was based on the belief that the PCM was commanding the rich condition without seeing a fault of some sort... like the car was suppose to run that rich at higher RPM. However, I think we've pretty much shot that idea to hell and determined that there is some sort of fault happening that the PCM is seeing, prompting it to stall spark advance and dump fuel to remedy the problem. So the focus of the thread has shifted to possible causes that wouldn't show up on a datalog. I've bought into the theory of detonation given my setup, (it's the only thing that seems to make sense), and am now trying to verify and possibly better the situation. If at all possible, I will find out exactly what's going on before any tuning. I'm going to eventually have headers anyway and tuning, (PRP), will be the LAST performance mod I do.

I think you are saying that the head is getting too hot from exhaust backing up, causing the ECU to add fuel. Is that it?

Sort of... I'm theorizing that the head could be retaining more heat because of the turbulence, (not backed up flow), caused by the precats, than it would with a set of headers. I'm thinking that headers could possibly help the situation.

 

[BurritaSVT]

The tune from the ford is off big time because the parameters on the 3 liter require us to change fuel maps for one because ford runs richer to protect precats from burning up under high loads and plus the displacement chart is way off making the setup run even richer throwing off the load charts by a far shot. The only thing headers do is create better flow and scavenging for induction draw more unburned air in the cylinder better bang and the precats are more restrictive than headers no doubt but they can still flow enough air not to back up the exhaust.

 

[SicSE]

So I go to put in the new style knock sensor today, (I would have bet my house that I had swapped over an old-style sensor from the 2.5L block), and discover that I am a complete moron... I don't have a knock sensor. That's right, after all this, I don't even have a fu-king knock sensor. Just to verify that I am indeed, losing my mind, I checked the pin on the PCM for the sensor... no wire. :blackeye: Ugh

So that explains the lack of timing retardation and verifies the detonation theory. The PCM is seeing the detonation as an unexpected change in crank speed via the CKP, and dumping fuel to save the engine from damage.

 

[striker2]

i agree that it seems to verify the theory, now you just need to figure out why its detonating. since there is no knock sensor, i wouldnt be suprised if its starting to detonate because the PCM isnt adjusting the timing properly for the 3L engine, espicially since its a hybride with the higher CR.