tuning- detnation

maxim123

Registered User
I put a 94-95 style charger 10% pulley on my 92 and now my car detonates really bad. i tuned the car with the other charger and pulley and basically just leaned it out by taking out 5psi fuel. so to improvise the extra boost i dialed in +5 psi fuel pressure. It appears that boost went from 12lbs max to pegging the stock guage (18lbs?) at 2000rpm. well i turned the fuel pressure up some more, 5 more psi, and it still detonates, ran down the road and played with it some more but couldn't get it to quit. So i pulley the superchip out and it lessen but its still there at high rpm with the boost over 5lbs and a lot less power?? what's going on here?
Mods
Cam
Port heads, valve job
exhuast
42lbs injectors
superchip
94 style blower
 
Who burned the chip? Is it one of Brians? You should get on a dyno and get the fuel pressure right for your boost levels. make sure its in the stock range. Are you still using the stock intercooler? If so using a 5% pulley may be a better choice until you have upgraded your intercooler. Also you could get a reburn to take some timing out and add fuel when it starts to detonate.
 
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Playing with the fuel pressure is a waste of time because the computer will adjust and compensate for the difference in pressure and tune around it. The Ford EEC-IV is different than Jap comp systems and does'nt respond to the same tricks that they can use.
 
There is much debate about the "adaptive" capabilities of the early processors. I have been told that the early EEC's do not adaptive learn at all. So adjusting fuel pressure WILL have a direct effect on AF ratio.

However, that being said there are several other things to consider in this case. Before you can begin "tuning" the car for performance you must ensure that you do not have a mechanical problem.

1. Do you have proper fuel pressure under load? Pressure should rise pound for pound with boost. I have seen many different situations which resulted in insufficient fuel pressure. Bad pump, leaking in-tank connections, insufficient pump size, pinched lines, faulty regulator and I am sure there are more.

2. Do you have an exhaust restriction? You didn't talk about exhaust but this is very important.

3. Is the motor using any oil? Bad valve seals or rings will cause excessive detonation. Are the plugs oily or sooty?

4. If your PCV valve is not new, then get a new one from Ford. A bad PCV can cause detonation as well.

5. Is your EGR connected? (does a 92 even have EGR?) I don't know.

Best bet then is to get the car on a dyno and watch the AF ratio. You need to know if you are close to being in line or not.

1. As a quick fix you probably need to retard timing. To do this, remove the octane plug next to the diagnostic port. This will retard timing 4 degrees and help control detonation.

2. You should already be running cooler running plugs. I recommend Autolite APP103's if you run the car hard and APP764's if you don't.

3. You should also be running the engine cooler. Do you have a 180 degree thermostat in the car? You can even run a 160 if you want but most people don't like it that cool. I have noted no detrimental effects from it over time, but you will get lots of opinions here.

4. I assume you have the proper MAF to run 42lb injectors?

5. If you have the stock IC, then anything over 15psi is a waste of time and all you are doing is superheating the air charge. you might want to find out just how much boost you are really getting.
 
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XR7 Dave:
There is much debate about the "adaptive" capabilities of the early processors. I have been told that the early EEC's do not adaptive learn at all. So adjusting fuel pressure WILL have a direct effect on AF ratio.

Dave think about it for a minute....for that to be true the engine would have to be running in open loop all the time ignoring the O2 sensors and using only the preprogramed fuel tables.
Every piece of writing I've seen on the EEC-IV says its an adaptive strategy system. The only discussion I've seen suggesting the oposite has been on this site.:)
 
MIKE 38sc said:
XR7 Dave:
There is much debate about the "adaptive" capabilities of the early processors. I have been told that the early EEC's do not adaptive learn at all. So adjusting fuel pressure WILL have a direct effect on AF ratio.

Dave think about it for a minute....for that to be true the engine would have to be running in open loop all the time ignoring the O2 sensors and using only the preprogramed fuel tables.
Every piece of writing I've seen on the EEC-IV says its an adaptive strategy system. The only discussion I've seen suggesting the oposite has been on this site.:)


OK, adaptive strategy that would be relevant here is the long term fuel trim which would be the result of the EEC continuously having to correct AF ratio due to incorrect fuel pressures. Since we all know that the EEC is in open loop operation under boost, I was not referring to anything that happens in closed loop.

Some people hold that the EEC DOES in fact remember the "fuel trim" that it was doing during closed loop operation and applies the same calculations to open loop (WOT) operation. This is what I was refering to. I know that current processors all do this, effectively cancelling any changes to fuel pressure. However, on the older processors, once you go into open loop (WOT) all adaptive strategies are thrown out the window and the tables take over. This is what I have been told, and what my experience reflects. Therefore, changes in fuel pressure WILL have long (and short) term effect on WOT AR ratio.

The extension of adaptive strategies to open loop operation is one of the features of OBD, and perhaps some of the late EEC IV's but I do not know that for sure.

Sorry I missed a few steps in there, but what I said before does apply in this case.
 
detonation.

dave is right.

to clarify a little:
1. good question i suspect not, stock fuel pump can't handle it maybe?
2. Another good question, its got headers, not cats, no resonator, and stock to rest of the way out. does it flow good maybe, but sounds like crap.
3. no oil consumption, but i rarely drive the car. i take it arounfd the block once every coupe of months. i'd like to drive it more but its always got issues.
4. less than 6k on it.
5. no egr in 92

forums id: maxim123
Engine
Modifications: Raised blower top
Long tube headers
42lb Lucas injectors and calibrated C&L maf
10% Blower pulley
Ported intake, 94-95 blower and inlet plenum
Intercooler fan
180 degree thermostat
Superchip Computer Chip
Heads ported and polished
Larger valves
Coy Miller Stage 2 cam
1.73 SVO roller rockers
Polished stock rods
ARP mains and rods bolts<

Drivetrain
Modifications: Centerforce dual friction clutch
(toasted 8k miles JUNK)
RAM HD clutch and pressure plate
3:73 gears (worst mod ever want 3:08 back)
F150 blocking rings in transmission (rebuilt again and now grinds in 2,4 but not 3rd!)
15k and rebuilding again.
Suspension
Modifications: Eibach 1.5" lowering springs
18" Racing Dynamics Wheels
fr 245/40/18 Nitto 555
rear 305/50/18 Nitto 555R

Cosmetic
Modifications: None
 
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Holy crap dude, I would suspect there is no way the stock pump would keep up. Get a 255lhp forced induction pump!!! :D

Exhaust is fine, but you need to do all the other things I mentioned.

Not for nothing, but an off the shelf Superchip always helped my car by about 10hp even at high mod levels.
 
Dave is correct on adaptive strategy. Unless the SCs were different then all of the other ford vehicles...They did not start it until EEC V. Then it is no good to adjust fuel pressurd. That is when the car started measuring long and short fuel trim and went to the 104 pin EEC. I also think you need a larger pump.
 
I don't see an aftermarket MAF listed either ? You will need one properly calibrated for the 42# injectors. Lowering the pressure isn't going to work.

David
 
fuel

I've been turning the fuel pressure up, up not down. i would suspect that it doesn't maintain fuel pressure a WOT.

i would have never noticed it but i left the sound deadening off when installing the tranny and drove down the street.
 
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I dont mean to insult you but if you dont know what you are doing I would SERIOUSLY suggest you get help when tuning the thing. The extra money spent will be well spent. If you take the fuel and timing too far in the wrong direction you can lean that beotch out too much and tear up your investment and have to start at square one. I can build a car from ground up but I would not tackle the tuning thing without help.
 
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