Hey guys (gals)

What's up with this wide open throttle high RPM detonation I'm getting all of a sudden???????

Man 13K miles on this Ford and already running into so many problems suddenly.

I run 93 octane gas. Have a Diablo chip. New plugs, wires, and coil pack.

Could it be the knock sensor? Cam sensor? Throttle positioning sensor? How about just a bad computer? Or a bad chip?

Can't figure it out but the detonation is extremely bad so I avoid full throttle applications at all costs.

Of course warranty wont cover anything because I've changed my lug nuts. Ford has the worst warrenty in the world.

Please help me fix this problem as I am clueless (ok, hold back on the jokes please there)

Tom

 

you most likley can't blame for for the detonation due to the fact that you have the chip installed, i would first look at the chip, it may be leaning the engine out too much at WOT

 

Why would it just do that all of a sudden for no reason?? I burnt out the wires and coil pack last week when my wires came loose from the coil and arc'd itself to death. The truck hasn't run right since. Replaced the coil pack, wires and plugs but am now getting the detonation. Why would the chip all of a sudden re-program itself to advance the timing more at WOT. If it was a rich/lean scenerio, I think one of my O2 Sensors would pick it up.

 

Tom,
I'd GUESS it's related to your under-hood lightning show. I'd guess it is more than coincidence that all this went wrong after you had electricity jumping all over the place.
Cam sensor? I doubt it.
TPS? well it's possible.
MAF? another possibility.
Knock sensor? I doubt it.

What causes knock?
Lean mixture.
High engine temps.
Timing advanced too much.
Low octane (for compression ratio).
Too high heat range spark plugs.
Plus I am sure there are others.

In your case I suspect the chipand/or computer were "messed up" by the arcing. Applying high volatge to the ground side of a 12 volt system can mess things up.

 

Tom, Ford won't look at your truck due to your lugnuts?!?! That's freakin' STUPID!

In your case, I'd just switch the chip off temporarily first and see if it fixes itself. If not, get the sensors checked. From experience, when I half shafted my throttle body I screwed up my TPS sensor (throttle positioning sensor), BUT it didn't run lean. The problem I had when I damaged it was that my truck idled higher at all RPM's. Whatever amount of gas I applied was almost doubled due to the sensor going out. Ford replaced it under warrantee for free. Truck worked fine ever since. Have you tried getting auto zone to do a systems check on it?

 

Do you think that switching back to a cooler plug will fix the problem?
Engine temp is normal. Currently I'm running stock Autolite plugs, that weren't giving me problems before. How can I test the computer to see if it's damaged? I don't think it's the chip, as it knocks when the chip is out as well.

How can I test the TPS or the MAF? Is there anyway? Or do you think I just take it to a dealer, which I hate. I'm not throwing any dummy lights? If one of those sensors were bad, shouldn't it throw a code?

 

Autozone? How much do they charge and what do they do? I have AutoZone's around here.

 

I don't think they charge anything. They are free and the will give you a code. Once you have the code, they give you a site to match the code with whats wrong.

 

Does thow need an appointment for such service??

 

Urg, I just called autozone. They said they'll only do the diagnostics if the check engine light is not, which it's not.

Is it possible that one of these sensors is bad, but NOT turn on the check engine light? I know the bulb isn't burnt out because it lights up when I turn on the ignition.

 

ooo, didn't think of that one...

What about a local mechanic or something? See if they can test it...otherwise I'm outta ideas.

 

I guess it's possible, but I've never heard of anybody having that problem.
My job, for the last 18 years, has been diagnosing and repairing MRI system problems.
In all cases where the problem is not readily identifiable, I always ask questions and try to find out if anything was altered, or anything unusual happened at the time the problem was first noted. In your case, your plug wires came off. Now if the problem is a bad O2 sensor, you'd have to have two different problems going on at the same time...you'd have to be running lean AND your O2 sensor would have to fail to detect that. I guess it's possible but not what I'd think most likely.

If it is, as you say, somethign that occured immediatley after your spark plug wire fiasco, we have to go to that specifc incident and think what all could have been messed up?
I keep coming back to the timing. Not sure why, but I do. I think it is because the ECM (computer) controls the timing electronicaly and it is something that could be way off and you can't fiddle with it by turning a distributor. The timing can be checked w/ a timing light - or at least it seems like I remember seeing that in my Haynes manual.
Have you disconnected the battery and let is sit for a hour or two to clear the computer so it will have to relearn?

Maybe you just need to let it suck in a 1/2 pint of Seafoam

edit to add: there is a way to test the TPS. I think I have seen it in the Haynes manual but don't couldn't tell you how to do it. The TPS is worth strong consideration. If you banged into it, or otherwise damaged it, I could sure throw things out of whack. You could be running WOT and the computer think you are putting around the parking lot...Hmmmmm.....

 

I keep thinking it could be the TPS as well, because it only happens WOT. Not to mention that my truck has MORE power partial throttle than full throttle, and at full throttle it has difficulties reaching speeds over 70 mph.

Here's another thought.

Right before the "incident" I took out my Autolite 764 (2 step colder plugs) that I was running because of the nitrous. I replaced them with OEM platinum Autolite's. I have heard someplace that Autolites are generally a hotter plug than normal. Now, since I don't usually go around full throttling my truck, could it be that the Autolite ARE in fact too hot of a plug and that's what's causing the detonation at full throttle and high rpm???? I've been giving that alot of thought as well.

The truck ran great at full throttle with the Autolite 764's gapped at .034 before. Now I'm running OEM replacement Autolite's gapped at a wopping .053 (because that's what my manual says to gap them at).

All my friends can't believe that a plug would ever have such a large gap. In fact, it is nearly impossible to find a high quality gap tool that even goes that large.

I'm considering putting the 764's back in with the .034 gap. Because in many cases a colder plug will reduce heat and detonation, whereas a hotter plug could cause excessive heat and detonation.

What are your thoughts on that? Do you think that this could have been a seperate problem due to the new Autolite's I put in and have nothing to do with what happened to the wires and coil pack. And that it's just that I didn't notice it until I started full throttling my truck all over the place to see if the plug wires and coil pack fixed the previous problem? Could the OEM Autolite's (if they are actually hotter than OEM) cause the detonation and deterioration of power at WOT?????

Tom

 

Tom,
I am a strong beliver in the value of addressing the knowns first. If you changed plugs right about the time this all started, then I'd throw the old ones back in and see what happens.
It's quick and easy and you'll know right afterwards.
I want to stick with you on this one - it is interesting.
Thanks.

 

I have a strange feeling without knowing a few things, any one of us are really grabbing at straws. It is obvious that the tesla coil under the hood effect did something, but what is the question. Besides making you mess your pants. The other fact remains is, you really don't want to hit WOT until you get the problem fixed, making harder to diagnose. If you think you can do it once or twice more, without causing serious damage this is what I would suggest. Go out and get a decent OBD setup, a bit of thermocouple wire (or EGT Kit). A few things you would like to be getting readings from when this happens, are your O2 sensors, Exhaust gas Temp., Timing, Intake Air tempeture, MAF Reading, Plus the usual search for misfire information. How is any of this going to help you diagnose your problems?? Well I would venture to guess when your engine decides to detonate, the computer in fact knows about it. Basically what you would be looking for is for any one or number of these sensors to appear abnrmal just before the incident. Almost all of them are going to go nuts during. Just another way to view the situation. Hope it helps.

//John