RE: Help Severe Detonation - Dodge Dakota Forum

Subject: RE: Help Severe Detonation
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Normally around $30, but Manciniracing.com is currently running a sale on several manuals, including an updated Magnum manual, each for $10.

sam
Dodge Dakota
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4/26/2004
03:10:56

RE: Help Severe Detonation
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I guess this is what I get for trying to help. I guess I jumped the gun on the timing issue. I just read a LOT of bad info on some of these forums and was not actually referring to this one. As for gen1dak, I am not sure what your problem is with all of the hostility and such. I am curious if you have actually ever used a scan tool on a magnum engine that had a massive intake leak? If you had you would know that for some reason the leak has very little effect on the MAP sensor, well, not enough to cause this rich mixture you are describing. As far as your description of the rich lean swing, that is very true but all fuel injected engines operate that way, vacuum leak or not the o2 sensor is constantly sending info to adjust the AF ratio,rich to lean, lean to rich-normal. You just described a normally operating speed density fuel management system. All your foot does is control the vacuum leak but with the aid of the TPS for fine tuning. The engine will run quite well with the TPS disconnected which shows how well it can adapt to a vacuum leak. I have not heard of valvespring seals, maybe you are referring to valve guide seals? Leaky valve seals tend to leak too much oil to burn and it is cooked and usually just fouls out the spark plug. Bad piston rings will also lower the compression pressures and not allow detonation. You are right about the drop of oil, it vaporizes quite well and when burned during the combustion process, will form a nice white carbon coating on the spark plug over time. As for the idea about hydrocarbons, yes they burn, gasoline is a hydrocarbon and the breather tube will supply some air, this will contribute to a SLIGHTLY lean mix that the engine controller will have no trouble adapting to. It is wierd how many different concerns you can get from a leaking intake plenum. Anything from a high idle, oil use, funny buzzing or squealing sounds to our much argued detonation issue. Some customers when presented with the intake estimate, just say change the sooty plugs and I will check my oil. No more detonation when the customer drives off with his leaky intake and new plugs-it may work for an hour or a month but that is why I said what I said in my earlier post. I have also sat through many hours of chrysler training and have talked at long lengths about this problem with the chrysler instructors and they all have said that the detonation develops over time and is due to carbon and not the air fuel ratio. If you have a scan tool and monitor the fuel system with a leaky intake, most everything will read normally. The long term fuel trim may read +10 (which means the pcm had to add 10%more fuel to get the air fuel ratio back to normal). That is why the intake leak does not cause a lean mix, the pcm will adapt to it and will operate ALMOST normally. If you read the TSB for this intake problem, they instruct you to perform as many combustion chamber clean procedures as it takes to get rid of the detonation. I have had some that you could not fix unless you did the PCM flash. Many of the engines ping badly and have a perfectly good intake seal-reflash fixes them. The intake leaks are not the biggest problem. A lot of the problem is software. I am sorry for the long post and in reality I am not an arrogant know it all, this is just what I do for a living and I am trying to help. I read these posts because I like the truck and like to read what others think about them. It seems like you (gen1dak) have as bad a temper as I do when you see a post you don't agree with. You are right about certificates,I have said the same thing. I feel rather a$$like for talking about my qualifications-I didn't want to be "that guy" if ya know what I mean. Did I miss anything? Thanks for reading (are your eyes tired?)

gen1dak
Dodge Dakota
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4/26/2004
12:16:42

RE: Help Severe Detonation
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1. I didn't say anything about the MAP sensor.
2. I didn't say hydrocarbons don't burn. However, part of the whole emissions movement was to reduce harmful emissions, in part, due to unburnt (partially consumed) hydrocarbons.
3. Hostility rises from someone popping off making references to "others" when their own information is erroneous or lacking. Starting out a sentence with "I don't know why..." and then stating someone else is wrong...This is not a good position to be in. It comes over as an attack without foundation.
As for the PCM adapting, it can, at least the OBDII models, but even they have limits. Once the problem exceeds these limits, you have the same problems, so basically, it just takes longer to notice the problem.
Referring to the repair issues,(and this is not a personal attack on you) a la TSB, and all. I'm rather suspicious of any group that has been supposedly dealing with the problem 12 years now, and they can't seem to remedy the problem, but they're more than happy to pour gobs of over-priced cleaners in an engine when a fine water mist will accomplish the same thing. Think about it. Does anyone else have this problem? I mean, how long have MPI systems been around? Programming. They can only correct it after the problem occurs? The engines do not even have knock sensors. They don't seem to adapt well to ping, now do they? Wonder why they'd omit such an important sensor? Other makes would use their adaptive ability to retard timing to reduce the ping (and save the engine), but no, Magnum owners must go in, get cleaners and/or flashing. Does that make any sense? Talk about mis-information.
I'm done here. Keep it between the ditches.

turbo-1
Dodge Dakota
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4/26/2004
17:50:34

RE: Help Severe Detonation
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about the engine temp. i have noticed on the factory gauge that it does read a little lower temp but i don't know by how much. (gen1dak) i have already tried unprogramming the hypertech programmer and resetting the pcm (disconnect the battery) and it still pings just as bad. sam gave his advice what's yours?? is there a better way of checking intake leaks than starting fluid?? thanks

gen1dak
Dodge Dakota
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4/26/2004
23:43:45

RE: Help Severe Detonation
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I always siphoned residual system power after unplugging the battery by going in and turning the key all the way on if as to start the thing, then let it sit for a few minutes, blip the headlights...anything to pull the last little bit of power. If you do this and it still acts up you should do the following test to rule out the pan gasket. It is possible that the gasket didn't seat properly, and is leaking. I haven't kept up with all the flash business. All else fails, Mopar may need to do that.

The official way is as follows:
Inspect the Positive Crankcase Ventilation (PCV) valve. Shake the PCV valve to verify that the pintle inside of the PCV valve is free. Replace the PVC if the pintle is not free.

If the intake manifold plenum pan gasket is leaking, an additional vacuum source will be created inside of the engine at the location of the pan gasket leakage.- Engine combustion blow-by gases, oil vapor, and air from the crankcase filter/breather may be drawn past the leaking pan gasket and into the intake manifold. In most cases when this condition occurs, an engine at idle will create the highest vacuum and lowest amount of engine blow-by.

1. Allow the engine to reach normal operating temperature.
2. Stop the engine.
3. Disconnect the breather hose from the air cleaner.
4. Attach a vacuum I pressure gauge to the end of the breather hose
5. Disconnect the PCV valve hose from the intake manifold.
6. Seal off the intake manifold PCV valve hose port opening.
7. Seal off the open end of the PCV valve hose.
NOTE: DURING THIS DIAGNOSIS, IT WOULD BE NORMAL FOR THE ENGINE TO DEVELOP PRESSURE WITHIN THE ENGINE CRANKCASE. THIS IS DUE TO -THE NORMAL PROCESS OF. EXHAUST BLOW-BY- GASES- LEAKING PAST THE ENGINE PISTON RINGS AND ACCUMULATING IN THE ENGINE CRANKCASE. DO NOT ALLOW MORE THAN 3 PSI (20.7 kPa) OF PRESSURE TO BUILD WITHIN THE ENGINE WHEN PERFORMING THE FOLLOWING DIAGNOSTIC PROCEDURE.
8. Start the warmed engine and observe the vacuum gauge.
9. Allow the engine to idle for approximately 30 seconds. Do not allow more than 3psi (20.7 kPa) of pressure to develop in the engine crankcase.
10. If the attached vacuum I pressure gauge does not indicate that a vacuum is present in the engine crankcase, then the intake manifold plenum pan gasket is good and no further internal engine vacuum leak diagnosis is required.
11. If an internal vacuum leak is present then perform the Repair Procedure.

Tedious, but it is the definitive way to determine if the gasket is leaking. After you determine the gasket is okay, I would also top up with premium (so it won't ping) and go run the Hell out of it. Get it hot and run it hard. That'll help clean up the cylinder head deposits that may have accumulated. Old school, but it works.

turbo-1
Dodge Dakota
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4/27/2004
16:19:24

RE: Help Severe Detonation
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thanks i will give it a try

turbo-1
Dodge Dakota
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4/27/2004
17:35:13

RE: Help Severe Detonation
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i did the test, and with the engine running for 30 seconds it built up 2.8 psi of pressure. is that just blow by? or does that mean that the plenum pan is leaking again. thanks

gen1dak
Dodge Dakota
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4/27/2004
22:23:43

RE: Help Severe Detonation
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That would indicate normal blow-by, so it would seem the plenum gasket is good. Now, on the computer reset, the reason I stress this is that if it isn't fully drained of power, it may retain previous codes. I have read that after disconnecting the cables, touching them together will drain the remaining power, and it is said this is the official way, but I have not had a chance to verify this, so I can't say for sure. Hence, I drain it as described previously. You could also have injectors that are sticking, which requires the good stuff to clean hard deposits. Over-the-counter gets the soft stuff, but not the harder deposits. I'm kinda grasping at straws here. Make sure you've given it a right and proper reset. Then go from there.

turbo-1
Dodge Dakota
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4/28/2004
08:56:44

RE: Help Severe Detonation
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thanks for the help

turbo-1
Dodge Dakota
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5/06/2004
19:59:52

RE: Help Severe Detonation
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i ran some wynn's fuel injector cleaner= no help. so i pulled the fuel rall and cleaned out the rall and sprayed down the injectors and raplaced the o-rings. ran great for four days, a couldn't get it to detonate no matter how hard i drove her. then all of a sudden it started detonating twice as bad as it ever did. could this mean that i have a bad/ clogged injecter or two. i have heard its almost cheaper to buy new FMS 19# injectors then to have the old ones cleaned. also could a bad egr or map sencer couse detonation??
thanks

gen1dak
Dodge Dakota
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5/06/2004
20:33:49

RE: Help Severe Detonation
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My experience with MAP sensors made the engine so rich it literally shot flames out the tailpipe. I'd go with the injectors sticking and causing a run-lean condition, especially if you have over 60,000 miles on them.

turbo-1
Dodge Dakota
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5/06/2004
20:41:03

RE: Help Severe Detonation
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my trial & error budget is getting thin, before i buy injectors is there anything else in the fuel systom that i can check??

Sephiroth
Dodge Dakota
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5/06/2004
22:32:11

RE: Help Severe Detonation
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How often do you guys change your injectors. I know it's not much of a help here, but I have 127k on my original ones in the V6, and 108k on the original ones in the V8. Neither detonate.

sam
Dodge Dakota
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5/06/2004
23:00:41

RE: Help Severe Detonation
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I have rarely seen failed injectors causing this problem (not to say it does not happen). I have seen some vehicles with rust scale in the fuel rails that have clogged injectors and have not had much luck in cleaning them. Usually that is fairly obvious when you remove the fuel rail.It is hard to tell exactly what is causing your detonation without a true fuel trim readout to tell if it is going lean or not. I have seen some MAP sensors cause a lean condition due to the barometric pressure input being out of spec. Is hard to say.

turbo-1
Dodge Dakota
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5/08/2004
17:49:16

RE: Help Severe Detonation
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i found a friend who would let me try his fuel rail and injectors out of his '98 5.2 that ran without detonation. and mine still detonated just as bad, it sounded the same too, same pattern. its gotten so bad i don't dare drive it, it even does it going down hill. i think i'am going to try to get it flashed on monday. unless i can figure something else out before then.

islander
Dodge Dakota
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5/08/2004
23:20:03

RE: Help Severe Detonation
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time for a leak down test.
or take it to a shop.

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