Serious engine detonation

[todd_c]

yob_yeknom

Have you checked the bolts on the upper intake manifold? They loosened slightly on my '95, allowing extra air into the engine. A quick re-torque on the bolts stopped the pinging I was experiencing.

 

[AgExplorer]

What are the torque specs for the upper air intake on the '95 4.0 OHV?

 

[Rhett]

Well when you find out what it was that caused the pinging, let me know. One other thing I thought of was fuel pressure regulator. It can malfunction and cause a lean condition. Make sure they test the fuel pressure, making sure it's within spec, especially at wide-open-throttle.

I want to know because I have to run mid-grade gas (89 or 90 octane) in my truck. It pings a little with 87. All the fixes I've done have helped but not eliminated it. The only thing I haven't changed over the last year or so is the O2s. Since I am not getting a check engine light and the truck still gets as good a mileage as it ever did, I have not changed them.

 

[todd_c]

The torque spec for the upper intake manifold is 18 ft-lbs. The manifold is plastic, so don't over tighten the bolts.

 

[Xplor]

I got the 2nd dealer to check it out. Well, they did the PCM test(computer) and said that the 1st dealer that I took it to set the timing too advance. Therefore, they retard the timing back. As a result, I still get the same spark knock after I got it. I even wrote a letter and tape it on the console for the tech to read. I was describing about the problem and made some suggestion of looking serveral different possible parts. I guess am going to have to stick with the higher octane. I even called a another dealer out of town about 45min from me and ask him about it. He told me he has customers coming in and he evens own a explorer with the same thing and says just run a higher octane. So I guess thats all some of us could do. I hope Ford Motor Co. gets a large complaint with this and do something about it.

 

[LXTra]

Bump.

 

[LXTra]

So did retarding the timing in the comp and going to higher octane fuel solve the problem?

 

[yob_yeknom]

Originally posted by timfretwell
yob_yeknom in Rocky Mount (Moon shine capital of USA), we are practically neighbors! My folks live in the great metropolis of Union Hall, just down the road from you. Let me know when your going 4-wheeling. I need some of that red Franklin county mud under my Yokohama Geolanders!
Later

I'm going wheeling this weekend with another guy on this board from Roanoke. I've been trying to get a hold of you via PM's and emails, but I guess you're not getting them. Maybe you'll get an email update on this thread and see this. Let me know man.
Later.

 

[Xplor]

LXTra, well with the retard timing and using a 93 octane still get same results, which is nothing. Pinging is still there. I ask a tech about cleaning the MAF and he says don't do it. I am really tempted of trying this, but afraid that I might mess up the sensor, by using a wrong cleaner. I think brake cleaner would be too harsh, because I seen it tear up plastic parts and the sensor is surrounded with it. Does anyone know if the sensor from a late model have to be taken apart? I rather not if possible. Seems like I don't have to, because I had the KKM and took the MAF body and see the inside of it. I know I read that early models are clean by taking them apart with security screw bits.

 

[Rhett]

Xplor, do NOT use brake cleaner to clean the MAF. Use only O2-SAFE throttle body and intake cleaner. It must say "O2-safe" and/or "safe for catalytic converters and oxygen sensors" on it. I used STP Throttle Body and Intake Cleaner on mine and it worked fine.

Also, it is interesting that the tech told you not to clean your MAF. Perhaps since you are still under warranty he didn't want his garage (I assume a dealership) taking the risk of letting you clean it. The dealerships always want to do the work themselves, ostensibly because of warranty concerns, but imo more likely because they want to charge you for it. I'd wager that this same tech that told you not to clean it would clean it himself in much the same way you would do it. I don't see anything wrong with cleaning it so long as you use the proper cleaner. As I have a 94 and you have a 00, perhaps they have done something to the MAF filament that makes it bad to attempt cleaning it, but as far as I know, it is still the same procedure.

However, it would surprise me if the MAF filament was dirty on a newer vehicle such as yours. It should take at least a couple of years to get dirty to the point where it starts sending misleading readings to the PCM. Mine went from 1994 to 1999 before I had to clean it.

 

[Empty Pockets]

How can we check the sensors first??

I have same pinging at partial throttle. I now have new plugs, wires, fuel filter, new O2 sensor, clean air intake, clean throttle body, clean fuel system & rails and a Clean MAF Sensor.

Any suggestions on how I might check the MAF, throttle position sensor & others with a multi-meter before I replace them?

I have the Chilton's book & that really doesn't help.

Thanx
Rob

 

[Yng_pnk]

Same Problem

I have tried everything, Higher octain Cleaning the Maf (i used gumout carb cleaner in the can) Im gettign the exaust fixed, could that be my problem wit hthe ping and boggy acceleration?

 

[Rhett]

A Haynes manual explains how to test an O2 Sensor with a multimeter. The method involves heating the business-end of the sensor with a blowtorch and measuring the voltage. hehehe.

 

[jemail]

Dielectric Grease

Hey Yng_pnk,

When you installed the new plug wires, did you squirt some dielectric grease into the boots at both ends. Besides helping the removing of the wires when you do your yearly plug gap check. It is a grease that helps the transfer of the high voltages from ignition box to wire and from wire to plug. Think of it as filling all the air gaps between all metal connectors to transfer more of the voltage.
This was a hard learned solution on our fleet of F150's.

Hope this helps a little,
Jeff