missfire and wierd noise from intake

[SHOspeed93]

Well my car just recently started missfiring alot and now whenever the tranny locks into 4th gear there is this knocking/popping noise coming thru the air filter(only under load). There is quite a bit of oil in the plug wells and the wires have about 75k on them I am ordering VC gaskets, wires, plugs for it...Do you guys think that there is a more serious problem...please help

Oh yea the car now has 131k on it.
Thanks

<small>[ January 24, 2003, 04:20 AM: Message edited by: SHOspeed93 ]</small>

 

[BlackOnBlackATX]

im having a hard time understanding the popping noise, but i think if you change out the gaskets plugs and wires then things would be ok. i recommend doing that first, then going from there. perhaps someone else has a different opinion though.

 

[rangerj]

SHOSPEED94,

Check for codes. The popping in the intake sounds like backfire, which is normally a timing issue.

The oil in the plugwells could be causing the misfire, but the Crankshaft Position Sensor (CPS) and/or the Cylinder Identification Sensor (CID) could be causing a backfire.

Remember, a code does not automatically mean a sensor is bad. It means that the computer is not getting the signal it is expecting. It could be a poor connection between the sensor and the computer.

In order to change the plugwell seals you have to remove the valve covers. In order to remove the valve covers, you have to remove the intake manifold and the plennum. You may as well clean the intake and plennum.

While the valve covers are off, why not check the valve lash, and put in new shims where necessary?
If you have to change the CPS, consider the timing belt and the front crankshaft seal.

The idea is that once you have so much time and effort into one job you "may as well" do other things while you have it "opened up". LOL rangerj

 

[twr]

Oil in the plug wells has fouled up the plug wires. Change the gaskets and replace the plug wires. The cps and the cid generally don't cause misfires, just no fire.

 

[SHOspeed93]

RANGERJ, I thought that it could be a back fire, I changed the CPS with the water pump about 35k ago I do think it would be bad already.
The car sometimes does fire al the cylnders but most of the time they dont, I hope this isnt a CPS problem. The only code that came up was a right O2 sensor and a code saying that the voltage coming from the TPS is sometimses to high??? I dunno what that means, but today I ordered the VC gaskets, wires, plugs, and intake gaskets, Ill replce those and then see what happens...The wierd thing is that all this started happening when one of the plug wires would stick to the plug any more, well I fixed that but I think maybe the wire is just damaged...what do you guess think

 

[rangerj]

SHOSPEED93,

I have to go with TWRSHO, he knows his SHOs. The new plugs, wires, and plugwell seals should solve the misfires.

The O-2 sensor should be replaced if it has 50K or more on it. Check the connections on the O-2 sensor, clear the codes, then recheck for the O-2 code. If it codes again, replace it.

The throttle position sensor (TPS) is a potentiometer (spelling?). Like the dash light dimmer switch, it varies the voltage as you move it from closed throttle to wide open throttle.

Given your O-2 AND TPS codes, along with your plug wire problems, you may be "popping" some unburned fuel. This may be the backfire like sounds you here. Terry, does that sound plausable? I've never run into this.

At closed throttle it sends about .3 volts to the computer. At wide open throttle the maximum voltage it should send is 5 volts. You can test it with a meter, and I can dig up the test proceedure if you are interested.

That having been said, usually if the TPS puts out to much voltage it needs to be replaced. This is not usually a connection problem. The TPS can develop a "wear" spot in the normal cruising range, say 2200 to 2700 RPM. I read that this problem has been resolved in the newer designed TPS.

I know Ford has made improvements in the TPS design. Terry, Steve, and any others, do you know if the newer design TPS can be used on the older generation SHOs? Do they all use the same TPS so that any replacement will be the redesigned version? Hope this helps, rangerj thumbs_u

 

[SHOspeed93]

Thanks again, ill check the voltage on the TPS tommorow, Does anyone else have any advice...


Thanks
Tony

 

[projectSHO89]

SHONUT's site lists the V6 TPS (Windstar TPS recall kit) F19Z-9B989-BA on his site.

I'm guessing he knows that that will work.

To "fine-tune" rangerj's comments. I looked in the Probst book for the test procedure for the TPS.

One terminal is ground, one is the Vref of 5 volts, the center wire is the signal output(TPsig).

TPsig should be around .6 V with the throttle closed and should approach Vref with the throttle fully open (book says 4.5 V). There should not be any breaks in the voltage measures as the throttle is moved through its range.

I recall a popular "mod" with the 5.0 Mustangs was to tweak the position of the TPS so that TPsig was as close to 1.0 V as possible without going over. Supposedly helped with performance, I never did it with our Mustang, though.

That wire sounds flakey. It could very well be the problem.

Steve