ignition timing 1988 4.0

[BillNJ]

1045680

Hello,

Is it possible to adjust the timing on a fuel injected 4.0? I have changed the oxygen sensor and the cps to try and cure a stalling problem now things are worse. The truck pings, knocks and blows blue smoke out the exhaust. The problems all started after changing the ccv system when finding oil in the air cleaner box. Thanks for any help you may have.



Bill[addsig]

 

[MudderChuck]

1045749

It´s possible but rarley necessary, to set timing, unless you´ve had the distributor out.

Sounds like you may have the firing order wrong. Cleaning out the tubing for the crankcase vent circuit and various vacumn lines is often benefitial. Also a look at the wiring around the exhaust manifold, often turns up problems.

A look at the plugs might be helpful. If they are covered in what looks like black lumps. could be oil getting in the cylinder.

Many people talk about replacing the position sensor, but I´ve rarley seen one go bad on the pre 91 models.[addsig]

 

[BillNJ]

1045751

Thanks for the tips. Yeah I'm not sure if the cps itself was bad but the pigtail was shot from being inches away from the exhaust manifold. I thought the same thing....firing order seemed wrong so I double checked all the wires yesterday. When I first started having problems I found that the distributor cap was cracked next to the block. When I took the cap off there was oil lying in the bottom. Any chance the pickup is shot?[addsig]

 

[MudderChuck]

1045781

Anything is possible, but to tell you the truth I´ve never seen a bad pickup. I´ve seen a couple of broken ones, when someone got a little frisky trying to remove them or dropped the distributor. Underneath the mounting plate for the trigger, there is often water or moisture, I blow mine out with air after every dip in the creek. Push on the distributor rotor shaft, sideways and check for play, should be none. There is often a little up and down play, less than a 16th. You can double check that your number one cable is going to the number one out on the dis cap, by holding your finger over the num 1 spark plug hole until pressure is felt(or compression gauge) and lining up the timing marks to zero. Then checking the rotor is pointed to number one sparkplug cable. Initial timing can be checked by the same method (close enough). Holding a timing light on a dark spot and checking your cables one at a time will often show up missfires and leaky cables. Should have a solid and consistant pulse. The coil cable is a little harder to check, it fires to quickly. I´ve on occasion, but rarley, seen the carbon in the top of the distributor cap seperate from the high voltage pole. Did you replace thje cap? Sometimes cracked caps are just plastic fatigue and cheap materials, sometimes the distributor shaft bounces around in strange ways and breaks them.[addsig]

 

[dingus]

1045782

hmm... doesn't blue smoke mean head gasket (coolant leaking into combustion chamber?)?[addsig]

 

[MudderChuck]

1045783

I guess you can tell by my replies that I´m apt to check most all of the general mechanics of a motor before replacing any sensors. For every sensor I´ve replaced I´ve found a half dozen general mechanical or electrical flaws. That often don´t show up, even on sophisticated test equipement and often cause diagnostic testers to give false readings. The old Sun oscilliscope, usually tells a better story about the general health of an ignition or internal motor functions. Check the general health of the motor out, to include the vacumn system, then the regulatory sensors (that regulate fuel and spark) then the electronics. Usually works for me. I sometimes get my model runs confused, but under the rubber intake, at the beginning of the intake manifold, isn´t there a lid with a spring that helps control vacumn. If I have my model right, I´ve seen these lids stick and cause problems like you´ve discribed. Pull a vacumn test at the intake manifold, anything below 10 inches of vacumn is an indicator of a vacumn leak or a restricted exhaust. Anything over about 15 is an indication of a restricted intake. I´ve run out of ideas fro now, let me know what you´ve found.[addsig]

 

[MudderChuck]

1045784

Dingus brought up a good idea, coolant or oil leaking into a cylinder will mess up the spark and the plugs, not to mention the 02 sensor. Hanyes has a plug chart in color that´s pretty good.[addsig]

 

[CTJeeper]

1045790

I thought blowing white smoke was head gasket and blue smoke was burning oil... or at least this was the case when my friend blew his head gasket in his supra. yes/no? maybe my memory is just givin out... damn and im only 18

[addsig]

 

[MudderChuck]

1045822

White or light smoke, most times is steam, dark gray or black is often too rich and blue is said to be oil. But to tell the truth, I often walk back to the exhaust pipe and rub my finger in there, smell and feel. An oily finger tells a story, smell like gas?, dry soot, wet soot etc. rubbing the moisture between your fingers, you can often feel a little anti-freeze as compared to condensation. Checking warm plugs after a moderate drive usually tells more.[addsig]

 

[flyboy]

1045915

This may sound stupid but you may want to check your egr valve. I had a staling problem with my 87 yj and that is what it was. It is pretty easy to check and they aren't that much at a wrecker.[addsig]

 

[BillNJ]

1045995

Thanks for all the help. But no luck so far and I give up....it's in the shop now. I'll let ya know what they find. They said it may be internal. I still have my fingers crossed that it's something simple. Just seems odd....the truck ran great before changing the ccv lines then the next day every thing went wrong.



Thanks again[addsig]