need help diagnosing engine issue

[1986 danger ranger]

Ok first I'm new to the forum and new to these old rangers.

Truck is an 86 manual 4x4 with the 2.9 EFI v6.

Now here the problem. It starts fine usually. will idle fine usually. If I start to drive it, it has a terrible miss mostly all the time. It also has a terrible tick coming from cylinder 2-3 area. I'm thinking possibly a lifter or cam issue. Every once in a while it'll run smoothe but it's pretty rare. because of the miss it often stalls. The truck is barely driveable and has little to no power. In an attempt to rule out the tick as the problem I've checked the following.

Note: that when the plugs were pulled several were wet with gas.

The engine light is not on. Things that have been checked.
Plugs
plug wires
distributor
coil
compression
fuel pressure
firing order
timing

Everything checks out ok on that list.

I'm thinking flattened cam or more likely a collapsed lifter.

You guys know these engines better than I, is my diagnosis likely the issue? Or is there anything else I can check before starting to pull valve covers and whatnot.

Thanks for your time!

 

[Big Jim M]

Yep!

Ok first I'm new to the forum and new to these old rangers.

Truck is an 86 manual 4x4 with the 2.9 EFI v6.

Now here the problem. It starts fine usually. will idle fine usually. If I start to drive it, it has a terrible miss mostly all the time. It also has a terrible tick coming from cylinder 2-3 area. I'm thinking possibly a lifter or cam issue. Every once in a while it'll run smoothe but it's pretty rare. because of the miss it often stalls. The truck is barely driveable and has little to no power. In an attempt to rule out the tick as the problem I've checked the following.

Note: that when the plugs were pulled several were wet with gas.

The engine light is not on. Things that have been checked.
Plugs
plug wires
distributor
coil
compression
fuel pressure
firing order
timing

Everything checks out ok on that list.

I'm thinking flattened cam or more likely a collapsed lifter.

You guys know these engines better than I, is my diagnosis likely the issue? Or is there anything else I can check before starting to pull valve covers and whatnot.

Thanks for your time!

If you have fuel wet plugs..the plug isn't fireing. So I'd be looking into why they aren't fireing. That certainly will cause a big miss. From the description of it "sometimes" idles well, the problem may be coil related.
I wouldn't consider the noise or the cam/lifters until I sorted out the cause of the non-fireing.

Big JIm

 

[1986 danger ranger]

well I replaced the coil with another one and it made no difference in the way the engine ran. Could it be something else in the firing?

 

[HndMeDnBroncoII]

so it misses under load does it have an egr valve,id double check the timing,maybe the chain is badly worn.also check the map sensor and ive seen a few exhaust manifolds on the passenger side crack under the heat shield so its unseen and causes a tick and make sure all ur grounds are good and clean.good luck

 

[Big Jim M]

Ya said

well I replaced the coil with another one and it made no difference in the way the engine ran. Could it be something else in the firing?

Ya said ya "checked" the wires... Does that mean you installed NEW wires?
Wet plugs strongly indicates no fire to the plug...OR BAD PLUGS!
Big JIm

 

[Dangeranger3]

I know it has been hit on already, but I suspect the coil or possibly other ignition part (i.e. wires). A collapsed lifter is highly possible, but the wet plugs scream ignition.

 

[1986 danger ranger]

the plugs were just replaced. The wires look pretty new but no they weren't replaced. They were checked to make sure sufficient power was getting through them.

I don't know if it has an EGR valve or not to be honest. I'd have to go out and check. Where is the map sensor?

I tried another coil off another truck and it ran the same. Unless both coils were bad, which I doubt, it isn't the coil.

Annoying as it is, if the tick is nothing to worry about I don't really care about it. I just want the truck to run so I can drive the stupid thing!

I should check the grounds though, where are all the main grounds located? Some vehicles have more than others of course. The main ground is easy enough to find, just follow the cable off the battery but are there any other grounds I should check?

Also, ther truck is running lean.

 

[customrangers]

Did you measure the resistance on the plug wires? 1000 ohms per inch of wire is the typical standard for basic plug wires. Any more and you might as well buy a new set. Also, your map sensor is on your firewall, at the top just to the left (passenger side) of the truck. It should have a vacuum line and an electrical plug. Egr valve is on the right side of the intake behind the throttle body, it's a round disk-looking thing.

 

[1986 danger ranger]

yes I checked the resistance on the plug wires and it was good. Thanks for the info on where the EGR and map sensor are.

Also, I think I'll check a few of the things you guys mentioned tomorrow and the next day as I will have a little bit of time in the evenings to have a look at the truck. I've been so busy lately... haven't had any time to check a single thing since I posted the thread.

 

[kimcrwbr1]

Ok let me get it right it has good compression on all cylinders what are the numbers when the engine is up to temp. Have you checked the vacuum pressure and does the needle hold steady between 17-21 hg. Put a spark plug in the coil wire and set it on a good ground and have someone crank on it you should get a steady brite blue spark if so work your way to the plugs. If not work back to the dizzy and computer.

http://www.therangerstation.com/tech_library/TFI_Diagnostic.html

 

[1986 danger ranger]

no I haven't checked the vacuum actually.

The compression is between 165 and 195, lowest to highest. each cylinder is pretty consistent to the one across from it though, within 5-10 psi. What I mean is cylinders 1 and 4 have very close compression numbers to each other. So does 2 and 5 to each other and 3 and 6 as well.

What do you mean set it on a good ground? as in touch the spark plug end to some good clean metal making a good ground? or?

 

[kimcrwbr1]

Plug it into the coil wire and set it on anything bare metal so the tip can be easily seen like the power steering mount. you can hold it with a insulated pair of pliers you want it to spark normal keeping the tip away from ground just touch the hex part to ground.

 

[1986 danger ranger]

ok, gotcha! thanks. I'll have a look tomorrow and see what I can come up with. I'll report back to here when I know more.

 

[kimcrwbr1]

You should be within 5% on the compression the vacuum guage will tell you more on whats going on inside the engine.

http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.htm

Weak springs, valve lash, guide seals carbon build up and rings all affect compression. How did you test the compression. I get the engine up to temp pull all the plugs and crank the engine until the guage stops moving usually two or three revolutions. Before you do the compression test get a can of seafoam and pull about half the can into a vacuum line fuel pressure regulator or egr on a hot engine and shut it down let it set for at least ten minutes. start it and rev it up to 2000 rpm and enjoy the smoke show. run it till it stops smoking then redo the compression test see if the numbers are more even write them down. A 30 lb difference in compression is a sign there is a problem somewhere. You can pour the rest of the seafoam in the gas tank if you want.

 

[Duane867]

Replace the rotor button and distributor cap.
Sounds lik eit just needs a ful tune up if you ask me.