Misfire and sounds

I got my 88 comanche with a 4.0 and 5 speed that has problems. got strong spark, but it Has a misfire, almost wants to shut off when idling. Driving, its bad, mostly in the lower RPMs, but gathering speed and rpms, it seems to get better, then sputters/ then picks up and so on. Its making a noise under the valve cover, like a dropped valve or something. and makes a tinking noise when i shut it off even if i just fire it up for a few seconds and not let it warm all the way up. Im not used to straight 6s, ive either worked on I4 or v8s. Check the spark plugs and cylinder 1 *first one closest to radiator* is fouled/sooty, indicating richness. all others are fine. Check compression on it and its at 120. Dipstick oil looks and smells normal, as well as antifreeze, so i dont think its a head gasket. I disconnected the fuel injector, and the idle doesnt change.

So maybe i have more than 1 problem. 1 being the valve, other being a fuel injector? it looks kinda wet under it, but it clicks.

I'm thinking just running it til it gives up lol. but id really like it to run right. 160k on the odo. I've got other projects to feed, but i really do enjoy 4wd!

is there a sticky somewhere for changing the head gasket or valve job.

120 compression should still be OK. Could there be a problem with the distributor cap, plug wire, or spark plug? You could swap the plug, wire, and injector to a different cylinder and see if the problem moves. What about the compression in the other cylinders? You could also take the valve cover off to see if you have some kind of rocker issue.

It really sounds like a bad injector to me, but winterbeater is right. Try moving the spark plug wire first--easiest, then the plug, then the injector. If nothing changes look at the cap and rotor. Having 120 in the one cylinder is good, but you need to know what it is in relation to the other 5.

if you unplugged the injector, and there is no change at all in idle, then most likely thats your problem. It may be clicking ok, but the injector may be plugged with rust and crap.

TAKE NOTE: I have never seen this happen in a jeep, but I have an 00 dakota that fouled injectors like a mother, the fuel rail delaminated inside and it rusted, I had to clean out the injectors every 6k to keep it running smootly. I just undid the fuel rail, popped em out, sprayed gas in my face, dumped all the rust out out of the tops, sprayed a little tb cleaner in them, tapped out again, and new injector rings sealed the deal. IO eventually replaced two of them, ran even better. Make sure you relieve the fuel pressure if you do tinker with the rail. Sorry I went off topic...

Many other things can cause the same issue, misfire. As far as your valvetrain noise, I've seen a misfire bend a pushrod, its easy to fix.

Winterbeater is right, start easy, cap/rotor, wires, move them around. Let us know. Its usually the easiest with these motors..

I think its going to be the injectors, The Coolant temp sensor is fine. 500 at ~170ish degrees.

Ill try moving the injectors around tomorrow, see if it changes anything. Tryed the wires/sparkplug, no change.

It misfires, and hunts *revs up for a bit, then sounds like its going to bog out, but doesnt die* I got rid of the sound by using a bit of seafoam thru the intake, so i know its valves are probably needing attention. did not use it as a fix because its not, just to see if it would change anything, and it did. Ill probably end up building the whole top end before its all said and done, throwing in some mustang injectors, and a valve job. But i got another project that is slowly being neglected more and more since i got the commanche, the nissan is prolly jealous, but at least she still runs right.

anyone tell me what this goes to? I saw one on the cherokee in the JY, but it had other options my comanche doesnt. Its located under the intake hose.

Gr8PlainsDriftr said:

anyone tell me what this goes to? I saw one on the cherokee in the JY, but it had other options my comanche doesnt. Its located under the intake hose.

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looks like your iac, idle air control connector. right behind your fingers it has little white writing on it, should plug in there.

i dont see or feel any unconnected plugs on that, or near it, i agree tho, that is what it looks like... ill need to follow the wires, see what sensor it goes to,

thanks for the responses guys,

It has 4 connectors, only 3 actually have wires to them. I dont see anywhere it should be connected to.

i unplugged the o2 sensor, and nothing changes, but i bought one anyway, and waiting on the zep to loosen up the rust. This truck is making me loose my patience. Its probably something simple...

If it comes from the tps it is not needed for your 5 spd.
John

i did a compression check on all cylinders, and changed out the spark plugs *ngk-champ copper*

150-140-145-133-141-125 but at the end, the battery was almost completely dead, and didnt crank much. first try it fired up and i shut it off quick, and gauge showed 180psi, so i think the 125 was because the battery wasnt cranking as well as when i had started.

Also, all spark plugs showed signs of running rich/fouling, except for the 3 and fourth one, this maybe due to the sea foam i ran through it not long ago. I jacked the back end up so as to even out the level of the engine. But after i changed the spark plugs it sounded better. for a bit, then it when back to what it was doing before.

fuel pressure from schrader valve is at 141 key on, engine off. i think pump is not a problem. Thru the process of elimination, It has to be injectors, i havent swapped injectors, id rather just swap them completely out for some mustang injectors or even LT1 injectors, b/c i hate dealing with o rings on them.

Gr8PlainsDriftr said:

i did a compression check on all cylinders, and changed out the spark plugs *ngk-champ copper*

150-140-145-133-141-125 but at the end, the battery was almost completely dead, and didnt crank much. first try it fired up and i shut it off quick, and gauge showed 180psi, so i think the 125 was because the battery wasnt cranking as well as when i had started.

Also, all spark plugs showed signs of running rich/fouling, except for the 3 and fourth one, this maybe due to the sea foam i ran through it not long ago. I jacked the back end up so as to even out the level of the engine. But after i changed the spark plugs it sounded better. for a bit, then it when back to what it was doing before.

fuel pressure from schrader valve is at 141 key on, engine off. i think pump is not a problem. Thru the process of elimination, It has to be injectors, i havent swapped injectors, id rather just swap them completely out for some mustang injectors or even LT1 injectors, b/c i hate dealing with o rings on them.

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Are you saying your fuel pressure is 141 psi?

sorry 41psi :wow:

so i got some hand me down presumably mustang injectors that work lol, but theyre not the 4 hole pintle type, just the one tire valve hole yellowish orange top feed ones. will these still work just to get by or am i taking too big of a risk?

thx all, this forum has been very useful, and i look forward to seeing some of you out at little sahara oklahoma state park, that is if your going for Rattle snake Weekend arty:

upon research found at injectorrx.com this part number on the injector itself shows

E6TE-A3B 14.2 ohms 194cc/min 18 Lb/hr

should get me by til payday

Little poser pic, got it running 99% right, 5 and 6 plug wires where swapped, Champ spark plugs helped, but i need to adjust the TPS, and Get a new muffler. still smells rich, ill be swapping out the old injectors as soon as i get a chance to get in the garage. Ill be knockin out the rust, por15 it, and cover with Diamond tread aluminum along the bottom side *doing away with the molding, or i might keep it if i can save it*.

so i got a lifter tick now, and its backfiring into the intake... distributor must have jumped?

also, i cant seem to get any Voltage reading from the TPS, key on engine off, sensor disconnected, ground on b, positive on C or A, and nothing.