'97 Ranger 2.3l misfiring after rebuild

[hoppy]

*EDIT* the jerking/lurching was caused by the tps connector that was faulty, so we spliced a new one in and the jerking/lurching is gone, still have a misfire though, compression is GOOD 150psi+ for all 4 cylinders, and we're getting the injectors rebuilt, so hopefully that will solve the misfire problems

(original post)Symptoms are rough idle, misfiring throughout the powerband, and jerking/lurching while at cruising speed. When under heavy acceleration, it does not misfire, but under light or steady throttle it misfires and lurches.

We just finished rebuilding the engine, and a few months before the rebuild, we replaced the cylinder head which probably acquired 3-5k miles before the rebuild. It has new pistons, rings and gaskets all the way around and after getting the engine back in, it started first turn of the key, and the check engine light didn't come on until about the 3rd drive around the neighborhood, or about 20-25 miles or so.

We think the problem could be one of 3 things OR a combination of these 3 things.
1)The cylinder head could be defective, and the valves could be not sealing properly. (Solution would be to return the cylinder head (under warranty) and get a new one and hope that it's not defective)
2)During the install of the engine, the tie-down bent the connector on the coil for the compression stroke spark plugs (remember, this engine has 8 spark plugs, 4 for the compression stroke, 4 for the exhaust stroke), SO replacing that coil could/should help. (Solution would be to buy a new coil or 2 just to be sure to have 2 new coils instead of one old and one new)
3)The fuel injectors could be clogged, and need cleaning. (Solution would be to take them in and get them cleaned)

Also, I read this article (http://www.hotrodhigh.ca/2300Shockin.html), and tried swapping the 1&4 and 2&3 plug wires going to the coil for the exhaust stroke spark plugs, and it ran just as poorly.

Now that you know the background info, do you have any ideas about what the cause of the problem could be? Have you had similar experiences? What did you do to solve the problem? Are we anywhere close to figuring out the solution?

Also, after a full rebuild, we could crank the engine with a ratchet and with only 1-2 slow cranks we got 60-70 psi. this is with no break in, and at slow hand crank speed. I feel we have decent compression.

We rebuilt an entire engine because of poor running and a flat cylinder (35-40 psi) and it still runs bad.
It seems to run well, though, when stone cold. like the start up system does something to the spark advance or the injection mixture that goes away after 30-90 seconds.

 

[grandpa]

Hope someone can give you an answer!! I have the same issue. I inherited the truck from my dad. It had a head gasket issue (slight water in the oil) that could be improved radiator stop leak. Finally went out a few weeks ago. Also had a major oil leak that I thought was from a pinched crank seal or pan gasket. Did the timing belt about a year ago. The oil leak started a while after that. Thought something didn't go right with the new seals. When I got everything out of the way to pull the head, the oil leak was from the oil passage to the head on the driver side by cylinder 1. Cylinder 2 had a the water leak. Head gasket looked OK though. Found out my brother's mechanic had put a used head on it and reused the head bolts. From what I have seen of their other work, I doubt they even torqued the head bolts. I have the same drivability issues as before. Slight stumble off idle (sounds like it's gasping for air), a rough idle, and the occaisional stumble while crusing the interstate. Have cleaned the throttle body and tried running without the EGR. I also suspected the ignition coil for the exhaust side plugs. The exaust plugs had a different look than the intake plugs when I did the head gasket. Runs great other wise. Motor has 230,000 miles. The cylinder walls looked like new. I hope someone has an answer for both of us. This is my winter/work truck. I can live with it's issues but would still like to resolve them.

 

[hoppy]

Sounds like similar issues.

Is it possible that it could be a clogged fuel filter, and it's just letting fuel trickle into the fuel rail?

I'm thinking it's not a defective cylinder head because with the sputtering and stumbling that it would be happening all the time instead of just at idle, at launch and at steady throttle. Might be the coil, and it would be worth replacing anyways. But I think that it is clogged fuel injectors OR fuel filter.

 

[grandpa]

Had a little time after work today to tinker with the idle issue. When I did the head gasket, I patched several of the hard plastic emission vacuum lines, mainly the EGR valve line from the EGR controller to the valve. It runs up and over the valve cover, under the intake and then up to the valve. Today, I unplugged the EGR valve line at the valve and there was absolutely no change in RPM. I went to the EGR contoller down below the coil packs and unplugged the electrical plug. The idle went smooth as silk immediately. I drove around the neighborhood and never felt a glitch, stumble etc. I feel like a big dummy!! Just thought I would share. Good luck!!

 

[grandpa]

Just read your post again. Would not be a fuel filter. A clogged fuel filter will idle OK but starve under power (when you need the most fuel). Check all your vacuum lines even the hard ones. In doing your rebuild, they get moved and handled more than they like. Mine were extremely brittle. I could look at them and they would break. The EGR line is in the plastic sleeve where it runs over the valve cover. I had a couple of thin spots and a few cracks inside. Happy hunting.

 

[hoppy]

I bought an obdII code reader and the only code it gave me was P0122 for the throttle position sensor, so I removed the throttle body and checked it out, and it seemed like it wasn't installed properly (of course this was the last component that was touched by the 'shop'...and it was wrong, go figure). Installed it properly and found that the tps connector has faulty wires which short out with certain vibrations or when touching or moving them in a certain position. Amazingly autozone and napa auto has the correct tps connector, for like $30, and I'm picking it up tomorrow. I'll also check the egr vacuum line for damage, and I still plan on cleaning the injectors. Will report back.

 

[beluga420]

If this doesn't fix the problem, be sure to double check that the timing belt is properly installed

 

[hoppy]

Hey beluga and grandpa,

I installed the new TPS connector, and all the lurching and jerking is gone. Hard to believe that what seems to be such a tiny part can cause such a headache.

I'm completely positive that the timing belt is installed correctly, we quadruple-checked everything before we did anything.

I am still going to do a compression check, and get those injectors cleaned/rebuilt.

So, for the jerking and lurching, the TPS connector fixed it. Misfire is still there, and the injector rebuild should fix that problem.

 

[beluga420]

If you want I have a set of 97 2,3 injectors laying in my garage with 140 000 kilometers on them... They were doing good before I got to turbo my truck. Could be cheaper than rebuilding them. PM me if you want them..

 

[hoppy]

Hi Beluga420.
Hoppy will get back to you (this is his dad)

The day after Hoppy last posted, the truck started running bad again, misfiring etc. we never checked any egr hoses etc except they are all hooked up. and none are broken. it is not consistent. it seems sure that all plugs are firing right, the timing is right(valve timing) we are somehow having an intermittent misfire. we DID surely have a bad TPS conector, we have a new TPS and re-wired a new connector in and it ran great, until the next day. still stumped. maybe we do have very clogged injectors.

On my dodge ram v-8, it started running poor then one day it barely made it home from work, took it in and it was injectors clogged. similar symptoms. started with a slight misfire at cruise speed, light throttle. then started misfiring worse through the range and finally, (a week later) would barely run.

 

[hoppy]

PM sent

 

[hoppy]

Tested compression yesterday. Worst was 150psi. (1 and 2) then 165 and 175. So we eliminated that concern.

 

[scotts90ranger]

did you make sure to line up the auxiliary pulley? the cam position sensor runs off of that which controls injection timing which could cause some inconsistent running

 

[hoppy]

yes, good question, we did indeed line up all of the marks and since we did this with the engine out, on a stand, we had a great view of all the timing marks. BUT you are the first to mention that secondary mark.

Still, I am going to keep this in the back of my mind if we are still stumped after we get the injectors back in.

Since we know the TPS connector went bad, maybe we have a similar reading problem with either the crank or cam sensor. It's worth a thought. we never touched them during the rebuild.

Everyone should know this fact, this Ranger is a 97, we got it with 130K on it, it know has 208K, when we measured the engine specs, from the crank journals to the bore, top to bottom, this engine was within stock specs entirely, except the rings, which were near the max. We dont know if this is the original engine though.

This entire rebuild was based on a shop telling us we had bad compression in one cylinder. we have now founf that shop made other diagnostic mistakes. so now we may have done a full rebuild because of an electrical / injector issue.

oh well, I needed the practice. It was good father - son time.

 

[chilsam]

Good point!

yes, good question, we did indeed line up all of the marks and since we did this with the engine out, on a stand, we had a great view of all the timing marks. BUT you are the first to mention that secondary mark.

Still, I am going to keep this in the back of my mind if we are still stumped after we get the injectors back in.

Since we know the TPS connector went bad, maybe we have a similar reading problem with either the crank or cam sensor. It's worth a thought. we never touched them during the rebuild.

Everyone should know this fact, this Ranger is a 97, we got it with 130K on it, it know has 208K, when we measured the engine specs, from the crank journals to the bore, top to bottom, this engine was within stock specs entirely, except the rings, which were near the max. We dont know if this is the original engine though.

This entire rebuild was based on a shop telling us we had bad compression in one cylinder. we have now founf that shop made other diagnostic mistakes. so now we may have done a full rebuild because of an electrical / injector issue.

oh well, I needed the practice. It was good father - son time.

If you get lemon's make LEMONADE!