Ok, fine. I need help. >:(

[Captain Ledd]

Allright 4-banger guru's, try this one out. I've done a lot of homework so get ready for a read.

1997 2.3L 2wd, Manual Trans, bone stock.

Major symptoms:
Computer says Misfire on Cyl #2 (that's it, nothing more)
Vehicle will NOT travel faster than 65mph. I managed 63 out of it and it did not go faster than this.
Once reaching top speed CEL will flash.
Until I replaced the #2 spark plug wire (later explained) the engine would try to escape from under the hood. It no longer does this with the new plug wire.
Also has a intermittent stumble at idle.
There's is a audible tick somewhere on the engine.



~10,000 miles ago we did the timing belt, it broke while driving. Has had a slight miss and lack of power when first releasing the clutch ever since, otherwise drove great. I still managed to pull probably 4-5K lbs of a friends truck 180 miles on the highway (albeit no faster than 60) afterwards without missing a beat.

~ 4,000 miles ago we did the fuel injectors (would not start unless you were on the gas). Truck continues to fire right up, no issues.

~30,000 ago all new Autolite plugs and Bosch wires. However 2 wires of the passenger side have broke, story as follows:

The end snap pulled out of #2 when I went to check it's compression the first time around before I realized my dad's harbor freight compression tester wouldn't go far enough down in the head to catch the threads. Tried the push down rubber stopper thingy and failed. 60psi in #2, 30psi in #3. I figured the engine would barely run at that point, if at all, and went out and rented a compression tester with the correct fitting.

The plug wire for #3 also pulled out the end snap over the spark plug during the 2nd check. I will be replacing the wire set when all said and done.

Vacuum check: 19in steady

Timing light determined Cyl 4 ignition is cutting out (at idle) when it stumbles. Driver's side slightly more so. All other cylinders checked out fine.

*Edit: Also cleaned the MAF today, with appropriate MAF cleaner. 5-28-11

Compression check:
#1 - 90psi
#2 - 90psi
#3 - 70psi
#4 - 90psi
^which I think is rather low.

Truck pulls great up until highway time. I've done several (FULL) loads to the dump at 50 just fine, hills aren't a problem.

truck revs just fine, I wound it up to 5.5K with no misses, stumbles or shutters. Pulled steady the whole way.

Tried to check fuel pressure but again, POS harbor freight tester isn't worth the box it came in. *EDIT* Got one from autozone, went right up to 40PSI and stayed at 38 for a good 2 minutes. After about 6 more it had shrank down to about 34.

Truck has had superb regular maintenance. I have records of every tank of gas, parts, and service we've put in/on/for it since it was 9,000 miles old (now 205,000). We purchased it as a early return lease.

I really don't feel like throwing parts at this thing, so i need to know some more ideas.

I find it odd that both coils, for cylinder #4, cut out for the timing light test. They run $50 apiece.

There's is the ignition control module. And honestly it kind of feels like alot of other truck's I've diagnosed where the Vac-advance isn't advancing. $150

I could replace all the wires now - $40

All the plugs looked great as is.

And my freaking FSM of all the things and specs it lists I could not for the life of me find a spec for Compression PSI.

I'm running out of tests and I can't afford to pitch another $200-$300 at it hoping it goes away.

 

[Bryan22]

that compression test looks really bad. maybe a bad gauge. Id try to do another test with a different tester. Your 97 doesn't have an ICM, it's build into the PCM.

since you've had an issue since the timing belt change, id be suspicious of it being off. check and double check all timing marks. The coil packs can be tested with a multi-meter. fuel pressure looks fine. as for a spec for compresion, should be at a minimum 120 psi across the board with less than a 10-20% discrepancy from cylinder to cylinder.

 

[TastySloth]

I was going to say something to do with the timing belt you replaced. But ^^^^ beat me to it.

Maybe the issue with compression could also come from the cam timing being off... valves opening at the incorrect times relative to stroke. Could cause the misfire too (maybe not, because of the coils cutting out). I honestly don't know if these statements are true, but it sounds good in my mind.

It is the first thing I would check because it doesn't cost money to do so.

 

[Moreflying]

After you try a new compression gauge and get the same results do a leak down test. Those readings are grossly low. Minimum per cylinder should be about 100 according to my books no less. It's no surprise you have no power. I'm wondering if that engine is non interference or not.

 

[Bryan22]

it is non-interference. all lima motors are.

 

[Captain Ledd]

After you try a new compression gauge and get the same results do a leak down test. Those readings are grossly low. Minimum per cylinder should be about 100 according to my books no less. It's no surprise you have no power. I'm wondering if that engine is non interference or not.

There-in lies my head scratching, see, it runs just fine until you get up to highway speed and then falls on it's face. It starts great too. and yeah, I thought if the compression was that low I'd be having more problems.

I'll switch out the compression tester this week.

I'll also double check the cam timing, but the engine doesn't feel like it makes (or doesn't make) power in any different spots that it used to.

 

[Moreflying]

If you do a leakdown test set up on #1 TDC and see what the reading is....If it's in the red low crank the engine around at least two times and watch the gauges. If during your turning the reading spikes up into the green 40-20% more than likely you cam timing is off.

 

[Captain Ledd]

Update:

Still haven't built my leakdown tester, didn't have the time this week.

However, my dad did manage to borrow some of his fancy OBDII software from work, and these are the more interesting findings. Looks like there's more than one issue (which I kinda got the feeling that was the case before).

See attached PDF for the readings.

The 400 numbers are time references to the best of our knowledge.

The others are either in Volts, percentage, degrees, etc. Unfortunately it doesn't list the units.

LOAD PCT - The low number is probably when it misfired.

#2 O2 sensor (O2S12) - every once and a while a little blip did show up, but 98% of the graph representation was at 0. Either that's dead or the cat's plugged.

#1 O2 Sensor (O2S11) - This jumped around everywhere, with no real pattern or rhythm.

Spark Advance - This page is misleading. When the engine first starts up it's around what's listed. But after a minute of idling it climbs up to between 30°-40° advanced! And it stays there while driving.