JR4WDTRBO

iTrader: (1)

M.net was letting me down with replies so i'll repost over here (you guys typically know more on the coil topic anyway ):

-'99, with 86,000 miles.
-Noticing some highway hesitation, and faint missing (no CEL for missing).
-Spark plugs have less than 3,000 miles (NGK BKR6E-11)
-CEL: 1 instance of P0420 w/ non-fouler mod (low load, at about 29mph, and 95F + out side). Cleared, and driven yesterday morning without it returning.
-No overheating
-No signs of spark bypassing plugs
-Can't tell if there are any significant signs of running rich on the spark plugs.

Coil tests:


Coil 1:
Tests: 1: 1.407 K Ohm
2: 8.82 M Ohm
3: 8.82 M Ohm
4: 10.28 K Ohm

Coil 2:
Tests: 1: 1.496 K Ohm
2: 7.64 M Ohm
3: 7.66 M Ohm
4: 10.4 K Ohm


All coil tests were done with car in the shade with ambient air temp of 84F and a cool engine (has not been ran yet for the day)

I was thinking the coils are weak..but I wanted some more eyes on the data to make sure there is nothing else I should test before popping for a new set of coils. If they are on the way out I am going to start picking up COP bits.

Edit: BTW, still NA for the moment.

BarbyCar

iTrader: (1)

Similar problem on 2000 after a warranty engine swap for #4 bearing issue.

The new motor had a bent crank nose causing the crank angle sensor to intermittently miss a timing lug on the plate. I'd check to make sure your sensor is in good shape, properly mounted and that the wiring to it isn't worn through (contact with water pump pulley) causing intermittent ground contact.

JR4WDTRBO

iTrader: (1)

Thanks, I'll check that out

chokeasphyxia

iTrader: (8)

I've got a '99 coil pack I just pulled out of my car, if you find that's your problem, $50 plus shipping.

JR4WDTRBO

iTrader: (1)

it actually seemed a lot better yesterday. The two main times I noticed an issue was on July 3rd while driving at 60mph-ish(still had a small coolant leak at the mixing manifold, ac was on) over the weekend driving to Tennessee and back, mainly back (80+mph sustained interstate, ac running hard, and 90F+ mid day driving.) Both time the humidity was high. The trip to TN was right after doing a water pump swap (and the misfire feeling was less than on July 3rd) so the valve cover had been off, and the spark plug wells were in open air during high humidity (no standing water or oil leaks though).

If the crank sensor wiring is the cause, its been since last week. I attribute the issues on July 3rd to a dirty crank sensor (had been covered in coolant and road grime). Since cleaning it and re-installing it with the proper gap (per service manual) it has ran a lot better. The current issue is somewhat vague.

I have been thinking of 3 possible culprits:
1. coil
2. fuel filter
3. dirty valves

I already know that I have valve clearances that are out of spec (not opening wide enough, I checked while the valve cover was off for the water pump swap), I don't know if that would contribute to dirty valves, but I know that a gross intake manifold is a good indication of gross valves, and my manifold was especially nasty when I cleaned it a few months ago.

So, I am going to replace the fuel filter, double check my crank sensor (wires included) and pull the spark plug wires on the next low humidity day (just encase, although I don't think this is the issue.) Then I will wait and see where things go from there.

I wish I had a prime example of what a '99 engine should sound and run like to compare it too. For all I know, my issues could be the valve clearance issues.