1999 Dodge Stratus Intermittent missing at all speeds

DESK JOCKEY

MEMBER
1999 DODGE STRATUS

Engine Performance problem
1999 Dodge Stratus 6 cyl Front Wheel Drive Automatic 140k miles

1999 Dodge Stratus 2.5L V6, 140k miles

Timing belt, water pump, cap, rotor, plugs, wires, air filter, PCV all replaced 8,000 miles ago, and has run fine since then - until this.

Car suddenly began very rough idle, with intermittent but significant missing throughout rpm range. Misses less when pulling hard, misses more under light load. Codes for intermittent miss and for missing on cylinder 5.

Problem occurred shortly after refueling. Added 'drygas' (02-safe fuel line antifreeze) and injector cleaner, immediately drove 200 miles to home. Upon arrival, problem not as noticable but still present.

Checked cap, rotor, and all plug wire connections that are accessible without removing intake manifold. All OK. Air filter and PCV OK. Inspected vacuum lines (visually), but see no problems. Changed fuel filter (above fuel tank), also replaced fuel pump since tank was already dropped and mileage is high.

Problem still present. To test for faulty EGR valve, I blocked the EGR tube inlet to intake manifold and reattached tube. No change - still runs rough with EGR tube blocked or open. Added 1 can SeaFoam (02 safe) and refilled gas tank. Drove another 70 miles, still no improvement.

After disconnecting battery to change fuel filter & pump, codes were erased. CEL light came back on this morning as I drove to work. Will read codes on generic OBD2 reader when I get home this evening, but expect to find same - intermittent miss, possibly missing on a specific cylinder.

My internet research shows a TSB for the EGR valve on this engine, and a lot of people with similar complaints of intermittent missing. The specified EGR test procedure seems to rule that out.

Any suggestions (short of throwing lots of parts at the problem) would be appreciated.

EDIT TO ADD: Codes now show random misfire (shows twice), miss in cylinder 4, miss in cylinder 5 (1 code each). I believe they are P0300, P0304, P0305, P0300.

5 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Check the distributor and coil output, the coil is part of the distributer on the 2.5 motor.

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Wednesday, August 6th, 2008 AT 5:59 AM

DESK JOCKEY

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3 POSTS

Thanks for the suggestion.

Coil checks out OK - mostly. Between terminals it shows 0.8 or 0.9 ohms (meter shows one or the other each time I check it). This may or may not be slightly out of spec. Between coil tower and each terminal shows slightly above 15k ohms, right in the middle of the specified range.

Since the coil/distibutor assembly is going to cost me $230 or more, I'm hesitant to replace it based on the questionable resistance value between terminals.

If this was an older car, I'd be thinking about replacing the ignition control module. But I think that function is now built into the PCM or other ignition electronics. Anyone know of any tests on the 6-pin connector at the distributor?

I guess I'll pull the intake manifold to access the rear plugs and verify all spark plugs and wires. Will also test/inspect all vacuum hoses again.

If those all check out and I haven't come up with any new theories or tests to run, I may bet $230 on a new distibutor unit. Hate to do that without being sure.

Yesterday's codes show same as before - P0300, P0304, P0305 (after erasing previous codes and making another 100-mile round trip).

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Thursday, August 7th, 2008 AT 4:47 PM

SERVICE WRITER

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Yeah.I understand.

Thank-you so much for the donation. IT is the ultimate compliment when someone donates after a question is posted, I truley want to help you get this solved.

The po300 shows as a multiple misfire. Probably beyond the 4th and 5th cylinder.

Looking at the diagram, you'll find the 4th and 5th cylinder on opposite sides. I may be wrong, but pulling the pleneum to get to those plugs may be fruitless, unless you have multiple problems.

Try to move the po304 (4th cyl. Misfire) by moving the plug and the wire to 2 separate cyls if you are thinking an ignition problem.

You can get a good appreciation of what a shop goes through when it comes down to what you believe and what you can test based on information and symptoms.

I still think distributer. But Picture this:

You come to the conclusion the the distributer is bad. But you don't know it's a for sure. But if it was your own, it is what you would do. Now you have to mark up the part and add labor and call a customer that the "possible/probable solution is going to cost $500-600. What if you are wrong?
Especially with coil reading that may or may not be what you expect.

There may be an answer to this to test it for sure.I just don't have it.

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Thursday, August 7th, 2008 AT 7:23 PM

DESK JOCKEY

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3 POSTS

Got it. Way too much money later.

I pulled the front plugs (2, 4, 6) and inspected them and the wires. Couldn't see anything wrong, #4 looked just as good as the others. Didn't pull the plenum to access the rear bank.

Bet $250 on the distributor. Wrong. Nothing changed. I closed the garage door, turned out the lights and let it idle with the hood open. Saw a few sparks while it was missing, so decided to try new plug wires, even though the old ones had only 8k miles on them. Pulled the plenum, checked the plugs back there (#1, 3, 5). All fine. Installed new plug wires and put everything back together. It ran great until it warmed up.

After it got warm, it was a little better than it had been, but still not right. Drove it long enough to get a CEL. Same codes as before, P0300, 304 and 305.

Decided that since the misfire on 4 and 5 always show up, it was now either the distributor cap or an injector(s) problem. Thought that if the wires went to crap that quickly, maybe the cap wasn't any better quality. Besides, if I replaced the cap and rotor and still had the problem, then the ignition system would be pretty much eliminated as a possible source.

Replaced the cap and rotor. Problem solved.

Moral of the story: Don't rule out parts just because they shouldn't be anywhere near worn out yet.

Lesson #2: Don't buy cheap parts. Go to NAPA. I follow that rule about half the time, but specifically recall buying this cap, rotor, and plug wires from elsewhere.

Thanks for your help with this.

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Saturday, August 9th, 2008 AT 6:19 PM

SERVICE WRITER

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Looks like I also made the assumption they were good.I expect parts to be good when they are new. Were they autozone ones? I empathyze with the situation, certainly would not have suggested the distributor if I didn't expect it based on what we had going.

Glad you're up and running.