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1994 Intrepid 3.3L idles rough, misfires

Tiny
THESANDMAN
  • MEMBER
  • 1994 DODGE INTREPID
  • 6 CYL
  • FWD
  • 110,000 MILES
Check engine light came on (code 43) but with no noticable symptoms until next day. Then engine started idling rough and with a noticable miss. Starts okay and seems to accelerate okay but when coasting/sitting you can feel the rough idle.

This is 2nd engine with about 110,000 miles on it. Still have original engine, so I exchanged cam sensor and coil pack but no change in symptoms.

Checked out air filter and intake and found rusty colored oil filmed water in intake boot.
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Monday, February 21st, 2011 AT 10:56 AM

6 Replies

Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
That's a code for the fan relay. It won't have anything to do with a misfire. Also, keep in mind there are two kinds of misfire: ignition and lean (fuel).

First check the quality of the spark at the plug. Use a spark checker. Spark should be bright and snappy. If not, change plugs/wires. If still weak, coils are bad.

If spark is good, check fuel pressure, clogged fuel filter and injector firing/quality of spray pattern. You check firing by listening to each injector with an automotive stethoscope. You should hear a clicking. You check spray pattern by taking out an injector, placing it in a glass container and starting the engine. Be careful and have a fire extinguisher near by.

NOTE: Check all vacuum lines, PCV valve and EGR valve as well. You can also clean the MAF if you see it's dirty.
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Monday, February 21st, 2011 AT 1:49 PM
Tiny
THESANDMAN
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  • 38 POSTS
Confusion on my part about your reply to trouble code 43. Book says that it is a "peak primary circuit current not achieved with the maximum dwell time." This is "not" related to rough idle and misfire problem?
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Monday, February 21st, 2011 AT 3:24 PM
Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
I got the information from alldata. The circuit is for the "high speed fan relay". And no, that won't cause a misfire. However, if your fan fails to function correctly, it will cause your engine to overheat and then you'll have all kinds of problems.

Here's the info from alldata:
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Monday, February 21st, 2011 AT 4:33 PM
Tiny
THESANDMAN
  • MEMBER
  • 38 POSTS
There is no high speed fan on this particular model of intrepid. You have a duel fan that operates in tandem. Now maybe the 3.5L or a newer model is designed as such, but not this particular 1994 3.3L. I have removed and or replaced the engine cooling fans on several occasions and I am well aware of their design.

I use a Haynes Repair Manual for 93-97 Intrepids and trouble code 43 is explained on page 6-7 (and quoted by me to you).

In the old days I would be checking the timing, points, dwell, distributor, rotor, plugs, wires, etc, but apparently I can only do the final two and I already replaced the coil pack with another (used, not new, but with no change in performance).

All plugs, except one, where clean and the bad one had minimum build up, but not fouled by any defintion. Compression test showed 150# on all cylinders except one, which was 120# (the one with the dirty spark plug).

Engine will start right up, but will check engine light will come on withing seconds (even after I reset the system), I have also changed fuel filter to eliminate that possiblity.
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Monday, February 21st, 2011 AT 5:58 PM
Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
If you prefer to go off of the information from Haynes, that's fine. If you need any other help write back.
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Wednesday, February 23rd, 2011 AT 2:41 AM
Tiny
THESANDMAN
  • MEMBER
  • 38 POSTS
It was not a question of whose of us is right, but obviously what information we rely on to solve the problem. If the car in question does not have a high speed fan, then in turn there would be no need for a high speed fan relay, but eventually the problem was found and fixed. It was a wiring harness short to the coil pack thus affecting the firing of the spark plugs and throwing the trouble code. Now I ask you my friend. Which code 43 would you say pointed us in the right direction (in this particular case). Alldata or haynes. In this case alldata was incorrect (not to imply that they are always wrong), but either way, the symptoms keep me (and it should have affected your opinion equally) in the right area of the engine until the problem was located. Now how about giving me my money back? (It will allow me to use your services again in the future.)
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Monday, February 28th, 2011 AT 8:11 PM

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