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Discussion Starter · #1 ·
Ok, I'd like some opinions. My service engine light keeps coming on with a Cylinder 6 Misfire. I have a 98 Caravan; 3.0 liter/3 speed; 103000 miles. I have changed the following:

Distributor Cap
Rotor Button
Ignition Coil
Spark Plugs
Spark Plug Wires

After changing all of those items, I still get trouble codes for Cylinder 6 Misfire!? Could the actual distributor be bad? Is it a dirty fuel injector (I have run fuel system cleaner through it)? Could the computer just be bad and telling me there is a misfire when there really isn't one? The van seems to run smooth. It doesn't run rough, or have problems accelerating. Any help will be appreciated.
 

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We had to replace a couple of injectors in our '96 V6 truck to fix a misfire.
When our injectors got that bad, cleaner didn't work.
My $.02
Scott
 

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I have been fighting the same problem for a month now.
I replaced
plugs
wires
cap
rotor
O2 sensor
PVC valve, Would recommend replacing this part only 5.00 and if it rattles that does not mean its good. Just replace it.
All vacuum lines around intake.
I removed cleaned and swapped the Fuel injectors from front to back.

My van is running too lean. I can tell because when I replaced the plugs there was white deposits on the spark plugs and the O2 sensor.

Next thing to check is fuel pressure and volume.
I am still getting a misfire cylinder 5 and random misfire. Hope you find yours and I find my problem.

In conclusion I either have too much air or not enough fuel or major engine work ahead.
I have checked for vacuum leaks and can find none.

After discussing my problem with several mechanics they think It may be valve job time. I will do compression tests tonight and see what that says.
Good luck
Anthony
 

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Ok After Vacuum test and using my OTC Mindreader scan tool I have discovered the problem. The Spark advance at idle is jumping from 17 to 23. I have checked several other cars with my scanner and notice the advance is constant, only varying 0.2. The vacuume test shows the reading slowly changing from 20Hg to 21.5Hg. This should be constant at idle. After reading, talking to mechanics and checking everything I can I have come to the conclusion that I have a valve problem or timing problem. I plan on replacing the timing belt, heads, AC compressor, clean intake plenum and all gaskets and hope that will take care of everything.
Anthony
 

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If I may, I would suggest that you take the vehicle to a reputable shop and spend a few bucks on a thorough analysis and diagnosis.

You may well be right in your findings and if the shop supports your findings then you can do your planned repair work

But Ii they come up with something that you did not, then there is another avenue to explore; they might find something more serious, or they might find something simple, for example, a perished vacuum line, that is causing grief

the bucks spent on a second opinion may well prevent you from spending on un-necessary repair work
 

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Thanks for your input. The key to your response is finding a reputable shop. I get shafted every time the wife takes it in to get serviced. I have worked on cars for 20 years as a hobby but these newer cars are going to take some time to learn all the systems and common problems. Thats why Im at this site. I would rather spend half the money replacing parts, based on inteligent info, than paying someone twice the amount to tell me its not worth fixing. Its 80.00 in these parts for a mechanic to make a guess at a problem around here. I enjoy the hunt and the work. ITS A CHALLENGE.
 

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what causes misfire.

A method of detecting a misfire condition in a spark ignited internal combustion engine where the idle speed of the engine is controlled by an idle speed control means which controls engine idle speed by varying the spark timing advance for the engine ignition system. With the engine running at idle speed, the instantaneous spark timing advance being developed is repeatedly sampled for a predetermined number of consecutively occurring data samples. The absolute difference in sampled spark timing advance values between each pair of data samples is calculated for all of the predetermined number of data samples. The absolute differences in spark timing values that occur between data samples are added together to provide a sum total. If the sum total exceeds a reference value, the engine is operating in a misfire condition.

http://www.freepatentsonline.com/5226322.pdf
http://www.autoshop101.com/forms/h40.pdf#search="varying spark advance "
Great information.

Anthony Bridges
 

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FOUND IT.
Bad head gasket. Did compression test and way low readings on cyl 5 and 3. Spent Sat. and Sun. taking apart and found burnt gasket between Cyl. 5 and Cyl 3. Was told that this was a COMMON PROBLEM with the Mitsu engine. Just ordered new gasket set and head bolts. Hope I can remember how to put back together?

Hope this helps someone else.
 

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Not good

In the same boat. #4cly misfire. Have done all of the above plus injector test,unplug cyl #4 and did not notice any change in RPM. My 97 3.0 was a quick buy to replace a van that was totaled with what money we got from the insurance. :buttkick: Found that the SES/MIL light bulb had been removed.
Have not read where any one said that the Eng. idle was bad. Mine shakes the Van at idle, in gear with brake and runs good other than idle.
So this site has been the first that has made sence with the head gasket :VHOT:
Not what I like reading but have to face the facts that I'm looking into more than I needed in another Vec. Don't mine doing small repairs and can rebuild this motor if needed. Wish it would of been something simple.
This site has been more helpfull and have read through probley all of the posts.
One Q? I have a Comp.tester with the flex rubber hose though can't seen to get it threaded with the sharp bend in the hose. What type would one use.
 

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cnctony said:
FOUND IT.
Bad head gasket. Did compression test and way low readings on cyl 5 and 3. Spent Sat. and Sun. taking apart and found burnt gasket between Cyl. 5 and Cyl 3. Was told that this was a COMMON PROBLEM with the Mitsu engine. Just ordered new gasket set and head bolts. Hope I can remember how to put back together?

Hope this helps someone else.
Well I found #4cly to only have 75lbs. Leak down test has air coming out of Ex.
So if one does a head job should one also replace.
Water pump
Timing belt
Vavle lash adjustor
Cam seals
Crank seal or any other items seeing how much work is there on that side/end of the Eng.?
 

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if you have it opened up anyway I would definitely do the water pump and timing belt.

I have heard/read from various threads and web sites dealing with the 3.0 that doing the seals is a good idea but I will let others advise you on that

I can offer no opinion on the valve although I have read nothing that indicates that these are problem causers
 

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Discussion Starter · #13 ·
I'd like to thank everyone for their responses. I decided to have a compression check done before dropping $100 on a fuel injector. Unfortunately, Cylinder 6 does have low compression, and the shop guy said that it was probably a bad exhaust valve. I was quoted $800 + tax to do a valve job on both heads, as well as put on anything else that I want while they are in there for no extra labor. I was going to need the timing belt changed anyway, and he said he'd put a new one on at no cost if I bring him the belt, since he has to take the belt off anyway. Does this sound like a reasonable price to have 2 heads reconditioned, not to mention I can have my valve cover gaskets and timing belt replaced for no additional cost?

If this is reasonable, and I have it done, are there any other things you guys here can think of that I should have them do while the engine is apart? Thanks so much for everyone who has helped. This forum is great!
 

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So that price includes all the gaskets, cam seals, valve seals and water pump. If it does sounds like a good deal. Note they mite have to replace that exhaust valve it is burn't real bad. Valve shouldn't be too much.
 

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Discussion Starter · #15 ·
TNCaravan said:
I'd like to thank everyone for their responses. I decided to have a compression check done before dropping $100 on a fuel injector. Unfortunately, Cylinder 6 does have low compression, and the shop guy said that it was probably a bad exhaust valve. I was quoted $800 + tax to do a valve job on both heads, as well as put on anything else that I want while they are in there for no extra labor. I was going to need the timing belt changed anyway, and he said he'd put a new one on at no cost if I bring him the belt, since he has to take the belt off anyway. Does this sound like a reasonable price to have 2 heads reconditioned, not to mention I can have my valve cover gaskets and timing belt replaced for no additional cost?

If this is reasonable, and I have it done, are there any other things you guys here can think of that I should have them do while the engine is apart? Thanks so much for everyone who has helped. This forum is great!
Any more ideas out there? Thanks.
 

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Just did my head job myself. Have lots of pictures. I bought heads on ebay 269.00 set. Head gasket kit, water pump, timing belt main belt and AC belt and head bolts 175.00. And that was the cheapest I could find everything for. It took me 3 full days as I cleaned every part and bolts and I painted every bracket and valve covers. It was fun and I enjoy working on cars. I found a local shop that is going to rebuild my old heads for 150.00 then sell on ebay. 800.00 sounds like a deal if you ask me. I could do this job again in a day now that Iv'e done it once. You do need a few special tools to do this job and luckly I had the tools. Parts to do your job are minimal but there is a lot of labor involved. Again $800.00 sounds like a great price I would do it. But I like to do things myself. ALSO I would have them clean and replace the O-rings in the water pump tube mine was in real bad shape. Good luck
Anthony
 

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One more inportant thing. Just found out my Main crank front seal is leaking and has been leaking for a while now. It is so easy to replace once you have everything off than to do it later. May think about having that done too!
 
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