How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Doug Your Own Question

Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6659
Experience:  Mitsubishi employed and Factory trained ASE certified technician
21364095
Type Your Mitsubishi Question Here...
Doug is online now
A new question is answered every 9 seconds

Mitsubishi Diamonte: My 1995 Mitsubishi Diamonte has a miss

Resolved Question:

My 1995 Mitsubishi Diamonte has a miss while running.Seems worse in hot weather.No idiot light has ever come on.Have changed all filters and had several mechanics look at it but they can't find anything-they say that until a light comes on on the dash,they don't know what it is.Car runs great otherwise.
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.
Hi,

Is this miss constantly occurring?

If it is, can you isolate the cylinder that is missing by unplugging one plug wire or injector at a time to see if any one cylinder does not affect the miss (I know the back injectors are not easy to do this)?
Customer: replied 1 year ago.

I would have to take it to someone.Could you tell me all the possible possibilities and I will print this out and take it to a mechanic. Thanks

Expert:  Doug replied 1 year ago.
I understand.

To have a consistent miss is going to be a pretty wide range of problems however they are all relatively easy to check out (compared to some other problems anyway).

To have a rough operation or miss in the running you are going to be looking primarily at an ignition related issue, followed by compression based issue, and lastly fuel based, by order of likelihood.

The first thing you are going to want to do is see if you can isolate the problem to an individual cylinder. This is called a cylinder balance test. The theory here is that if you have a single cylinder (or two etc) that are consistently missing and the others are not, when you cut power to the "Bad" cylinder, the engine will not really change condition any, whereas if you cut power to a "Good" cylinder it will cause the engine to stumble since it is losing power when the good cylinder is turned off.
On newer cars this can be done by scan tool, however on a 95 this is a hands-on vehicle, as you've experienced already... these cars are what separate the veterans from the new kids, as less experienced techs have a hard time diagnosing without a computer that tells you everything for you... these older cars you have to get your hands dirty on them.

The easiest way to do this balance test is to unplug the injector for each cylinder one at a time. If the engine does not change on any one cylinder being unplugged at the injector, you know that cylinder is not firing properly. The rear injectors are very hard to get to due to the intake manifold, and it is easier to unplug the spark plug wires from the distributor instead for them... the same effect is had.

If you isolate it to an individual cylinder, you will then want to inspect the spark plug and especially the wire to that cylinder. Note that generic spark plugs do not work well on these cars.... No Bosch, No Autolite, No Champion.... NGK or Denso only, and only original equipment replacement (no gimmick plugs like four electrode, glow in the dark, whatever they are pushing). The plug wires are OK to use any decent quality wires that are "fitted" (correct length for the specific vehicle). Plug wires are extremely difficult to verify condition accurately, especially when partially concealed. If it is unknown how old they are, it is best to replace them. Note that Mitsubishi plug wires have manufacturing date printed on them which can give you an idea of the age.

If nothing is found with the ignition system, then looking into the compression would be next.
This also happens to be what you would do if you did not have a specific cylinder issue. A compression test would be in order to verify the internal health of the engine. This can tell you two things.... first if there is any internal issue (leaking piston rings, leaking valves not seating properly), and second if the timing belt jumped a tooth which would cause the same miss but would be identified by low compression values. You should see about 200 psi per cylinder ideally, 185 if you have the rare DOHC model... if you see any major differences between cylinders for example 180 180 190 120 180 185 or something like that, you found your miss... and unfortunately it is time to go internal for repair. If you see all of them low (140 140 150 140 130 155 etc), then we would first suspect a slipped timing belt, followed by a severely worn out engine... the former corrected with a new timing belt set properly, the latter with internal repairs.


If the compression is good (say 170s or higher and all relatively even), then we would want to check out your fuel supply.... checking operating pressure (with the engine running, not just pump pressure) to see if there is a pump or regulator issue. A fuel sample would be in order to make sure you don't just have a bunch of muck in there. And finally a spray pattern check by lifting the injector rail off the engine and cranking the engine to make sure the injectors are all working properly and spraying nicely (no kitchen faucet looking sprays, just fine atomizing).


It will be very rare to see anything outside that range.... while it is possible to have wiring damage (rodents, accident damage etc) cause some odd behavior, it isn't the norm. In typical situations you will always be able to narrow the issue down to one of those three areas if you have no malfunction lights coming on, as those areas are rare to set warning lights (on a 95 model that is.... 98 and up is a different story) until they get very bad.
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6659
Experience: Mitsubishi employed and Factory trained ASE certified technician
Doug and 4 other Mitsubishi Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
 
 
 

Meet The Experts:

 
 
 
  • Doug C.

    ASE Certified Technician

    Satisfied Customers:

    3981
    Mitsubishi employed and Factory trained ASE certified technician
< Last | Next >
  • http://ww2.justanswer.com/uploads/SU/superbovine/2012-6-6_233210_547717101510889173290181666093332n.64x64.jpg Doug C.'s Avatar

    Doug C.

    ASE Certified Technician

    Satisfied Customers:

    3981
    Mitsubishi employed and Factory trained ASE certified technician
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    243
    ASE Master tech 15+ years
  • http://ww2.justanswer.com/uploads/tsmodie/2009-6-10_144056_tim.jpg Tim Mohr's Avatar

    Tim Mohr

    ase master

    Satisfied Customers:

    172
    30 yrs foriegn and domestic, gas and diesel
  • http://ww2.justanswer.com/uploads/05/05muranosl/2012-1-26_195212_JA.64x64.JPG Jake's Avatar

    Jake

    Automotive Technician

    Satisfied Customers:

    111
    Experienced collision repair technician, Pulaski Tech graduate and DSM hobbyist.
  • http://ww2.justanswer.com/uploads/MI/mikeamechanic/2013-4-2_175558_photo.64x64.JPG Mike Kelly's Avatar

    Mike Kelly

    Mitsubishi Mechanic

    Satisfied Customers:

    104
    17 years experience as an auto mechanic, foreign and domestic. 5 years running my own repair business.
  • http://ww2.justanswer.com/uploads/AM/amdhcds/2012-4-1_04039_3911361015044607312849462040349387767831419345287n.64x64.jpg AMD's Avatar

    AMD

    Master Technician

    Satisfied Customers:

    48
    L1 Advanced Level Diagnostics Specialist
  • http://ww2.justanswer.com/uploads/pentico/2008-11-09_032258_dad1.jpg BigBob's Avatar

    BigBob

    Service manager/Technician

    Satisfied Customers:

    45
    25 years in the auto repair business
 
 
 
Chat Now With A Mitsubishi Mechanic
Doug
Doug
Technician
5209 Satisfied Customers
Mitsubishi employed and Factory trained ASE certified technician