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1992 Mitsubishi Galant Poor Acceleration

Tiny
JETT_001
  • MEMBER
  • 1992 MITSUBISHI GALANT
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 86,000 MILES
Hi,

Hello from the Philippines! I have a 92 Galant MPI which recently had issues with acceleration. I feel that it doesnt have any juice left on the freeway. I used to run 3000 RPM and the speed would pick-up to 140KPH and yesterday, its 30KPH slower.

A couple of other observations:

* Timing of second gear shifting is a bit off. It now requires a higher RPM to shift to second gear from a full stop

* I also hear a bit of a whining sound in the engine (not too loud)

* RPM is erratic (from 1000rpm on standstill it goes up to 1500rpm and drops). This doesnt happen all the time though

* I just replaced the high-tension wires about 2 months ago, spark plugs are just about that old as well

* I had the air filter air-pressure cleaned yesterday thingking it was clogged, no luck

* It does NOT stall on standstill or during acceleration.

* Oil was newly changed (about 2000KMS ago)

* Upon reseacrch, the answers I get are usually on: bad spark plugs/wire, dirty injector/fuel pump/fuel filter or bad catalytic converter
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Sunday, October 25th, 2009 AT 8:41 PM

11 Replies

Tiny
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Hello,

Have you checked the tranny fluid. Sounds like it may be slipping at times.

Also check for Vacuum Leaks. Check the IAC (Idle Air Control) Valve.

.
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Sunday, October 25th, 2009 AT 9:57 PM
Tiny
JETT_001
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I just got it checked, apparently, the fluid is really black and it smells burnt. I'm thinking of getting another opinion to rule it out.

Luckily, the fix is kinda cheap, or I hope thats the trouble.

Where do I find the IAC? Is that were the air filter is connected to the engine? Sorry, i'm not good AT ALL with cars, LOL.
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Monday, October 26th, 2009 AT 12:27 AM
Tiny
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Ok, well if your tranny fluid is Black and Smells Burnt that is your problem.

The IAC is located on the Intake near the throttle body. It looks like this.
Image (Click to make bigger)
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Monday, October 26th, 2009 AT 10:10 AM
Tiny
JETT_001
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  • 6 POSTS
Thanks for your inputs, i'm going to have the tranny fluid drained and refilled today.

2 more questions:

1. Is it absolutely necessary to replace the service filter when flushing?

2. Could there be any issues on air/fuel stuff on top of this?

I'm gonna check if the transmission slips later, someone told me to put it in L, then let it run and shift to drive (rev-up should sound like normal shifting). I hope that works well.
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Monday, October 26th, 2009 AT 7:09 PM
Tiny
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I would highly recommend changing the filter. If the fluid is black the there is good chance the filter is partially clogged from trying to filter the dirty fluid.

It is possible there could be an Air/Fuel problem along with the tranny. However, before you go any further have the tranny serviced then see if there is still a problem. I honestly don't believe you will have any other problem once the tranny filter and fluid are changed.

.
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Tuesday, October 27th, 2009 AT 10:13 AM
Tiny
JETT_001
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Yes indeed! I got the filter serviced and fluid flushed and it seems its back to normal. The shift lever itself is smoother. :-)

Thanks!

All I have to worry about now is the idling problem. I think its the dirty throttle body. The mechanic did notice a bit of carbon accumulating

When I start the engine, the RPM goes down to 600, then jumps to 1500 and settles at 1200 (my setting) after like 3 secs. The mechanic said it could be a dirty valve throttle that can be easily cleaned. But how far do I have to clean it? Does it need to go beyond the valve throttle? Would a clean rag and toothbrush work?

Do you think thats would be the solution? After that is solved, I dont see any other problems. :-)

BTW, thank you for all your help and suggestions, 'really appreciate it!
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Tuesday, October 27th, 2009 AT 11:03 PM
Tiny
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To clean the throttle body just go by your local parts store and get a can or 2 of Throttle Body Cleaner. If you use any type of clothe make sure it is link free, wouldn't recommend a brush, brissles may come off and get into the intake and cause some problems.

.
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Wednesday, October 28th, 2009 AT 8:47 PM
Tiny
JETT_001
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I was able to clean the throttle body yesterday (w/o the throttle cleaner) by just using a clean rag. I did get a healthy amount of carbon off and hoped to get a better idling.

Using the wrong end of a screwdriver, I was able to reach behind the butterfly and got more dirt and thick, black carbon.

When I started the engine this morning, it made no difference at all, the idling still drops to around 400rpm, then shoots up to 1500rpm and settles at 1000rpm all within 5secs.

Do you think I have a combustion problem that only a top overhaul can fix? Or probably a clogged/dirty injector that would require ultrasonic cleaning?
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Thursday, October 29th, 2009 AT 5:47 PM
Tiny
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You should check the IAC that I posted above also check for vacuum leak or leaks check all hoses for cracks, compressed/flat, broken in two, or even just disconnected. And make sure to check the throttle intake hose, you know the 3 1/2" hose going between the breather housing and the throttle body, make sure it doesn't have any cracks or holes, and check the clamps it they are loose and air is getting by it can cuase the problem.

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Thursday, October 29th, 2009 AT 9:28 PM
Tiny
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Is this the IAC?


https://www.2carpros.com/forum/automotive_pictures/426570_jay4jpgth_1.jpg

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Sunday, November 1st, 2009 AT 9:34 PM
Tiny
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  • 3,711 POSTS
Can't really tell. Here is a pic of the location...
And they call it an Idle Speed Control Motor (ISC) instead of a IAC...


https://www.2carpros.com/forum/automotive_pictures/188069_92galantiscmotor_1.jpg



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Sunday, November 1st, 2009 AT 9:53 PM

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