Poor engine performance under load

**cramp** · July 13th, 2012 08:41 PM

Hi everyone!

Warning I'm a total car noob, I've only had my 2nd hand car since april of 2012, and it was in pretty bad shape when I got it.

Background:
1. 1997 Kia Sportage
2. newly changed oil, oil filter and atf (twice)
3. new spark plugs, high tension wires
4. had a compression test and low compression on valve #3 (compared to the other 3)
5. Fuel: Caltex Silver Gasoline
6. Transmission shifts fine up to 4th gear
7. newly cleaned throttle body

Symptoms:
1. Car is noticeably slower with A/C is turned on and with passengers, as in it takes 10-15 seconds before it accelerates above 40 km/h.
2. Intermittent "pop" sound coming from exhaust.
3. Medyo rough idle (around 750 rpm, 1000-1200 with AC on)

Description:

Starting the car is no problem, one click lang sya mag start. pero minsan pag naka reverse sya it would stumble and then stall, but not all the time. Under load with one passenger, the car suddenly loses most of its power, noticeable when accelerating on a high way from a stop. The speed would go to 20kmh with the gas pedal depressed half way to full (RPM stays on 2000 for a while), it shifts fine naman eventually pero it just takes a long time to go to around 60 (15-20 seconds).

The car runs a bit better without any load (a/c off, no passengers) pero hirap parin up hill, goes only about 20 kmh. Shifts fine and runs quite peppy on non-inclined roads.

Dilemma:
I've had my transmission checked, according to the mechanic it shifts fine naman daw. Ang tingin ko it's the engine itseft ang may problem, kasi without the a/c ok naman andar nya eh even after a cold start. Plus nung sinabi sakin na mababa yung compression results nung valve 3 dun ko na naisip na baka nga engine. I started to think about getting an Engine top overhaul, but not sure if this would be fix the problem. Also, after reading a bit more about the problem, I'm starting to believe na baka it could be other things in the fuel system. Maybe a fuel injector or fuel pump that gone bad. Baka its running poorly as it is, hindi lang masyado noticeable pag walang load yung car.

Question:

What's the first thing to do when I visit my mechanic? I'm avoiding to be bombarded with his theories, and wanted to minimize the "guessing" replacement parts. And of course, would not want to spend so much right away. Should I commit to the engine and go for a top overhaul? Or should I get my fuel pump/injectectors/filter checked? Ano po sa palagay nyo?

Sorry for the long post, I've been trying to fix this problem for weeks and I obviously am desperate.

**batangtalyer** · July 13th, 2012 10:43 PM

sir cramp, major tune up lang ang katapat nyan.

**cramp** · July 14th, 2012 01:00 AM

Originally Posted by batangtalyer

sir cramp, major tune up lang ang katapat nyan.

Salamat sa tip sir batangtalyer! What's a reliable place to get one? Thanks again for the response!

**cramp** · July 14th, 2012 01:01 AM

Originally Posted by batangtalyer

sir cramp, major tune up lang ang katapat nyan.

Sorry if ang noob ng questions hehe. My 1st car din kasi.

What's a reliable place to get one?

Thanks for the response!

**SiRbossR** · July 14th, 2012 02:30 AM

^SpeedyFix, PTT Service, or any Servitek Branches.

**onemph05** · July 14th, 2012 02:41 AM

Get the compression issue fixed and see if the catalytic converter has been replaced.

**kinyo** · July 14th, 2012 03:47 AM

check timing advance mechanisn ... this is not routinely checked during regular tune-up

**cramp** · July 14th, 2012 08:13 PM

Thank you very much for the responses guys!

So would it be a good 1st step, get a major tune up to diagnose fuel system, timing advance mechanism and catalytic converter?

Next, get a top overhaul?

How much would you think the total cost of the top overhaul and the catalytic converter replacement?

Thanks again guys!

**sirkosero** · July 14th, 2012 11:16 PM

do u know the compression per cylinder? baka off ka lang sa timing

**batangtalyer** · July 15th, 2012 07:12 AM

ndi ako makakapag recomend sayo kase maraming magagaling talaga. pero eto yung procedure na kadalasan ginagawa namin jan.
basic mechanical condition vs. manufacturers specification. data scanning, code reading and sensor or circuit integrity test. tapos yung gas analysis ( emission output.) yan yung basic data na kinukuha namin bago kami mag start ng tuning. sa mga shop na may engine analyzer alam po nila yan sir. sa usok pa lang nalalaman na kung ano ang posible na problema nyan.