Kia stumbles/hesitates

POOT

MEMBER
KIA

I've a 1995 Sportage 4 x 4 2.0 single overhead cam, a 5 speed, with 116k miles. I drove it for about 1 year when it started hesitating. To date I've replaced the fuel pump, checked the pickup sock in the tank (ok), changed plugs/wires/air and fuel filters, cleaned the throttle body inside and out, replaced the position sensor, replaced the mass airflow sensor, the pcv valve, and checked the egr valve which seems to be working ok and pulled a vacuum on it and the diaphram holds. I also checked the fuel pump pressure and although it's been a while and I can't recall the exact pressure, I do remember it's well within factory specs. And for what good it does, over time I've ran several bottles of Lucas injector cleaner through it. It hesitates and idles a little rough but what in the heck am I missing? Possibly a bad cam or crankshaft position sensor? The check engine bulb works but never comes on other then when I first start it as it should. Other then this issue it runs great, get's 25mpg, and is fun to drive!

3 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Did you clean the intake valves at all?

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Friday, August 24th, 2007 AT 6:32 PM

POOT

MEMBER
2 POSTS

Thanks for the response but I forgot to add this info.
When I bought it @ 109k miles it had jumped time so the resulting damage was a broken piston, broken off valve, and a torn up head. Luckly the cylinder wasn't hurt so after a good honing, new piston/rings, and a brand new (not reman) head, it was running and now has 116k. When I got it running there was no hesitation until around 114k then it started. So to answer your question, it only had 5k on a brand new new head when this started however over a period of a month I ran three cans of seafoam injector cleaner through it which would also clean the valves but it made no difference. Oh, when this started I also checked the valves and clearance was good. So, in all I've checked the valves clearance, replaced the fuel filter, fuel pump, plugs/wires/air filter, replaced throttle position and maf sensor, three cans of seafoam injector cleaner, checked manifold vacuum which is good/no leaks, cleaned throttle body. And I'm out of ideas yet it still stumbles/hesitates.

Quote="Service Writer"]Did you clean the intake valves at all?

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Friday, August 24th, 2007 AT 8:47 PM

SERVICE WRITER

MECHANIC
9,123 POSTS

This is where we need to go regardless of what was replaced. There are new parts that are defective so we shouldn't assume they are good. I would start with vacuum check. Here is the list to start with:

There was a recall campaign for the cat. Converters. Typically with a recall for emision or saftey, it will go beyond the normal warranty period. IT was regarding internal deterioration. May be worth a call to the dealer.
You can disconnect the exhaust to check for restrictions.

Measure the vacuum at the manifold it should be more than 17.7 Hg

Check the MAF voltage.
At idle it should be 1.8 to 1.2V and
at increased idle it should be 3.5 to 4.0V

Re-check the fuel pressure for spec.

With engine speed at Idle (750-850 rpm) and pressure gauge connected between fuel inlet hose and fuel filter, is should be at 34 psi. With the vacuum hose disconnected at pressure regulator is should jump to 42 psi.

IF all of the above checks out good, then you'll need to go to checking the in voltage at the ecm.

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Saturday, August 25th, 2007 AT 4:31 AM