Greetings!

my car misbehaves lately, when I give it some gas it looses power for a split second before starting to accelerate. When driving it makes unpleasant 'jerk' in the drivetrain, pretty annoying...

When car idles, if I stay on top of the engine and pull the throttle cable - loss of power is accompanied by a vacuum 'hiss'... then engine revs.

Tried to disconnect vacuum line from distributor - no difference(yet vacuum is delivered to distributor when I pull throttle cable as expected). Checked timing with strobe - about 18deg as expected.

I replaced spark plugs yesterday(not because I thought it will fix the problem), they were on 'white color' side, like engine is running lean.

I suspect the problem started after I took car for tune-up to reduce slightly elevated CO level.


Any ideas where I should look for the problem?

Thank you.

 

You need to find the source of the vacuum leak first.

 

Thank you. Will look for it(if there is one). The hissing sound seems to come 'from inside' , but I will try....

 

A hose is a good diagnostic tool. Put it to your ear and it allows you to locate noises in a noisy engine bay.

 

I had the car for a while now and replaced few parts, but problem is still there. Here is some more info about it, maybe someone will spot the offending unit now.

To start with I have idle problem, when car is cold it is high. I can bring it down using air bypass screw but when car is hot - it drop so much that car stalls. It also floats (like the car is alive) all of a sudden it shoots up. Can someone refer to the proper procedure of setting idle? I've heard there is an adjustment on ECU for idle - is that true?

Another problem: when car is hot and I accelerate - car is kinda 'coughing and sneezing' for period of few moments to few seconds and then it picks up. Once it picks-up it runs pretty smooth. When I first start it(cold) it runs fine.

I replaced TPS - no change (well, there is a change, throttle is a bit smoother, but not to this behavior).

Wanted to replace oxygen sensor, but could not find it. Manual I have said it should have one, but it's not there. I have AKM 9063 manual, I guess I need 'earlier' version. I believe earlier cars did not have oxygen sensors.

I am planning to replace coolant temperature sensor next, as it seem very important as if I unplug it - car dies ( in contrast if I unplug air temp sensor - no change at all).

Anyone have suggestions how to fix these problems?

Thank you.

 

I believe the I6 uses a MAF sensor, these can be fickle and cause hesitation due to dirty hot wire. To clean it remove it and use a cotton bud with alcohol (IPA not Whiskey), be gentle and clean the element.

I'm not familiar with the I6 IAC so someone else with hopefully chime in.

 

Well, today I caught my car loosing power again, this time during idle.
By disconnecting spark plugs one-by-one I found the issue - 3 cylinders (4-6) are not firing! (I have total of 6, 3.6L model) I replaced first three plugs with last three - same thing. Checked for spark - sparks are flying in back cylinders wires. Then I was disconnecting injectors and here it is - injectors 3 -6 are not injecting! What is strange is that this problem was intermittent for a while.

I doubt that all 3 injectors stick together by accident, it must be some common fuse or something of that sort. Anyone knows the cure? Please save me from digging-up and tracing electrical schema :-)

 

Just traced it, there is in fact 3 injectors in one circuit. Cleaning of couple connectors with 'electric contacts cleaner' did the trick! Hope it will stay that way for a while...